Effective removal and adsorption mechanism of fluoride from water by biochar-based Ce(III)-La(III)-crosslinked sodium alginate hybrid hydrogel.

An eco-friendly macroparticle biochar (BC)-based Ce(III)-La(III) crosslinked sodium alginate (SA) hybrid hydrogel (BC/Ce-SA-La) was synthesized by droplet polymerization and characterized by SEM-EDS, XRD, FTIR, UV-Vis and XPS. The effects of dosage, pH, contact time, temperature and coexisting ions on the F- ions removal by hybrid hydrogel, and the adsorption performance, interaction mechanism and reusability were investigated. The results demonstrate that the composite has a fancy wrinkle structure with a particle size of about 1.8 mm and abundant porosity on the surface. The removal rate of F- ions by BC/Ce-SA-La reached 90.2 % under the conditions of pH 2.0, 200 min of contact time and 298 K. The adsorption behavior was perfectly explained by Langmuir model, and the maximum adsorption capacity reached 129 mg/g. The adsorption process was an endothermic spontaneous reaction and followed Pseudo-second-order rate model. The strong adsorption was attributed to multi-interactions including complexation, hydrogen bonding and electrostatic adsorption between the composite and F- ions. Coexisting ions hardly interfered with the adsorption of F- ions by BC/Ce-SA-La except for a slight effect of phosphate. The composite after F- ion adsorption was easily separated and could be reused at least three times. BC/Ce-SA-La is a cost-effective and promising granular biosorbent.

Facile synthesis and ultrastrong adsorption of a novel polyacrylamide-modified diatomite/cerium alginate hybrid aerogel for anionic dyes from aqueous environment.

An eco-friendly cationic polyacrylamide (CPAM)-modified diatomite/Ce(III)-crosslinked sodium alginate hybrid aerogel (CPAM-Dia/Ce-SA) was synthesized successfully and characterized by SEM-EDS, XRD, FTIR, UV-Vis and XPS. Adsorption performance, interaction mechanism and reusability of CPAM-Dia/Ce-SA used for the removal of acid blue 113 (AB 113), acid blue 80 (AB 80), acid yellow 117 (AY 117), Congo red (CR) and Direct Green 6 (DG 6) anionic dyes from aqueous media were investigated in detail. The results demonstrate that CPAM-Dia/Ce-SA aerogel is macroscopic polymer hybrid spheres with a particle size of around 1.3 mm, unique undulating mountain-like surface and porous mesostructure, and exhibits outstanding adsorption capacity for anionic dyes and good reusability. The maximum adsorption amounts of AB 113, AB 80, AY 117, CR and DG 6 by CPAM-Dia/Ce-SA were 3008, 1208, 914, 1832 and 1232 mg/g at pH 2.0, 60 min contact time and 25 °C, and corresponding removal efficiency reached individually 97.5, 96.6, 99.7, 99.9 and 98.5 % respectively and were less affected by increasing pH up to 10.0. Dye adsorption behaviour and adsorption processes with spontaneous and exothermic nature were perfectly interpreted by the Langmuir and Pseudo-second-order rate models respectively. Physicochemical and multisite-H-bonding synergies promoted the ultrastrong biosorption of anionic dyes by CPAM-Dia/Ce-SA.

Super-efficient removal and adsorption mechanism of anionic dyes from water by magnetic amino acid-functionalized diatomite/yttrium alginate hybrid beads as an eco-friendly composite.

The development of eco-friendly, large-capacity and easy-to-separate adsorbent materials has always been the focus and difficulty of adsorption technology in wastewater treatment applications based on the characteristics of dye wastewater. Therefore, in this study, a green magnetic glycine(Gly)-functionalized diatomite(Dia)/yttrium alginate (Y-SA) hybrid bead composite (Dia-Gly-Y-SA@Fe3O4) was synthesized by the droplet polymerization, and characterized by various modern analytical techniques. The adsorption performance and adsorption mechanism of the composite were evaluated and elucidated by the removal of anionic dyes direct Blue 106 (DB 106), Congo red (CR) and direct red 13 (DR 13) from water. The results show that the composite is a macroparticle gelpolymer with an average particle size of about 1.5 mm, flower-like fold surface structure, abundant porosity and sensitive magnetic response, and displays ultrastrong adsorption ability for three dyes. The adsorption equilibrium of each dye can be reached quickly within 30 min, and the removal efficiency is more than 95% at pH 2.0 and decreases slightly with pH up to 9.0. The adsorption processes could be explained by the Pseudo-second-order rate equation well. All isotherm data fitted the Langmuir model well, and the maximum adsorption capacities were 1635, 2359 and 1165 mg/g for DB 106, CR and DR 13 at 298 K, respectively. The ultrastrong adsorption performance was due to the multisite interaction of physicochemical action and various hydrogen bonds between hybrid beads and dye anions. As a cost-effective magnetic macroparticle adsorbent prepared by natural ingredients, Dia-Gly-Y-SA@Fe3O4 composite exhibits much more stronger adsorption efficiency, better collectability and no secondary pollution than powder Dia, and would have a good application prospect for the purification of anionic dye wastewater with a wide pH range.

Preparation and Superstrong Adsorption of a Novel La(â ¢)-Crosslinked Alginate/Modified Diatomite Macroparticle Composite for Anionic Dyes Removal from Aqueous Solutions.

In order to solve the problem of dye pollution of the water environment, a green macroparticle composite (CPAM-Dia/SA-La) as a bioadsorbent was prepared through a sodium alginate (SA) reaction with a polyacrylamide (CPAM)-modified diatomite (Dia) and further La(III) ion crosslinking polymerization, and characterized by various analytical methods. The important preparation and adsorption conditions of the composite were explored by the adsorption of Acid blue 113 (AB 113) and Congo red (CR) dyes. The dye adsorption efficiency was evaluated. The results show that CPAM-Dia/SA-La composite prepared under the optimized conditions displays superstrong adsorption capacities of 2907 and 1578 mg/g for AB 113 and CR and almost 100% removal efficiency within 60 min adsorption time at pH 2.0 and 298 K, and they decrease slightly with the pH increase to 10. The fitting of equilibrium data to the Langmuir model is the best and the adsorption kinetic processes can be expressed by the Pseudo-second-order kinetic model. The adsorption processes are both spontaneous and exothermic. The analysis results of FT-IR and XPS revealed that the superstrong adsorption of CPAM-Dia/SA-La for dyes. The composite adsorbed by the dye can be recycled. CPAM-Dia/SA-La is a promising biosorbent for dye wastewater treatment.