Advances in Sorptive Removal of Hexavalent Chromium (Cr(VI)) in Aqueous Solutions Using Polymeric Materials

Abstract

Sorptive removal of hexavalent chromium (Cr(VI)) bears the advantages of simple operation and easy construction. Customized polymeric materials are the attracting adsorbents due to their selectivity, chemical and mechanical stabilities. The mostly investigated polymeric materials for removing Cr(VI) were reviewed in this work. Assembling of robust functional groups, reduction of self-aggregation, and enhancement of stability and mechanical strength, were the general strategies to improve the performance of polymeric adsorbents. The maximum adsorption capacities of these polymers toward Cr(VI) fitted by Langmuir isotherm model ranged from 3.2 to 1185 mg/g. Mechanisms of complexation, chelation, reduction, electrostatic attraction, anion exchange, and hydrogen bonding were involved in the Cr(VI) removal. Influence factors on Cr(VI) removal were itemized. Polymeric adsorbents performed much better in the strong acidic pH range (e.g., pH 2.0) and at higher initial Cr(VI) concentrations. The adsorption of Cr(VI) was an endothermic reaction, and higher reaction temperature favored more robust adsorption. Anions inhibited the removal of Cr(VI) through competitive adsorption, while that was barely affected by cations. Factors that affected the regeneration of these adsorbents were summarized. To realize the goal of industrial application and environmental protection, removal of the Cr(VI) accompanied by its detoxication through reduction is highly encouraged. Moreover, development of adsorbents with strong regeneration ability and low cost, which are robust for removing Cr(VI) at trace levels and a wider pH range, should also be an eternally immutable subject in the future. Work done will be helpful for developing more robust polymeric adsorbents and for promoting the treatment of Cr(VI)-containing wastewater.

N-Phenyl acrylamide-incorporated porous silica-bound graphene oxide sheets with excellent removal capacity for Cr(iii) and Cr(vi) from wastewater

“…113 The Cr(III) solution contains a supporting electrolyte (0.1 M HCl), which is responsible for the presence of Cr(III) as a mixture of Cr(H current adsorbent with those of the reported adsorbents is presented in Table 8. [115][116][117][118][119][120][121][122]…”

“…114 A comparison of the adsorption capacity of the current adsorbent with those of the reported adsorbents is presented in Table 8. 115–122…”

Microwave-assisted Chitosan Based Activated Bentonite (CAB) for Cr (VI) Removal from Acid Mine Drainage

“…The increase in adsorption can be attributed to the increased attraction of Cr (VI) molecules for the surface of the beads as their concentration rises. It has been previously noted that an increased concentration of Cr (VI) leads to a greater driving force for mass transfer (10,21) . The impact of varying contact duration, ranging from 0 to 180 minutes, on the adsorption of Cr (VI) by nanocomposite beads is illustrated in the accompanying figure.…”

Silk/Polyamidoamine Membranes for Removing Chromium VI from Water

“…Currently, the most common remediation strategies for Cr(VI)-contaminated waters include activated carbon [8][9][10], reactive barriers [11], ion exchange [12][13][14][15][16], electrochemical precipitation [17], reverse osmosis [18], chemical precipitation [19], adsorption, and combined reduction-coagulation-filtration [20]. In the last decade, polymeric materials [21][22][23], composites [24][25][26], and nanocomposites [27,28] have also been proposed for this purpose. In addition, several side product deriving from agriculture proved to be efficient low-cost adsorbents for the removal of Cr(VI) from water, among which lignocellulosic residues were highly considered [29][30][31].…”