Adsorbent For Water Treatment Research Articles

Synthesis and Performance Analysis of a Mesoporous Polydopamine-Functionalized Magnetic Microcapsule Adsorbent in Water Treatment

Synthesis and Performance Analysis of a Mesoporous Polydopamine-Functionalized Magnetic Microcapsule Adsorbent in Water Treatment

The Synthesis of Magnetic Nitrogen-Doped Graphene Oxide Nanocomposite for the Removal of Reactive Orange 12 Dye

Herein, we report the nanofabrication of magnetic calcium ferrite (CaFe2O4) with nitrogen-doped graphene oxide (N-GO) via facile ultrasonication method to produce CaFe2O4/N-GO nanocomposite for the potential removal of reactive orange 12 (RO12) dye from aqueous solution. The successful construction of the nanocomposite was confirmed using different characterization techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The magnetic properties were studied using vibrating sample magnetometer (VSM) indicating ferromagnetic behavior of the synthesized materials that facilitate their separation using an external magnetic field after adsorption treatment. The addition of N-GO to CaFe2O4 nanoparticles enhanced the BET surface area from 24 to 52.93 m2/g as resulted from the N2 adsorption-desorption isotherm. The adsorption of the synthesized nanomaterials is controlled by several parameters (initial concentration of dye, contact time, adsorbent dosage, and pH), and the RO12 dye removal on the surface of CaFe2O4 nanoparticles and CaFe2O4/N-GO nanocomposite was reached through the chemisorption process as indicated from the kinetic study. The adsorption isotherm study indicated that the adsorption process of RO12 dye was best described through the Langmuir isotherm approving the monolayer adsorption. According to the Langmuir model, the maximum adsorption capacity for RO12 was 250 and 333.33 mg/g for CaFe2O4 nanoparticles and CaFe2O4/N-GO nanocomposite, respectively. The adsorption capacity offered by CaFe2O4/N-GO nanocomposite was higher than reported in the literature for adsorbent materials. Additionally, the regeneration study indicated that CaFe2O4/N-GO nanocomposite is reusable and cost-effective adsorbent. Therefore, the nanofabricated CaFe2O4/N-GO hybrid material is a promising adsorbent for water treatment.

Novel pseudopolyrotaxane composite based on biopolymers: Synthesis, characterization and application in water treatment

Pseudopolyrotaxane CMC-Na/β-CD (1), polymer composite CMC-Na/TiO2(2) and pseudopolyrotaxane composite CMC-Na/β-CD/TiO2(3) were synthesized for the first time from carboxymethyl cellulose sodium salt (CMC-Na) which synthesized from recycling of sugarcane bagasse, β–cyclodextrin (β-CD) and TiO2 without toxic agent by simple and eco-friendly approach. The synthesized polymers were used in water treatment to remove organic dyes. The structures of novel polymers were characterized by various techniques FTIR, SEM, TGA and XRD measurements. The maximum adsorption for MB could reach 526, 385 and 370 for CMC-Na/β-CD/TiO2, CMC-Na/TiO2 and CMC-Na/β-CD composite respectively. The adsorption results of the composites were fitted with the 2nd order kinetic model (correlation coefficients > 0.99) and the isotherm studies were fitted to the Langmuir model. In the current article successfully prepared promising sustainable composites containing carboxymethyl cellulose (CMC) as new sustainable, cost effective reusable composite and efficient adsorbents for water treatment.

Calcium ion adsorption of <em>Leucaena leucocephala</em> wood biochar activated with coconut vinegar

A positive correlation has been reported recently among the number of Chronic Kidney Disease of Unknown Etiology (CKDu) patients and the levels of groundwater hardness. Hence, the need for a low cost and a simple domestic process to reduce the hardness of potable water is identified to improve living standards of low-income communities in these disease affected areas. Biochar has emerged as a low cost adsorbent for water treatment, because of its abundance and cost-effectiveness. This study was aimed to evaluate the ability of natural coconut vinegar, in activating Leucaena leucocephala wood biochar to be used in calcium ion (Ca2+) removal from potable water. Column tests showed a 1.7 fold increase of Ca2+ adsorption capacity and a 7 fold increase of Ca2+ retaining capacity upon the vinegar treatment. Batch studies matched with both Langmuir (R2 = 0.9761) and Freundlich (R2 = 0.9785) isotherm models. Ca2+ amount in solutions were measured using flame photometry. Ca2+ adsorption capacities of raw biochar and activated biochar determined by column tests ranged from 3.10-3.82 mg/g and 5.27-6.68 mg/g respectively while Ca2+ retaining capacities ranged from 0.16-0.22 mg/g and 1.28-1.4 mg/g respectively. Fourier transform infrared spectra, suggests hydration of the C-O-C bridges of the biochar surface introducing new -O-H groups and possible introduction of carbonyl/ ester/carboxylic functional groups to the biochar surface upon vinegar treatment. According to scanning electron microscopy porosity of the biochar remained stable after the vinegar treatment.

Bio-Char Characterization Produced from Walnut Shell Biomass through Slow Pyrolysis: Sustainable for Soil Amendment and an Alternate Bio-Fuel

Bio-char has the ability to isolate carbon in soils and concurrently improve plant growth and soil quality, high energy density and also it can be used as an adsorbent for water treatment. In the current work, the characteristics of four different types of bio-chars, obtained from slow pyrolysis at 375 °C, produced from hard-, medium-, thin- and paper-shelled walnut residues have been studied. Bio-char properties such as proximate, ultimate analysis, heating values, surface area, pH values, thermal degradation behavior, morphological and crystalline nature and functional characterization using FTIR were determined. The pyrolytic behavior of bio-char is studied using thermogravimetric analysis (TGA) in an oxidizing atmosphere. SEM analysis confirmed morphological change and showed heterogeneous and rough texture structure. Crystalline nature of the bio-chars is established by X-ray powder diffraction (XRD) analysis. The maximum higher heating values (HHV), high fixed carbon content and surface area obtained for walnut shells (WS) samples are found as ~ 18.4 MJ kg−1, >80% and 58 m2/g, respectively. Improvement in HHV and decrease of O/C and H/C ratios lead the bio-char samples to fall into the category of coal and confirmed their hydrophobic, carbonized and aromatized nature. From the Fourier transform infra-red spectroscopy (FTIR), it is observed that there is alteration in functional groups with increase in temperature, and illustrated higher aromaticity. This showed that bio-chars have high potential to be used as solid fuel either for direct combustion or for thermal conversion processes in boilers, kilns and furnace. Further, from surface area and pH analysis of bio-chars, it is found that WS bio-chars have similar characteristics of adsorbents used for water purifications, retention of essential elements in soil and carbon sequestration.

Preparation of new triptycene- and pentiptycene-based crosslinked polymers and their adsorption behavior towards aqueous dyes and phenolic organic pollutants

• New triptycene- and pentiptycene-based crosslinked polymers namely P1 and P2 are successfully prepared. • The reaction is simple and can be conducted at a relatively mild temperature. • Both P1 and P2 exhibit good adsorption performance for dyes and phenolic organic pollutants at low concentrations. • Both P1 and P2 show highly selective adsorption capacities towards phenolic organic pollutants. Rigid triptycene- and pentiptycene-based monomers, with intrinsic hierarchical structures, were polymerized using tetrafluoroterephthalonitrile as the crosslinker to fabricate crosslinked porous architectures named P1 and P2. The reaction is simple and can be conducted at a relatively mild temperature. Both P1 and P2 exhibit good thermal stability, and good adsorption performance for dyes and phenolic organic pollutants including MB, MO, Pol and BPA. The removal efficiency of P2 is >99% within 10 min for BPA and an adsorption equilibrium for Pol can be reached within 5 min. The adsorption kinetics fit the pseudo-second-order model and the adsorption isotherms follow the Langmuir model and the maximum adsorption capacity of P1 and P2 for BPA can reach 212.06 mg g −1 and 330.02 mg g −1 , respectively. In addition, the obtained crosslinked polymers show a highly selective adsorption capacity towards phenolic organic pollutants. Featuring a simple synthesis, porous architecture and efficient adsorption capability, such triptycene-based and pentiptycene-based crosslinked polymers may be ideal adsorbents for water treatment and purification.

Recycling spent water treatment adsorbents for efficient electrocatalytic water oxidation reaction

Heavy metal contaminated spent adsorbents are of great environmental concern due to their hazardous effects and large-scale accumulation in the natural environment. Converting massive spent adsorbents into efficient electrocatalysts with a facile strategy can address the challenge of growing energy demand and achieving carbon neutral goal. Herein, we demonstrated a "spent adsorbents to heterostructured electrocatalysts" conversion strategy based on the "waste-to-wealth" principle. Via a facile boriding process, the metal ions laden biochar-based spent adsorbents (SA) have been totally transformed into magnetic metal borides/biochar heterostructures, which exhibit excellent activities towards oxygen evolution reaction. The optimized NiCuFeB/SA catalyst takes a low overpotential of 251 mV to drive a current density of 10 mA cm−2, outperforming many Ni/Fe-based catalysts synthesized from commercial material resources. Comprehensive analyses suggest the high catalytic efficiency mainly attributes to the porous biochar confined well-dispersed nano-sized metallic borides, the in-situ evolved active metal (oxy)hydroxides, favourable charge-transfer kinetics, as well as the heterostructure and amorphous feature. This work offers a general strategy to efficiently reutilize the spent metal-bearing biochar-based adsorbents, which can be extended to advanced energy applications-oriented reutilization of other metal-contaminated solid wastes in an economically and environmental-benign manner.

Comparing the morphologies and adsorption behavior of electrospun polystyrene composite fibers with 0D fullerenes, 1D multiwalled carbon nanotubes and 2D graphene oxides

Nanoscale adsorbents with unique engineered morphologies give them properties that can be transformative for water treatment. Unlike bulk-scale and top-down sorbents such as activated carbon, bottom-up nanoscale adsorbents dispersed into water are difficult to recover from water unless enmeshed in macro-scale architectures. Electrospinning is a facile and scalable method of immobilizing nanomaterials (NM) including fullerenes (C60), multi-walled carbon nanotubes (MWCNT) and graphene oxide (GO) into non-woven, flexible polymeric fabric architectures. In this study, electrospinning was used to compare three types of NM-polystyrene (PS) composites. The integration of NMs into electrospun fibers created pores, increased fiber diameter, decreased polymer beading and maintained fibers’ surface pore size distribution for all composites. The scanning electron microscopy inspection indicated that GO in electrospun PS coated the surface of the fibers. This was attributed to the 2D sheet like structure of GO that was pushed outside by the evaporating organic solvent during electrospinning. Phenanthrene adsorption experiments indicated that GO preserved adsorptive properties when incorporated into PS whereas MWCNT and C60 did not. The restricted adsorption of MWCNT and C60 was caused by the concealing of NMs within the PS filaments. On the other hand, partial exposure of GO surfaces enabled adsorption of phenanthrene by GO. Despite the similarities in pore formation and increased diameter when NMs are incorporated into electrospun PS, the type, and morphological properties of the NMs played a critical role on their application potential as an adsorbent for water treatment. Further advances in fiber synthesis are needed such as higher NM loadings in fibers, partial exposure without compromising the composite integrity and continuous pores that allow pollutant access to NM surfaces where adsorption occurs.

Protocols for synthesis of nanomaterials, polymers, and green materials as adsorbents for water treatment technologies

Water pollution caused by numerous pollutants has become one of the critical problems globally. Different technologies and materials are used for the treatment of wastewater. There is a need for protocols and procedures that act as guidelines for researchers to develop and evaluate new adsorbent materials for wastewater treatment. This review takes a step toward developing organized protocols and procedures for the synthesis of nanomaterials, polymers, and green materials as adsorbents used for water purification. In the present review, protocols, and procedures for the synthesis of adsorbents, such as nanomaterials, waste-derived materials, and polymers are proposed Furthermore, protocols for evaluating these materials for water treatment are provided. The reported protocols and procedures will provide guidelines for researchers and industrial workers to develop and evaluate new materials for water treatment. • Protocols for preparing various adsorbents for water treatment have been highlighted. • Protocols of testing adsorbents for water treatment have been designed. • Procedures of column testing for water treatment have been designed. • Protocols and Procedures provide guidelines for researchers to develop and evaluate new materials for water treatment.

Cd(II) removal from aqueous solutions by pomelo peel derived biochar in a permeable reactive barrier: modelling, optimization and mechanism

Biochar can have multiple benefits, such as solid waste recycling, water pollution treatment, carbon fixation and sustainability, and it is green, friendly, inexpensive and highly efficient. Therefore, the present study aimed to investigate Cd(II) removal from aqueous solutions using pomelo peel derived biochar combined with a permeable reactive barrier (PRB). Meanwhile, the materials were characterized using SEM, FIIR, XRD, N2 adsorption, Zeta potential, TGA and XPS. The removal conditions were optimized by a response surface methodology (RSM) and a back propagation combined with genetic algorithm (BP-GA). The results show that there were slight changes in the structure of the pomelo peel derived biochar before and after activation, while the variation was not significant. The specific surface areas of the not activated and activated pomelo peel derived biochars were 3.207 m2 g−1 and 6.855 m2 g−1, respectively. The pore diameter of the former was 4.165 nm and that of the latter was 4.425 nm, indicating that the two materials are mainly mesoporous. BP-GA is more suitable than RSM for optimizing the removal conditions of Cd(II) using the prepared materials combined with PRB. The maximum removal efficiency of Cd(II) was 90.31% at biochar dosage = 4.84, reaction time = 53.75 min, initial Cd(II) concentration = 19.36 mg l−1 and initial pH = 6.07. The verification experiment was 88.74% under these experimental conditions, and the absolute error was 1.57%. The saturated adsorption capacity of quartz sand for Cd(II) is approximately 0.08 mg g−1 when reaching equilibrium. The saturated adsorption capacity of biochar for Cd(II) is approximately 29.76 mg g−1. Pseudo second order kinetics and Langmuir isotherm adsorption were more suitable for describing the Cd(II) adsorbed from an aqueous solution by activated pomelo peel derived biochar. The adsorption process of Cd(II) by the prepared biochar was spontaneous, endothermic and entropy driven. Our results suggest that the modified pomelo peel derived biochar can be regenerated within the fourth cycle and that it has application prospects as a useful adsorbent for water treatment in PRB systems. This finding provides a reference for relieving Cd pollution and for its large scale removal from wastewater when combined with a PRB system.

A highly efficient adsorbent constructed by the in situ assembly of Zeolitic imidazole framework-67 on 3D aramid nanofiber aerogel scaffold

• ZIF-67 was in situ assembled onto ANF aerogel to get 3D monolith adsorbent. • ANF/ZIF-67 aerogel showed stable and competitive structural features. • ANF/ZIF-67 aerogel demonstrated high adsorption capacity for Cu 2+ and Cr 6+ . • ANF/ZIF-67 aerogel displayed excellent adsorption capacity for CV and MO. • The adsorption capacity maintained up to 80% after five times of usage. The fabrication of a high-efficiency adsorbent, as a promising candidate for removing metal ions and organic dyes from aqueous solution, is a research hotspot but remains challenging. Aramid nanofibers (ANFs) are emerging building blocks that have realized multifunctional applications in various fields because of their intrinsic mechanical and chemical stability. In this research, three-dimensional (3D) ANF aerogel was assembled and applied in for in situ assembly of zeolitic imidazole framework-67 (ZIF-67). The aim, was to fully exploit the structural advantages of this composite’s ultra-low bulk density, large specific surface area, and high porosity, as well as provide more available adsorption sites by ZIF-67 polyhedrons, to facilitate pollutant adsorption from waste water. The prepared 3D ANF/ZIF-67 composite aerogel possessed favorable adsorption performance for heavy metal ions (250.95 and 183.29 mg/g for Cu 2+ and Cr 6+ , respectively) and organic dyes (199.36 and 65.98 mg/g for CV and MO, respectively), greatly exceeding that of the corresponding 3D ANF aerogel. Desorption experiments further demonstrated that up to 80% adsorption performance for heavy metal ions and organic dyes could be maintained after five times of usage. Hence, this research can provide new insights into the preparation of highly efficient adsorbents for water treatment.

Preparation and Application in Water Treatment of Magnetic Biochar.

This paper reviews the preparation of magnetic biochar and its application in wastewater treatment, and briefly discusses the adsorption mechanism of biochar to remove pollutants and the modification methods of biochar. Due to the good physical and chemical properties of biochar, including its rough porous structure, it has been widely used to absorb pollutants from water. Magnetic biochar is commonly prepared by combining biochar with magnetic material. The biochar is endowed with the characteristics of the magnetic material, which could effectively solve the problems of difficult recovery and easy loss of adsorbent in water treatment. Magnetic biochar with high carbon content, large specific surface area, magnetic separation, and other excellent properties, has become a hot research topic in recent years. The preparation methods and application properties of magnetic biochar are reviewed. The future research directions of magnetic biochar are put forward to provide directions for further research and application of magnetic biochar materials.

Preparation and characterisation of polypyrrole nanoparticles for enhancement of granular activated carbon (GAC) as adsorbent

BackgroundThe adsorption capacity of Granular Activated Carbon (GAC) is being enhanced using various nanoparticles. A special category of nanohybrid materials also called Janus particles have gained huge interest owing to their tunable properties. The purpose of this work is to report on the synthesis and characteristics of a Janus Ppy-GAC nanocomposite with increased functionality to be applied as a robust adsorbent for efficient and simultaneous removal of organic and inorganic pollutants from wastewater. MethodsA novel method for the preparation of Polypyrrole (Ppy) nanoparticles is presented. All materials were characterised using Raman spectroscopy and Atomic Force Microscopy (AFM). Significant findingsRaman spectroscopy of Janus Ppy-GAC nanocomposite depicts peaks for both Ppy and GAC with slight shifts of major peaks denoting a strong interfacial bond between the two phases. Ppy nanoparticles were successfully attached to one side of the GAC surface with relatively strong adhesion forces amounting to 10.8 nN on average. An increase in adhesion forces of 25% was observed when Ppy nanoparticles were deposited on the surface of GAC particles as compared to pristine GAC. This implies that the Janus Ppy-GAC nanocomposite is sufficiently robust to be used as an adsorbent for water treatment.

Development and characterization of polymer-modified vermiculite composite as novel highly-efficient adsorbent for water treatment

Expanded vermiculite (EVMT) modified with polyethylenimine (PEI) was developed, characterized, and evaluated as a promising adsorbent efficacious aquatic adsorption of Thorium (Th(IV)) ions. The foremost adsorptive chemical groups and surface morphologies of EVMT and PEI modified-EVMT (PEI-EVMT) were investigated by FTIR spectroscopy and SEM/EDX techniques. The change in Th(IV) adsorption yield with respect to the experimental parameters was methodically studied using factorial design analysis. The isotherm modeling studies showed that the adsorption data were in good correlation with the non-linear Langmuir model and the adsorption capacity of the PEI-EVMT adsorbent was determined to be as 872.2 mg g−1 during the 30 min contact time at pH 5 and 20°C. The kinetic studies demonstrated that the pseudo-second-order kinetic model is well appropriate for recognizing Th(IV) adsorption mechanism onto PEI-EVMT composite. The negative ΔG° (between -19.02 kJ.mol−1 and -16.76 kJ.mol−1) showing the spontaneity of Th(IV) adsorption onto PEI-EVMT composite in a temperature range of 293 to 333 K. The negative ΔH (-34.90 kJ.mol−1) proved that the adsorption proceeded exothermically under the studied temperature range. The ΔS value (-53.97 J.mol−1.K−1) demonstrated the decreased randomness throughout Th(IV) adsorption onto PEI-EVMT composite. The adsorption efficiency of PEI-EVMT composite for the removal of 5 mL of 10 mg L−1 Th(IV) ions in wastewater samples was found 90%. The desorption/desorption yield of the composite adsorbent was determined as 94/92%, 87/81%, 74/70%, 46/40, and 32/25% after the first, third, 5th, 8th, and 10th cycle, respectively. All obtained results revealed that the developed PEI-EVMT composite can be used as a promising adsorbent for considerable elimination of Th(IV) from aquatic media.

High-efficient, broad-spectrum and recyclable mesoporous TiO2 adsorbent for water treatment

Cooperative adsorption and degradation in situ, known as “hook and destroy” strategy, is an appealing idea to scavenge pollutants from water efficiently. However, commercial high-adsorption-capacity adsorbents are usually based on activated carbon, which is easily damaged in the pollutant degradation process, resulting in decreasing of the adsorption performance, while the adsorption capability of most inorganic adsorbents is inadequate for practical applications. To address the issues, we prepared a novel mesoporous titanium dioxide (m-TiO 2 ) by facile one-step hydrolysis method at room temperature. The m-TiO 2 exhibits both high adsorption capacity and short equilibrium time for a wide range of pollutants, such as dyes, pharmaceuticals and pesticides, due to its large surface area and abundant functional groups. The surface charge of the m-TiO 2 adsorbent can be regulated by adjusting the acidity and alkalinity of preparation conditions, hence the m-TiO 2 is capable of adsorbing either positively or negatively charged pollutants. The versatility for adsorption of diverse contaminants was demonstrated in the experiment of purifying lake water with multiple pollutants. More significant, the m-TiO 2 can be regenerated in minutes by in-situ degrading the adsorbed molecules using common oxidants, such as hypochlorite, the active ingredient of disinfectants. The adsorption performance has little deterioration in at least five successive cycles of adsorption and degradation. Considering the excellent adsorption performance, wide applicability and high recyclability, the mesoporous TiO 2 offers a sustainable approach to increasingly complex water environmental problems. ● Cooperative adsorption and degradation of pollutants in situ. ● Simultaneous degradation of adorbates and regeneration of adsorbents. ● Mesoporous structure expediting degradation. ● Large adsorption capacity and short equilibrium time. ● Broad applicability to diverse pollutants.

Super-adsorbent poly(acrylic acid)/laponite hydrogel with ultrahigh mechanical property for adsorption of methylene blue

Dye pollution has become a serious threat to environment and human health. Although versatile hydrogels have attracted intensive attentions due to their outstanding adsorption properties, the ultrahigh adsorption capacity and mechanical property are still two critical challenges for the practical applications. Herein, a super-adsorbent poly(acrylic acid)/laponite (PAAc/Lap) nanocomposite hydrogel with ultrahigh mechanical property and adsorption capacity of methylene blue (MB) is prepared by incorporating physical cross-linking with sparse chemical cross-linking. The hydrogel possesses porous 3D network structures and a fairly high water penetration with 1360 times of swelling ratio, which can allow the internal adsorption sites to be fully exposed and facilitate the adsorption. The adsorption capacity of MB can reach up to 3846 mg/g, which is almost the first time that a PAAc-based adsorbent could display superior adsorption capacity of more than 3800 mg/g towards MB. Important factors affecting the adsorption are also investigated, and the adsorption behavior is well fitted by the pseudo-second-order model and Langmuir isotherm model. More importantly, the appropriate physical cross-linking and sparse chemical cross-linking in the polymeric network endows hydrogel with superior mechanical properties. The tensile stress and strain are as high as 1.18 MPa and 2192%, which can facilitate the expansive applications and practical treatment. Mechanism analyses illustrate that the electrostatic interactions and cation-exchange between the functional groups of hydrogel and MB molecules contribute to the extraordinary adsorption ability. The proposed PAAc/Lap hydrogel with ultrahigh adsorption capacity and mechanical property is highly promising as an efficient super adsorbent for water treatment.

Kinetics, process design and implementation of zwitterionic adsorbent coating for dipolar dyes removal in wastewater treatment industry

Kinetic, thermodynamics and process design of the adsorption of dipolar dye molecules, namely Brilliant green (BG) and Naphthalene Blue 12B (NB12B), from aqueous solution using a zwitterionic adsorbent coating (ZwitAd) were investigated. This zwitterionic adsorbent coating was synthesized by a facile technique, which implied only 3 main chemicals: acrylic polymer emulsion (binder), bentonite (fillers) and EPIDMA (cationic polyelectrolyte). The scale-up of this formulation was proved showing that this coating adsorbent is viable to be adopted in a large-scale production. This novel adsorbent was synthesized in a coating form to obtain a feasible and practical application for the adsorption of both cationic and anionic dyes from wastewaters. Besides, this new adsorbent could be easily separated from the system without applying extra processing methods such as filtration or centrifugation. Adsorption studies showed that Freundlich model described satisfactorily the BG adsorption, whereas the NB12B adsorption was fitted with Langmuir isotherm. A single stage process was designed and the corresponding mathematical formulations was developed using the best adsorption models. Process design was performed to optimize the adsorbent amount for achieving a specific target of given initial effluent concentration and volume of treated wastewater. This optimization contributed to minimize the capital investment cost in order to satisfy a standard defined for the dye removal. Different alternatives for the application of this novel adsorbent in an industrial facility have been described and discussed. This study contributes with new findings to improve the implementation of novel adsorbents for water treatment and purification at industrial scale.

Study on removal of organic dyes by Fe3O4/amidation modified waste polystyrene composites

Design and fabrication of structurally optimized absorbents are important for wastewater treatment such as dyes removal. Herein, modifying the environmentally harmful waste polystyrene foam as an efficient recyclable adsorbent for organic dyes is important Magnetic amidated modified polystyrene (Fe 3 O 4 /PS-SD) was prepared by Friedel–Crafts reaction, N,N”-dicyclohexylcarbodiimide (DCC) dehydration condensation, and chemical co-precipitation reaction. Fe 3 O 4 /PS-SD had highly efficient removing performance for organic dyes in large volume of water sample solutions, and the equilibrium was achieved in 0.5 h. The maximum adsorption capacity for Methylene blue (MB), Safranine T (ST), and Congo red (CR) were 620.32 mg g −1 , 679.63 mg g −1 , and 1425.77 mg g −1 , respectively, at room temperature according to the Langmuir adsorption isotherm (R 2 > 0.91). The kinetic data of the three dyes followed pseudo-second-order kinetics. After ten regeneration cycles, the removal rate remained high (> 80%). Experimental results showed that Fe 3 O 4 /PS-SD was an excellent adsorbent for water treatment with high regeneration property and thermal stability. • Modification of waste materials. • High adsorption capacity. • Separable and thermally stable. • Recyclable.

Adsorption of benzene and toluene from aqueous solution using a composite hydrogel of alginate-grafted with mesoporous silica

Hydrogels are often claimed as optimal adsorbents for water treatment; however, their efficiency towards the removal of hydrophobic pollutants is still limited. As an alternative, hydrogels prepared from polymers functionalized with siliceous materials can overcome this issue. Here, a composite hydrogel (denoted as GEL-SBA15) was prepared using alginate grafted with mesoporous silica (SBA15) and poly(vinyl alcohol) for benzene and toluene adsorption from aqueous solutions. Adsorption studies demonstrated that a low dosage of GEL-SBA15 (10 mg) has a high adsorption capacity for benzene (1482.8 mg/g) and toluene (596.6 mg/g) under mild experimental conditions (pH 7.0, at 25 °C). Besides, the adsorption capacities of GEL-SBA15 for both pollutants were enhanced compared to the conventional hydrogel. Kinetic analysis showed that the adsorption of benzene and toluene follows a pseudo-second order model, while the experimental adsorption data were well-fitted by the Freundlich isotherm. According to this isotherm, the adsorption occurs via a collaborative process, and weak physical forces (π-π interactions, van der Waals and hydrophobic) are involved. Hence, the post-utilized GEL-SBA15 can be recycled and reused up to 6 times without losing adsorption performance. Although hydrogels are not common adsorbents for aromatic hydrocarbons, the results reported here rank GEL-SBA15 as a promising adsorbent for the removal of these pollutants from water.

Effective adsorption of carbamazepine from water by adsorbents developed from flax shives and oat hulls: Key factors and characterization

In this work, flax shives and oat hulls representative of cellulosic materials of agricultural byproducts were used to develop hydrochars and steam-activated hydrochar adsorbents. They were used to adsorb carbamazepine (CBZ) as a model pharmaceutical pollutant from artificially contaminated water. The adsorbents were characterized by surface properties and composition. CBZ equilibrium adsorption was investigated at various temperatures (20−40 °C) and solution pH (2−10). Steam-activation enhanced the CBZ equilibrium uptake of hydrochars made from either flax shives or oat hulls; however, both the hydrochars with or without steam-activation demonstrated effective CBZ adsorption in comparison with numerous adsorbents reported in the literature. The achieved CBZ uptake was insignificantly affected by solution pH, indicating that the adsorbents developed in this work could be applied to remove CBZ and similar pharmaceutical pollutants from water/wastewater with a wide range of pH values. The CBZ adsorption was effective at room temperature which was enhanced at a higher temperature, showing the adsorption was endothermic in nature. The results demonstrated that flax shives and oat hulls were a promising feedstocks for making into adsorbents for water treatment.