Removal of Cd2+ from water by use of super-macroporous cryogels and comparison to commercial adsorbents

In this study amphoteric cryogels were synthesized by the use of free-radical co-polymerization of acrylate-based precursors (methacrylic acid and 2-acrylamido-2-methyl-1-propansulfonic acid) with allylamine at different ratios. The physico-chemical characteristics of the cryogels were examined using SEM/EDX, FT-IR, XPS and zeta potential measurements. The cryogels were tested toward Cd 2+ removal from aqueous solutions at various pH and initial concentrations. Equilibrium studies revealed a maximum sorption capacity in the range of 132–249 mg/g. Leaching experiments indicated the stability of Cd 2+ in the cryogel structure. Based on kinetics, equilibrium and characterization results, possible removal mechanisms are proposed, indicating a combination of ion exchange and complexation of Cd 2+ with the cryogels’ surface functional groups. The cryogels were compared to commercially available adsorbents (zeolite Y and cation exchange resin) for the removal of Cd 2+ from various water matrices (ultrapure water, tap water and river water) and the results showed that, under the experimental conditions used, the cryogels can be more effective adsorbents

Experimental and modeling studies of Sr2+ and Cs+ sorption on cryogels and comparison to commercial adsorbents

In this work, two cryogels with the key monomers methacrylic acid and 2-acrylamido-2-methyl-1-propansulfonic acid (named AAC and SAC, respectively) with various functional groups were used as adsorbents for the removal of cesium and strontium ions from aqueous solutions. Kinetics, equilibrium, and column studies were carried out including experiments in different water matrices (ultrapure, tap, and river water) and comparison to commercial adsorbents. AAC reached sorption capacity of 362 mg g–1 for Cs+ and 209 mg g–1 for Sr2+, whereas SAC polymer showed maximum removal capacities of 259 and 211 mg g–1 for Cs+ and Sr2+, respectively. The five cycles of adsorption/desorption experiments showed a maximum of 8% loss of effectiveness for both cryogels. Batch kinetics adsorption data were modeled by using a rigorous diffusional model coupled to a novel fractal-like expression for variable surface diffusivity. The model revealed that the surface diffusivity dependence on time is nonmonotonic, with the occurrence of a maximum. Also, both fluid film and intraparticle transport resistances were shown to be important, with the internal one being more influential. The cryogels and two commercial materials (ion-exchange resin and zeolite) were tested for the removal of Cs+ and Sr2+ in ultrapure, tap, and river water; the results showed that the cryogels exhibit competitive effectiveness

EXPERIMENTAL AND MODELING STUDIES OF SR2+ AND CS+ SORPTION ON CRYOGELS AND COMPARISON TO COMMERCIAL ADSORBENTS

In this work, two cryogels with the key monomers methacrylic acid and 2-acrylamido-2-methyl-1-propansulfonic acid (named AAC and SAC, respectively) with various functional groups were used as adsorbents for the removal of cesium and strontium ions from aqueous solutions. Kinetics, equilibrium, and column studies were carried out including experiments in different water matrices (ultrapure, tap, and river water) and comparison to commercial adsorbents. AAC reached sorption capacity of 362 mg g−1 for Cs+ and 209 mg g−1 for Sr2+, whereas SAC polymer showed maximum removal capacities of 259 and 211 mg g−1 for Cs+ and Sr2+, respectively. The five cycles of adsorption/desorption experiments showed a maximum of 8% loss of effectiveness for both cryogels. Batch kinetics adsorption data were modeled by using a rigorous diffusional model coupled to a novel fractal-like expression for variable surface diffusivity. The model revealed that the surface diffusivity dependence on time is nonmonotonic, with the occurrence of a maximum. Also, both fluid film and intraparticle transport resistances were shown to be important, with the internal one being more influential. The cryogels and two commercial materials (ion-exchange resin and zeolite) were tested for the removal of Cs+ and Sr2+ in ultrapure, tap, and river water; the results showed that the cryogels exhibit competitive effectiveness

Efficient removal of mercury (II) from water by use of cryogels and comparison to commercial adsorbents under environmentally relevant conditions

Mercury is a toxic element, which can be found in air, water and soil in several inorganic and organic forms. Mercury pollution comes from a variety of industrial sources, including vinyl-chloride, pulp and paper, fertilizers and pharmaceuticals industry, gold mining and cement production. Gels have increasingly attracted the interest over the past decades and one of the investigated applications is the fast removal of organic substances, metals and other cations and anions from water. In this work, two types of cryogels were synthesized at sub-zero temperature by free-radical polymerization technique, characterized by using a set of complimentary methods and used for the removal of mercury from aqueous solutions of different chemistry. Kinetics and equilibrium studies were performed in ultra-pure water solutions in order to study the mechanisms in the presence nitrate and chloride ions. The cryogels exhibited excellent efficiency towards mercury removal from all model solutions. Moreover, the cryogels were tested in different water matrixes (tap, river and sea water) and compared to commercial adsorbents (activated carbon, strong acid resin and zeolite Y). Cryogels were able to remove mercury much faster than commercial adsorbents with the exception of seawater where activated carbon was superior

EFFECTIVE REMOVAL OF METHYLENE BLUE DYE BY A NOVEL 4-VINYLPYRIDINE-CO-METHACRYLIC ACID CRYOGEL: KINETIC, ISOTHERM, AND BREAKTHROUGH STUDIES

BACKGROUND: Industrial streams are the source of increasing amounts of textile dye pollution every year. Among the various adsorbents that have been tested for the removal of dyes, synthetic macroporous polymers are a promising choice due to their developed structure, the presence of active functional groups, and the possibility of regeneration and reuse for several cycles. In this work, a 4-vinylpyridine-co-methacrylic acid based cryogel (4-VP-MAAc) was synthesized at -12 °C by the free-radical polymerization technique, it was characterized using a set of complimentary methods, and then applied for the removal of methylene blue (MB) from water solutions. RESULTS: The adsorption of MB was enhanced at pH values higher than 7 due to the presence of anionic functional groups. The maximum equilibrium adsorption capacity achieved by 4-VP-MAAc was 703.6 mg/g at pH 8. Several kinetics, equilibrium, pH studies, and fixed-bed column experiments were completed in ultra-pure water to evaluate the performance and the mechanism of interaction of positively-charged dye with the polymer. Among the kinetic models applied, the pseudo-second order model best fit the experimental observations. The Langmuir model efficiently described the adsorption of MB onto the prepared cryogel, thus indicating monolayer adsorption. The ion exchange of the Na+ ions present in the structure of the cryogel with dye was found to be the main removal mechanism accompanied with a complexation reaction. No loss of adsorption capacity was observed in four successive adsorption/desorption cycles of 4-VP-MAAc use. CONCLUSION: This is the first time that a 4-vinylpyridine-co-methacrylic acid based cryogel has been synthesized and successfully applied to remove MB from water. © 2022 Society of Chemical Industry (SCI

ANTIMICROBIAL PROPERTIES OF THE TRICLOSAN-LOADED POLYMERIC COMPOSITE BASED ON UNSATURATED POLYESTER RESIN: SYNTHESIS, CHARACTERIZATION AND ACTIVITY

The manufacturing of sanitary and household furniture on a large scale with inherently antimicrobial properties is an essential field of research. This work focuses on the synthesis of polymer composites based on the unsaturated polyester of resin loaded with 5 wt.%-Triclosan produced by a co-mixing approach on automated technological complex with a potential for broad applications. According to findings, the polymer composite has a non-porous structure (surface area < 1.97 m2/g) suitable for sanitary applications to reduce the growth of bacteria. The chemical composition confirmed the presence of major elements, and the inclusion of Triclosan was quantitatively confirmed by the appearance of chlorine on XRF (1.67 wt.%) and EDS (1.62 wt.%) analysis. Thermal analysis showed the difference of 5 wt.% in weight loss, which confirms the loading of Triclosan into the polymer matrix. The polymer composite completely inhibited the strains of S. aureus 6538-P, S. aureus 39, S. epidermidis 12228, and Kl. Pneumoniae 10031 after 5-min contact time. The antimicrobial effects against Kl. pneumoniae 700603, Ps. aeruginosa 9027 and Ps. aeruginosa TA2 strains were 92.7%, 85.8% and 18.4%, respectively. The inhibition activity against C. albicans 10231 and C. albicans 2091 was 1.6% and 82.4%, respectively; while the clinical strain of C. albicans was inhibited by 92.2%. The polymer composite loaded with 5 wt.%-Triclosan displayed a stability over the period that illustrates the possibility of washing the composite surface

НҰР СҰЛТАН ҚАЛАСЫНДАҒЫ ЖӘНЕ ОНЫҢ ТӨҢІРІНДЕГІ (ҚАЗАҚСТАН РЕСПУБЛИКАСЫ) ҚАЛЫҚТЫҚ ЖӘНЕ ЖЕТІСТІК СУЛАРЫНДАҒЫ ДӘРІЛІК ЗАТТАРДЫҢ МОНИТОРИНГІ

The article presents the monitoring data of medicinal substances (PM) in the surface waters of the city of Nur-Sultan and its environs (Republic of Kazakhstan). The results show the presence of carbamazepine and sulfamethaxazole in surface waters. Samples were taken monthly from April to December 2021. Analysis of medicinal substances was carried out using the method of high performance liquid chromatography (HPLC). A possible reason for the presence of medicinal substances in surface waters is their entry with wastewater from the public utility sector of the city of Nur-Sultan into surface sources after treatment

Synthetic amphoteric cryogels as an antidote against acute heavy metal poisoning

The effectiveness of an amphoteric cryogel (AAC) as an oral sorbent (enerosorbent) for the treatment of acute poisoning of small animals (rats) with heavy metals (HMs) was studied in in vivo experiments. The morphological structure of the cryogel was examined using scanning electron microscopy/energy-dispersive X-ray analysis and confocal microscopy. The use of the cryogel in the treatment of rats administered an LD50 dose of Cd(NO3)2, CsNO3, Sr(NO3)2, or HgCl2 in aqueous solution showed their high survival rate compared to the control group, which did not receive such treatment. The histological and chemical analysis of internal tissues and the biochemical analysis of the blood of the experimental animals showed the effectiveness of the cryogel in protecting the animals against the damaging effect of HMs on the organism comparable with unithiol, a chelating agent based on 2,3-dimercapto-1-propane sulfonic acid sodium salt (DMPS) approved for the treatment of acute poisoning with some heavy metals

Removal of Cd2+ from Water by Use of Super-Macroporous Cryogels and Comparison to Commercial Adsorbents

In this study amphoteric cryogels were synthesized by the use of free-radical co-polymerization of acrylate-based precursors (methacrylic acid and 2-acrylamido-2-methyl-1-propansulfonic acid) with allylamine at different ratios. The physico-chemical characteristics of the cryogels were examined using SEM/EDX, FT-IR, XPS and zeta potential measurements. The cryogels were tested toward Cd2+ removal from aqueous solutions at various pH and initial concentrations. Equilibrium studies revealed a maximum sorption capacity in the range of 132&ndash;249 mg/g. Leaching experiments indicated the stability of Cd2+ in the cryogel structure. Based on kinetics, equilibrium and characterization results, possible removal mechanisms are proposed, indicating a combination of ion exchange and complexation of Cd2+ with the cryogels&rsquo; surface functional groups. The cryogels were compared to commercially available adsorbents (zeolite Y and cation exchange resin) for the removal of Cd2+ from various water matrices (ultrapure water, tap water and river water) and the results showed that, under the experimental conditions used, the cryogels can be more effective adsorbents

MACROPOROUS CRYOGEL COMPOSITES FOR REMOVAL OF HEAVY METALS FROM AQUEOUS AND BIOLOGICAL MEDIA

The deficiency of clean water is intensely associated with poor health, poverty and a general decline in living standards. Water is important not only for life but it is also the main resource for food and crops production and is used in most industrial processes. In spite of the natural source of water contamination, a continuous rise of heavy metals discharges to aquatic bodies caused by fast industrial development over the last century has been observed. Heavy metals such Cd2+ and Hg2+ are of the most toxic and, as all heavy metals, have a tendency to accumulate in the food chain potentially causing serious health disorders. Another source of water contamination is the nuclear power plants. Among the harmful radionuclides discharged are the radioisotopes of I-, Cs+ and Sr2+. To improve the availability of clean water, low-cost and effective treatment methods must be developed to remove toxic metal ions. Several water treatment technologies are available with adsorption/ion-exchange combined to chelation/complexation are the most effective. In this work, highly effective adsorbents based on polymeric cryogels were developed for the removal of Cd2+ Hg2+, Sr2+, Cs+ and silver-modified forms for targeted removal of I-. Two types of macroporous cryogels were synthesized by free-radical co-polymerization of acrylate-based precursors with allylamine under sub-zero temperature conditions. The adsorption/ion exchange capacity of cryogels is due to the presence of key monomers, methacrylic acid and 2-acrylamido-2-methyl-1-propansulfonic acid. The cryogels were comprehensively characterized and used for the removal of the above mentioned ions from model solutions. Kinetics and equilibrium studies were conducted, models were applied and in combination to post-sorption characterizations potential removal mechanisms were proposed. Finally, the cryogels were tested under environmentally relevant conditions (tap water, river water and sea water) and compared to commercial adsorbents (zeolite Y, ion exchange resin and activated carbon) for the removal of Hg2+ showing excellent behavior. After successful experiments on water, cryogels were used as enterosorbents in animal experiments by using rats. The rats were poisoned with LD50 dose of metals and were treated by cryogels. The results showed high survival rate and an overall decline of concentration of metals in animal tissues. The discoveries of this work demonstrate that cryogelic sorbents have possible implementation in water treatment and as poisoning antidotes