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Copper is one of the toxic heavy metal, it has to be eliminated from the polluted environment. Thus, the present work was aimed to prepare glutaraldehyde crosslinked chitosan oligosaccharide (COS)-based binary and ternary blend using carboxymethyl starch (CMS) and kaolin clay (KC) and applied as a sorbent for copper(II) ions to overcome excessive heavy metal pollution. Initially, the binary and ternary blends are prepared using sol–gel method and then examined for its formation and suitability for adsorption using FTIR, XRD, BET, Zeta potential and SEM studies. The prepared COS/CMS and COS/CMS/KC blends demonstrated outstanding adsorption properties for the arrest of Cu2+ ion. The adsorption efficiency of the prepared binary and ternary blends was examined through batch mode, and the experimental data were fitted with Langmuir and Freundlich isotherm models and kinetic models. The obtained results revealed that the Langmuir model showed better fit for binary blend and for ternary blend Freundlich isotherm model showed better fit through the highest R2 values. The maximum adsorption capacity was 98.91 mg/g and 132.45 mg/g for binary and ternary blends, respectively. [ABSTRACT FROM AUTHOR]

Recently, 3D cryogels with the interconnected macropore structure have gained great attention owing to their immense application potential in wastewater cleanup. Here, we fabricated a pure poly(vinyl imidazole) cryogel through improved cryogelation method, adding the pre-freezing–thawing step, which reduced the temperature difference between the different positions of the precursor solution during reaction. Compression experiments showed that the prepared 3D cryogel featured a robust underwater elastic performance. The adsorption capacity of Cu(II), Ni(II), Zn(II), Co(II), Pb(II), and Cd(II) ions from aqueous solutions by the poly(vinyl imidazole) cryogel was explored. The results showed the specific adsorption of Cu(II), in which the adsorption capacity and removal efficiency reached 148 mg/g and 99.99%, respectively. The adsorption capacity was 58 times higher than that of the reported poly(vinyl imidazole) cryogel which was prepared using hydroxyethyl methacrylate as the comonomer frameworks. In the reusability studies, the cryogel exhibited accumulating Cu(II) ions performance and excellent regeneration capability, making it a promising adsorbent for Cu(II) removal. [ABSTRACT FROM AUTHOR]

This study mainly focuses on the preparation, characterization, and sorption performance for Cu(II) and Zn(II) by using nano-alumina material (NA) synthesized through the sol-gel method. The SEM, EDS, FT-IR, and XRD analysis methods were implemented to identify the micromorphology and crystal structure of the synthesized NA absorbent and its structure after the adsorbing procedure. The effect of effective variables including various absorbent dose, contact time, initial ion concentration, and temperature on the removal of Cu(II) and Zn(II) from aqueous solution by using NA was investigated through a single factor experiment. Kinetic studies indicated that adsorption of copper and zinc ions by NA was chemical adsorption. The adsorption isotherm data were fitted by Langmuir (R2: 0.919, 0.914), Freundlich (R2: 0.983, 0.993), and Temkin (R2: 0.876, 0.863) isotherms, indicating that copper and zinc ions were easily adsorbed by NA with maximum adsorption capacities of 87.7 and 77.5 mg/g for Cu2+ and Zn2+, respectively. Thermodynamic parameters indicated that the adsorption of Cu2+ was spontaneous(G<0) and the adsorption of Zn2+ might not be spontaneous (G > 0) by NA.ᅟ [ABSTRACT FROM AUTHOR]

Abstract: A lignocellulose-based composite hydrogel, as a novel biosorbent, was prepared for Cu2+ removal from wastewater. TEMPO-oxidized cellulose nanofibrils (TOCN) were dispersed in a 7 wt% NaOH/12 wt% urea aqueous solution at room temperature. Meanwhile, the dissolved cellulose was obtained in the same system at subzero temperature. The composite hydrogels were prepared by blending the dissolved cellulose solution, TOCN dispersion, and alkali lignin solution in an NaOH/urea aqueous solution. The composite hydrogel exhibits excellent adsorption capacity for heavy metals, which can be attributed to the synergistic effects of physical adsorption (porous 3D structure) and chemical adsorption (active sites: carboxyl and phenolic groups). The maximum amount of adsorbed Cu2+ onto composite hydrogel can reach 541 mg/g, which was achieved after 45 min. The adsorption behavior is well-described by the pseudo-second-order kinetics and the Freundlich model (R2 > 0.999). Furthermore, the composite hydrogel exhibits high-strength properties, indicating that the presence of TOCN and lignin contributes to mechanical improvements.Graphical abstract: [ABSTRACT FROM AUTHOR]