A Comparative Study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ Metal Ions Removal from Industrial Wastewaters by Chitosan-Based Composite Cryogels

Abstract

Materials coming from renewable resources have drawn recently an increased attention in various applications as an eco-friendly alternative in the synthesis of novel functional materials. Polysaccharides, with their prominent representative – chitosan (CS), are well-known for their sorption properties, being able to remove metal ions from dilute solutions either by electrostatic interactions or chelation. In this context, we proposed here a comparative study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ metal ions removal from industrial wastewaters by CS-based composite cryogels using batch technique. The composite cryogels consisting of CS embedding a natural zeolite, namely clinoptilolite, were synthesized by cryogelation, and their sorption performance were compared to those of CS cryogels and of acid-activated zeolite. A deeper analysis of thermodynamics and kinetics sorption data was performed to get insights into the sorption mechanism of all metal ions onto sorbents. Based on the optimized sorption conditions, the removal of the above-mentioned ions from aqueous solutions by the composite sorbent using dynamic technique was also evaluated.

An Overview on Composite Sorbents Based on Polyelectrolytes Used in Advanced Wastewater Treatment

“…Composite gels based on polyelectrolytes represent a class of composite soft materials consisting of hydrophilic charged/uncharged chains that absorb a high content of water (>95%) [133]. These low cost and high efficient 3D-dimensional networks are based on polyelectrolytes of different types: (i) synthetic, such as: PEI [36,92], PAH [93,118], PAA [38], PAMPS [106,118,119], or (ii) natural, like the following: CS [30,[32][33][34]38,39], modified CS [37,84,85], SA [33,70,73], modified SA [72], modified cellulose [104]. Many studies reported the incorporation of organic/inorganic entities into the gel structure, including GO [70,73], Fe 3 O 4 [36,106], SiO 2 [113], zeolites [30,32], clays [72].…”

Synthesis of Ethylenediaminetetraacetic Acid-Functionalized Chitosan Cryogels as Potential Sorbents of Heavy Metal Ions

“…The overall porosity of the CS cryogels (P, %) was estimated by the liquid displacement technique, and was calculated by Eq. (2) [4,6].…”

“…Compared to conventional adsorbents such as activated carbon (AC) or synthetic ion exchangers, biopolymers represent valuable alternatives for sorption of various contaminants [1][2][3]. Consequently, over the years numerous biopolymers have been used as main matrix to develop composite-based sorbents for removal of heavy metal ions (HMIs) [4][5][6], dyes [7,8], or other pollutants [9,10]. One of the most promising biopolymers is chitosan (CS), a low-cost renewable polycation which is obtained from shells of crustaceans (crabs, shrimps, lobsters, etc.)…”

Analysis of Copper(II), Cobalt(II) and Iron(III) Sorption in Binary and Ternary Systems by Chitosan-Based Composite Sponges Obtained by Ice-Segregation Approach

“…In this context, the discharge of HMIs from aqueous solutions has been intensively carried out using various processes, including chemical precipitation, extraction with different solvents, flocculation, ion exchange, ultrafiltration, reverse osmosis and adsorption [5][6][7][8][9][10]. Among these, adsorption is considered a simple and efficient technique to remove HMIs from wastewaters [8][9][10][11][12]. A large variety of sorbent materials, such as metal oxides/hydroxides [13,14], zeolites [15,16], commercial or synthetic activated carbon [17,18], biomass [19], synthetic organic supports [6,8,9], and unmodified or functionalized polysaccharides (chitosan, salecan, pullulan, alginate) [20][21][22][23][24][25][26][27][28][29] have been reported to remove HMIs from contaminated waters.…”

“…Lately, the employment of inexpensive and eco-friendly sorbents, such as renewable natural polymers, in the extraction and recovery of certain HMIs has drawn considerable interest [2,3,10,11,[20][21][22][23][24][25][26][27][28][29]. Amongst these low-cost sorbents, chitosan (CS) displayed promising abilities to bind different HMIs due to the presence of numerous amino and hydroxyl groups in its structure [2,20,27].…”