Physicochemical characteristics of epichlorohydrin, pyridine and trimethylamine functionalized cotton stalk and its adsorption/desorption properties for perchlorate.

Amine-impregnated cotton stalk (AICS) prepared by the reaction of cotton stalk with epichlorohydrin, pyridine and trimethylamine was used as the effective adsorbent for perchlorate removal. Solid-state (13)C NMR spectra, FT-IR, BET principle and element analysis provided evidence that amine groups have been successfully introduced onto the surface of AICS. The adsorption capacity of perchlorate by AICS was about 83.8 mg g(-1) at 20 °C. It was decreased to 80.6 mg g(-1) as the temperature was increased to 40 °C, which implied an exothermic nature for this adsorption process. Perchlorate adsorption capacity in fixed-bed column was optimum at neutral condition (pH: 6.0, 70.8 mg g(-1)) with bed depth of 2.7 cm and flow rate of 5 ml min(-1). In addition, chemical regeneration by HCl or NaOH (0.1 mol L(-1)) achieved more than 95% of regeneration efficiency. Biological regeneration of the saturated AICS with mixed bacteria has shown its merit with regeneration and biological perchlorate destruction simultaneously although its regeneration efficiency was only 56.8-74.8%.