Alginate Composites Reinforced with Polyelectrolytes and Clay for Improved Adsorption and Bioremediation of Formaldehyde from Water

Abstract

In this study, polyethylenimine (PEI) and PEI-montmorillonite clay composites (PMt) were encapsulated in alginate beads, with or without formaldehyde (FA)-degrading bacteria, to remove FA from water. The effects of additives on the structural and functional properties of the beads, including their water content, stability, mechanical strength, surface area, and morphology, were studied. The adsorption kinetics and adsorption capacity of the beads were investigated, and the FA removal efficiency was established by co-encapsulating bacteria with PEI or PMt in alginate beads. Montmorillonite reduced PEI leaching and curbed swelling and shrinking effects induced by PEI−alginate interactions. The mechanical strength increased by 65% for PEI beads and up to 130% for PMt beads compared to that of plain alginate. FA adsorption reached 59 mg•g −1 for PEI beads or 32 mg•g −1 for PMt beads. When combined with FA-degrading Pseudomonas putida, the PMt composite could stabilize pH for a longer period of time, and a high removal performance was achieved upon repeated use. The obtained results highlight the potential of alginate beads reinforced by clay composites to serve as an efficient platform for the removal of FA from industrial wastewater. Furthermore, these hybrid materials could be designed to improve various chemical reactions and applied as robust sorbents and/or catalysts in industrial and environmental settings.

Granulation of Bismuth Oxide by Alginate for Efficient Removal of Iodide in Water

“…The Alg beads without BO exhibited 0% iodide adsorption capacity even after 24 h. When BO was introduced, the iodide adsorption capacity gradually increased with the weight ratio (from 3.7 mg/g (1:5) to 6.9 mg/g (1:30)) after 24 h. However, when the weight ratio was increased to 1:40, the adsorption capacity decreased by approximately 25%. These results were attributable to the aggregation of BO particles when the amount of BO was increased in the Alg matrix for granulation [ 36 , 37 ]. Considering these preliminary iodide adsorption results for different ratios of Alg and prepared BO, Alg–BO with a weight ratio of 1:20 was selected for further study.…”

Progress of Ultrafiltration-Based Technology in Ion Removal and Recovery: Enhanced Membranes and Integrated Processes

“…Different technologies, such as precipitation–coagulation–flocculation (Figure a), adsorption (Figure b), ion exchange (Figure c), flotation (Figure d), and membrane-based separation have been developed for ion removal from wastewater. − Precipitation combined with coagulation, flocculation, and flotation has been widely applied for the removal of ions from wastewater due to their low cost. However, several major problems, such as the large volumes of generated sludge and the additional of extra chemicals limit their further application .…”

Liquid-Core Encapsulation of Biogenic Mn Oxides for Improved Oxidation Kinetics of Organic Pollutants

“…In environmental studies, encapsulated catalysts or sorbents are often proposed without comparison to their performance in suspension; another major area of interest, pollutant bioremediation using entrapped microbes, normally benefits from slowed diffusion because it protects the cells from toxic shock. 11,15 Slow-release formulations, commonly using encapsulated drugs, pesticides, and probiotics, are understandably not designed to promote rapid mass transfer.…”

“…As a result, diffusion of substrates to surface sites becomes a rate-limiting factor, often leading to slowed reaction kinetics. − Though some efforts have been made to produce more porous carriers, current developments in encapsulation techniques seldom focus on optimizing for fast solute transport. In environmental studies, encapsulated catalysts or sorbents are often proposed without comparison to their performance in suspension; another major area of interest, pollutant bioremediation using entrapped microbes, normally benefits from slowed diffusion because it protects the cells from toxic shock. , Slow-release formulations, commonly using encapsulated drugs, pesticides, and probiotics, are understandably not designed to promote rapid mass transfer. The literature therefore provides few solutions for transformation processes whose kinetics rely on quick diffusion to active sites.…”