Removal of hexavalent chromium from aqueous solution using exfoliated polyaniline/montmorillonite composite

• Published in: Water science and technology Vol. 70; no. 4; pp. 678 - 684
• Main Authors: Chen, Jun, Hong, Xiaoqin, Zhao, Yongteng, Zhang, Qianfeng
• Format: Journal Article
• Language: English
• Published: London International Water Association 01-01-2014; IWA Publishing
• Subjects: Adsorbents; Adsorption; Ammonium; Ammonium chloride; Ammonium compounds; Aniline Compounds - chemistry; Applied sciences; Bentonite - chemistry; Bridges; Capacity; Carboxylic acids; Chromium; Chromium - chemistry; Clay; Endothermic reactions; Exact sciences and technology; Hexavalent chromium; Hydrogen-Ion Concentration; Kinetics; Methacrylates - chemistry; Montmorillonite; Montmorillonites; Oxidation; Particulate composites; pH effects; Platelets; Platelets (materials); Pollution; Polyanilines; Polymerization; Polymers; Removal; Temperature; Thermodynamics; Waste Disposal, Fluid - methods; Water Pollutants, Chemical - chemistry; Water treatment and pollution; Hexavalent metal; Montmorillonite; hexavalent chromium; Mutagen; Composite material; Heavy metal; composites; Trace element; Carcinogen; removal; Poison; Aqueous solution; Teratogen; polyaniline; Chromium VI
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2014.277

Exfoliated polyaniline/montmorillonite (PANI/MMT) composites with nanosheet structure were successfully prepared by in situ chemical oxidation polymerization with MMT platelets as the scaffold. Amphoteric polymer, (2-methacryloyloxyethyl)trimethyl ammonium chloride and methacrylate acid copolymer, was used to modify montmorillonite and a large number of carboxylic acids were introduced on the surface of the clay platelets, which can be used as a dopant of PANI and play a 'bridge' role to combine PANI with clay. Adsorption experiments were carried out to study the effects of pH, contact time, Cr(VI) concentration, adsorbent dose and temperature. The adsorption of Cr(VI) on the PANI/MMT was highly pH dependent and the adsorption kinetics followed a pseudo-second-order model. The Langmuir isothermal model described the adsorption isotherm data well and the maximum adsorption capacity increased with the increase in temperature. Thermodynamic investigation indicated that the adsorption process is spontaneous, endothermic and marked with an increase in randomness at the adsorbent - liquid interface. The maximum adsorption capacity of the PANI/MMT composites for Cr(VI) was 308.6 mg/g at 25 °C. The excellent adsorption characteristic of exfoliated PANI/MMT composites will render it a highly efficient and economically viable adsorbent for Cr(VI) removal.