Characteristics of natural biopolymers and their derivative as sorbents for chromium adsorption: a review
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(2020) 2:24
REVIEW
Journal of Leather Science and Engineering
Open Access
Characteristics of natural biopolymers and their derivative as sorbents for chromium adsorption: a review Ruoshi Zhang1,2 and Yongqiang Tian1,2*
Abstract Chromium is widely used in industry, and improper disposal of wastewater and industrial residues containing excessive chromium can contaminate water and soil, endangering both environmental and human health. Natural biopolymers and their derivatives have been investigated for removal of chromium (Cr) from wastewater. Cellulose, lignin, tannin, chitin, chitosan, and polypeptides are abundant in nature, and have high potential as adsorbents due to their easy access, low cost, and the recyclability of the captured heavy metals. In order to improve their mechanical strength, recyclability, specific surface area, binding site number, and adsorption rate as adsorbents, native materials have also been modified. This review discusses the source of chromium contamination and the main species of interest, as well as their toxicity. The structures of the aforementioned biopolymers were analyzed, and the adsorption mechanism of chromium and the main influencing factors on this process are discussed. The modification methods of various adsorbents and their adsorption effects on chromium are also detailed, and the developmental direction of research on the use of biopolymer adsorption remediation to control chromium contamination is discussed. Keywords: Biopolymer, Adsorbent, Adsorption, Chromium
1 Introduction Chromium-containing chemicals are wildly used in many industries such as leather tanning, the mining of chrome ore, metal finishing, pigment manufacturing, and wood preservation [1]. Over the past few decades industrialization has accelerated, and the amount of chromium in aquatic and terrestrial ecosystems has increased [2]. There are relevant regulations on the threshold of chromium content in water and soil. Many countries have established 50 μg/L as the maximum permissible limit of total chromium in drinking water [3]. In China, the risk control values of chromium pollution in agricultural soil are 800 mg/kg (pH ≤ 5.5), 850 mg/kg * Correspondence: [email protected] 1 College of Biomass Science and Engineering, Sichuan University, No.24 South Section, 1st Ring Road, Chengdu 610065, PR China 2 Key Laboratory of Leather Chemistry and Engineering (Sichuan University), Ministry of Education, No.24 South Section, 1st Ring Road, Chengdu 610065, PR China
(5.5 < pH ≤ 6.5), 1000 mg/kg (6.5 < pH ≤ 7.5), or 1300 mg/ kg (pH > 7.5), dependent on the pH as indicated [4]. Contamination of water and soil can indirectly affect human health, and thus the remediation of chromium has always been a focus of heavy metal pollution treatment. The traditional methods for treating heavy metal contamination include chemical precipitation, ion exchange, membrane separation, reverse osmosis, evaporation, electrochemical treatment, and adsorption [5–7]. Amongst these, the adsorption method has become the focus in rece
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