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Innovative Adsorbents for Water Treatment

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 15664

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Prof. Dr. Oualid Hamdaoui

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Chemical Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia
Interests: hydrogen energy; energy storage and management; solar energy and its application; process modeling and simulation, advanced oxidation processes (AOPs); ultrasound and sonochemistry
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Dear Colleagues,

Adsorption is one of the preferred separation processes for the removal of contaminants from water and wastewater, and for the control of chemical and biochemical oxygen demands, because of its simplicity of design, ease of operation, efficiency, flexibility, insensitivity to toxic substances, and ease of adaptation at industrial scale. Additionally, adsorption processes are performed at low temperatures, and are therefore less-energy-intensive and relatively cost-effective techniques. Conventional adsorbents are not always popular because they are not economically viable or technically efficient. In recent years, innovative adsorbents with a high efficiency have been prepared and synthesized for this purpose in order to overcome several shortcomings of classical adsorbent materials.

The present Special Issue aims to gather a panoply of recent innovations in adsorbent materials preparation, synthesis, characterization and application in water and wastewater treatment. Papers dealing with all aspects of adsorption processes, from fundamental view point to industrial scale facets, are welcome. Works highlighting aspects of advanced adsorption processes, hybrid adsorption techniques, desorption and regeneration of adsorbents are highly encouraged.

Prof. Dr. Oualid Hamdaoui
Guest Editor

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Keywords

water treatment
adsorption
innovative adsorbents
advanced adsorption processes
hybrid adsorption processes
desorption
regeneration of adsorbents

Published Papers (11 papers)

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Research

15 pages, 2917 KiB

Open AccessArticle

Production of Activated Carbon from Sifted Coke and Determination of Its Physicochemical Characteristics

by Aigul T. Ordabaeva, Zainulla M. Muldakhmetov, Arstan M. Gazaliev, Sergey V. Kim, Zhazira S. Shaikenova and Mazhit G. Meiramov

Molecules 2023, 28(15), 5661; https://doi.org/10.3390/molecules28155661 - 26 Jul 2023

Cited by 3 | Viewed by 898

Abstract

The possibility of obtaining effective coal sorbents from a low-liquid product of coke chemical production—coke fines—has been studied. To obtain a coal sorbent, coke fines with a size of ≤10 mm were crushed and sieved to obtain a fraction of 2–5 mm. The resulting fraction was activated in a specially designed reactor at 850 °C with steam treatment. Activation was carried out at different durations of the process: 60, 90, and 120 min. It was found that the sample obtained with a process duration of 120 min has the best indicator for the ability to remove phenol from aqueous solutions (74.94 mg/g) and methylene blue (145 mg/g). When cleaning tap water with the resulting carbon sorbent, there is a decrease in the content of calcium, sulfates, and bicarbonate and a decrease in total mineralization. Obtained activated carbon was studied by scanning electron microscopy, low-temperature nitrogen adsorption (BET), and FTIR spectroscopy. It was found that the resulting activated carbon has a porous structure consisting of meso- and macropores, and the specific surface value was ~301 m²/g. The presence of high-intensity absorption bands corresponding to acid functional groups has also been established. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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23 pages, 4392 KiB

Open AccessArticle

Biosorption of Triphenyl Methane Dyes (Malachite Green and Crystal Violet) from Aqueous Media by Alfa (Stipa tenacissima L.) Leaf Powder

by Lamia Ouettar, El-Khamssa Guechi, Oualid Hamdaoui, Nadia Fertikh, Fethi Saoudi and Abudulaziz Alghyamah

Molecules 2023, 28(8), 3313; https://doi.org/10.3390/molecules28083313 - 08 Apr 2023

Cited by 5 | Viewed by 1857

Abstract

This study includes the characterization and exploitation of an abundant agricultural waste in Algeria, Alfa (Stipa tenacissima L.) leaf powder (ALP) as a biosorbent for the removal of hazardous triphenylmethane dyes, malachite green (basic green 4) and crystal violet (basic violet 3), from aqueous media under various operating conditions in batch mode. The effect of experimental parameters such as initial dye concentration (10–40 mg/L), contact time (0–300 min), biosorbent dose (2.5–5.5 g/L), initial pH (2–8), temperature (298–328 K), and ionic strength on dye sorption was investigated. The results of both dyes show that the increase in initial concentration, contact time, temperature, and initial pH of solution leads to an increase in biosorbed quantity, unlike the effect of ionic strength. The biosorption kinetics for triphenylmethane dyes on ALP was analyzed by pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models proposed by the Weber–Morris equation. Equilibrium sorption data were analyzed by six isotherms, namely the Langmuir, Freundlich, Harkins–Jura, Flory–Huggins, Elovich, and Kiselev isotherms. The thermodynamic parameters were evaluated for both dyes. The thermodynamic results suggest that both dyes’ biosorption is a typical physical process, spontaneous and endothermic in nature. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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17 pages, 4879 KiB

Open AccessFeature PaperArticle

New Carbamoyl Surface-Modified ZrO₂ Nanohybrids for Selective Au Extraction from E-Waste

by Sarah Asaad, Marwa Hamandi, Guilhem Arrachart, Stéphane Pellet-Rostaing, Serge Kimbel and Stéphane Daniele

Molecules 2023, 28(5), 2219; https://doi.org/10.3390/molecules28052219 - 27 Feb 2023

Cited by 2 | Viewed by 1151

Abstract

Efficient and selective extractions of precious and critical metal ions such as Au(III) and Pd(II) were investigated using zirconia nanoparticles surface modified with different organic mono- and di-carbamoyl phosphonic acid ligands. The modification is made on the surface of commercial ZrO₂ that is dispersed in aqueous suspension and was achieved by optimizing the Bronsted acid–base reaction in ethanol/H₂O solution (1:2), resulting in inorganic–organic systems of ZrO₂-Lⁿ (Lⁿ: organic carbamoyl phosphonic acid ligand). The presence, binding, amount, and stability of the organic ligand on the surface of zirconia nanoparticles were confirmed by different characterizations such as TGA, BET, ATR-FTIR, and ³¹P-NMR. Characterizations showed that all the prepared modified zirconia had a similar specific surface area (50 m².g⁻¹) and the same amount of ligand on the zirconia surface in a 1:50 molar ratio. ATR-FTIR and ³¹P-NMR data were used to elucidate the most favorable binding mode. Batch adsorption results showed that (i) ZrO₂ surface modified with di-carbamoyl phosphonic acid ligands had the highest adsorption efficiency to extract metals than mono-carbamoyl ligands, and (ii) higher hydrophobicity of the ligand led to better adsorption efficiency. The surface-modified ZrO₂ with di-N,N-butyl carbamoyl pentyl phosphonic acid ligand (ZrO₂-L⁶) showed promising stability, efficiency, and reusability in industrial applications for selective gold recovery. In terms of thermodynamic and kinetic adsorption data, ZrO₂-L⁶ fits the Langmuir adsorption model and pseudo-second-order kinetic model for the adsorption of Au(III) with maximum experimental adsorption capacity q_max = 6.4 mg.g⁻¹. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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14 pages, 3230 KiB

Open AccessArticle

Removal of Methylene Blue from Water Using Magnetic GTL-Derived Biosolids: Study of Adsorption Isotherms and Kinetic Models

by Shifa Zuhara, Snigdhendubala Pradhan, Yahya Zakaria, Akshath Raghu Shetty and Gordon McKay

Molecules 2023, 28(3), 1511; https://doi.org/10.3390/molecules28031511 - 03 Feb 2023

Cited by 2 | Viewed by 1452

Abstract

Global waste production is significantly rising with the increase in population. Efforts are being made to utilize waste in meaningful ways and increase its economic value. This research makes one such effort by utilizing gas-to-liquid (GTL)-derived biosolids, a significant waste produced from the wastewater treatment process. To understand the surface properties, the biosolid waste (BS) that is activated directly using potassium carbonate, labelled as KBS, has been characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), and Brunauer–Emmett–Teller (BET). The characterization shows that the surface area of BS increased from 0.010 to 156 m²/g upon activation. The EDS and XPS results show an increase in the metal content after activation (especially iron); additionally, XRD revealed the presence of magnetite and potassium iron oxide upon activation. Furthermore, the magnetic field was recorded to be 0.1 mT using a tesla meter. The magnetic properties present in the activated carbon show potential for pollutant removal. Adsorption studies of methylene blue using KBS show a maximum adsorption capacity of 59.27 mg/g; the adsorption process is rapid and reaches equilibrium after 9 h. Modelling using seven different isotherm and kinetic models reveals the best fit for the Langmuir-Freundlich and Diffusion-chemisorptionmodels, respectively. Additional thermodynamic calculations conclude the adsorption system to be exothermic, spontaneous, and favoring physisorption. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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16 pages, 3961 KiB

Open AccessArticle

Efficient Lead Pb(II) Removal with Chemically Modified Nostoc commune Biomass

by Carmencita Lavado-Meza, Leonel De la Cruz-Cerrón, Carmen Lavado-Puente, Julio Angeles-Suazo and Juan Z. Dávalos-Prado

Molecules 2023, 28(1), 268; https://doi.org/10.3390/molecules28010268 - 28 Dec 2022

Cited by 7 | Viewed by 1847

Abstract

A new biosorbent based on Nostoc commune (NC) cyanobacteria, chemically modified with NaOH (NCM), has been prepared, characterized and tested as an effective biomass to remove Pb(II) in aqueous media. The adsorption capacity of NCM was determined to be q_e = 384.6 mg g⁻¹. It is higher than several other biosorbents reported in the literature. Structural and morphological characterization were performed by FTIR, SEM/EDX and point zero of charge pH (pH_PZC) measurements. NCM biosorbent showed more porous surfaces than those NC with heterogeneous plates including functional adsorption groups such as OH, C = O, COO⁻, COH or NH. Optimal Pb(II) adsorption occurred at pH 4.5 and 5.5 with a biomass dose of 0.5 g L⁻¹. The experimental data of the adsorption process were well fitted with the Freundlich-isotherm model and pseudo-2nd order kinetics, which indicated that Pb(II) adsorption was a chemisorption process on heterogeneous surfaces of NCM. According to the thermodynamic parameters, this process was exothermic (∆H⁰ < 0), feasible and spontaneous (∆G⁰ < 0). NCM can be regenerated and efficiently reused up to 4 times (%D > 92%). NCM was also tested to remove Pb (%R~98%) and Ca (%R~64%) from real wastewater. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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14 pages, 1133 KiB

Open AccessEditor’s ChoiceArticle

Possibility of New Active Substrates (ASs) to Be Used to Prevent the Migration of Heavy Metals to the Soil and Water Environments

by Katarzyna Witt, Waldemar Studziński and Daria Bożejewicz

Molecules 2023, 28(1), 94; https://doi.org/10.3390/molecules28010094 - 22 Dec 2022

Viewed by 1196

Abstract

This paper aims to propose an alternative to the known permeable reactive barriers (PRBs). PRB is one of the methods, which is a reactive barrier placed below the ground, to clean up contaminated groundwater. New polymer active substrates (ASs) were used to prevent soil contamination by toxic heavy metals. The active substrates consisted of a mixture of poly(vinyl chloride), Aliquat 336, and bis(2-ethylhexyl)adipate, which was applied to the skeleton material (fiberglass or textile). Aliquat 336 was used as a binding agent for metal ions (Cr(VI), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II)). In contrast with the PRBs, the ASs (from AS-1 to AS-5) were obtained in a simple way using the pouring method. The obtained ASs could be recycled and reused. The active substrates were used for the binding of various metal ions from aqueous solutions and the examined soil. It was found that the active substrate AS-1 decreased the concentrations of nickel, cadmium, and lead by more than 50% and that of chromium by more than 90% in the aqueous solution. High sorption efficiency for chromium and zinc metals (81% and 66%) with the use of AS-2 was also found, owing to which the migration of metals from soil to water can be limited. In the soil environment, active substrate AS-5 with the addition of a plasticizer showed the greatest effectiveness. This solution resulted in a reduction in each tested metal ion of at least 50%, and reductions in cadmium, lead, and copper of over 70%. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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11 pages, 3961 KiB

Open AccessArticle

Egg White-Mediated Fabrication of Mg/Al-LDH-Hard Biochar Composite for Phosphate Adsorption

by Xiaolong Ma, Shuqi Li, He Ren, Yin Zhang and Zichuan Ma

Molecules 2022, 27(24), 8951; https://doi.org/10.3390/molecules27248951 - 15 Dec 2022

Cited by 5 | Viewed by 1305

Abstract

Phosphorus is one of the main causes of water eutrophication. Hard biochar is considered a promising phosphate adsorbent, but its application is limited by its textural properties and low adsorption capacity. Here, an adhesion approach in a mixed suspension containing egg white is proposed for preparing the hybrid material of Mg/Al-layered double hydroxide (LDH) and almond shell biochar (ASB), named L-A_E or L-A (with or without egg white). Several techniques, including XRD, SEM/EDS, FTIR and N₂ adsorption/desorption, were used to characterize the structure and adsorption behavior of the modified adsorbents. The filament-like material contained nitrogen elements at a noticed level, indicating that egg white was the crosslinker that mediated the formation of the L-A_E hybrid material. The L-A_E had a higher phosphate adsorption rate with a higher equilibrium adsorption capacity than the L-A. The saturation phosphate adsorption capacity of L-A_E was nearly three times higher than that of L-A. Furthermore, the number of surface groups and the density of the positively charged surface sites follow the ASB < L-A < L-A_E order, which is consistent with their phosphate adsorption performance. The study may offer an efficient approach to improving hard biochar’s adsorption performance in wastewater treatment. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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19 pages, 5291 KiB

Open AccessArticle

Integrated Adsorption–Photodegradation of Organic Pollutants by Carbon Xerogel/Titania Composites

by Anam Safri, Ashleigh Jane Fletcher, Ramsha Safri and Hifza Rasheed

Molecules 2022, 27(23), 8483; https://doi.org/10.3390/molecules27238483 - 02 Dec 2022

Cited by 3 | Viewed by 1243

Abstract

Recent studies on the removal of pollutants via adsorption include the use of carbon-based adsorbents, due to their high porosity and large surface area; however, such materials lack photoactive properties. This study evaluates the synergistic effect of integrated mesoporous carbon xerogel (derived from resorcinol formaldehyde) and titanium dioxide (TiO₂) for combined adsorption and photodegradation application. The complex formed between carbon xerogel and TiO₂ phase was investigated through FTIR, proving the presence of a Ti-O–C chemical linkage. The physicochemical properties of the synthesised adsorbent–photocatalyst were probed using FESEM, BET analysis and UV–Vis analysis. The kinetics, equilibrium adsorption, effect of pH, and effect of adsorbent dosage were investigated. The expansion of the absorbance range to the visible range was verified, and the corresponding band gap evaluated. These properties enabled a visible light response when the system was exposed to visible light post adsorption. Hence, an assistive adsorption–photodegradation phenomenon was successfully executed. The adsorption performance exhibited 85% dye degradation which improved to 99% following photodegradation. Further experiments showed the reduction of microorganisms under visible light, where no microbial colonies were observed after treatment, indicating the potential application of these composite materials. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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19 pages, 1535 KiB

Open AccessArticle

Natural Zeolite for The Purification of Saline Groundwater and Irrigation Potential Analysis

by Timoth Mkilima, Davud Devrishov, Kydyrbekova Assel, Nurbala Ubaidulayeva, Almas Tleukulov, Alissa Khassenova, Nargiza Yussupova and Dinara Birimzhanova

Molecules 2022, 27(22), 7729; https://doi.org/10.3390/molecules27227729 - 10 Nov 2022

Cited by 3 | Viewed by 1550

Abstract

Groundwater is one of the main sources of water for irrigation used worldwide. However, the application of the resource is threatened by the possibility of high saline levels, especially in low-lying coastal regions. Furthermore, the lack of readily accessible materials for successful treatment procedures makes the purification of such water a constant challenge. Based on the fact that natural zeolite is one of the easily accessible and relatively cheap filter materials, this study examined the potential use of high-salinity groundwater filtered by natural zeolite for irrigation. Zeolite-filled filters at two different depths (0.5 m and 1 m) were studied. The samples were collected from the low-lying areas of Dar es Salaam City, Tanzania. The study observed that when the raw groundwater samples were exposed to the 0.5 m column depth, sodium (Na⁺) had the lowest removal efficiency at 40.2% and calcium (Ca²⁺) had the highest removal efficiency at 98.9%. On the other hand, magnesium (Mg²⁺) had the lowest removal efficiency, at about 61.2%, whereas potassium (K⁺) had up to about 99.7% removal efficiency from the 1 m column depth treatment system. Additionally, from the salinity hazard potential analysis, most of the samples fell within C4 (based on the electrical conductivity), which is a “very high salinity” class, and based on the quality it means the water cannot be directly applied for irrigation purposes. From the 0.5 m column depth, most of the samples fell within C3 (the “high salinity” class), and from the 1 m column depth most of the samples fell within C1 (“low salinity” class). The findings of this study offer some valuable insight into the prospective use of natural zeolite for the filtration of saline groundwater before its application for irrigation. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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16 pages, 2669 KiB

Open AccessArticle

Simultaneous Removal of Polymers with Different Ionic Character from Their Mixed Solutions Using Herb-Based Biochars and Activated Carbons

by Marlena Gęca, Małgorzata Wiśniewska and Piotr Nowicki

Molecules 2022, 27(21), 7557; https://doi.org/10.3390/molecules27217557 - 04 Nov 2022

Cited by 8 | Viewed by 1064

Abstract

Nettle and the sage herbs were used to obtain carbonaceous adsorbents. For the biochar preparation the precursors were dried and subjected to conventional pyrolysis. Activated carbons were obtained during precursor impregnation with phosphoric(V) acid and multistep pyrolysis. The textural parameters and acidic-basic properties of the obtained adsorbents were studied. The activated carbons prepared from the above herbs were characterized by the largely developed specific surface area. The obtained carbonaceous adsorbents were used for polymer removal from aqueous solution. Poly(acrylic acid) (PAA) and polyethylenimine (PEI) were chosen, due to their frequent presence in wastewater resulting from their extensive usage in many industrial fields. The influence of polymers on the electrokinetic properties of activated carbon were considered. PAA adsorption caused a decrease in the zeta potential and the surface charge density, whereas PEI increased these values. The activated carbons and biochars were used as polymer adsorbents from their single and binary solutions. Both polymers showed the greatest adsorption at pH 3. Poly (acrylic acid) had no significant effect on the polyethylenimine adsorbed amount, whereas PEI presence decreased the amount of PAA adsorption. Both polymers could be successfully desorbed from the activated carbons and biochar surfaces. The presented studies are innovatory and greatly required for the development of new environment protection procedures. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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10 pages, 1272 KiB

Open AccessArticle

Biomass Novel Adsorbents for Phenol and Mercury Removal

by Joao Manuel Valente Nabais, Carlos Eduardo Laguinhas and Silvia Román

Molecules 2022, 27(21), 7345; https://doi.org/10.3390/molecules27217345 - 28 Oct 2022

Cited by 1 | Viewed by 1150

Abstract

This paper reports the use of activated carbons made from novel agriculture and industrial wastes, namely sunflower, vine shoots, and coffee endocarp, to remove two high-priority contaminants: phenol and mercury species (under different forms) from aqueous solutions. The activated carbons were used as prepared and also modified with nitric acid and triethylenediamine in order to explore additional adsorption mechanisms. The results showed an interesting potential of the materials to be used for water decontamination as indicated by the mercury uptake up to 1104 mg/g for Hg²⁺, 771 mg/g for [HgCl₄]²⁻, 966 mg/g for HgCl₂ and the maximum phenol adsorption capacity of 190 mg/g. The modification with triethylenediamine led to a significant increase in the phenol and mercury adsorption reaching an increment of 85% for phenol and 250% for Hg²⁺. Full article

(This article belongs to the Special Issue Innovative Adsorbents for Water Treatment)

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