Chitosan–Clay Composites for Wastewater Treatment: A State-of-the-Art Review

Abstract

In recent decades, increased domestic and industrial activities have led to the release of various pollutants into the aquatic environment. A robust and eco-friendly technique for removing these pollutants from wastewater is a crucial need. Among existing technologies, adsorption is considered to be a simple, cost-effective, and sustainable method. Recently, chitosan−clay nanocomposites have emerged because of their high abundance, ease of fabrication, and efficacy as adsorbents. Quantitatively, this particular class of composites is capable of removing ∼99% of dyes, metals, and harmful negative ions from various solutions. Also, the composite is designed to remove a maximum of ∼94% of the targeted herbicides from media under investigation. This review summarizes important information about this adsorbent in removing micropollutants from various water sources. A short overview of the chemical structure and the modification of chitosan and clay, along with their interaction within the composite matrix and with contaminants, is presented. Finally, a critical analysis of the removal performance of these composites compared with that of other industrial adsorbents is provided. Future research directions are suggested on the basis of the technological challenges faced in the industrial implementation of these materials.

Recent Advances in Adsorptive Nanocomposite Membranes for Heavy Metals Ion Removal from Contaminated Water: A Comprehensive Review

“…The majority of these technologies produce minimal industrial impacts, since they are time-consuming, costly, and result in secondary pollutants. Adsorption is one of the most efficient and extensively employed technologies for wastewater treatment due to the utilization of widely accessible by-products and inexpensive substitutes, including bio-wastes, fly ash, chitosan [ 78 ], and chitin. Additionally, adsorption involves the application of nanostructures for the extraction of these toxic substances from water bodies.…”

Examining the Effect of a Chitosan Biopolymer on Alkali-Activated Inorganic Material for Aqueous Pb(II) and Zn(II) Sorption

“…Because of the renewability, biodegradability, nontoxicity, biocompatibility, and functionality, biopolymers have attracted more research attention in the recent decade for applications in many fields, including agriculture, food, , cosmetics, biomedicine, , electronics, building, , and environmental remediation. − Chitosan, a poly-β-glucosamine biopolymer produced by alkaline deacetylation of chitin derivatives found in the exoskeleton of arthropods, , has been widely studied for its application in water treatment and contaminant removal. − Various studies have shown that chitosan exhibits excellent performance in removing cationic heavy metals, e.g., Pb­(II), , oxoanionic heavy metals, e.g., As, and dyes and organic contaminants . However, chitosan as an adsorbent has major drawbacks, including a low porosity and a small surface area, low acid stability and thermal stability, poor mechanical properties, and hydrophilicity. , As a result, chitosan is often used in composites with inorganics or modified with other materials to address the various deficiencies to produce a robust adsorbent. ,, …”

“…20,23 As a result, chitosan is often used in composites with inorganics or modified with other materials to address the various deficiencies to produce a robust adsorbent. 17,23,24 Alkali-activated materials such as geopolymers or poly-sialate inorganic polymers are low-cost materials known to also exhibit excellent performance in removing and immobilizing aqueous heavy metal ions. 25−28 These classes of materials are prepared by reacting aluminosilicate precursors such as fly ash, slag, or calcined clay with alkaline activating solutions.…”

Effect of ultrasound on the physical properties and processing of major biopolymers—a review

“…Besides being biodegradable, they are biocompatible 2 and many of the biopolymers possess significant antibacterial activity. 3 As a result, these are preferred by the researchers over conventional synthetic polymers for various applications in food, 4 cosmetics, 5 commercial manufacturing goods, 6 pharmaceutical and medical products, [7][8][9] drug development, 10,11 nanofiber fabrication, 12 wastewater treatment, [13][14][15][16] energy storage devices, 17 etc. However, these applications demand a biopolymer of specific physical properties extracted via a simple pathway using fewer toxic chemicals.…”