# Nitrogen, Phosphorus, and Potassium Adsorption and Desorption Improvement and Soil Buffering Capacity Using Clinoptilolite Zeolite

^{1}

^{2}

^{3}

^{4}

^{5}

^{*}

## Abstract

**:**

## 1. Introduction

_{4}

^{+}retention in soils, adsorption improves N use efficiency of crops in addition to preventing leaching of NH

_{4}

^{+}and nitrate (NO

_{3}

^{−}) to contaminate water bodies which commonly causes algae bloom. The adsorption of K

^{+}using clinoptilolite zeolite (CZ) is similar to NH

_{4}

^{+}. Thus, the technology for extracting K

^{+}from seawater using CZ as an adsorbent has been adopted into industrial operation [5]. However, for anion such as phosphate (PO

_{4}

^{3−}), surfactant-modified zeolites could be used to remove P anionic through adsorption. Reports from several studies suggest that surfactant-modified zeolite adsorbs anions such as NO

_{3}

^{−}, sulphate (SO

_{4}

^{2}), chromate (CrO

_{4}

^{2−}), and hydrogen arsenate (HAsO

_{4}

^{2−}) [6], CrO

_{4}

^{2−}[7,8], and HAsO

_{4}

^{2−}[9].

_{4}

^{+}and K

^{+}) selection ability [19,20]. The selective nutrient adsorption nature of zeolites also ensures timely release of adsorbed nutrients (for example, NH

_{4}

^{+}and K

^{+}) in a manner is that in synchrony crop needs to guarantee nutrient use efficiency in sustainable farming systems [21,22,23]. The cation exchange property of zeolites have been exploited to sorb NH

_{4}

^{+}and K

^{+}from aqueous solution in addition to using the pores of aluminosilicate groups in zeolites to adsorb cations. In terms of soil P and soil acidity management, capitalizing on the CEC and pH of CZ might not only reverse P fixation but it will also increase soils pH. Based on these rationales, our premonition is that amending acid soils with CZ will improve soil pH resilience, N, P, and K availability besides minimizing P fixation by Al and Fe.

_{4}

^{+}and K

^{+}, can complement to chemical fertilization and liming programs, the literature is not replete with data on how acid soils could be amended with CZ to significantly improve N, P, and K availability. To this end, this present study addressed the following research questions: (i) Is it possible to use CZ to amend acid soils’ to significantly improve retention of N, P, and K in addition to improving soil pH resilience and, (ii) what is the optimum rate of CZ that improve acid soils’ N, P, and K availability and buffering capacity? To answer the afore-stated research questions, the objectives of this study were to determine the effects of amending Bekenu Series (Typic Paleudults) with CZ on adsorption and desorption of N, P, and K, soil pH, and soil pH buffering capacity. Studies on nutrients adsorption such as N, P, and K and soil pH buffering capacity using CZ as soil amendment are essential in determining soil response to N, P, and K additions and the capacity to buffer the net inputs of acid. The implications of including CZ as a soil amendment is an attempt to delay nutrients migration out of farms. With our intervention, fertilizer applications following using CZ at optimum amount, leaching loss of nutrients such as N, P, and K could be prevented. This study also provides information on the mechanism of N, P, and K adsorb and desorb reflected by the different sorption isotherms and the capacity of Bekenu Series (Typic Paleudults) to buffer the changes in pH from acidity input.

## 2. Materials and Methods

#### 2.1. Soil Sampling, Preparation, and Selected Physico-Chemical Analyses

_{4}

^{+}and available NO

_{3}

^{−}after which the concentrations of these ions were determined using steam distillation. The selected physical and chemical properties of the soil (Bekenu Series, Typic Paleudults) that was used in the adsorption and desorption studies are comparable to those reported by Paramananthan [28] except for CEC, sand, silt, and clay contents. The selected chemical properties of the soil are summarized in Table 1.

#### 2.2. Clinoptilolite Zeolite Characterization

#### 2.3. Determination of Nitrogen, Phosphorus, and Potassium Adsorption and Desorption

^{−1}) N solutions prepared. These concentrations were prepared by dissolving ammonium chloride (NH

_{4}Cl) in 0.2 M NaCl. Afterwards, a 20 mL of the isonormal N solution was added to the centrifuge bottles to obtain 0, 500, 1000, 2000, 3000, and 4000 µg of added N sample

^{−1}. The isonormal solution was used to preserve constant ionic strength in the mixtures (adsorbent and solution). Additionally, the isonormal solution was used to provide competing ions for exchange sites [31]. To de-activate micro-organisms activity, two drops of toluene were added to the samples [32] after which they were equilibrated for 24 h at 180 rpm on an orbital shaker, centrifuged at 10,000 rpm for 15 min, and N determined [30]. Nitrogen adsorbed per gram soil (µg g

^{−1}soil) was calculated as the difference between the initial amount of N added and the amount in the equilibrium solution. After N adsorption, the samples were washed using ethanol followed by centrifugation at 10,000 rpm for 15 min [30] to discard the ethanol. Thereafter, a 20 mL of 2 M KCl was added, equilibrated for 24 h at 180 rpm on an orbital shaker followed by centrifugation at 10,000 rpm for 15 min. Afterwards, the desorbed N in the supernatant was determined [30].

^{−1}were prepared by dissolving potassium dihydrogen phosphate (KH

_{2}PO

_{4}) in a 0.01 M CaCl

_{2}solution, after which a 25 mL of the isonormal P solutions were added to the centrifuge bottles to obtain 0, 652, 1250, 2500, 3750, and 5000 µg of added P sample

^{−1}. Following centrifugation at 10,000 rpm for 15 min, P in the supernatant was determined [26]. For the amount of P desorbed, the centrifuged samples were used where a 20 mL of 0.01 M CaCl

_{2}was added to the samples and equilibrated for 24 h at 180 rpm on an orbital shaker, centrifuged at 10,000 rpm for 15 min, and the P in the supernatants was determined [26] as desorbed P.

^{−1}were prepared by dissolving potassium chloride (KCl) in 0.01 M CaCl

_{2}solution after which, a 20 mL of the isonormal K solution was added to the centrifuge bottles to give 0, 500, 1000, 2000, 3000, and 4000 µg of added K sample

^{−1}, centrifuged at 10,000 rpm for 15 min after which the K in the supernatants were determined using atomic absorption spectrophotometery (AAS). For the amount of K desorbed, the centrifuged samples were used where a 20 mL of 0.01 M CaCl

_{2}was added to the samples and equilibrated for 24 h at 180 rpm on an orbital shaker, centrifuged at 10,000 rpm for 15 min, and the K in the supernatants determined using AAS as desorbed K.

#### 2.4. Nitrogen, Phosphorus, and Potassium Adsorption Isotherms

#### 2.5. Soil pH Buffering Capacity Determination

^{+}kg

^{−1}samples suspended in water. A 1:2.5 sample:water (w:v) ratio was used for soil alone, CZ, CZ1, CZ2, and CZ3. During the titration, 10 g of soil, CZ, CZ1, CZ2, and CZ3 were weighed into 100 mL plastic vials followed by adding 25 mL distilled water. Then, 1 mL 0.05 M CaCl

_{2}was added to the samples to minimize variations in ionic strength followed by adding 0.2 mL toluene to impede microbial activity [35]. Afterwards, the samples were equilibrated for 15 min at 180 rpm on an orbital shaker for seven days at 25 °C [35,36,37] after which a digital pH meter (SevenEasy pH, Mettler-Toledo GmbH, Switzerland) was used to determine the pH of the samples. For the samples, whose initial pH were less than 5.5, a 0.1 M NaOH was added using Eppendorf pipette to reduce suspension effect [34]. A 0.1 M HCl was used for the samples whose initial pH were greater six or were slightly acidic to basic. For all of the samples, 1, 2, 3, 4, 6, 8, and 10 mL of 0.1 M HCl or 0.1 M NaOH were used. The suspensions were stirred using a glass rod for 10 s following addition of 0.1 M HCl or 0.1 M NaOH. Thereafter, the pH of the suspensions were determined using a digital pH meter. The amount of mmol H

^{+}needed to change pH by one unit was calculated as the negative reciprocal of the slope of the linear regression based on sample pH (Y-axis) and addition rate of mmol H

^{+}kg

^{−1}sample (X-axis):

#### 2.6. Experimental Design and Statistical Analysis

^{2}). These statistical tests were carried out using the Statistical Analysis System version 9.2 [38]. The N, P, and K adsorption isotherm equations were subjected to Chi-square analysis to obtain best-fit isotherm. The isotherm model with the smallest chi-square value was deemed the best best-fit isotherm. The stated formula was used for the Chi-square value calculation:

_{e}is the equilibrium capacity from the experimental data and q

_{e,m}is the equilibrium capacity obtained by calculation from model.

## 3. Results

#### 3.1. Nutrient Concentrations in Equilibrated Samples

#### 3.2. Adsorption Isotherm of Nitrogen, Phosphorus, and Potassium

#### 3.3. Nitrogen, Phosphorus, and Potassium Adsorption Isotherms

^{2}and lower χ

^{2}value (Table 13). This is unlike those with Langmuir (type 4) and Temkin adsorption equations (Table 13). High antilog (intercept) K

_{F}values (N adsorption) were observed in CZ alone, CZ1, CZ2, and CZ3 compared with soil alone (Table 14).

^{2}and lower χ

^{2}values (Table 15) and this is in contrast to those of Freundlich and Temkin (Table 16). The treatment without CZ (Soil only) demonstrated the highest bonding energy constant (K

_{L}) for P adsorption (Table 17).

^{2}value (Table 18 and Table 19). Potassium adsorption data for soil only and CZ alone best fitted best with Freundlich due to the significant R

^{2}and lower χ

^{2}values (Table 19). Langmuir bonding energy constant (KL), maximum adsorption capacity (qm), and maximum buffering capacity (MBC) of K adsorption were determined from Langmuir type 2 equations for CZ1, CZ2, and CZ3 (Table 20).

#### 3.4. Nitrogen, Phosphorus, and Potassium Desorbed by Soil Only, Clinoptilolite Zeolite Only, and Soil with Different Amounts of Clinoptilolite Zeolite

#### 3.5. pH Buffering Capacity of Clinoptilolite Zeolite

^{+}related negatively (Figure 2). The pH and pH buffering capacity of the soil without clinoptilolite zeolite were lower because of the lower organic matter content and CEC of the soil (Table 22).

## 4. Discussion

#### 4.1. Nitrogen, Phosphorus, and Potassium in Equilibrium Solution

_{4}

^{+}, K, (Table 4 and Table 6), and available P (Table 5). The decreasing rate of N or P or K remaining in the equilibrium solution with increasing amount of the CZ suggests that the use of increased the adsorption of these nutrients. However, the increasing or similar rate of P or K remaining in the equilibrium solution with increasing amount of the CZ suggests that the addition of the CZ in Typic Paleudults did not maximize adsorption of these nutrients (Table 7). In contrast to the use of natural zeolite as an ammonia adsorbent and N carrier, adsorption capacity of natural zeolite increases with the initial NH

_{4}

^{+}solution concentration [39]. Different type of zeolites affect adsorption capacity differently. For example, zeolite prepared from raw fly which has a slow adsorption capacity for NH

_{4}

^{+}, and its application is in fields with high concentration wastewater is limited [40]. In this present study, the different amounts of CZ used for N, P, and K adsorption affected the N, P, and K in equilibrium solutions and this observation is consistent with the findings of Tang et al. [40] who also reported that adsorption equilibrium between adsorbent and adsorbate is controlled by the adsorbent dosage.

#### 4.2. Nitrogen, Phosphorus, and Potassium Adsorption Isotherms

_{4}

^{+}and K

^{+}) and lower anion (phosphate) adsorption rates of the treatments with CZ was because of the negative charges of the CZ but the opposite was true for P which might have been repelled [41]. The increasing rates of CZ (CZ1 < CZ2 < CZ3) increased cations (NH

_{4}

^{+}and K

^{+}) adsorption (Table 8 and Table 10) because of the higher CEC of the CZ. However, the CZ (CZ1 < CZ2 < CZ3) treatments reduced P adsorption because of the negative-negative charge coulumbic repulsive forces [42].

_{4}

^{+}and K

^{+}(Table 11).

_{F}values of CZ alone, CZ1, CZ2, and CZ3 compared with soil alone suggests that the CZ has higher N adsorption capacity because of its higher CEC (Table 13 and Table 14). In addition, the 1/n > 1, regardless of treatment suggests that the N adsorption is not a favorable adsorption reaction [33]. Langmuir P adsorption isotherm for soil only, CZ only, CZ1, CZ2, and CZ3 (Table 15, Table 16 and Table 17) suggests that P was adsorbed by formation of a monolayer on the outermost surface of the adsorbent [10,11]. Irrespective of treatment, the highest bonding energy constant (K

_{L}) for P adsorption of soil only (Table 17) was due to precipitation of P by exchangeable Al

^{3+}[41] because highly weathered tropical soils have anion exchange capacity to adsorb anions such as phosphates [42]. In addition, CZ alone, CZ1, CZ2, and CZ3 showed lower K

_{L}compared with soil alone (Table 17) because of the high CEC of the CZ and this means the negative charges of the afore-stated amendment might have repelled phosphates [41].

_{m}requires less P saturation maximum mass adsorbed at saturation conditions per mass unit of adsorbent is referred to as maximum adsorption capacity (q

_{m}) [44]. Therefore, the higher maximum adsorption capacity (q

_{m}) of CZ only relative to soil only (Table 17) suggests that CZ only needs less P for adsorbent saturation because the negatively charged exchange sites of the CZ only repelled P. Similarly, q

_{m}of CZ1, CZ2, and CZ3 compared with soil alone shows that the CZ treatments (CZ1, CZ2, and CZ3) required similar P to saturate the adsorbent. The lower q

_{m}of soil, CZ1, CZ2, and CZ3 compared with CZ alone was because of the lower P content in the soil. Maximum buffering capacity (MBC) of P is the level at which adsorbent replenishes P to sample solution because being inclined depletion [45] and this lend to support or add credence the reason why soil only significantly release P relative to CZ alone, CZ1, CZ2, and CZ3 (Table 17).

_{L}compared with those with higher rate (CZ2 and CZ3) because of the lower K content of the CZ but higher CEC (Table 18, Table 19 and Table 20). The affinity of the CZ was higher at the higher rate of CZ. Increasing rate of CZ (CZ1 < CZ2 < CZ3) increased q

_{m}because lower amount of K was required to saturate the adsorbent. This was possible because of the inherent or native K of the CZ compared with soil alone. The increasing rate of CZ (CZ1 < CZ2 < CZ3) increased MBC because of the higher CEC of the CZ. The higher K

_{F}value of CZ only compared with soil only was due to the high CEC of the CZ (Table 20). The 1/n < 1 for soil only and 1/n ≈ 1 for CZ only suggest favorable K adsorption (Table 20). The high N or P or K desorption rates of the CZ suggest they can temporary retain these nutrients although the CEC of the CZ is high. The lower K desorption rate (Table 21) but higher K adsorption capacity of CZ only (Table 20) compared with soil only suggests that sorption of K by CZ was more to absorption.

#### 4.3. Nitrogen, Phosphorus, and Potassium Desorption

_{4}

^{+}compared with K

^{+}[46]. The increasing rate of the CZ (CZ1 < CZ2 < CZ3) reduced P and K desorption rate. The reduction in P desorption rate with the increasing CZ rate is consistent with the reduced maximum buffering capacity (Table 17) where, adsorbed P were not readily replenished during P depletion in the soil following the application of CZ. Hence, CZ can be used to reduce P leaching. The increasing maximum buffering capacity (Table 20) with decreasing K desorption rate upon increasing CZ application suggests that K was more to absorption compared with adsorption, hence, the lower desorption. Absorption of K is further supported by the fact that the CZ demonstrated higher affinity for K

^{+}compared with other cations [47].

#### 4.4. Clinoptilolite Zeolite and Bekenu Series Soil Buffering Capacity

^{−1}pH

^{−1}) [34]. pH buffering capacity of the CZ only was higher than that of soil only due to the high CEC of the CZ. The increasing rate of the CZ (CZ1 < CZ2 < CZ3) increased soil pH and pH buffering capacity because of the high pH and pH buffering capacity of the CZ (Figure 2 and Table 22). The pH buffering capacity soil only and the soil with different amounts of CZ were within the standard range of 10 to 100 mmol H

^{+}kg

^{−1}pH

^{−1}[33].

## 5. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Abbreviations

_{4}

^{+}-ammonium; NO

_{3}

^{−}-nitrate; C-carbon; EC-electrical conductivity; ANOVA-analysis of variance; CRD- completely randomized design; Fe-Iron, Al-aluminium; nd-not determine, NA-not applicable; KCl-potassium chloride; CaCl-calcium chloride.

## References

- Daković, A.; Tomašević-Čanović, M.; Rottinghaus, E.G.; Matijašević, S.; Sekulić, Z. Fumonisin B1 adsorption to octadecyldimetylbenzyl ammonium-modified clinoptilolite-rich zeolitic tuff. Microporous Mesoporous Mater.
**2007**, 105, 285–290. [Google Scholar] [CrossRef] - Latifah, O.; Ahmed, O.H.; Majid, N.M.A. Enhancing nitrogen availability from urea using clinoptilolite zeolite. Geoderma
**2017**, 306, 152–159. [Google Scholar] [CrossRef] - Ashman, M.R.; Puri, G. Essential Soil Science: A Clear and Concise Introduction to Soil Science; Blackwell Science Ltd.: England, UK, 2002. [Google Scholar]
- Latifah, O.; Ahmed, O.H.; Majid, N.M.A. Enhancing nitrogen availability, ammonium adsorption-desorption, and soil pH buffering capacity using composted paddy husk. Eurasian Soil Sci.
**2017**, 50, 1–11. [Google Scholar] [CrossRef] - Jin, N.; Meng, C.X.; Hou, J. Preparation and characterization of merlinoite for potassium extraction from seawater. J. India Eng. Chem.
**2014**, 20, 1227–1230. [Google Scholar] [CrossRef] - Li, Z.; Anghel, I.; Bowman, R. Sorption of oxyanions by surfactant-modified zeolite. J. Dispers. Sci. Techol.
**1998**, 19, 843–857. [Google Scholar] [CrossRef] - Haggerty, G.M.; Bowman, R.S. Sorption of chromate and other inorganic anions by organo zeolite. Environ. Sci. Techol.
**1994**, 28, 452–458. [Google Scholar] [CrossRef] [PubMed] - Li, Z. Influence of solution pH and ionic strength on chromate uptake by surfactant-modified zeolite. J. Environ. Eng.
**2004**, 130, 205–208. [Google Scholar] [CrossRef] - Li, Z.; Beachner, R.; McManama, Z.; Hanlie, H. Sorption of arsenic by surfactant-modified zeolite and kaolinite. Microporous Mesoporous Mater.
**2007**, 105, 291–297. [Google Scholar] [CrossRef] - Okeola, F.O.; Odebunmi, E.O. Freundlich and Langmuir Isotherms parameters for adsorption of methylene blue by activated carbon derived from agro wastes. Adv. Nat. Appl. Sci.
**2010**, 4, 281–288. [Google Scholar] - Dada, A.; Olalekan, A.; Olatunya, A.; Dada, O. Langmuir, Freundlich, Temkin and Dubinin—Radushkevich isotherms studies of equilibrium sorption of Zn
^{2+}unto phosphoric acid modified rice husk. J. Appl. Chem.**2012**, 3, 38–45. [Google Scholar] - Dada, A.O.; Ojediran, J.O.; Olalekan, A.P. Sorption of Pb
^{2+}from aqueous solution unto modified rice husk: Isotherms studies. Adv. Phys. Chem.**2013**, 2013, 1–6. [Google Scholar] [CrossRef] [Green Version] - Foo, K.Y.; Hameed, B.H. Insights into the modeling of adsorption isotherm systems. Chem. Eng. J.
**2010**, 156, 2–10. [Google Scholar] [CrossRef] - Obiri-Nyarko, F.; Kwiatkowska-Malina, J.; Malina, G.; Kasela, T. Removal of lead and benzene from groundwater by zeolite and brown coal: Isotherm and kinetic studies. In Proceedings of the 4th International Conference on Environmental Pollution and Remediation, Prague, Czech Republic, 11–13 August 2014; pp. 1–7. [Google Scholar]
- Ahmed, M.F.; Kennedy, I.R.; Choudhury, T.M.; Kecskes, M.L.; Deaker, R. Phosphorus adsorption in some Australian soils and influence of bacteria on the desorption of phosphorus. Commun. Soil Sci. Plant Anal.
**2008**, 39, 1269–1294. [Google Scholar] [CrossRef] - Bloom, A.J.; Frensch, J.; Taylor, A.R. Influence of inorganic nitrogen and pH on the elongation of maize seminal roots. Ann. Bot.
**2006**, 97, 867–873. [Google Scholar] [CrossRef] [PubMed] [Green Version] - Jusop, S.; Ishak, C.F. Weathered Tropical Soils the Ultisols and Oxisols; Universiti Putra Malaysia Press: Serdang, Malaysia, 2010. [Google Scholar]
- Ahmed, O.H.; Husni, A.; Ahmad, H.N.M.; Jalloh, M.B.; Rahim, A.A.; Majid, N.M.A. Enhancing the urea-N use efficiency in maize (Zea mays) cultivation on acid soils using urea amended with zeolite and TSP. Am. J. Appl. Sci.
**2009**, 6, 829–833. [Google Scholar] [CrossRef] [Green Version] - Peres-Caballero, R.; Gil, J.; Gondalez, J.L. The effect of adding zeolite to soils in order to improve the N-K nutrition of olive trees. Am. J. Aric. Biol. Sci.
**2008**, 2, 321–324. [Google Scholar] - Inglezakis, V.J.; Loizidou, M.D.; Grigoropoulou, H.P. Equilibrium and kinetic ion exchange studies of Pb
^{2+}, Cr^{3+}, Fe^{3+}, and Cu^{2+}on natural clinoptilolite. Water Res.**2002**, 36, 2784–2792. [Google Scholar] [CrossRef] - Gruener, J.E.; Ming, D.W.; Henderson, K.E.; Galindo, C. Common ion effects in zeoponic substrates: Wheat plant growth experiment. Microporous Mesoporous Mater.
**2003**, 61, 223–230. [Google Scholar] [CrossRef] - McGilloway, R.L.; Weaver, R.W.; Ming, D.W.; Gruener, J.E. Nitrification in a Zeoponic substrate. Plant Soil
**2003**, 256, 371–378. [Google Scholar] [CrossRef] [PubMed] - Rehakova, M.S.; Cuvanova, M.; Dzivak, J.; Gaval’ovác, J. Agricultural and agrochemical uses of natural zeolite of the clinoptilolite type. Curr. Opin. Solid State Mater. Sci.
**2004**, 8, 397–404. [Google Scholar] [CrossRef] - Palanivell, P.; Ahmed, O.H.; Latifah, O.; Majid, N.M.A. Adsorption and desorption of nitrogen, phosphorus, potassium, and soil buffering capacity following application of chicken litter biochar to an acid soil. Appl. Sci.
**2020**, 10, 295. [Google Scholar] [CrossRef] [Green Version] - Tan, K.H. Soil Sampling, Preparation, and Analysis, 2nd ed.; CRC Press: Boca Raton, FL, USA, 2005. [Google Scholar]
- Murphy, J.; Riley, R.I. A modified single solution method for the determination of phosphate in natural waters. Anal. Chim. Acta
**1962**, 27, 31–36. [Google Scholar] [CrossRef] - Keeney, D.R.; Nelson, D.W. Nitrogen-inorganic forms. In Method of Soil Analysis: Part 2; Page, A.G., Keeney, D.R., Baker, D.E., Miller, R.H., Rhoades, J.D., Eds.; Agronomy Monograph: Madison, WI, USA, 1962. [Google Scholar]
- Paramananthan, S. Soil of Malaysia: Their Characteristics and Identification, Malaysia; Academy of Sciences Malaysia: Kuala Lumpur, Malaysia, 2000; Volume 1, pp. 11–125. ISBN 9839445065.
- Bremner, J.M. Total Nitrogen. In Methods of Soil Analysis: Part 2; Black, C.A., Evans, D.D., Ensminger, L.E., White, J.L., Clark, F.F., Dinauer, R.C., Eds.; American Society of Agronomy: Madison, WI, USA, 1965; pp. 1149–1178. [Google Scholar]
- Ming, D.W.; Dixon, J.B. Clinoptilolite in South Texas soils. Soil Sci. Soc. Am. J.
**1986**, 50, 1618–1622. [Google Scholar] [CrossRef] - Kithome, M.; Paul, J.W.; Lavkulich, L.M.; Bomke, A.A. Kinetics of ammonium adsorption and desorption by the natural zeolite clinoptilolite. Soil Sci. Soc. Am. J.
**1998**, 62, 622–629. [Google Scholar] [CrossRef] - Chowdhury, S.; Misra, R.; Kushwaha, P.; Das, P. Optimum sorption isotherm by linear and nonlinear methods for safranin onto alkali-treated rice husk. Bioremediat. J.
**2011**, 15, 77–89. [Google Scholar] [CrossRef] - Salarirad, M.M.; Behnamfard, A. Modeling of equilibrium data for free cyanide adsorption onto activated carbon by linear and non-linear regression methods. In Proceedings of the 2011 International Conference on Environment and Industrial Innovation (IPCBEE), Singapore, 26–28 February 2011; Volume 12, pp. 79–84. [Google Scholar]
- Rowell, D.L. Soil Science: Methods and Applications; Longman Scientific & Technical: Essex, UK, 1994. [Google Scholar]
- Xu, R.; Zhao, A.; Yuan, J.; Jiang, J. pH buffering capacity of acid soils from tropical and subtropical regions of China as influenced by incorporation of crop straw biochars. J. Soils Sedim.
**2012**, 12, 494–502. [Google Scholar] [CrossRef] - Kissel, D.E.; Sonon, L.S.; Cabrera, M.L. Rapid measurement of soil pH buffering capacity. Soil Sci. Soc. Am. J.
**2012**, 76, 694–699. [Google Scholar] [CrossRef] - Castello, R.C.; Sullivan, D.M. Determining the pH buffering capacity of compost via titration with dilute sulphuric acid. Waste Biomass Valor
**2014**, 5, 505–513. [Google Scholar] [CrossRef] - SAS. SAS/STAT Software; SAS Institute: Cary, NY, USA, 2008. [Google Scholar]
- Jelena, M.; Susanne, E.; Tore, K.; Vesna, R.; Nevenka, R. The use in grass production of clinoptilolite as an ammonia adsorbent and a nitrogen carrier. J. Serb. Chem. Soc.
**2015**, 80, 1203–1214. [Google Scholar] - Tang, H.; Xiaoyi Xu, X.; Wang, B.; Lv, C.; Shi, D. Removal of ammonium from swine wastewater using synthesized zeolite from fly ash. Sustainability
**2020**, 12, 3423. [Google Scholar] [CrossRef] [Green Version] - Onyango, M.S.; Masukume, M.; Ochieng, A.; Otieno, F. Functionalised natural zeolite and its potential for treating drinking water containing excess amount of nitrate. Water SA
**2010**, 36, 655–662. [Google Scholar] [CrossRef] [Green Version] - Kiurski, J.; Adamovic, S.; Oros, I.; Krstic, J.; Kovacevic, I. Adsorption feasibility in the Cr (total) ions removal from waste printing developer. Global NEST J.
**2012**, 14, 18–23. [Google Scholar] - Hinsinger, P. Bioavailability of soil inorganic P in the rhizosphere as affected by root-induced chemical changes: A review. Plant Soil
**2001**, 237, 173–195. [Google Scholar] [CrossRef] - Brady, N.C.; Weil, R.R. The Nature and Properties of Soils, 14th ed.; Pearson Education: Upper Saddle River, NJ, USA, 2008. [Google Scholar]
- Ali, W.; Hussain, M.; Ali, M.; Mubushar, M.; Tabassam, A.R.M.; Mohsin, M.; Nasir, A. Evaluation of Freundlich and Langmuir isotherm for potassium adsorption phenomena. Int. J. Agric. Crop Sci.
**2013**, 6, 1048–1054. [Google Scholar] - Mehdi, S.M.; Sajjad, N.; Sarfraz, M.; Khalid, B.Y.; Hussan, G.; Sadiq, M. Response of wheat to different phosphatic fertilizer in varying textured salt affected soils. Pak. J. Appl. Sci.
**2003**, 3, 474–480. [Google Scholar] [CrossRef] - Fu, K.; Li, Z.; Xia, Q.; Zhong, T. Change and improving of ammonium exchange capacity onto zeolite in seawater. In Proceedings of the 2nd International Conference on Environmental Engineering and Applications, Shanghai, China, 19–21 August 2011; IACSIT Press: Singapore, 2011. [Google Scholar]

**Figure 2.**The linear between the added mmol H

^{+}kg

^{−1}sample and pH of suspension demonstrating R

^{2}> 0.73 at p = 0.01.

Property | Current Study | Range * (0–36 cm) |
---|---|---|

pH | 4.41 | 4.6–4.9 |

EC (µS cm^{−1}) | 53.90 | NA |

Bulk density (Mg m^{−3}) | 1.16 | NA |

Total organic carbon (%) | 1.43 | 0.57–2.51 |

Organic matter (%) | 2.47 | NA |

Total N (%) | 0.08 | 0.04–0.17 |

Exchangeable NH_{4}^{+} (mg kg^{−1}) | 21.02 | NA |

Available NO_{3}^{−} (mg kg^{−1}) | 7.01 | NA |

Available P (mg kg^{−1}) | 4.85 | NA |

---------------------------------------------------------(cmol (+) kg^{−1}) -------------------------------------------------- | ||

Cation exchange capacity | 11.97 | 3.86–8.46 |

Exchangeable K^{+} | 0.10 | 0.05–0.19 |

Exchangeable Ca^{2+} | 0.25 | NA |

Exchangeable Mg^{2+} | 0.34 | NA |

Exchangeable Na^{+} | 0.22 | NA |

Exchangeable Fe^{2+} | 0.19 | NA |

Exchangeable Cu^{2+} | Trace | NA |

Exchangeable Zn^{2+} | 0.01 | NA |

Exchangeable Mn^{2+} | 0.02 | NA |

Total titratable acidity | 0.86 | NA |

Exchangeable H^{+} | 0.22 | NA |

Exchangeable Al^{3+} | 0.64 | NA |

Sand (%) | 71.04 | 72–76 |

Silt (%) | 14.58 | 8–9 |

Clay (%) | 14.38 | 16–19 |

Texture (USDA) | Sandy loam | Sandy loam |

Property | Clinoptilolite Zeolite (%) |
---|---|

Total N | 0.22 |

Total P | 0.01 |

Total K | 0.37 |

Total Ca | 0.67 |

Total Mg | 0.10 |

Total Na | 0.76 |

Total Fe | 0.11 |

Total Zn | 15 |

Total Mn | 17 |

Total Cu | 125 |

Isotherm | Nonlinear Form | Linear Form | Plot | Variables |
---|---|---|---|---|

Langmuir−1 | ${\mathrm{q}}_{\mathrm{e}}=\frac{{\mathrm{q}}_{\mathrm{m}}{\mathrm{K}}_{\mathrm{L}}{\mathrm{C}}_{\mathrm{e}}}{{1+\mathrm{K}}_{\mathrm{L}}{\mathrm{C}}_{\mathrm{e}}}$ | $\frac{{\mathrm{C}}_{\mathrm{e}}}{{\mathrm{q}}_{\mathrm{e}}}=\frac{{\mathrm{C}}_{\mathrm{e}}}{{\mathrm{q}}_{\mathrm{m}}}+\frac{1}{{\mathrm{K}}_{\mathrm{L}}{\mathrm{q}}_{\mathrm{m}}}$ | $\frac{{\mathrm{C}}_{\mathrm{e}}}{{\mathrm{q}}_{\mathrm{e}}}{\text{}\mathrm{vs}\text{}\mathrm{C}}_{\mathrm{e}}$ | ${\mathrm{K}}_{\mathrm{L}}=\frac{\mathrm{slope}}{\mathrm{intercept}}$ ${\mathrm{q}}_{\mathrm{m}}{=\mathrm{slope}}^{-1}$ |

Langmuir−2 | $\frac{1}{{\mathrm{q}}_{\mathrm{e}}}=\left(\frac{1}{{\mathrm{K}}_{\mathrm{L}}{\mathrm{q}}_{\mathrm{m}}}\right)\frac{1}{{\mathrm{C}}_{\mathrm{e}}}+\frac{1}{{\mathrm{q}}_{\mathrm{m}}}$ | $\frac{1}{{\mathrm{q}}_{\mathrm{e}}}\text{}\mathrm{vs}\text{}\frac{1}{{\mathrm{C}}_{\mathrm{e}}}$ | ${\mathrm{K}}_{\mathrm{L}}=\frac{\mathrm{intercept}}{\mathrm{slope}}$ ${\mathrm{q}}_{\mathrm{m}}{=\mathrm{intercept}}^{-1}$ | |

Langmuir−3 | ${\mathrm{q}}_{\mathrm{e}}{=\mathrm{q}}_{\mathrm{m}}-\left(\frac{1}{{\mathrm{K}}_{\mathrm{L}}}\right)\frac{{\mathrm{q}}_{\mathrm{e}}}{{\mathrm{C}}_{\mathrm{e}}}$ | ${\mathrm{q}}_{\mathrm{e}}\text{}\mathrm{vs}\text{}\frac{{\mathrm{q}}_{\mathrm{e}}}{{\mathrm{C}}_{\mathrm{e}}}$ | ${\mathrm{K}}_{\mathrm{L}}{=-\mathrm{slope}}^{-1}$ ${\mathrm{q}}_{\mathrm{m}}=\mathrm{intercept}$ | |

Langmuir−4 | $\frac{{\mathrm{q}}_{\mathrm{e}}}{{\mathrm{C}}_{\mathrm{e}}}{=\mathrm{K}}_{\mathrm{L}}{\mathrm{q}}_{\mathrm{m}}-{\mathrm{K}}_{\mathrm{L}}{\mathrm{q}}_{\mathrm{e}}$ | $\frac{{\mathrm{q}}_{\mathrm{e}}}{{\mathrm{C}}_{\mathrm{e}}}{\text{}\mathrm{vs}\text{}\mathrm{q}}_{\mathrm{e}}$ | ${\mathrm{K}}_{\mathrm{L}}=-\mathrm{slope}$ ${\mathrm{q}}_{\mathrm{m}}=-\frac{\mathrm{intercept}}{\mathrm{slope}}$ | |

Freundlich | ${\mathrm{q}}_{\mathrm{e}}{=\mathrm{K}}_{\mathrm{F}}{\mathrm{C}}_{\mathrm{e}}^{\frac{1}{\mathrm{n}}}$ | $\mathrm{log}\left({\mathrm{q}}_{\mathrm{e}}\right)=\mathrm{log}\left({\mathrm{K}}_{\mathrm{F}}\right)+\frac{1}{\mathrm{n}}\mathrm{log}\left({\mathrm{C}}_{\mathrm{e}}\right)$ | $\mathrm{log}\left({\mathrm{q}}_{\mathrm{e}}\right)\text{}\mathrm{vs}\text{}\mathrm{log}\left({\mathrm{C}}_{\mathrm{e}}\right)$ | ${\mathrm{K}}_{\mathrm{F}}=\mathrm{antilog}\left(\mathrm{intercept}\right)$ $\frac{1}{\mathrm{n}}=\mathrm{slope}$ |

Temkin | ${\mathrm{q}}_{\mathrm{e}}{=\mathrm{B}}_{\mathrm{T}}\mathrm{ln}\left({\mathrm{K}}_{\mathrm{T}}{\mathrm{C}}_{\mathrm{e}}\right)$ | ${\mathrm{q}}_{\mathrm{e}}{=\mathrm{B}}_{\mathrm{T}}{\mathrm{ln}\text{}\mathrm{K}}_{\mathrm{T}}{+\mathrm{B}}_{\mathrm{T}}{\mathrm{ln}\text{}\mathrm{C}}_{\mathrm{e}}$ | ${\mathrm{q}}_{\mathrm{e}}{\text{}\mathrm{vs}\text{}\mathrm{lnC}}_{\mathrm{e}}$ | ${\mathrm{K}}_{\mathrm{T}}=\mathrm{exp}\left(\frac{\mathrm{intercept}}{{\mathrm{B}}_{\mathrm{T}}}\right)$ ${\mathrm{B}}_{\mathrm{T}}=\mathrm{slope}$ |

**Table 4.**Interactive effects of the different concentrations of nitrogen and treatments (Soil only, clinoptilolite zeolite only, and soil with different amounts of clinoptilolite zeolite) on nitrogen content.

Treatment | Nitrogen Left in the Equilibrated Samples (µg mL^{−1}) C_{e} | |||||
---|---|---|---|---|---|---|

0 | 500 | 1000 | 2000 | 3000 | 4000 | |

Added N (µg) | ||||||

Soil | 23.35 F a (±2.14) | 62.11 E a (±1.62) | 95.74 D a (±1.62) | 174.19 C a (±0.81) | 240.04 B a (±2.14) | 294.21 A b (±1.40) |

CZ | 6.54 F c (±0.81) | 14.94 E e (±1.62) | 28.95 D d (±1.62) | 50.44 C d (2.81) | 77.99 B e (±2.14) | 107.88 A e (±1.40) |

CZ1 | 24.75 F a (±1.62) | 49.51 E b (0.81) | 84.06 D b (±1.40) | 139.17 C b (±1.62) | 212.02 B b (±1.62) | 298.41 A a (±1.40) |

CZ2 | 19.15 F b (±1.62) | 44.36 E c (±2.14) | 70.98 D c (±0.81) | 135.43 C b (±0.81) | 205.48 B c (±0.81) | 270.86 A c (±1.62) |

CZ3 | 16.34 F b (±0.81) | 40.16 E d (±0.81) | 71.45 D c (±1.40) | 126.56 C c (±0.81) | 177.46 B d (±1.62) | 248.45 A d (±0.81) |

**Table 5.**Interactive effects of the different concentrations of phosphorus and treatments (Soil only, clinoptilolite zeolite only, clinoptilolite zeolite only, and soil with different amounts of clinoptilolite zeolite) on phosphorus content.

Treatment | Phosphorus Left in the Equilibrated Samples (µg mL^{−1}) C_{e} | |||||
---|---|---|---|---|---|---|

0 | 675 | 1250 | 2500 | 3750 | 5000 | |

Added P (µg) | ||||||

Soil | 0.06 F a (±0.03) | 16.76 E c (±1.26) | 55.10 D c (±1.34) | 147.46 C b (±1.13) | 236.17 B b (±2.86) | 333.38 A b (±6.22) |

CZ | 0.02 F b (±0.00) | 41.03 E a (±0.95) | 89.00 D a (±2.87) | 174.29 C a (±2.24) | 269.67 B a (±5.27) | 365.13 A a (±7.45) |

CZ1 | 0.02 F b (±0.01) | 18.50 E bc (±0.25) | 58.32 D bc (±1.55) | 148.69 C b (±1.48) | 239.13 B b (±5.00) | 334.88 A b (±4.71) |

CZ2 | 0.04 F ab (±0.01) | 18.95 E b (±0.30) | 58.59 D bc (±1.80) | 147.88 C b (±1.80) | 243.75 B b (±1.96) | 339.80 A b (±1.51) |

CZ3 | 0.02 F b (±0.00) | 19.87 E b (±0.73) | 60.81 D b (±1.41) | 151.29 C b (±1.99) | 242.29 B b (±1.48) | 341.04 A b (±2.15) |

**Table 6.**Interactive effects of the different potassium concentrations and treatments (Soil only, clinoptilolite zeolite only, and soil with different amounts of clinoptilolite zeolite) on potassium content.

Treatment | Potassium Left in the Equilibrated Samples (µg mL^{−1}) C_{e} | |||||
---|---|---|---|---|---|---|

0 | 500 | 1000 | 2000 | 3000 | 4000 | |

Added K (µg) | ||||||

Soil | 3.92 F a (±0.08) | 45.37 E a (±0.31) | 85.80 D a (±1.23) | 109.20 C a (±0.30) | 268.87 B a (±1.33) | 362.80 A a (±2.09) |

CZ | 3.14 F b (±0.08) | 4.80 E e (±0.10) | 6.67 D e (±0.08) | 8.53 C e (±0.18) | 20.47 B e (±0.25) | 29.10 A e (±0.17) |

CZ1 | 3.30 F b (±0.23) | 18.70 E b (±0.30) | 40.80 D b (±0.89) | 57.83 C b (±0.38) | 179.07 B b (±1.10) | 262.47 A b (±1.33) |

CZ2 | 3.12 F b (±0.08) | 12.67 E c (±0.15) | 26.87 D c (±0.38) | 37.00 C c (±0.17) | 133.67 B c (±0.31) | 193.53 A c (±1.53) |

CZ3 | 3.15 F b (±0.10) | 10.00 E d (±0.10) | 20.73 D d (±0.15) | 26.97 C d (±0.38) | 101.60 B d (±0.53) | 149.93 A d (±0.76) |

**Table 7.**Linear relationships between the added amounts nitrogen, phosphorus, and potassium and their contents in the equilibrated samples.

Treatment | Regression Equation | R^{2} Value |
---|---|---|

------------------------------------------- N -------------------------------------- | ||

Soil | y = 28.128 + 0.067x | 0.9954 ** |

CZ | y = 3.435 + 0.025x | 0.9941 ** |

CZ1 | y = 16.314 + 0.068x | 0.9906 ** |

CZ2 | y = 12.681 + 0.064x | 0.9973 ** |

CZ3 | y = 13.183 + 0.057x | 0.9965 ** |

-------------------------------------------- P ------------------------------------- | ||

Soil | y = −19.377 + 0.069x | 0.9902 ** |

CZ | y = −3.877 + 0.073x | 0.9993 ** |

CZ1 | y = −18.033 + 0.069x | 0.9917 ** |

CZ2 | y = −18.798 + 0.070x | 0.9910 ** |

CZ3 | y = −17.605 + 0.070x | 0.9921 ** |

-------------------------------------------- K ------------------------------------- | ||

Soil | y = -9.004 + 0.089x | 0.9456 ** |

CZ | y = 0.811 + 0.006x | 0.9079 ** |

CZ1 | y = −19.646 + 0.065x | 0.9105 ** |

CZ2 | y = −16.243 + 0.048x | 0.8916 ** |

CZ3 | y = −12.414 + 0.037x | 0.8817 ** |

**Table 8.**Interactive effects of the different nitrogen concentrations and treatments (Soil only, clinoptilolite zeolite only, and soil with different amounts of clinoptilolite zeolite) on the amounts of nitrogen adsorbed.

Treatment | Adsorbed N (µg g^{−1}) q_{e} | ||||
---|---|---|---|---|---|

500 | 1000 | 2000 | 3000 | 4000 | |

Added N (µg) | |||||

Soil | 112.39 E c (±16.18) | 276.15 D d (±16.18) | 491.59 C d (±8.09) | 833.12 B d (±21.40) | 1291.40 A d (±14.01) |

CZ | 415.96 E a (±16.18) | 775.86 D a (±16.18) | 1561.04 C a (±28.02) | 2285.51 B a (±21.40) | 2986.63 A a (±14.01) |

CZ1 | 252.48 E b (±8.09) | 406.90 D c (±14.01) | 855.84 C bc (±16.18) | 1127.32 B c (±16.18) | 1263.37 A d (±14.01) |

CZ2 | 247.85 E b (±21.40) | 481.66 D b (±8.09) | 837.20 C c (±8.09) | 1136.70 B c (±8.09) | 1482.90 A c (±16.18) |

CZ3 | 261.88 E b (±8.09) | 448.99 D b (±14.01) | 897.93 C b (±8.09) | 1388.90 B b (±16.18) | 1679.06 A b (±8.09) |

**Table 9.**Interactive effects of the different phosphorus concentrations and treatments (Soil only, clinoptilolite zeolite only, and soil with different amounts of clinoptilolite zeolite) on the amounts of phosphorus adsorbed.

Treatment | Adsorbed Phosphorus (µg g^{−1}) q_{e} | ||||
---|---|---|---|---|---|

625 | 1250 | 2500 | 3750 | 5000 | |

Added P (µg) | |||||

Soil | 416.31 C a (±15.79) | 562.00 B a (±16.81) | 675.52 B a (±14.18) | 798.68 A a (±35.78) | 833.56 A a (±77.75) |

CZ | 112.40 B c (±11.86) | 137.75 B c (±35.86) | 321.61 A b (±27.96) | 379.42 A b (±65.85) | 436.19 A b (±93.08) |

CZ1 | 394.00 D ab (±3.15) | 521.22 C ab (±19.42) | 641.66 B a (±18.47) | 761.19 A a (±62.56) | 814.32 A a (±58.94) |

CZ2 | 388.63 D b (±3.79) | 518.14 C ab (±22.47) | 652.06 B a (±22.49) | 703.63 AB a (±24.56) | 753.10 A a (±18.84) |

CZ3 | 376.92 D b (±9.03) | 490.11 C b (±17.54) | 609.10 B a (±24.83) | 721.60 A a (±18.51) | 737.23 A a (±26.90) |

**Table 10.**Interactive effects of the different potassium concentrations and treatments (Soil only, clinoptilolite zeolite only, and soil with different amounts of clinoptilolite zeolite) on the amounts of potassium adsorbed.

Treatment | Adsorbed Potassium (µg g^{−1}) q_{e} | ||||
---|---|---|---|---|---|

500 | 1000 | 2000 | 3000 | 4000 | |

Added K (µg) | |||||

Soil | 85.53 E e (±3.06) | 181.20 D e (±12.29) | 947.20 A e (±3.00) | 350.53 C e (±13.32) | 411.20 B e (±20.88) |

CZ | 483.30 E a (±1.00) | 964.63 D a (±0.76) | 1945.97 C a (±1.76) | 2826.63 B a (±2.52) | 3740.30 A a (±1.73) |

CZ1 | 346.00 E d (±3.00) | 625.00 D d (±8.89) | 1454.67 A d (±3.79) | 1242.33 C d (±11.02) | 1408.33 B d (±13.32) |

CZ2 | 404.53 E c (±1.53) | 762.53 D c (±3.79) | 1661.20 C c (±1.73) | 1694.53 B c (±3.06) | 2095.87 A c (±15.28) |

CZ3 | 431.50 E b (±1.00) | 824.17 D b (±1.53) | 1761.83 C b (±3.79) | 2015.50 B b (±2.59) | 2532.17 A b (±7.57) |

**Table 11.**Linear relationships between the added nitrogen, phosphorus, and potassium concentrations and the amounts of nitrogen, phosphorus, and potassium adsorbed.

Treatment | Regression Equation | R^{2} Value |
---|---|---|

------------------------------------------------------------- N -------------------------------------------------- | ||

Soil | y = -83.035 + 0.326x | 0.9746 ** |

CZ | y = 53.933 + 0.739x | 0.9994 ** |

CZ1 | y = 146.621 + 0.302x | 0.9507 ** |

CZ2 | y = 112.365 + 0.345x | 0.9954 ** |

CZ3 | y = 54.958 + 0.419x | 0.9915 ** |

------------------------------------------------------------- P -------------------------------------------------- | ||

Soil | y = 409.661 + 0.093x | 0.9154 ** |

CZ | y = 70.878 + 0.079x | 0.9219 ** |

CZ1 | y = 379.546 + 0.094x | 0.9397 ** |

CZ2 | y = 396.420 + 0.079x | 0.8676 ** |

CZ3 | y = 370.058 + 0.083x | 0.8987 ** |

------------------------------------------------------------ K -------------------------------------------------- | ||

Soil | y = 224.575 + 0.081x | 0.1726 ^{ns} |

CZ | y = 40.336 + 0.929x | 0.9994 ** |

CZ1 | y = 398.747 + 0.294x | 0.6096 ^{ns} |

CZ2 | y = 336.429 + 0.470x | 0.8704 * |

CZ3 | y = 270.473 + 0.592x | 0.9438 ** |

**Table 12.**Fitting Langmuir type 1, 2, and 3 isotherms to the nitrogen adsorption data based on simple regression and Chi-square analyses results.

Treatment | Regression Equation | R^{2} | χ^{2} |
---|---|---|---|

--------------------------------------------Langmuir−1--------------------------------------------------- | |||

Soil | y = 0.101 − 0.0002x | 0.7476 * | 2.71 × 10^{−3} |

CZ | y = 0.016 − 0.00001x | −0.0357 ^{ns} | 1.82 × 10^{−4} |

CZ1 | y = 0.062 − 0.00003x | −0.0035 ^{ns} | 2.45 × 10^{−3} |

CZ2 | y = 0.054 − 0.00002x | −0.0349 ^{ns} | 1.39 × 10^{−3} |

CZ3 | y = 0.052 − 0.00005x | 0.5247 ^{ns} | 7.89 × 10^{−4} |

--------------------------------------------Langmuir−2--------------------------------------------------- | |||

Soil | y = –0.00023 + 0.111x | 0.9720 ** | 4.17 × 10^{−5} |

CZ | y = –0.00002 + 0.017x | 0.9980 ** | 3.90 × 10^{−5} |

CZ1 | y = –0.00009 + 0.069x | 0.9903 ** | 2.55 × 10^{−5} |

CZ2 | y = –0.00007 + 0.060x | 0.9782 ** | 2.66 × 10^{−5} |

CZ3 | y = –0.00007 + 0.055x | 0.9980 ** | 6.75 × 10^{−6} |

**Table 13.**Fitting Langmuir type 4, Freundlich, and Temkin isotherms to the nitrogen adsorption data based on simple regression and Chi-square analyses results.

Treatment | Regression Equation | R^{2} | χ^{2} |
---|---|---|---|

-------------------------------------------------Langmuir−4----------------------------------------------- | |||

Soil | y = 10.154 + 0.0015x | 0.8848 * | 0.273 |

CZ | y = 62.131 + 0.0008x | −0.0013 ^{ns} | 0.761 |

CZ1 | y = 16.109 + 0.0006x | 0.0704 ^{ns} | 0.696 |

CZ2 | y = 18.565 + 0.0004x | −0.0224 ^{ns} | 0.457 |

CZ3 | y = 19.107 + 0.0009x | 0.5794 ^{ns} | 0.291 |

-------------------------------------------------Freundlich------------------------------------------------ | |||

Soil | y = 0.414 + 1.337x | 0.9932 ** | 9.45 × 10^{−4} |

CZ | y = 1.734 + 1.048x | 0.9953 ** | 5.14 × 10^{−4} |

CZ1 | y = 1.019 + 1.109x | 0.9832 ** | 1.77 × 10^{−3} |

CZ2 | y = 1.141 + 1.074x | 0.9896 ** | 1.22 × 10^{−3} |

CZ3 | y = 1.072 + 1.131x | 0.9957 ** | 4.54 × 10^{−4} |

---------------------------------------------------Temkin-------------------------------------------------- | |||

Soil | y = −11411 + 2820.63x | 0.8989 ** | 870.84 |

CZ | y = −7985 + 3071.78x | 0.9302 ** | 1356.40 |

CZ1 | y = −9620 + 2569.88x | 0.9665 ** | 393.00 |

CZ2 | y = −9153 + 2530.55x | 0.9508 ** | 330.51 |

CZ3 | y = −9765 + 2723.95x | 0.9320 ** | 951.02 |

--------------------------------------------Langmuir−3--------------------------------------------------- | |||

Soil | y = −5825.393 + 596.686x | 0.8848 * | 5726 |

CZ | y = −16184.00 + 305.264x | −0.0013 ^{ns} | 5224 |

CZ1 | y = −5783.607 + 483.720x | 0.0704 ^{ns} | 3549 |

CZ2 | y = −7957.093 + 549.928x | −0.0224 ^{ns} | 3586 |

CZ3 | y = −13020.00 + 731.534x | 0.5794 ^{ns} | 1418 |

**Table 14.**Adsorption capacity (KF) and adsorption isotherm constant of Freundlich in relation to adsorption condition (1/n) for nitrogen adsorption.

Treatment | Freundlich | |
---|---|---|

K_{F}(µg g ^{−1}) | $\frac{1}{\mathit{n}}$ | |

Soil | 2.594 | 1.337 |

CZ | 54.200 | 1.048 |

CZ1 | 10.447 | 1.109 |

CZ2 | 13.836 | 1.074 |

CZ3 | 11.803 | 1.131 |

**Table 15.**Fitting Langmuir type 1, 2, and 3 isotherms to the phosphorus adsorption data based on simple regression and Chi-square analyses results.

Treatment | Regression Equation | R^{2} | χ^{2} |
---|---|---|---|

---------------------------------------------------Langmuir−1------------------------------------------- | |||

Soil | y = 0.021 + 0.0001x | 0.8371 * | 4.30 × 10^{−3} |

CZ | y = 0.058 + 0.00003x | 0.5481 ^{ns} | 4.51 × 10^{−4} |

CZ1 | y = 0.023 + 0.0001x | 0.8315 * | 3.90 × 10^{−3} |

CZ2 | y = 0.023 + 0.0001x | 0.8553 * | 3.46 × 10^{−3} |

CZ3 | y = 0.025 + 0.0001x | 0.8347 * | 3.64 × 10^{−3} |

---------------------------------------------------Langmuir−2------------------------------------------- | |||

Soil | y = 0.0002 + 0.013x | 0.9362 ** | 5.63 × 10^{−5} |

CZ | y = 0.0001 + 0.054x | 0.9939 ** | 7.49 × 10^{−6} |

CZ1 | y = 0.0002 + 0.015x | 0.9410 ** | 5.36 × 10^{−5} |

CZ2 | y = 0.0002 + 0.016x | 0.9467 ** | 4.81 × 10^{−5} |

CZ3 | y = 0.0002 + 0.017x | 0.9447 ** | 5.09 × 10^{−5} |

---------------------------------------------------Langmuir−3------------------------------------------- | |||

Soil | y = 5948.693 − 87.142x | 0.5825 ^{ns} | 1685 |

CZ1 | y = 6219.856 − 103.925x | 0.5878 ^{ns} | 1729 |

CZ2 | y = 6257.001 − 108.028x | 0.6224 ^{ns} | 1668 |

CZ3 | y = 6364.248 − 116.858x | 0.5996 ^{ns} | 1750 |

**Table 16.**Fitting Langmuir type 4, Freundlich, and Temkin isotherms to the phosphorus adsorption data based on simple regression and Chi-square analyses results.

Treatment | Regression Equation | R^{2} | χ^{2} |
---|---|---|---|

---------------------------------------------------Langmuir−4------------------------------------------- | |||

Soil | y = 56.484 − 0.008x | 0.5825 ^{ns} | 14.057 |

CZ | y = 17.418 − 0.0005x | 0.4944 ^{ns} | 0.131 |

CZ1 | y = 50.176 − 0.007x | 0.5878 ^{ns} | 10.155 |

CZ2 | y = 49.458 − 0.007x | 0.6224 ^{ns} | 9.032 |

CZ3 | y = 46.207 − 0.006x | 0.5996 ^{ns} | 7.974 |

----------------------------------------------------Freundlich------------------------------------------- | |||

Soil | y = 2.289 + 0.574x | 0.9868 ** | 1.07 × 10^{−3} |

CZ | y = 1.360 + 0.927x | 0.9975 ** | 2.97 × 10^{−4} |

CZ1 | y = 2.221 + 0.600x | 0.9882 ** | 9.97 × 10^{−4} |

CZ2 | y = 2.216 + 0.600x | 0.9914 ** | 7.18 × 10^{−4} |

CZ3 | y = 2.176 + 0.615x | 0.9894 ** | 9.09 × 10^{−4} |

-----------------------------------------------------Temkin---------------------------------------------- | |||

Soil | y = −3779.082 + 1527.953x | 0.8630 * | 853 |

CZ | y = −7605.247 + 2113.290x | 0.9059 ** | 1266 |

CZ1 | y = −4122.104 + 1583.930x | 0.8666 * | 885 |

CZ2 | y = −4112.305 + 1572.963x | 0.8777 * | 794 |

CZ3 | y = −4304.231 + 1603.415x | 0.8724 * | 871 |

**Table 17.**Results from Langmuir and Freundlich isotherms for phosphorus adsorption by soil only, clinoptilolite zeolite only, and different amounts of clinoptilolite zeolite.

Treatment | Langmuir | Freundlich | |||
---|---|---|---|---|---|

K_{L}(µg g ^{−1}) | q_{m} | MBC (µg g ^{−1}) | K_{F}(µg g ^{−1}) | $\frac{1}{\mathit{n}}$ | |

Soil | 0.015 | 5000 | 75 | nd | nd |

CZ | 0.002 | 10,000 | 20 | nd | nd |

CZ1 | 0.013 | 5000 | 65 | nd | nd |

CZ2 | 0.013 | 5000 | 65 | nd | nd |

CZ3 | 0.012 | 5000 | 60 | nd | nd |

**Table 18.**Fitting Langmuir type 1, 2, and 3 isotherms to the potassium adsorption data based on simple regression and Chi-square analyses results.

Treatment | Regression Equation | R^{2} | χ^{2} |
---|---|---|---|

--------------------------------------------Langmuir−1---------------------------------------------- | |||

Soil | y = 0.060 + 0.00006x | −0.1017 ^{ns} | 0.018 |

CZ | y = 0.004 − 0.000001x | −0.3330 ^{ns} | 1.06 × 10^{−3} |

CZ1 | y = 0.017 + 0.0001x | 0.8537 * | 3.34 × 10^{−3} |

CZ2 | y = 0.011 + 0.0001x | 0.8681 * | 2.28 × 10^{−3} |

CZ3 | y = 0.008 + 0.0001x | 0.8479 * | 1.84 × 10^{−3} |

--------------------------------------------Langmuir−2---------------------------------------------- | |||

Soil | y = −0.00008 + 0.078x | 0.9072 ** | 2.44 × 10^{−4} |

CZ | y = −0.00011 + 0.005x | 0.8190 * | 2.68 × 10^{−4} |

CZ1 | y = 0.00008 + 0.020x | 0.9533 ** | 6.57 × 10^{−5} |

CZ2 | y = 0.00007 + 0.013x | 0.9469 ** | 7.35 × 10^{−5} |

CZ3 | y = 0.00005 + 0.010x | 0.9349 ** | 8.74 × 10^{−5} |

--------------------------------------------Langmuir−3---------------------------------------------- | |||

Soil | y = 2765.355 − 4.025x | −0.3332 ^{ns} | 5328 |

CZ | y = 2851.258 + 3.109x | −0.3183 ^{ns} | 6845 |

CZ1 | y = 6361.361 − 104.068x | 0.2767 ^{ns} | 928 |

CZ2 | y = 6205.703 − 65.332x | 0.3004 ^{ns} | 4020 |

CZ3 | y = 6019.559 − 44.594x | 0.1712 ^{ns} | 4119 |

**Table 19.**Fitting Langmuir type 4, Freundlich, and Temkin isotherms to the potassium adsorption data based on simple regression and Chi-square analyses results.

Treatment | Regression Equation | R^{2} | χ^{2} |
---|---|---|---|

------------------------------------------------Langmuir−4------------------------------------------------- | |||

Soil | y = 16.050 − 0.00002x | −0.3332 ^{ns} | 3.687 |

CZ | y = 261.133 + 0.004x | −0.3183 ^{ns} | 105.637 |

CZ1 | y = 46.108 − 0.004x | 0.2767 ^{ns} | 9.595 |

CZ2 | y = 71.396 − 0.007x | 0.3004 ^{ns} | 17.375 |

CZ3 | y = 92.676 − 0.008x | 0.1712 ^{ns} | 28.994 |

------------------------------------------------Freundlich--------------------------------------------------- | |||

Soil | y = 1.362 + 0.911x | 0.7972 * | 0.025 |

CZ | y = 2.436 + 1.028x | 0.8367 * | 0.020 |

CZ1 | y = 2.171 + 0.664x | 0.8455 * | 0.015 |

CZ2 | y = 2.349 + 0.643x | 0.8360 * | 0.017 |

CZ3 | y = 2.423 + 0.657x | 0.8291 * | 0.018 |

------------------------------------------------Temkin------------------------------------------------------- | |||

Soil | y = −6074.48 + 1752.61x | 0.8527 * | 513.40 |

CZ | y = −4445.60 + 3557.64x | 0.9573 * | 293.35 |

CZ1 | y = −4042.13 + 1668.18x | 0.9085 * | 354.72 |

CZ2 | y = −3630.82 + 1799.48x | 0.9101 * | 399.18 |

CZ3 | y = −3522.93 + 1953.97x | 0.9130 * | 441.91 |

**Table 20.**Results from Langmuir and Freundlich isotherms for potassium adsorption by soil only and different amounts of clinoptilolite zeolite.

Treatment | Langmuir | Freundlich | |||
---|---|---|---|---|---|

K_{L}(µg g ^{−1}) | q_{m} | MBC (µg g ^{−1}) | K_{F}(µg g ^{−1}) | $\frac{1}{\mathit{n}}$ | |

Soil | nd | nd | nd | 23.01 | 0.911 |

CZ | nd | nd | nd | 272.90 | 1.028 |

CZ1 | 0.0040 | 12,500 | 50.00 | nd | nd |

CZ2 | 0.0538 | 14,286 | 768.59 | nd | nd |

CZ3 | 0.0500 | 20,000 | 1000.00 | nd | nd |

**Table 21.**Linear relationships between the added amounts nitrogen, phosphorus, and potassium and their amounts desorbed.

Treatment | Regression Equation | R^{2} Value |
---|---|---|

------------------------------------------------------------------- N ----------------------------------------- | ||

Soil | y = 9.576 + 0.0034x | 0.9758 ** |

CZ | y = 4.514 + 0.0276x | 0.9995 ** |

CZ1 | y = 13.725 + 0.0070x | 0.9781 ** |

CZ2 | y = 16.388 + 0.0093x | 0.9888 ** |

CZ3 | y = 17.402 + 0.0122x | 0.9621 ** |

------------------------------------------------------------------- P ------------------------------------------ | ||

Soil | y = 0.217 + 0.0037x | 0.9678 ** |

CZ | y = 0.964 + 0.0043x | 0.9855 ** |

CZ1 | y = −0.400 + 0.0041x | 0.9994 ** |

CZ2 | y = −0.069 + 0.0036x | 0.9987 ** |

CZ3 | y = −0.187 + 0.0038x | 0.9964 ** |

------------------------------------------------------------------- K ----------------------------------------- | ||

Soil | y = 4.100 + 0.0045x | 0.9559 ** |

CZ | y = 2.457 + 0.0014x | 0.9333 ** |

CZ1 | y = 3.691 + 0.0043x | 0.9719 ** |

CZ2 | y = 2.633 + 0.0039x | 0.9536 ** |

CZ3 | y = 2.943 + 0.0031x | 0.9506 ** |

**Table 22.**Effects of soil only, clinoptilolite zeolite only, and soil with different amounts of clinoptilolite zeolite on the initial suspension pH and pH buffering capacity.

Treatment | Initial pH | pH Buffering Capacity (mmol H^{+} kg^{−1} pH^{−1} Sample) |
---|---|---|

Soil | 4.52 (±0.02) | 17.86 |

CZ | 7.87 (±0.03) | 27.03 |

CZ1 | 4.80 (±0.04) | 18.18 |

CZ2 | 4.96 (±0.04) | 18.52 |

CZ3 | 5.14 (±0.02) | 18.52 |

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Palanivell, P.; Ahmed, O.H.; Omar, L.; Abdul Majid, N.M.
Nitrogen, Phosphorus, and Potassium Adsorption and Desorption Improvement and Soil Buffering Capacity Using Clinoptilolite Zeolite. *Agronomy* **2021**, *11*, 379.
https://doi.org/10.3390/agronomy11020379

**AMA Style**

Palanivell P, Ahmed OH, Omar L, Abdul Majid NM.
Nitrogen, Phosphorus, and Potassium Adsorption and Desorption Improvement and Soil Buffering Capacity Using Clinoptilolite Zeolite. *Agronomy*. 2021; 11(2):379.
https://doi.org/10.3390/agronomy11020379

**Chicago/Turabian Style**

Palanivell, Perumal, Osumanu Haruna Ahmed, Latifah Omar, and Nik Muhamad Abdul Majid.
2021. "Nitrogen, Phosphorus, and Potassium Adsorption and Desorption Improvement and Soil Buffering Capacity Using Clinoptilolite Zeolite" *Agronomy* 11, no. 2: 379.
https://doi.org/10.3390/agronomy11020379