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Solid/Liquid Adsorption in Water and Wastewater Treatment

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A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Wastewater Treatment and Reuse".

Deadline for manuscript submissions: closed (15 October 2022) | Viewed by 37782

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Special Issue Editor

Dr. Tushar Kanti Sen

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Guest Editor

1. Chemical Engineering Department, King Faisal University (KFU), P.O. Box 380, Al-Ahsa 31982, Saudi Arabia
2. Chemical Engineering, WA School of Mines: Minerals, Energy and Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
Interests: water research; wastewater treatment; adsorption at solid/liquid interface; biosorption; anaerobic digestion and dewatering of wastewater sludge; rheology of slurry/sludge; chemical enhanced oil recovery (CEOR)
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Special Issue Information

Dear Colleagues,

Water pollution occurs when toxic inorganic and organic pollutants/potential pollutants from various industrial and human activities are directly and indirectly discharged into water bodies without adequate treatment. A number of treatment technologies such as membrane processes, filtration, adsorption, ion exchange, solid/liquid adsorption, coagulation, oxidation/reduction, etc., have been used to separate various water pollutants. Among the various separation techniques in water pollution control, adsorption at the solid/liquid interface is considered to be a superior technique because of its simple design, universal nature, high effectiveness, ease of operation and regeneration. When our water is polluted, it is not only devastating to the environment, but also to human health. Further, there are various federal and state government and environmental protection agencies who strictly enforce regulations on minimizing pollutants from liquid discharge effluent streams. In view of the importance of water quality and the environmental aspect, it is considered worthwhile to address the state-of-the-art adsorption at the solid/liquid interface for the removal of water pollutants from water and wastewater systems. Adsorption at the solid/liquid interface may be defined as the selective concentration or retention of one or more liquid phase component of a mixture on a solid surface or at the solid/liquid interface by various physical and chemical forces. The nature and types of adsorbents are the main controlling parameters for effectiveness of the adsorption process. Therefore, the present Special Issue entitled “Solid/Liquid Adsorption in Water and Wastewater Treatment” aims for the publication of original research or review papers on the removal of inorganic/organic pollutants from water by various conventional and nonconventional alternative adsorbents and to provide more research information on the mechanism of adsorption. The overall scope of this Special Issue includes up-to-date development on the current state of knowledge on various adsorbents such as activated carbon, nanomaterials, functional materials, clay minerals and various agricultural biomass-based adsorbents and their applications in the broad field of the separation and purification of water pollutants. Specifically, the topics for this Special Issue include but are not restricted to:

The synthesis and characteristics of various adsorbent materials including biomass adsorbents, clay minerals and new emerging alternative adsorbents, composite adsorbents and their adsorptive effectiveness in water purification under various physicochemical process parameters;
Kinetics, thermodynamics and equilibrium: experimental data, novel theories and models;
Adsorption calculations and modelling;
Continuous column process and process design: packed bed and moving bed systems, fluidised bed, bubble column operations and dynamic modelling;
Industrial wastewater treatments—any case study.

Dr. Tushar Kanti Sen
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

water pollution
adsorptive separation technique
agricultural by-product solid waste adsorbents
clay minerals
wastewater treatment
nanomaterials in wastewater treatment
anaerobic digestion
conditioning agents in dewatering
sludge rheology

Published Papers (13 papers)

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Research

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23 pages, 3834 KiB

Open AccessArticle

Assessment of Cyprinus carpio Scales as a Low-Cost and Effective Biosorbent for the Removal of Heavy Metals from the Acidic Mine Drainage Generated at Rosia Montana Gold Mine (Romania)

by Gianina Damian and Simona Varvara

Water 2022, 14(22), 3734; https://doi.org/10.3390/w14223734 - 17 Nov 2022

Cited by 1 | Viewed by 1913

Abstract

In the present study, the biosorptive potential of Cyprinus carpio scales for the removal of Fe, Mn, and Zn ions from real acidic mine drainage (AMD) generated at the Rosia Montana gold mine (Romania) was explored for the first time. The collected AMD solution is very acidic, and the concentrations of Fe, Mn, and Zn ions exceed more than 34 to 56 times the disposal standards imposed by legislation. Batch adsorption experiments were carried out to study the effect of the sorbent dosage, sorbent particle size, pH, and contact time on the adsorption performance of the fish scales. Before and after the adsorption process, the biosorbent was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (SEM-EDX). In the investigated experimental conditions, about 100%, 87.1%, and 100% of Fe, Mn, and Zn ions were removed from the AMD after 240 min of contact with the finest-grained Cyprinus carpio scale samples using a solid:liquid ratio of 20:1 (g:L). The adsorption data were analyzed using the pseudo-first order, pseudo-second order, intraparticle diffusion rate, and Elovich equations. The adsorption process was found to follow the pseudo-second-order kinetic model. The maximum adsorption capacities of the fish scales were about 2.46 mg/g for Mn and 0.85 mg/g for Zn ions, respectively. Aside from their significant efficiency in the removal of metals from AMD, Cyprinus carpio scales also have the potential to neutralize the acidic wastewater. Thus, the removal process of metal ions from AMD is ruled by a complex mechanism, including adsorption and iron precipitation. The recycled scales are still able to remove the metal ions from AMD with a better performance during the first regeneration cycle. Based on the obtained results, it might be assessed that the low-cost biowaste of Cyprinus carpio scales have great potential and could be effectively used for the remediation of real acidic mine drainage from a sustainable perspective. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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14 pages, 3097 KiB

Open AccessArticle

Al-Impregnated Granular Activated Carbon for Removal of Fluoride from Aqueous Solution: Batch and Fixed-Bed Column Study

by Zheng Liu, Sijie Zheng and Daolong Zhang

Water 2022, 14(21), 3554; https://doi.org/10.3390/w14213554 - 04 Nov 2022

Cited by 1 | Viewed by 1726

Abstract

Fluoride pollution in water has been reported in many regions and countries. Adsorption is the most commonly used process for treating fluoride-containing water. For industrial applications, the treatment of a pollutant is normally performed in continuous column mode. In this work, batch and lab-scale column studies were conducted by applying modified granular activated carbon (MGAC) to remove fluoride (F⁻) from an aqueous solution. MGAC was prepared by a wet impregnation method and characterized using SEM and FTIR. Batch studies presented the adsorption of F⁻ onto MGAC following the Freundlich model and the pseudo-second-order model, indicating the dominant adsorption was a multilayer adsorption and chemisorption process. The breakthrough time, exhaustion time, adsorption capacity, and adsorption efficiency in breakthrough curves were evaluated under varying influent F⁻ concentrations, flow rates, and bed heights. Thomas, Yoon-Nelson, and Yan models were employed to describe the whole breakthrough behavior, showing their suitability to predict the features of the breakthrough curves of the MGAC continuous flow system. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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10 pages, 1065 KiB

Open AccessArticle

Selective and Competitive Adsorption of Anions in Solution on Porous Adsorbent from Zea mays Steams: Kinetic and Equilibrium Study

by Angel Villabona-Ortíz, Rodrigo Ortega-Toro and Candelaria Tejada-Tovar

Water 2022, 14(18), 2906; https://doi.org/10.3390/w14182906 - 17 Sep 2022

Cited by 2 | Viewed by 1296

Abstract

Surface modification can improve the adsorption capacity of biochar. Biochar was produced from corn stalks (Zea mays) by pyrolysis at 520 °C, activated with sulfuric acid (H₂SO₄) using impregnation ratios of biomass weight: volume 1:2 (B 1:2) and 1:3 (B 1:3). The kinetic study showed that the equilibrium is reached at 180 min; the maximum adsorption capacity of nitrate and sulphate was obtained with B 1:2 and for phosphate with B 1:3. The adsorption of nitrate and phosphate with the two biochars presented a good fitting to the pseudo-first order and pseudo-second-order model, while that of sulphate for B 1:2 is described by Elovich’s model. Freundlich’s model describes the equilibrium of adsorption of nitrate and phosphate using B 1:2 and B 1:3, while Dubinin–Radushkevich adjusts the removal of sulphate for C 1:2 and C 1:3; therefore it is suggested that adsorption occurs in multilayers. The multicomponent study evidences the preference of biocarbon for phosphate, without indicating competition for the active centers of the material among the anions studied. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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15 pages, 1782 KiB

Open AccessArticle

Enhancing the Efficiency of Banana Peel Bio-Coagulant in Turbid and River Water Treatment Applications

by Abdassalam A. Azamzam, Mohd Rafatullah, Esam Bashir Yahya, Mardiana Idayu Ahmad, Japareng Lalung, Mahboob Alam and Masoom Raza Siddiqui

Water 2022, 14(16), 2473; https://doi.org/10.3390/w14162473 - 11 Aug 2022

Cited by 7 | Viewed by 5941

Abstract

The aim of the present work is to investigate the potential use of banana peel waste as a natural coagulant and to enhance its coagulation performance using a green modification approach for the removal of synthetic water turbidity and river water treatment. Here, the regular banana peel powder had an average particle size and diameter of 978 ± 37 nm and 602 ± 13 nm, respectively, while the modified powder possessed 571 ± 41 nm and 360 ± 19 nm particle size and diameter, respectively. The coagulation performance was investigated at different pH levels, doses, sedimentation times, and NaCl quantities. The optimum dose was found to be 0.4 g/L for modified banana peel with turbidity removal of up to 90%. NaCl slightly enhanced the coagulation performance at low quantities of less than 0.4 g/L, but the activity was reduced at higher concentrations even in the modified powder. Banana peel powder had a weaker turbidity reduction of 76 and 84% for non-modified and modified powders in river water, respectively, in addition to significant reduction in water color, total dissolved and suspended solids, and chemical and biochemical oxygen demand. SEM and FT-IR characterization were performed to investigate and confirm the coagulation mechanism. Such a green modification of banana peel powder can be an alternative with significantly potential as a low cost and easily available bio-coagulant, which can certainly contribute to the waste reduction. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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18 pages, 7356 KiB

Open AccessArticle

The Sorbents Based on Acrylic Fiber Impregnated by Iron Hydroxide (III): Production Methods, Properties, Application in Oceanographic Research

by Nikolay A. Bezhin, Mariya A. Frolova, Illarion I. Dovhyi, Ol’ga N. Kozlovskaia, Evgenii V. Slizchenko, Iuliia G. Shibetskaia, Vasiliy A. Khlystov, Eduard A. Tokar’ and Ivan G. Tananaev

Water 2022, 14(15), 2303; https://doi.org/10.3390/w14152303 - 24 Jul 2022

Cited by 7 | Viewed by 1723

Abstract

Sorbents based on Fe(OH)₃ and aluminum oxide are widely used in oceanology for the recovery of cosmogenic radionuclides ⁷Be, ³²Si, ³²P, and ³³P from the seawater. It is also possible to use them for the recovery of the natural radionuclides ²¹⁰Pb, ²³⁴Th. A comparative study of the sorbents based on Fe(OH)₃ and acrylic fiber obtained through various impregnation methods was carried out, and their comparison with granulated aluminum oxide. The possibility of extracting trace amounts of phosphorus and beryllium under laboratory and field conditions with these sorbents was studied. The sorption of ⁷Be, ²¹⁰Pb, and ²³⁴Th on the natural content by the two-column method was investigated. It is shown that fiber samples obtained by oxidation with sodium ferrate and the “classical” method have the highest sorption characteristics. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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15 pages, 4096 KiB

Open AccessFeature PaperArticle

Enhanced Methylene Blue Adsorption by Cu-BTC Metal-Organic Frameworks with Engineered Particle Size Using Surfactant Modulators

by Shanli Wang, Lu Zhang, Mingyan Zhang, Licong Xu, Qian Hu, Tao Yang, Kaili Tu, Minghua Wu and Deyou Yu

Water 2022, 14(12), 1864; https://doi.org/10.3390/w14121864 - 10 Jun 2022

Cited by 5 | Viewed by 2295

Abstract

Metal–organic frameworks (MOFs) featuring porous structures and large specific surface areas have shown great potential in removing organic pollutants from wastewater via adsorption processes. Although the particle size of MOFs determines the adsorption performance (something known as the size-dependent effect), engineering it into desirable dimensions for enhancing the adsorption performance is a great challenge. Here, we develop a practical and facile approach to regulate the particle size of copper benzene-1,3,5-tricarboxylate (Cu-BTC) adsorbents with high tunability by screening the functional modulator of various surfactants adding in hydrothermal synthesis procedure. The effect of surfactant type and concentration on the particle size of Cu-BTC was systematically investigated. The results show that the nonionic surfactant polyvinylpyrrolidone (PVP) demonstrated the greatest ability to control the particle size of Cu-BTC among other counterparts (e.g., N, N, N-trimethyl-1-dodecanaminium bromide (DTAB), polyethylene glycol (PEG1000), sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS) and hexadecyl trimethyl ammonium bromide (CTAB)). By increasing the PVP concentration to 0.14 mmol L⁻¹, the average particle size of Cu-BTC could be correspondingly reduced by more than ten times, reaching to a comparative smaller value of 2.4 μm as compared with the reported counterparts. In addition, the PVP allowed a large increase of the surface area of Cu-BTC according to porosity analysis, resulting in a great enhancement of methylene blue (MB) adsorption. The PVP-modulated Cu-BTC showed fast adsorption kinetics for MB removal accompanied with a maximum adsorption capacity of 169.2 mg g⁻¹, which was considerably competitive with most of the analogs reported. Therefore, our study may inspire concepts for engineering the particle size of Cu-BTCs with improved properties for more practical applications. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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12 pages, 1273 KiB

Open AccessArticle

Copper Bioremediation Ability of Ciliate Paramecium multimicronucleatum Isolated from Industrial Wastewater

by Ayesha Liaqat, Itrat Zahra, Syed Zaghum Abbas, Saikh Mohammad Wabaidur, Gaber E. Eldesoky, Md Ataul Islam, Mohd Rafatullah, Farah R. Shakoori and Abdul R. Shakoori

Water 2022, 14(9), 1419; https://doi.org/10.3390/w14091419 - 29 Apr 2022

Cited by 3 | Viewed by 2211

Abstract

The growing problems of environmental damage have been caused by the continuous outrush of heavy metals from industrial wastewater. To resolve this issue, bioremediation is playing a safe and eco-friendly role in the removal of these heavy metals from environmental wastewater bodies. It has provoked demand with regard to understanding the mechanisms of bioaccumulation and detoxification developed by the organisms living in the heavy metal-exposed industrial wastewater. The present investigation focuses on Paramecium multimicronucleatum, a ciliated protozoan isolated from industrial wastewater, with the objective of assessing its capabilities as an environmental bioremediator. Purified cell culture was maintained in bold basal salt medium and optimum growth conditions were determined. A maximum growth rate of 6.0–9.0 × 10³ cells/mL at 25–30 °C and pH 7.0 was observed, and therefore revealed to be the optimal growth conditions for this species. It can tolerate 40–50 µg/mL of copper ion stress with little effect on growth rate as compared to control. It is able to uptake more than 80% of copper ions from the medium in 96 h. A significant twofold rise in glutathione content and non-protein thiols was recorded as an indication of a defensive mechanism in place to fight against the oxidative stress caused by the copper treatment. A notable increase of 50–70 µg/mL in total protein content of stressed cells in comparison to non-stressed was also observed as potential induction of some particular proteins for the purpose of resistance against copper stress. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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16 pages, 3343 KiB

Open AccessArticle

Evaluation of Kinetic, Equilibrium and Thermodynamics of Cationic Ion Using Agro-Industrial Residues of Plantain (Musa paradisiaca)

by Angel Villabona-Ortíz, Ángel Darío González-Delgado and Candelaria Tejada-Tovar

Water 2022, 14(9), 1383; https://doi.org/10.3390/w14091383 - 24 Apr 2022

Cited by 4 | Viewed by 1394

Abstract

This study aimed to evaluate the adsorptive capacity of Cr (VI) on the residues of the plantain starch extraction process in a batch system, determining the effect of temperature, initial concentration and adsorbent dose. The adsorbent was characterized by FTIR and SEM. The Cr (VI) solution was placed in contact with the adsorbent at pH 2 and 200 rpm. The results revealed the presence of COO⁻, OH⁻ and CH_x⁺ functional groups in the adsorbent. In addition, the adsorption process is controlled by chemisorption and electrostatic interactions. We also found that temperature and adsorbent dose are the variables with significant influence. The highest adsorption capacity was 64.46 mg/g at 55 °C, 200 mg/L and 0.14 g of biomaterial. Based on the kinetic behavior, it was found that the data are adjusted by the pseudo-second order, Elovich and intraparticle diffusion models. The fit of the isotherms to the Freundlich and Dubinin–Radushkevich models establishes that the limiting step of the process is the chemical reaction. The thermodynamic parameters determine that the process is endothermic, with strong biomass–metal bonds that are favorable and spontaneous as the temperature increases. The results indicate that the residual plantain pulp is a residue that can be used in the removal of Cr (VI) ions, and it contributes to the state of the art in terms of the use of new agro-industrial waste. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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15 pages, 2750 KiB

Open AccessArticle

Evaluation of Three Biomaterials from Coconut Mesocarp for Use in Water Treatments Polluted with an Anionic Dye

by Angel Darío González-Delgado, Angel Villabona-Ortíz and Candelaria Tejada-Tovar

Water 2022, 14(3), 408; https://doi.org/10.3390/w14030408 - 29 Jan 2022

Cited by 5 | Viewed by 2612

Abstract

Coconut consumption leads to the generation of a large number of fibrous residues such as epicarp and mesocarp. In this study, bioadsorbents were prepared from coconut shells (CS), coconut cellulose (CC) and treated coconut cellulose (MCC) with cetyl trimethyl ammonium chloride (CTAC) for the elimination of Congo red (CR) in a watery solution. The impact of the adsorbent quantity (15, 25 and 35 mg) and initial concentration (40, 70 and 100 mg/L) were evaluated. Fourier transform infrared spectra (FTIR) confirmed the existence of OH⁻, C=O, COOH and CH₂ groups in the adsorbents as well as the deformation of the bands between 3400 and 3800 cm⁻¹ after the adsorption of CR, which was attributed to its capture in the bioadsorbent. From the bromatological analysis, a content of 48.94% lignin, 35.99% cellulose and 10.51% hemicellulose was found. SEM images showed a lignocellulosic essential surface origin for all adsorbents with presence of folds, roughness of an irregular exposed area and fibrous filaments. The average particle size was 0.45 mm and adsorbents had a mean porosity of 0.58. Increasing the initial concentration had a beneficial influence on the removal efficiency of CR, achieving a 99.9% removal with MCC. CS showed slow kinetics in the initial stages whereas CC and MCC achieved 78% and 99.98% removal at 120 min, respectively; an equilibrium was reached at 480 and 20 min, respectively. MCC, CC and CS achieved a maximum q_e of 256.12 mg/g, 121.62 mg/g and 17.76 mg/g, respectively. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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25 pages, 5624 KiB

Open AccessArticle

Effectiveness and Characterization of Novel Mineral Clay in Cd²⁺ Adsorption Process: Linear and Non-Linear Isotherm Regression Analysis

by Szende Tonk, László Előd Aradi, Gábor Kovács, Alexandru Turza and Eszter Rápó

Water 2022, 14(3), 279; https://doi.org/10.3390/w14030279 - 18 Jan 2022

Cited by 12 | Viewed by 2703

Abstract

The excellent adsorption properties of clay minerals make the optimization of heavy metal removal the subject of numerous research projects. In the present study, ASLAVITAL cosmetic clay (ACC) powder was applied for the removal of Cd²⁺ from water. The main deposit of ACC clay is the Pădurea Craiului Mountains in Romania. A wide range of morpho-structural approaches (SEM, EDX, FTIR, Raman, XRD) were used to characterize the morphology and elemental composition of the adsorbent. As expected for clay minerals, Al (Wt(%) = 11.4 ± 0.9) and Si (Wt(%) = 13.7 ± 1.4) are the main constituents of ACC. After adsorption, Wt(%) = 0.2 ± 0.01 Cd²⁺ was detected in the sample. As proved before, the initial metal concentration is the primary influencing factor; therefore, batch adsorption of 10–160 mg/L Cd²⁺ was investigated. After 190 min, an efficiency of 99% was reached, and the quantity in equilibrium increased from 1–8 mg/g. The best fit in linear form was obtained for the Langmuir II. model, where R² = 0.954 (R_L = 0.037–0.027). Based on linear isotherm models, physical bonds formed between ACC and Cd²⁺ during the favorable adsorption. For the non-linear fits, the Liu model proved to be the best R² = 0.965, χ² = 1.101. Pseudo-II-order kinetic model described the experimental data R² = 0.988–0.999; q_exp and q_calc were almost identical (the differences ranged 0.03–0.34). Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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18 pages, 6805 KiB

Open AccessArticle

Enhanced Single and Simultaneous As(III) Adsorption in Pearl River Delta Water by Hexylamine Functionalized Vermiculite

by Zubair Ahmed, Pingxiao Wu, Yijing Xu, Hareef Ahmed Keerio, Jiayan Wu, Quanyun Ye, Wenchao Niu, Meiqing Chen and Zhi Dang

Water 2021, 13(17), 2412; https://doi.org/10.3390/w13172412 - 02 Sep 2021

Cited by 4 | Viewed by 2105

Abstract

Enhanced As(III) removal (>99.7) was achieved by a novel organoclay (HEX-VER) adsorbent in Pearl River Delta water. Single and simultaneous As(III) removal in the presence of Cd(II) and/or Pb(II) by batch adsorption tests was analyzed. Spectroscopic, spectrometric, microscopic, and potentiometric techniques were used for characterization of the adsorbents. The parameters affecting As(III) adsorption, including pH, kinetic, isotherm, thermodynamic, and co-existing ions (Cl⁻, F⁻, NO₃⁻, CO₃²⁻, SO₄²⁻, Ca²⁺ and Mg²⁺) were also investigated. The results showed that HEX-VER owned different morphology and larger average pore diameter after functionalization, resulting in an improvement of As (III) adsorption capacity. Further analysis confirmed that adsorption was of the monomolecular layer, well-described by the Langmuir isotherm model. The dominant mechanisms for As(III) removal were ion-exchange and complexation. Moreover, HEX-VER was regenerated for five consecutive cycles, and the removal ratio was ≈ 92%, showing its great regeneration potential. These findings suggest that the proposed inexpensive adsorbent has potential for practical applications of As(III) removal from river water. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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14 pages, 1567 KiB

Open AccessFeature PaperArticle

Comparison of Sr Transport in Compacted Homoionous Na and Ca Bentonite Using a Planar Source Method Evaluated at Ideal and Non-Ideal Boundary Condition

by Lucie Baborová, Eva Viglašová and Dušan Vopálka

Water 2021, 13(11), 1520; https://doi.org/10.3390/w13111520 - 28 May 2021

Cited by 2 | Viewed by 2323

Abstract

With the aim to determine the influence of dominant interlayer cation on the sorption and diffusion properties of bentonite, diffusion experiments with Sr on the compacted homoionous Ca- and Na-forms of Czech natural Mg/Ca bentonite using the planar source method were performed. The bentonite was compacted to 1400 kg·m⁻³, and diffusion experiments lasted 1, 3 or 5 days. Two methods of apparent diffusion coefficient D_a determination based on the analytical solution of diffusion equation for ideal boundary conditions in a linear form were compared and applied. The determined D_a value for Ca-bentonite was 1.36 times higher than that for Na-bentonite sample. Values of K_d were determined in independent batch sorption experiments and were extrapolated for the conditions of compacted bentonite. In spite of this treatment, the use of K_d values determined by batch sorption experiments on a loose material for the determination of effective diffusion coefficient D_e values from planar source diffusion experiments proved to be inconsistent with the standard Fickian description of diffusion taking into account only the pore diffusion in compacted bentonite. Discrepancies between K_d and D_e values were measured in independent experiments, and those that resulted from the evaluation of planar source diffusion experiments could be well explained by the phenomenon of surface diffusion. The obtained values of surface diffusion coefficients D_s were similar for both studied systems, and the predicted value of total effective diffusion coefficient D_e(tot) describing Sr transport in the Na-bentonite was four times higher than in the Ca-bentonite. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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Review

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37 pages, 11769 KiB

Open AccessReview

Low-Cost Adsorbents for the Removal of Phenol/Phenolics, Pesticides, and Dyes from Wastewater Systems: A Review

by Soonmin Ho

Water 2022, 14(20), 3203; https://doi.org/10.3390/w14203203 - 12 Oct 2022

Cited by 23 | Viewed by 7560

Abstract

The huge development of industrial production and human activities throughout the world has resulted in serious water pollution. Pesticides, dyes, phenol, and phenolic compounds may be life-threatening to humans and marine aquatic animals, even at low concentrations. These pollutants must be removed by using different techniques to provide high-quality water. So far, the adsorption process has been considered an effective method to remove pollutants from an aqueous solution. The adsorption method has several advantages, such as low cost, easy operation, and high performance. This article reviewed the removal of dye, pesticides, phenol, and phenolic compounds through zeolite, activated carbon, clay, ash fly, and carbon nanotubes by reviewing the existing literature from 2000 to 2022. The properties of the adsorbent, adsorption studies, the method of design, and optimization conditions were reported. The thermodynamic studies were conducted to determine Gibbs free energy change, standard entropy change, and standard enthalpy change. Adsorption isotherms (Langmuir, Freundlich, and Temkim models) revealed the relationship between the amount of adsorbates per unit adsorbent in the equilibrium process. The adsorption kinetic investigations (pseudo-first-order and pseudo-second-order kinetic model) were carried out to determine the rate of adsorption and correlate the experimental data. Experimental results indicated that a higher adsorption capacity can be observed when the adsorbents have a high surface area and high-porosity structure. The removal percentage of pollutants increased when the adsorbent dosage was increased due to the availability of a larger number of adsorption sites. In conclusion, cheaper adsorbents can be used in wastewater treatment to improve water quality and protect the environment. Full article

(This article belongs to the Special Issue Solid/Liquid Adsorption in Water and Wastewater Treatment)

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