Brewers draff as a new low-cost sorbent for chromium (VI): Comparison with other biosorbents

► Brewers draff showed to be an efficient Cr(VI) biosorbent. ► Chemically pre-treated biosorbents showed an increased specific surface area. ► Cr(VI) reduction was observed after its contact with the biosorbent. ► The Cr(VI)-reducing capacity was lowered by the chemical pre-treatment. ► Spectroscopic, batch, and column experiments described the sorption potential.