Hydrogel Adsorbent Research Articles

Clay minerals/sodium alginate/polyethylene hydrogel adsorbents control the selective adsorption and reduction of uranium: Experimental optimization and Monte Carlo simulation study

Clay minerals formations are potential geological barrier (host rocks) for the long-rerm storage of uranium tailing in deep geological repositories. However, there are still obstacles to the efficient retardation of uranium because of the competition between negatively charged regions at the clay minerals end face, surface and between layers, as well as low mineralization capacity. Herein, employing a simple method, we used sodium alginate (SA), an inexpensive natural polymer material, polyethylene (PE), and the natural clay minerals montmorillonite (Mt), nontronite (Nt), and beidellite (Bd) to prepare three hydrogel adsorbents, (denoted as Mt/PE-@SA, Nt/PE-@SA, and Bd/PE-@SA), respectively. The application of obtained hydrogel adsorbents further extends to uranium(VI) removal from aqueous. Due to the synergistic action of SA group and PE group, hydrogel adsorbents showed select adsorption and mineralization effect on uranium(VI), among which the maximum uranium(VI) adsorption capacity of Nt/PE-@SA was 133.3 mg·g-1 and Mt/PE-@SA exhibited strong selectivity for uranium(VI) in the presence of coexisting metal ions. Cyclic voltammetry studies indicated the mitigation and immobilization of uranium species onto adsorbents by both reduction and mineralization. Besides, the synergistic adsorption of SA and PE on clay minerals was hypothesized, and the idea was supported by structure optimizations results from Monte Carlo dynamics simulation (MCD). Three obtained hydrogel adsorbents structural model was constructed based on its physicochemical characterization, the low energy adsorption sites and adsorption energies are investigated using MCD simulation. The simulation results show that obtained hydrogel adsorbents have a strong interaction with uranium(VI), which ensures the high adsorption capacity of those materials. Most importantly, this work demonstrates a new strategy for preparing mineral-based hydrogel adsorbents with enough stability and provides a new perspective for uranium(VI) removal in complex environment.

Green chemistry route to chitosan hydrogels and investigation of the materials as efficient dye adsorbents

Abstract Biopolymer-based materials for the adsorption of toxic dyes represent an interesting class of materials for environmental applications. Here we report on chitosan as the starting material for synthesizing dye adsorbents. In particular, the synthesis, characterization, and cationic dye adsorption properties of chitosan hydrogel adsorbents are reported. Polyanionic itaconated chitosan derivatives were synthesized in solvent-less conditions for the first time. Itaconated chitosan was cross-linked using thiol-ene chemistry to obtain hydrogels. The influence of the incorporated carboxylate groups and the cross-linker fraction on the adsorption of Methylene Blue (MB) was investigated. In addition, the impact of pH, adsorbent dose, initial concentration, and ionic strength were investigated to determine the optimum conditions for MB uptake, and the dye uptake kinetics, adsorption isotherms, selectivity, and reusability of the adsorbents were unveiled. A maximum adsorption capacity of 556 mg/g could be achieved, outperforming commercial activated charcoal and ion exchange resins. Furthermore the chitosan hydrogel adsorbents were shown to capture >90 % of cationic MB from a binary equimolar mixture with the anionic dye Methyl Orange. Since the adsorbents can be regenerated and re-used afterwards at least 20 times, retaining a high dye adsorption fraction of >95 %, these materials are promising candidates for environmental applications.

Integrating DFT and machine learning for the design and optimization of sodium alginate-based hydrogel adsorbents: Efficient removal of pollutants from wastewater

This study presents a novel approach to design and optimize a sodium alginate-based hydrogel (SAH) for efficient adsorption of the model water pollutant methylene blue (MB) dye. Utilizing density functional theory (DFT) calculations, sodium alginate-g-poly (acrylamide-co-itaconic acid) was identified with the lowest adsorption energy (Eads) for MB dye among 14 different clusters. SAHs were prepared using selected monomers and sodium alginate combinations through graft co-polymerization, and swelling studies were conducted to optimize grafting conditions. Advanced characterization techniques, including FTIR, XRD, XPS, SEM, EDS, and TGA, were employed, and the process was optimized using statistical and machine learning tools. Screening tests demonstrated that Eads serves as an effective predicting indicator for adsorption capacity (qe) and MB removal efficiency (RRMB,%), with reasonable agreement between Eads and both responses under given conditions. Process modeling and optimization revealed that 5 mg of selected SAH achieves a maximum qe of 3244 mg g−1 at 84.4% RRMB under pH 8.05, 98.8 min, and MB concentration of 383.3 mg L−1, as identified by the desirability function approach. Moreover, SAH effectively eliminated various contaminants from aqueous solutions, including sulfasalazine (SFZ) and dibenzothiophene (DBT). MB adsorption onto selected SAH was exothermic, spontaneous, and followed the pseudo-first-order and Langmuir-Freundlich isotherm models. The remarkable ability of SAH to adsorb MB is attributed to its well-designed structure predicted through DFT and optimal operational conditions achieved by AI-based parametric optimization. By integrating DFT-based computations and machine-learning tools, this study contributes to the efficient design of adsorbent materials and optimization of adsorption processes, also showcasing the potential of SAH as an efficient adsorbent for the abatement of aqueous pollution.

Alkali-treated yttrium-containing chitosan-based hydrogels for phosphate recover with highly selective in wide pH aqueous solution

Excessive discharge of wastewater containing phosphorus is the leading cause of water eutrophication. In this study, yttrium ions were embedded in chitosan/polyvinyl alcohol hydrogel beads by adsorption of amino functional groups. After alkali treatment, a new chitosan-based yttrium hydrogel adsorbent (PC-Y-OH) with porous channels was perpetrated. The results showed that alkali treatment reduced the protonation of amino functional groups in hydrogel and made PC-Y-OH have stable adsorption of phosphate in the initial solution of pH 4∼10. Compared with hydrogel beads without alkali treatment (PC-Y3+), the inhibition of high concentration bicarbonate and sulfate of PC-Y-OH was reduced by 47 % and 43 %, respectively, under acidic conditions (initial pH of 3). In weak acid (initial pH of 6) or alkaline (initial pH of 8) conditions, its adsorption capacity is almost uninhibited by co-existing substances. After regenerating the adsorbent with an alkali solution 7 times, the adsorption capacity was still over 80 % of the first adsorption. The adsorption kinetics and thermodynamics results indicated that PC-Y-OH could reach the adsorption equilibrium within 2 h, and the adsorption process was a spontaneous exothermic process with a maximum adsorption capacity of 62.36 mg-P/g. Surface chemical analysis of the adsorbent indicated that phosphate adsorption on the adsorbent was primarily driven by chemical complexation. Moreover, this provides a promising adsorbent for recovering phosphorus from aquatic environments.

Preparation of modified humic acid/TiO2/P(AA-co-AM) nanocomposite hydrogels with enhanced dye adsorption and photocatalysis.

A novel composite hydrogel with exceptional adsorption and photocatalytic properties was synthesized using modified coal-based humic acid (HA-C), modified titanium dioxide (TiO2) nanoparticles, acrylic acid (AA), and acrylamide (AM) as precursors. The modification of HA-C and TiO2 significantly enhances the structural support provided by the hydrogel for photocatalytic components. Moreover, we investigated the effects of monomer ratio, dye concentration, temperature, and pH on the material properties. Additionally, we tested the mechanical strength, swelling behavior, and reusability of the hydrogels. The composite hydrogel's adsorption performance and synergistic adsorption-photocatalytic performance were evaluated based on its removal rate for both absorbed and degraded methylene blue (MB). Remarkably, incorporating HA-C greatly improved the adsorption efficiency of the composite hydrogel for methylene blue to a maximum capacity of 1490 mg g-1. Furthermore, TiO2 nanoparticles in the structure promoted MB degradation with an efficiency exceeding 96.5%. The hydrogel exhibited excellent recoverability and reusability through nine cycles of adsorption/desorption as well as six cycles of degradation.

Removal of methylene blue dye from water with Fe3O4/poly(HEMA-co-AMPS) magnetic hydrogels

In this research, a novel magnetic hydrogel (MHG) adsorbent based on Fe3O4/poly(2-hydroxyethylmethacrylate-co-2-acrylamido-2-methylpropanesulfonic acid) Fe3O4/poly(HEMA-co-AMPS) was synthesized by in situ co-precipitation of Fe3O4 magnetic particles inside poly(HEMA-co-AMPS) hydrogels. This adsorbent was used to adsorb the organic cationic dye methylene blue (MB) from aqueous solutions. The properties of the adsorbent were characterized by FT-IR, TGA, XRD, VSM, and EDX-SEM techniques. The degree of swelling was recorded in water, acidic medium (HCl 0.01 M), and basic medium (NaOH 0.01 M). The results confirmed that Fe3O4 particles were successfully synthesized within the poly(HEMA-co-AMPS) hydrogel structure. Magnetic hydrogels have higher swelling and reach equilibrium faster than hydrogels. The magnetic hydrogel prepared with 3 % crosslinker and 10 % AMPS (MHG3(10)) showed better potential to remove MB dye, adsorption capacity Qmax = 445.35 mg/g, this was obtained under the best conditions at pH 6.5, dose of 1 g/L, and contact time of 10 min. Over the test pHpzc, the surface of the MHG3(10) is predominantly negative at pH values higher than 2.47. The adsorption process of MHG3(10) for MB removal follows the Langmuir model and obeys pseudo-second-order kinetics. In addition, thermodynamic studies performed show that the adsorption process is endothermic (ΔH0 = 75.946 kJ/mol) and spontaneous with a positive value of entropy (ΔS0 = 263.562 J/mol·K). Regeneration experiments showed that MHG3(10) can be reused several times as its removal efficiency is still 94 % after 10 adsorption–desorption cycles. Therefore, the magnetic hydrogel MHG3(10) proved to be a promising adsorbent for the removal of the pollutant MB dye from aqueous media.

SYNTHESIS, STRUCTURE AND PROPERTIES OF BENTONITE - ACTIVATED CARBON COMPOSITE

The development of adsorption purification technology in industry is divorced from research in the development of new methods for the synthesis and modification of composites, while the efficiency of the adsorbent directly depends on its structural and surface properties. Currently, there is an increasing demand for hydrogel adsorbents used in pharmaceuticals, medicine, and the chemical industry for wastewater treatment. Dash-Salakhlinsky bentonite, a natural clay mineral and activated carbon of the BAU-A brand, was used as an object of study. By intercalation of bentonite with activated carbon, a bentonite-coal composite was obtained. Grinding equipment of medium energy density was used: roller-ring vibrating mill VM-4. Activation time was 15 min. The average particle size of the initial bentonite and bentonite-carbon composite was determined by laser diffraction on a particle size analyzer. During mechanical activation of bentonite, the nature of the distribution of particles indicates the predominant process of aggregation over grinding. The morphology, structure, and textural properties of the composite were studied by the methods of low-temperature nitrogen adsorption-desorption and IR spectroscopy. An increase in the specific surface area and porosity after mechanochemical activation as compared to the calculated values indicates the interaction between the components. IR spectroscopy established the formation of additional functional groups that can act as active centers, which positively affects the adsorption properties. It is shown that the bentonite-charcoal composite has a high sorption activity with respect to the brilliant green dye. The data obtained can be useful in the development of effective sorbents for wastewater treatment from pollution by organic compounds, as well as in medicine and pharmaceuticals.

Effects of Silica Hydrogel on Degumming of Fragrant Rapeseed Oil.

Hot-pressed rapeseed oils with pleasant flavor, i.e., fragrant rapeseed oils, are favored by consumers, especially people from the southwest provinces of China. Although degumming is an important section in producing edible rapeseed oils, conventional degumming techniques are generally suffered from disadvantages such as moisture control, and large losses of micronutrients and flavors. In the present paper, hot-pressed rapeseed oils were treated with silica hydrogel to remove their gums, and changes in phospholipids, acid values, peroxide values, tocopherols, total phenols, and flavor compounds were analyzed to compare the silica hydrogel-degumming with conventional methods. The optimized conditions were suggested to be carried out at 45°C for 15 min, and the silica hydrogel dosage was 1.10%. More than 97.00% of phospholipids were removed after the degumming, and more than 85.00% of micronutrients, were retained in the treated oils. The degumming efficiency was therefore significantly higher than those operated by conventional acid degumming and soft degumming techniques. It was found that the dosage of the silica hydrogel significantly affected the removal rate of phospholipids compared with degumming time and temperature. There were nearly typical volatile compounds found in the rapeseed oils, while most of them kept almost stable after the silica hydrogel-degumming. In this regard, silica hydrogel adsorption exhibited little effect on volatile compounds, making it more suitable for the production of fragrant rapeseed oils.

Low-cost and eco-friendly PVA/carrageenan membrane to efficiently remove cationic dyes from water: Isotherms, kinetics, thermodynamics, and regeneration study

Methylene blue (MB), a common dye in the textile industry, has a multitude of detrimental consequences on humans and the environment. Accordingly, it is necessary to remove dyes from water to guarantee our health and sustainable ecosystem. In this study, we developed polyvinyl alcohol (PVA)-based hydrogel adsorbents with high adsorption capacity by adding three types of carrageenan (kappa, iota, and lambda) to remove MB from water. Thanks to the functional groups, the PVA/carrageenan membranes dramatically increased the removal efficiency (kappa, 98.8%; iota, 97.0%; lambda, 95.4%) compared to the pure PVA membrane (6.3%). Among the three types of PVA/carrageenan membranes, the PVA/kappa-carrageenan membrane exhibited the best adsorption capacity of 147.8 mg/g. This result implies that steric hindrance was considerably significant, given that kappa carrageenan has only one sulfate group in the repeating unit, whereas iota and lambda carrageenan composite PVA membranes possess two and three sulfate groups. Apart from the maximum adsorption capacity, this study addressed a variety of characteristics of PVA/carrageenan membranes such as the effects of initial MB concentration, kappa carrageenan weight percentage, contact time, adsorbent dosage, and temperature on the adsorption performance. In addition, the kinetic and thermodynamic studies were also carried out. Lastly, the reusability of the PVA/carrageenan membrane was verified by the 98% removal efficiency maintained after five adsorption-desorption cycles.

Photovoltaic passive cooling via water vapor sorption-evaporation by hydrogel

Photovoltaic (PV) power generation, which converts sunlight into electricity, stands as a pivotal mode of solar energy utilization. The thermal effect poses a significant challenge for all types of PV panels under real operating conditions, as it diminishes both the photovoltaic conversion efficiency and the lifespan of the PV panels. This paper presents a novel passive cooling approach for silicon-based photovoltaic panels, employing night-time hygroscopic hydrogel adsorption, daytime desorption, and subsequent water evaporation for cooling. Both laboratory and outdoor experiments were conducted to validate this strategy. Experimental results reveal that under simulated laboratory light of 1 kW m−2, the hydrogel cooling layer delivers an average cooling power of 288.2 W m−2. It lowers the PV panel temperature by 9.9 °C and enhances both the maximum power and efficiency at equilibrium by 5.92% and 5.93%, respectively. Outdoor experiments in Beijing, China, during summer demonstrated that this method reduced the average daytime temperature of the PV plate by 7.1 °C and increased the average maximum power by 5.21%. The hydrogel layer's high hygroscopicity enables it to support passive cooling effectively all day. Passive cooling strategies for PV panels, leveraging the atmospheric water harvesting cycle, face fewer application constraints. They offer the potential to increase power generation and reduce CO2 emissions from PV plants both now and in the future.

One-step green construction of granular composite hydrogels for ammonia nitrogen recovery from wastewater for crop growth promotion

The great application potential of hydrogel adsorbent in water treatment has been widely reported in recent years. However, practical application is severely restricted due to the tedious preparation procedures, high energy consumption, and potential environmental threat of spent adsorbent after adsorption. To address these challenges, a new method was proposed in this study to prepare granular hydrogel composites through one-step polymerization induced phase separation (PIPS), initiated via a redox reaction consisting with calcined oil shale semi-coke (COSSC) and active ingredients of in green tea (GT) at 40 °C. Then granular hydrogel was applied to remove NH4-N in wastewater, and the spent adsorbent after adsorbing was used as the medium for plant growth. The granular hydrogel exhibited a favorable swelling capacity of 205 g/g and excellent adsorption capacity of 40.2 mg/g for NH4-N. Remarkably, the adsorption process achieved equilibrium only within 30 min. To avoid the influence of soil and other factors, we conducted a soilless cultivation experiment, and the results showed that the total seed biomass of mung bean increased by 33.69% with adding 1% of spent hydrogels into the culture medium. Based on above excellent performance, this study presented a feasible idea for the green preparation granular hydrogel composites and offered a promising strategy for the sustainable utilization of spent adsorbent.

Fabrication of in situ metal-organic framework grown on sodium lignosulphonate hydrogel for removal of Pb2+, methylene blue and crystal violet from aqueous solution

In this study, the metal-organic framework (MOF) was successfully compounded with lignosulfonate/diethylenetriaminepentaacetic acid (SLS/DTPA) hydrogels adsorbent using an assembly strategy that combined free radical polymerization and in-situ growth. The SLS/DTPA@ZIF-8 adsorbent exhibited excellent performance in removing heavy metal ions (Pb2+) and cationic dyes (methylene blue, MB and crystal violet, CV) from wastewater. To determine the maximum adsorption capacity, various influencing factors such as contact time, initial concentration of contaminant solution, adsorbent dosage and pH of solution were systematically discussed. The maximum adsorption capacities of Pb2+, MB and CV were calculated from Langmuir isotherm model to be 1021.85, 890.90 and 827.54 mg g−1, respectively (C0 (Pb2+) = 100 mg L−1, C0 (MB) = C0 (CV) = 25 mg L−1, pH = 6 ± 0.2, dosage = 0.2 g L−1 and T = 298K). The results of adsorption kinetic and isotherm experiments indicate that the pseudo-second-order and Langmuir isotherm models are most appropriate for describing physical and chemical adsorption processes occurring simultaneously. The XPS results confirmed that functional groups containing O and C were involved in the interaction of hydrogen bonding and electrostatic attraction between pollutants and hydrogel adsorbents. Additionally, the adsorbent's regeneration capabilities were studied. Five regeneration cycles later, the adsorbent still had good adsorption performance for the target pollutant. Overall, the present study shows a low-cost, green and efficient hydrogel adsorbent that exhibits remarkable efficacy in removing Pb2+ and dye from aqueous solutions.

Synthesis of Carboxymethylcellulose–Acrylamide–Montmorillonite Composite Hydrogels for Wastewater Purification

The three-dimensional network and ample pore structure of novel hydrogel materials enable outstanding adsorption performance for pollutants such as methylene blue (MB) and Cr6+ ions in wastewater. In order to develop an environmentally friendly hydrogel with high adsorption performance and low cost, a type of carboxymethyl cellulose (CMC) composite hydrogel was synthesised with montmorillonite (MMT) via chain radical polymerization, which gives it great potential for application in the field of wastewater purification. A series of hydrogel samples were characterised through SEM, FTIR and nitrogen porosimetry analysis, indicating the successful intercalation of MMT nanosheets into the hydrogel crosslinking network. The mass ratio of CMC to MMT, the amounts of adsorbent, the initial concentration of wastes, pH, and the adsorption temperature were investigated and optimised for hydrogel adsorption performance. When the initial concentration of MB is 60 mg/L, pH is 7, the dosage of MB is 0.5 g/L, and the adsorption temperature is 30 °C, the hydrogel sample the highest adsorption capability for MB removal, with an adsorption amount of 112.9 mg/g. When the initial concentration of Cr6+ is 10 mg/L with a pH of 7, the highest adsorption capacity of the hydrogel for Cr6+ removal is 1.35 mg/g. The fitting results of the isothermal models, the kinetic models, internal particle diffusion models and the thermodynamics of the experimental data of the adsorbate adsorption process show that the adsorption of MB by hydrogel is a spontaneous segmented process of multi-layer physical and chemical adsorption. Additionally, the adsorption of Cr6+ ions by hydrogel is a spontaneous segmented process of multi-layer physical adsorption.

Controllable microfluidic fabrication of honeycomb capsule adsorbent via the one-step titration-gel method

The hydrogel capsule adsorbent with honeycomb architectures was prepared via the one-step titration-gel method (OSTGM), which the casting solution contained polyvinyl alcohol (PVA), sodium alginate (SA) and tetraethyl orthosilicate (TEOS) were directly dripped into CaCl2 and H3BO3 aqueous mixture through a controllable microfluidic device. The microscopic morphology and adsorbed capacity of the SA-PVA-SiO2 capsules (SPSC) were absolutely depended on the parameter conditions during preparation. In this paper, at optimal synthesis situations [SA: PVA = 3: 7 (w: w), TEOS: (SA-PVA) = 2: 30 (v: w), the titration-gel distance was 14 cm and the feed flowed rate was 13 mL/h], the maximal removed capacity of the MB by the SPSC was 392.54 mg/g, and the SiO2 NPs accounted for 17.94 wt % of the polymers. The prepared SPSC, also, could work in overly acid and alkaline aqueous solutions (pH 1-13). The authors of this manuscript hoped this work would provide a corresponding guideline for the researchers who are aiming at preparing the spherical hydrogel adsorbents for waste water treatments.

Efficient treatment of palladium from wastewater by acrolein cross-linked chitosan hydrogels: Adsorption, kinetics, and mechanisms

Herein we present a study on the preparation and properties of a hydrogel adsorbent for treatment of wasted palladium souring from actial petrochemical industrial wastewater. Chitosan was used as the raw material and acrolein as the cross-linking agent for the hydrogel (A/CS). The adsorption behaviors of the hydrogel for Pd(II) ions were characterized and analyzed. The effect of pH, temperature, adsorption kinetics, and thermodynamics were investigated. Langmuir models were employed to describe the adsorption isotherms, while the pseudo-second-order equation was applied to describe the adsorption kinetics. The experimental results demonstrated that the adsorption was a monolayer chemical adsorption, and the adsorption capacity was found to reach 505.05 mg/g under optimal conditions. In addition, FT-IR and XPS analyses, combined with MS calculations confirmed that chelation and electrostatic attraction were dominated in the adsorption process. Overall, the development of this hydrogel adsorbent will provide a practical approach to the treatment of industrial wastewater containing palladium and have great potential for practical applications.

Sodium alginate hydrogel-encapsulated trans-anethole based polymer: Synthesis and applications as an eradicator of metals and dyes from wastewater

Clean and safe water resources are essential for environmental safety and human health. Hydrogels and biomass polymers have attracted considerable attention in recent years, considering their nontoxicity, controllable performance, and high adsorption capacity. The interpenetrating network described here is a combination of a biomass polymer and a hydrogel adsorbent was established, the biomass polymer microspheres were first prepared with the combination of biomass monomer trans-anethole and maleic anhydride copolymer. A simple, environmentally friendly, and facile method of incorporating biomass polymer into sodium alginate biopolymer was developed by introducing the cross-linking agents calcium chloride and glutaraldehyde into the biomass polymer. Furthermore, the biomass polymer sodium alginate hydrogel (BP@SA/H) was characterized by FTIR, XPS, SEM, and XRD. In order to test materials' performance, the removal of pollutants and the adsorption study were also investigated after and before adsorption toward metals and dyes in water. We examined the factors influencing the materials, adsorption capability, such as initial concentration, time, absorbent amount, and pH. Moreover, the maximum adsorption values for Pb+2 and Cd+2 were 734.9 and 722 mg/g. While the adsorption toward RhB dye are 745 mg/g. In addition, the adsorption results were investigated using kinetic and isothermal models, demonstrating that biomass polymer hydrogel adsorption is chemisorption. Therefore, the as-developed biomass polymer sodium alginate hydrogel (BP@SA/H) is an exceptional multifunctional material that can be used to remove hazardous pollutants from wastewater.

Fabrication of sodium alginate-doped carbon dot composite hydrogel and its application for La (III) adsorption and enhanced the removal of phosphorus.

Adsorption is an effective method for the removal of hazardous substances from wastewater. In this work, a low-cost and environmental-friendly composite hydrogel material of sodium alginate doped with nitrogen doped carbon dots (SA@NCDs) was fabricated by impregnation for lanthanide and enhanced phosphorus adsorption in wastewater. The effects of NCDs doping amount, dosage, pH, initial solution concentration, adsorption time and temperature on the process of La (III) adsorption by SA@NCDs were investigated. The adsorption isotherms fitted to Langmuir isotherm model (R2 = 0.9970-0.9989) and the adsorption kinetics followed pseudo-second-order kinetic model (R2 = 0.9992). The maximum adsorption capacity of the adsorbent for La (III) was 217.39mg/g according to the Langmuir model at 298.15K. After five cycles, the removal efficiency of La (III) adsorbed by SA@NCDs was still 85.1%. Moreover, the loaded La (III) enhanced the adsorption of phosphorus. The La (III)-SA@NCDs-5 hydrogel adsorbent greatly improved the adsorption capacity for phosphorus compared with the La (III)-free adsorbent, and the adsorption amount can reach 9.64mg-P/g. The SA@NCDs complex hydrogels for rare earth adsorption were prepared by introducing NCDs rich in amino group into SA hydrogels. The introduction of NCDs increases the adsorption sites of hydrogels, and also overcomes the problem that NCDs itself is difficult to recover in wastewater treatment applications. The lanthanide adsorbed material has a stable structure and can be used to remove phosphorus to deal with waste using the waste. It indicates the SA@NCDs hydrogel composite adsorbent have good potential for wastewater treatment.

Preparation, properties and applications of porous hydrogels containing thiol groups for heavy metal removal

A novel porous hydrogel adsorption material, called PAM/PAA/PDMTM gel, has been developed for the removal of heavy metal ions in complex systems. The gel is composed of polyacrylamide, polyacrylic acid, and poly(2,4-dimercapto-6-mercaptopropenyl-1,3,5-triazine) monomer. This hydrogel material features a large pore structure, abundant active functional groups, high swelling properties, good thermal stability, and remarkable regeneration ability. More importantly, the hydrogels contain a variety of active groups, they show good complex adsorption properties for heavy metals. The PAM/PAA/PDMTM gel demonstrated excellent adsorption performance, with the maximum adsorption capacity of Cu2+, Cd2+ and Pb2+ reaching 92.33, 110.08 and 200.97 mg g−1 (pH 5, 298 K), respectively. And the adsorption was in accord with the pseudo-second-order model and Langmuir model. Notably, the PAM/PAA/PDMTM gel also demonstrated remarkable adsorption capacity for Pb even in soil, making it an efficient adsorption material for removing heavy metals from both water and soil samples.

Facile construction of lignin-based network composite hydrogel for efficient adsorption of methylene blue from wastewater

Adsorption method is an effective approach to treat wastewater containing methylene blue. Herein, a cost-effective and eco-friendly lignin-based network composite hydrogel adsorbent (PAA@SML) was constructed by using polyacrylic acid (PAA) to crosslink with sulfomethylated lignin (SML) via free radical polymerization for adsorption of methylene blue (MB) from wastewater. The constructed PAA@SML-0.2 exhibited remarkable adsorption performance towards removal of MB, with a maximum theoretical adsorption capacity of 777.1 mg·g−1. The improved efficiency can be attributed to the well-established network structure and abundant hydrophilic functional groups present in the adsorbent, promoting the interaction between methylene blue (MB) molecules and the adsorption sites of the adsorbent. The adsorption process of the adsorbent for MB followed the pseudo-second-order kinetic and the Langmuir isotherm models, which illustrated the adsorption process attributed to monolayer chemisorption. Mechanism investigation confirmed that the adsorption of MB by PAA@SML-0.2 primarily relied on hydrogen bonding and electrostatic interactions. Moreover, the recyclability test demonstrated excellent regeneration usability and stability of PAA@SML-0.2, and the adsorption capacity maintained above 74.0 % after five cycles. This constructed lignin-based network composite hydrogel is considered to have great potential in the treatment of organic dye in wastewater.

Synthesis of a gelatin based molecularly imprinted hydrogel with high selectivity on adsorbing bovine serum albumin

Molecularly imprinted polymers are confronted with many challenges during application to separating proteins, this study synthesized a molecularly imprinted hydrogel (MIP hydrogel) for specifically separating bovine serum albumin (BSA) with high selectivity. By using the ionic liquid [VAFMIM]Cl as the structure functional monomer and N-isopropylacrylamide (NIPAM) as the thermo-sensitive functional monomer, the obtained gelatin based MIP hydrogel was porous, showed good mechanical properties and outstanding swelling ability. The methacrylation of gelatin improved the MIP hydrogel greatly on mechanical strength. The employment of NIPAM enabled the obtained MIP hydrogel thermo-responsive on swelling ability and adsorption capacity. The BSA adsorption capacity of MIP hydrogel was as high as 150.18 mg/g when the BSA initial concentration was used at 0.5 mg/mL, and the imprinting factor of MIP hydrogel was achieved as high as 5.17. The selectivity coefficients against bovine hemoglobin and lysozyme achieved as high as 11.83 and 9.39, respectively. In BSA/BHb mixture, the MIP hydrogel separation factor toward BSA was still as high as 23.97, and the MIP hydrogel adsorption capacity toward BSA was 4.64-fold larger than that of NIP hydrogel. The adsorption kinetics and isotherm study demonstrated the surface of the synthesized MIP hydrogel was homogenous, the adsorbing active sites were identical with equal energy, the BSA molecules were adsorbed monolayer on MIP hydrogel, the adsorption process was chemisorption and diffusion-controlled. The prepared MIP hydrogel was favorable and showed high potentiality on specific separation of BSA.