Biopolymer-based flocculants: a review of recent technologies

Abstract

Biopolymer-based flocculants have become a potential substitute for inorganic coagulants and synthetic organic flocculants due to their wide natural reserves, environmental friendliness, easy natural degradation, and high material safety. In recent years, with more and more attention to clean technologies, a lot of researches on the modification and application of biopolymer-based flocculants have been carried out. The present paper reviews the latest important information about the base materials of biopolymer-based flocculants, including chitosan, starch, cellulose, and lignin etc. This review also highlights the various modification methods of these base materials according to reaction types in detail. Via the recent researches, the flocculation mechanisms of biopolymer-based flocculants, such as adsorption, bridging, charge neutralization, net trapping, and sweeping, as well as, some other special mechanisms are comprehensively summarized. This paper also focuses on the water treatment conditions, the removal efficiency, and advantages of biopolymer-based flocculants in applications. Further, this review sheds light on the future perspectives of biopolymer-based flocculants, which may make progress in the sources of base materials, modification processes, multi-function, and deepening application researches. We believe that this review can guide the further researches and developments of biopolymer-based flocculants in the future, to develop them with a higher efficiency, a lower cost, more safety, and multi-function for more diversified applications.

Environmental and human health implications of metal(loid)s: Source identification, contamination, toxicity, and sustainable clean-up technologies

“…This technique has a few drawbacks, such as high functioning expenses owing to the broad utilization of chemicals. Macromolecule flocculants are being applied as efficient flocculants for metal(loid)s remediation from wastewater (Maćczak et al, 2020;Jiang et al, 2021). Shen et al (2015) investigated the removal of Cr (III), Zn (II), and Cd (II) metal ions using flocculation.…”

Water-Soluble Starch-Based Copolymers Synthesized by Electron Beam Irradiation: Physicochemical and Functional Characterization

“…Grafting is an effective way of regulating the properties of biopolymers, which can be “tailor-made” according to the needs and produce highly efficient graft copolymers usable as flocculants [ 17 , 18 ]. Cross-linking is another type of reaction that can lead to modification and functionalization of natural polymers by increasing their molecular weight and consequently improving and extending their functionality as flocculants [ 18 ].…”

“…Grafting is an effective way of regulating the properties of biopolymers, which can be “tailor-made” according to the needs and produce highly efficient graft copolymers usable as flocculants [ 17 , 18 ]. Cross-linking is another type of reaction that can lead to modification and functionalization of natural polymers by increasing their molecular weight and consequently improving and extending their functionality as flocculants [ 18 ]. However, the most used method for the synthesis of biopolymer-based flocculants is graft copolymerization because the chemical combination of organic synthetic polymer with natural polymer produces organic, natural polymer hybrid materials with desirable properties of both components [ 19 ].…”

Application of Advanced Oxidation Technology in Sludge Conditioning and Dewatering: A Critical Review

“…The main methods of sludge treatment are sanitary landfills and incineration. The moisture content of the sludge be less than 60% and 50%, respectively, based on the requirements of sanitary landfills and incineration [ 4 ]. In most cases, the moisture content of excess sludge is more than 95%, and there are four main types of sludge water, namely free water, interstitial water, adsorbed water, and bound water.…”