Uncovering the flocculating and dye recovery potential of pH‐responsive bioflocculant produced by Bacillus thuringiensis

Abstract

AbstractIn this study, the decolorization of anionic dyes was investigated using a novel pH‐responsive bioflocculant (named BF‐TWB10) derived by Bacillus thuringiensis. The BF‐TWB10 showed a dye removal capacity of 99.06% for C.I. Direct Red 224 (DR 224) and 99.22% for C.I. Acid Black 172 (AB 172) at pH 2.0. Its dye removal capacity decreased with increasing pH and the zeta potential analysis revealed that the dye particles exhibited stronger dispersion forces at higher pH levels. Owing to this pH‐responsive property, BF‐TWB10 could be utilized to recover anionic dyes. The recovery rate was 83.46% for DR 224 and 76.46% for AB 172. We then attempted to concentrate the regenerated dye solutions by regenerating the dye‐loaded floc in one‐tenth of its original volume. The concentration multiple of the regenerated dye solutions reached 8.220 and 7.758 times for DR 224 and AB 172, respectively. In addition, the recovery rate of both dyes increased after three cycles of decolorization/regeneration. The results suggested that BF‐TWB10 has potential not only to remediate dyes from textile effluent but also to recover dyestuffs.