Perchlorate uptake by wheat straw based adsorbent from aqueous solution and its subsequent biological regeneration

Abstract

A new innocuous disposal for perchlorate was presented in this study. Perchlorate was first concentrated by wheat straw based adsorbent, and then biologically reduced by mixing with heterotrophic bacteria. The physicochemical properties of modified wheat straw (MWS) were evaluated by SEM, BET specific area, TGA, 13C solid state NMR and Raman spectra. The adsorption capacity for perchlorate was determined by the kinetics and isotherm tests. The surface areas of the raw wheat straw and MWS were in range of 4.6–5.9m2g−1, which illustrated the absence of porous adsorption in potential adsorption mechanism. The uptake of perchlorate by MWS was based on ion exchange, which would benefit the biological reduction on surface of the biosorbent. The maximum adsorption capacity (Qmax) of perchlorate by MWS was about 119.0mgg−1 (20°C) and decreased as temperature grew. The mixed perchlorate-reduction bacteria could reduce about 91% of loaded perchlorate (23.94mgg−1) on MWS in the first biological-reduction cycle and 87% in second cycle, indicating an available method of innocuous disposal for concentrated perchlorate wastes.