Removal of Hazardous Substances from Water Resources

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Materials materials	3.1	5.8	2008	13.9 Days	CHF 2600
Minerals minerals	2.2	4.1	2011	18 Days	CHF 2400
Processes processes	2.8	5.1	2013	14.9 Days	CHF 2400
Sustainability sustainability	3.3	6.8	2009	19.7 Days	CHF 2400
Toxics toxics	3.9	4.5	2013	18.3 Days	CHF 2600
Water water	3.0	5.8	2009	17.5 Days	CHF 2600

15 pages, 3367 KiB

Open AccessArticle

Structural Analysis and Adsorption Studies of (PbO, MgO) Metal Oxide Nanocomposites for Efficient Methylene Blue Dye Removal from Water

by Saloua Helali, Mohamed Rashad, Anouar Ben Mabrouk, Munirah A. A. Alanazi and Manahil S. Mustafa

Materials 2024, 17(12), 2890; https://doi.org/10.3390/ma17122890 - 13 Jun 2024

Cited by 5 | Viewed by 1463

Abstract

In the present work, magnesium oxide (MgO) and lead oxide (PbO) nanoparticles were prepared by the co-precipitation method. Their structural parameters and morphology were investigated using XRD, HRTEM, and FTIR. The formation of the phases was seen to have small average crystallite sizes [...] Read more.

In the present work, magnesium oxide (MgO) and lead oxide (PbO) nanoparticles were prepared by the co-precipitation method. Their structural parameters and morphology were investigated using XRD, HRTEM, and FTIR. The formation of the phases was seen to have small average crystallite sizes and an orthorhombic crystal structure for both MgO and PbO nanoparticles. The results of HR-TEM showed irregularly shaped nanoparticles: quasi-spherical or rod-like shapes and spherical-like shapes for MgO and PbO nanoparticles, respectively. The produced nanoparticles’ size using X-ray diffraction analysis was found to be 17 nm and 41 nm for MgO and PbO nanoparticles, respectively. On the other hand, it was observed from the calculations that the optical band gap obeys an indirect allowed transition. The calculated values of the band gap were 4.52 and 4.28 eV for MgO and PbO NPs, respectively. The MB was extracted from the wastewater using the prepared composites via absorption. Using a variety of kinetic models, the adsorptions were examined. Out of all the particles, it was discovered that the composites were best. Furthermore, of the models currently under consideration, the pseudo-second-order model best fit the degradation mechanism. The resultant composites could be beneficial for degrading specific organic dyes for water purification, as well as applications needing a wider optical band gap. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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16 pages, 4096 KiB

Open AccessArticle

Biotransformation of Chlorpyrifos Shewanella oneidensis MR-1 in the Presence of Goethite: Experimental Optimization and Degradation Products

by Shen Tang, Yanhong Li, Zongqiang Zhu, Yaru Wang, Yuqing Peng, Jing Zhang, Peijie Nong, Shufen Pan, Yinming Fan and Yinian Zhu

Toxics 2024, 12(6), 402; https://doi.org/10.3390/toxics12060402 - 31 May 2024

Cited by 1 | Viewed by 980

Abstract

In this study, the degradation system of Shewanella oneidensis MR-1 and goethite was constructed with chlorpyrifos as the target contaminant. The effects of initial pH, contaminant concentration, and temperature on the removal rate of chlorpyrifos during the degradation process were investigated. The experimental [...] Read more.

In this study, the degradation system of Shewanella oneidensis MR-1 and goethite was constructed with chlorpyrifos as the target contaminant. The effects of initial pH, contaminant concentration, and temperature on the removal rate of chlorpyrifos during the degradation process were investigated. The experimental conditions were optimized by response surface methodology with a Box–Behnken design (BBD). The results show that the removal rate of chlorpyrifos is 75.71% at pH = 6.86, an initial concentration of 19.18 mg·L⁻¹, and a temperature of 30.71 °C. LC-MS/MS analyses showed that the degradation products were C₄H₁₁O₃PS, C₇H₇Cl₃NO₄P, C₉H₁₁Cl₂NO₃PS, C₇H₇Cl₃NO₃PS, C₉H₁₁Cl₃NO₄P, C₄H₁₁O₂PS, and C₅H₂Cl₃NO. Presumably, the degradation pathways involved are: enzymatic degradation, hydrolysis, dealkylation, desulfur hydrolysis, and dechlorination. The findings of this study demonstrate the efficacy of the goethite/S. oneidensis MR-1 complex system in the removal of chlorpyrifos from water. Consequently, this research contributes to the establishment of a theoretical framework for the microbial remediation of organophosphorus pesticides in aqueous environments. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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24 pages, 5496 KiB

Open AccessArticle

Investigation of Kinetic, Equilibrium, and Thermodynamic Modeling of Perfluorooctanoic Acid (PFOA) Adsorption in the Presence of Natural Organic Matter (NOM) by Dielectric Barrier Discharge Plasma-Modified Granular Activated Carbon (GAC)

by Thera Sahara, Doonyapong Wongsawaeng, Kanokwan Ngaosuwan, Worapon Kiatkittipong, Peter Hosemann and Suttichai Assabumrungrat

Water 2024, 16(11), 1499; https://doi.org/10.3390/w16111499 - 24 May 2024

Viewed by 1707

Abstract

Perfluorooctanoic acid (PFOA) contamination in water sources poses significant environmental and health concerns. The kinetic, equilibrium, and thermodynamic features of PFOA adsorption in the existence of natural organic matter (NOM) were thoroughly investigated in this work using granular activated carbon (GAC) modified by [...] Read more.

Perfluorooctanoic acid (PFOA) contamination in water sources poses significant environmental and health concerns. The kinetic, equilibrium, and thermodynamic features of PFOA adsorption in the existence of natural organic matter (NOM) were thoroughly investigated in this work using granular activated carbon (GAC) modified by dielectric barrier discharge (DBD) plasma. The impacts of DBD plasma parameters on the adsorption process were systematically examined. The results demonstrated that GAC modified by DBD plasma exhibited enhanced adsorption performance for PFOA, even in the presence of NOM. The optimal condition for plasma-treated GAC was achieved with 20 min of plasma treatment time and 100 W of plasma power, resulting in 92% PFOA removal efficiency in deionized water (DIW) and 97% removal efficiency in Chao Phraya River water (CPRW). A kinetic investigation using the pseudo-first-order model (PFOM), the pseudo-second-order model (PSOM), and the Elovich model (EM) indicated that plasma treatment time and NOM presence influenced the adsorption capacity and rate constants of PFOA with the PSOM having emerged as the most fitting kinetic model. The Langmuir isotherm model indicates monolayer adsorption of PFOA on plasma-treated GAC, with higher maximum adsorption capacity while NOM is present. The Redlich–Peterson and Sips isotherm models indicated varying adsorption capacity and heterogeneity in the adsorption system. The Sips model was determined as the most fitting isotherm model. Furthermore, the favorable and spontaneous character of PFOA adsorption onto plasma-treated GAC was validated by thermodynamic analysis, with endothermic heat absorption during the process. Overall, this comprehensive investigation provides valuable insights into the adsorption characteristics of PFOA in the existence of NOM using GAC modified by DBD plasma. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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17 pages, 4871 KiB

Open AccessArticle

Enhanced Nitrate Nitrogen Removal from Wastewater Using Modified Reed Straw: Adsorption Performance and Resource Utilization

by Haodong Zhang, Zhan Yang, Jiawang Tian, Changyi Liu and Zhe Qin

Sustainability 2024, 16(10), 4001; https://doi.org/10.3390/su16104001 - 10 May 2024

Cited by 1 | Viewed by 1365

Abstract

This paper presents a study on the efficient removal of nitrate nitrogen from wastewater using modified reed straw (MRS) and its subsequent resource utilization. The modification of the reed straw involved the introduction of branching quaternary amine groups to enhance its adsorption capacity [...] Read more.

This paper presents a study on the efficient removal of nitrate nitrogen from wastewater using modified reed straw (MRS) and its subsequent resource utilization. The modification of the reed straw involved the introduction of branching quaternary amine groups to enhance its adsorption capacity for nitrate nitrogen. Experimental investigations were conducted to analyze the impact of packing height, flow rate, and initial solution concentration on the dynamic adsorption performance of the MRS. The results revealed that the maximum dynamic adsorption capacity of the MRS for nitrate nitrogen reached 14.76 mg/g. Furthermore, valuable nitrate nitrogen nutrient solution was successfully recovered through subsequent desorption experiments for resource recycling. Moreover, the application of the MRS led to notable enhancements in column height, fresh weight, chlorophyll content, and nitrogen content of the treated plants, indicating its efficacy in promoting plant growth. Overall, the findings demonstrate that MRS serves as a versatile adsorbent capable of efficient nitrate nitrogen removal and subsequent resource utilization. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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18 pages, 6596 KiB

Open AccessArticle

In Situ Utilization of Electron-Enhanced Degradation of Azo Dyes in a Constructed Wetland–Microbial Fuel Cell Coupling System

by Xiangfeng Xie, Jijing Hu, Xian Cao, Shuai Zhang, Takashi Sakamaki and Xianning Li

Sustainability 2024, 16(8), 3181; https://doi.org/10.3390/su16083181 - 10 Apr 2024

Cited by 6 | Viewed by 1717

Abstract

In this study, a constructed wetland was coupled with a microbial fuel cell to establish a coupled system known as the constructed wetland–microbial fuel cell (CW–MFC), utilized for the treatment of X-3B azo dye wastewater at varying concentrations. Experimental results indicated that the [...] Read more.

In this study, a constructed wetland was coupled with a microbial fuel cell to establish a coupled system known as the constructed wetland–microbial fuel cell (CW–MFC), utilized for the treatment of X-3B azo dye wastewater at varying concentrations. Experimental results indicated that the anodic region made the primary contributions to the discoloration of azo dyes and COD removal, with a contribution rate of 60.9–75.8% for COD removal and 57.8–83.0% for the effectiveness of discoloration. Additionally, the role of plants in the constructed wetland area could achieve the removal of small molecular substances and further discoloration. In comparison to open-circuit conditions, under closed-circuit conditions the CW–MFC effectively degraded X-3B azo dye wastewater. Under an external resistance of 2000 Ω, a maximum COD removal rate of 60.0% and a maximum discoloration rate of 85.8% were achieved for X-3B azo dye at a concentration of 100 mg/L. Improvements in the treatment efficiency of X-3B dye wastewater were achieved by altering the external resistance. Under an external resistance of 100 Ω and an influent concentration of X-3B of 800 mg/L, the COD removal rate reached 78.6%, and the decolorization rate reached 85.2%. At this point, the CW–MFC exhibited a maximum power density of 0.024 W/m³ and an internal resistance of 99.5 Ω. Spectral analysis and GC–MS results demonstrated the effective degradation of azo dyes within the system, indicating azo bond cleavage and the generation of numerous small molecular substances. Microbial analysis revealed the enrichment of electrogenic microorganisms under low external resistance conditions, where Geobacter and Trichococcus were dominant bacterial genera under an external resistance of 100 Ω, playing crucial roles in power generation and azo dye degradation within the system. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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17 pages, 5330 KiB

Open AccessArticle

Adsorption Performance and Mechanism of Fe(II) Adsorption in Abandoned Mine Water of Nonstick Coal

by Zhuolin Shi, Chengle Wu, Furong Wang, Jialong Sun, Yingnan Xu and Jinhang Shen

Processes 2024, 12(1), 188; https://doi.org/10.3390/pr12010188 - 15 Jan 2024

Cited by 2 | Viewed by 1418

Abstract

Aiming at the problem of the low reuse rate of mine water due to the high content of heavy metals in mine water, in this research, the microcharacterization means of EDX, XRD, BET, SEM, and FT-IR were used to characterize the nonstick coal [...] Read more.

Aiming at the problem of the low reuse rate of mine water due to the high content of heavy metals in mine water, in this research, the microcharacterization means of EDX, XRD, BET, SEM, and FT-IR were used to characterize the nonstick coal in a mine in western China. The effects of solid–liquid ratio, solution pH, solution temperature, adsorption time, and initial concentration of the solution on the adsorption of Fe(II) by the nonstick coal were analyzed. The adsorption performance of nonstick coal on adsorbed Fe(II) was analyzed under different influencing factors. The results showed that the adsorption capacity and unit removal rate of the coal samples gradually decreased with the increase in the solid–liquid ratio; the adsorption amount increased with the increase in pH in an “S” shape, and the adsorption effect was better in the range of pH = 5~7; and the adsorption amount increased linearly with the temperature. The quasi-secondary kinetic model and Langmuir model could fit the adsorption kinetic curve and isothermal adsorption curve better, which indicated that the adsorption of Fe(II) by the nonstick coal was dominated by the chemical adsorption of the monomolecular layer. The quantitative analysis of the FT-IR results showed that the adsorption of Fe(II) was mainly by complexation with -OH detached from the coal samples to produce precipitation. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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15 pages, 2797 KiB

Open AccessArticle

Effective Use of Sugarcane-Bagasse-Derived KOH-Activated Biochar for Remediating Norfloxacin-Contaminated Water

by Yan Zhou, Yongtao Lan, Michael Douglas Short, Juanjuan Shi, Qiugui Zhang, Junhao Xu and Gujie Qian

Toxics 2023, 11(11), 908; https://doi.org/10.3390/toxics11110908 - 6 Nov 2023

Cited by 6 | Viewed by 2357

Abstract

Bagasse-derived biochar (SCB₇₅₀) was prepared at 750 °C using Chinese sugarcane bagasse as a carbon source and then modified with KOH for the removal of the antibiotic norfloxacin (NOR) from aqueous solutions. 3K-SCB₇₅₀, prepared using a solid-to-liquid mass ratio [...] Read more.

Bagasse-derived biochar (SCB₇₅₀) was prepared at 750 °C using Chinese sugarcane bagasse as a carbon source and then modified with KOH for the removal of the antibiotic norfloxacin (NOR) from aqueous solutions. 3K-SCB₇₅₀, prepared using a solid-to-liquid mass ratio of bagasse:KOH = 1:3, was found to have the best adsorption performance for NOR. Under the conditions of pH 5, 25 °C, 2.4 g L⁻¹ adsorbent, and 300 mg L⁻¹ NOR, its adsorption of NOR reached equilibrium (97.5% removal) after 60 min. The adsorption behaviours were in line with the quasi-second-order kinetic and Langmuir isotherm models, respectively. The maximum theoretical adsorption capacity reached up to 157.4 mg·g⁻¹ at 40 °C. The thermodynamic parameters showed that the adsorption of NOR onto 3K-SCB₇₅₀ was a spontaneous, endothermic, and physical process. In addition, Brunauer−Emmett−Teller analysis (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy were conducted to investigate the structural and adsorption properties of 3K-SCB₇₅₀. Fourier transform infrared spectroscopy (FTIR) was also applied to understand the mechanism of adsorption of NOR onto 3K-SCB₇₅₀. All of the results indicated that 3K-SCB₇₅₀ had a large specific surface area of 1038.8 m²·g⁻¹, an average pore size of 1.9 nm, and hierarchical structures with random pores and cracks for efficient removal of NOR. NOR adsorption mechanisms on 3K-SCB₇₅₀ were related to the pore-filling effect and electrostatic attraction. Therefore, 3K-SCB₇₅₀ biochar may be used as a promising adsorbent of antibiotics in wastewaters. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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12 pages, 1944 KiB

Open AccessArticle

Study of Modified Magnesium Phosphate Cement for Fluoride Removal

by Sana Gharsallah, Abdulrahman Mallah, Abdulrahman Alsawi, Bechir Hammami, Mohamed Khitouni, Clarence Charnay and Mahmoud Chemingui

Materials 2023, 16(17), 5749; https://doi.org/10.3390/ma16175749 - 22 Aug 2023

Cited by 3 | Viewed by 1764

Abstract

In this study, we used a novel composite material based on magnesium phosphate cement (MPC) to explore the retention of fluoride from used water. Dead-burned magnesium oxide (MgO), ammonium dihydrogen phosphate (NH₄H₂PO₄), and a few retarders were [...] Read more.

In this study, we used a novel composite material based on magnesium phosphate cement (MPC) to explore the retention of fluoride from used water. Dead-burned magnesium oxide (MgO), ammonium dihydrogen phosphate (NH₄H₂PO₄), and a few retarders were used to create this particular substance. Several studies have corroborated the performance of using aluminum in the capture of fluoride. From this perspective, we attempted to reinforce our matrix with different quantities of aluminum, which increased the resistance of the composite in water. The optimal conditions that were obtained were evaluated and scrutinized using a range of techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transforms infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET). The adsorbents demonstrated a powerful ability to remove fluoride from contaminated water and the defluoridation capacity was evaluated at 4.84 mg/g. Equilibrium modeling was carried out, and the experimental data were expressed in accordance with the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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16 pages, 2772 KiB

Open AccessArticle

Banana Peel Powder Biosorbent for Removal of Hazardous Organic Pollutants from Wastewater

by Kelly C. S. Farias, Rita C. A. Guimarães, Karla R. W. Oliveira, Carlos E. D. Nazário, Julio A. P. Ferencz and Heberton Wender

Toxics 2023, 11(8), 664; https://doi.org/10.3390/toxics11080664 - 1 Aug 2023

Cited by 13 | Viewed by 6189

Abstract

Disposing of pollutants in water sources poses risks to human health and the environment, but biosorption has emerged as an eco-friendly, cost-effective, and green alternative for wastewater treatment. This work shows the ability of banana peel powder (BPP) biosorbents for efficient sorption of [...] Read more.

Disposing of pollutants in water sources poses risks to human health and the environment, but biosorption has emerged as an eco-friendly, cost-effective, and green alternative for wastewater treatment. This work shows the ability of banana peel powder (BPP) biosorbents for efficient sorption of methylene blue (MB), atrazine, and glyphosate pollutants. The biosorbent highlights several surface chemical functional groups and morphologies containing agglomerated microsized particles and microporous structures. BPP showed a 66% elimination of MB in 60 min, with an adsorption capacity (q_e) of ~33 mg g⁻¹, and a combination of film diffusion and chemisorption governed the sorption process. The biosorbent removed 91% and 97% of atrazine and glyphosate pesticides after 120 min, with q_e of 3.26 and 3.02 mg g⁻¹, respectively. The glyphosate and atrazine uptake best followed the Elovich and the pseudo-first-order kinetic, respectively, revealing different sorption mechanisms. Our results suggest that BPP is a low-cost biomaterial for green and environmentally friendly wastewater treatment. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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16 pages, 1513 KiB

Open AccessArticle

Removal and Adsorption Mechanisms of Phosphorus, Cd and Pb from Wastewater Conferred by Landfill Leachate Sludge-Derived Biochar

by Huiqin Zhang, Kexin Lu, Juan Zhang, Chao Ma, Zixian Wang and Xiaofang Tian

Sustainability 2023, 15(13), 10045; https://doi.org/10.3390/su151310045 - 25 Jun 2023

Cited by 5 | Viewed by 1607

Abstract

There is a high treatment cost and secondary pollution to the environment due to the high organic content and complex composition in landfill leachate sludge in refuse incineration power plants. Landfill leachate sludge-derived biochar (LLSDB) was prepared via pyrolysis in order to realize [...] Read more.

There is a high treatment cost and secondary pollution to the environment due to the high organic content and complex composition in landfill leachate sludge in refuse incineration power plants. Landfill leachate sludge-derived biochar (LLSDB) was prepared via pyrolysis in order to realize its resource utilization and remove pollutants from wastewater. The study focused on the removal of nutrients phosphorus and heavy metals (Cd(II) and Pb(II)) from wastewater through the adsorption process using LLSDB. The investigation also looked into the kinetics and thermodynamics of the adsorption process. It was found that the Freundlich–Temkin–Langmuir model was the best model for describing the initial concentration of total phosphorus, (TP) 0–1.0, 1.0–20, and 20–120 mg/L, respectively, while the Freundlich–Langmuir model was the best model for Cd(II) 100–500 mg/L, Pb(II) 500–5000 mg/L, respectively. Additionally, while the exothermic entropy reduction process for TP (˂1.0 mg/L) was spontaneous, the endothermic entropy increment processes for TP (≥1.0 mg/L), Pb(II) and Cd(II) in wastewater increased with the adsorption temperature. It was inferred for the adsorption mechanism of LLSDB that the adsorption of low concentrations of TP, Cd(II) and Pb(II) from wastewater was mainly physical adsorption, following a linear distribution, while that of high concentrations was mainly chemical adsorption because of a series of chemical reactions; TP, Cd(II) and Pb(II) from wastewater were nicely adsorbed and removed by LLSDB600, which was an incredibly superior strategy for controlling waste with waste. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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13 pages, 4158 KiB

Open AccessArticle

Insights into Phosphate Adsorption Performance onto Magnetic Thermal Modified Palygorskite Nanocomposites

by Min Pan, Jingfeng Su, Leting Tang, Zimin Hu and Xiaoming Huang

Minerals 2023, 13(2), 293; https://doi.org/10.3390/min13020293 - 20 Feb 2023

Cited by 2 | Viewed by 2509

Abstract

Eutrophication caused by excessive discharging of phosphorus is a global water pollution problem. To further improve the phosphorus adsorption capacity of natural palygorskite and easy separation from liquid, magnetic thermal modified palygorskite nanocomposite (MTPG) was firstly fabricated and then characterized by XRD and [...] Read more.

Eutrophication caused by excessive discharging of phosphorus is a global water pollution problem. To further improve the phosphorus adsorption capacity of natural palygorskite and easy separation from liquid, magnetic thermal modified palygorskite nanocomposite (MTPG) was firstly fabricated and then characterized by XRD and SEM-EDS. The characterization results showed Fe₃O₄ in nano-diameters was prosperously immobilized on the surface of thermal modified palygorskite (TPG) calcinated at a temperature of 700 °C. Abundant nano-scale Fe₃O₄ loading almost doubled the specific surface area (SSA) of TPG. The adsorption of phosphate onto MTPG was highly pH-dependent and slightly influenced by ionic strength. According to the results from the Langmuir model, the maximum adsorptive quantity of 400.00 mg/g was counted at 298 K. The regeneration ratio was 80.98% after three regeneration cycles. The process of phosphate adsorption was confirmed to be an endothermic and spontaneous chemisorption. Thus, the cost-effective, excellent phosphate affinity, great magnetic recovery performance, and high adsorption capacity of MTPG had an enormous promising utilization on phosphate removal from aqueous solutions. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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16 pages, 4467 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Assessment and Management of Mercury Leaching from a Riverbank

by Hasti Ziaei, Balaji Rao, Tea V. Wood, Uriel Garza-Rubalcava, Ashkan Alborzi, Huayun Zhou, Paul Bireta, Nancy Grosso and Danny Reible

Toxics 2023, 11(2), 179; https://doi.org/10.3390/toxics11020179 - 15 Feb 2023

Cited by 1 | Viewed by 2780

Abstract

The South River located in the city of Waynesboro, Virginia, contains mercury (Hg) contamination due to historical releases from an industrial facility operating between 1929 and 1950. In 2015, two sampling events were conducted in two of the contaminated bank regions (Constitution Park [...] Read more.

The South River located in the city of Waynesboro, Virginia, contains mercury (Hg) contamination due to historical releases from an industrial facility operating between 1929 and 1950. In 2015, two sampling events were conducted in two of the contaminated bank regions (Constitution Park and North Park) to evaluate non-particulate total mercury (THg) and methylmercury (MeHg) concentrations in bank interstitial waters during river base flows and during bank drainage after flooding events. Porewater THg and MeHg at the bank–water interface were measured using diffusive gradient in thin-film devices (DGTs). The results showed THg mercury concentrations during bank drainage were approximately a factor of 3 higher than during base flow conditions. To have a better understanding of the parameters that control Hg leaching, a series of laboratory experiments were designed using South River sediments. The field and laboratory assessment showed that drainage/inundation cycles can lead to high THg concentration leachate from contaminated sediment due to increased partitioning from solids under oxic bank conditions and mobilization by the drainage waters. The results also demonstrated that methyl mercury concentrations at the bank–water interface are highest under base flow when conditions are more reduced due to the absence of oxic water exchange with the surface water. A remedial approach was implemented involving partial removal of surficial sediments and placement of biochar (to reduce non-particulate THg) and an armoring layer (to reduce erosion). DGT Measurements after bank stabilization showed THg decreased by a factor of ~200 and MeHg concentration by a factor of more than 20. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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18 pages, 3400 KiB

Open AccessFeature PaperArticle

Photocatalytic Treatment of Emerging Contaminants with Ag-Modified Titania—Is There a Risk Arising from the Degradation Products?

by Robert Frankowski, Agnieszka Zgoła-Grześkowiak, Tomasz Grześkowiak, Ewa Stanisz, Justyna Werner and Julia Płatkiewicz

Processes 2022, 10(12), 2523; https://doi.org/10.3390/pr10122523 - 28 Nov 2022

Cited by 6 | Viewed by 1724

Abstract

Bisphenol A, bisphenol S, and fluconazole are environmental contaminants widely found in surface waters because of their extensive usage and low biodegradability. Therefore, other methods are often considered for the removal of these compounds. The present study aims at their photodegradation with the [...] Read more.

Bisphenol A, bisphenol S, and fluconazole are environmental contaminants widely found in surface waters because of their extensive usage and low biodegradability. Therefore, other methods are often considered for the removal of these compounds. The present study aims at their photodegradation with the use of UV light and three different catalysts, ZnO, TiO₂, and Ag-TiO₂. The results obtained show that photocatalytic removal of these compounds is also problematic and the use of catalysts, such as ZnO and TiO₂, at increasing concentrations mostly leads to lower degradation of the tested compounds. The modification of TiO₂ with silver increases the degradation of both bisphenols up to 100%, which was achieved in 60 min by bisphenol A and in as little as 10 min by bisphenol S. Nevertheless, the degradation of fluconazole remained at the same level, not exceeding 70% in 60 min, i.e., still much lower than expected. In addition, the degradation products of bisphenols show the hydroxylation and destruction of their phenolic rings, while no degradation products were found during the test with fluconazole. Although the potentially genotoxic bisphenol A degradation product was found, the acute toxicity of the formed compounds differs little in comparison to the parent bisphenols. Full article

(This article belongs to the Topic Removal of Hazardous Substances from Water Resources)

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