Zn2+ adsorption from wastewater using a chitosan/β‐cyclodextrin‐based composite membrane

• Published in: Journal of food biochemistry Vol. 44; no. 12
• Main Authors: Liu, Jiaxin, Wang, Siqi, Fu, Jingyi, Ding, Xiuqing, Zhao, Jun
• Format: Journal Article
• Language: English
• Published: 01.12.2020
• Subjects: composite membrane; CTS; Zn2; β‐CD
• ISSN: 0145-8884; 1745-4514
• DOI: 10.1111/jfbc.13483

In this study, a β‐cyclodextrin polymer (β‐CDP) was synthesized by pretreating β‐cyclodextrin (β‐CD) with citric acid (CA), and then, chitosan (CTS) and β‐CDP were cross‐linked to prepare a biomass‐based (CTS/β‐CDP) composite membrane. The effects of the preparation conditions in sodium hydroxide on the adsorption amount and adsorption rate of zinc ions (Zn2+) from simulated wastewater were investigated. The results showed that a maximum adsorption amount 123.7 μg/g and adsorption rate 94.14% of Zn2+ were obtained when the reaction between CTS and β‐CDP was performed at 50°C, the concentration of acetic acid was 2%, dissolving β‐CDP water dosage was 30 ml, and the soaking time in sodium hydroxide was 1 hr. Comparative studies on the adsorption of CTS membranes, β‐CD, β‐CDP, and CTS/β‐CDP composite membrane showed that the CTS/β‐CDP composite membrane had the highest Zn2+ adsorption efficiency. The CTS/β‐CDP composite membrane was characterized by FTIR, SEM, and XRD. Characteristic absorption peaks of CTS and β‐CDP appeared in the FTIR spectra of the CTS/β‐CDP composite membrane, confirming its synthesis. The SEM images showed that the surface of the composite membrane was rougher than the porous CTS membrane, which increased the number of adsorption sites and the adsorption efficiency. XRD patterns showed that the CTS/β‐CDP composite membrane was amorphous, indicating that β‐CDP changed the crystal structure of the CTS. The swelling degree and transmittance of the CTS/β‐CDP composite membrane were lower than the CTS membrane, which should be conducive to recycling after wastewater treatment. Practical applications Industrial wastewater often contains heavy metal ions such as Zn2+, which are difficult to degrade and are highly toxic, and direct wastewater discharge can greatly harm the ecosystems and humans. In this study, CTS and β‐CD were cross‐linked to synthesize a biomass membrane for adsorbing Zn2+ to reduce the Zn2+ content in wastewater via adsorption.The results show that the CTS/β‐CDP composite membrane can be applied to small‐scale wastewater treatment fields such as food and chemical industry. After the Zn2+‐containing wastewater underwent pretreatment, the composite membrane was placed into the wastewater for effective adsorption, which could achieve high adsorption efficiency. The process played a major role in effectively treating Zn2+ and other difficult to degrade heavy metal ions; thereby, simplifying Zn2+‐containing wastewater. The treatment process reduces the investment and operating costs of sewage treatment, and at the same time, has a significant removal effect, and hence, can meet the requirements of environmental protection discharge. In this study, CTS and β‐CD were cross‐linked to synthesize a biomass membrane for adsorbing Zn2+ to reduce the Zn2+ content in wastewater via adsorption. The results show that the CTS/β‐CDP composite membrane was placed into the wastewater for effective adsorption Zn2+,which could achieve high adsorption efficiency.