Synthesis of hydrous iron oxide/aluminum hydroxide composite loaded on coal fly ash as an effective mesoporous and low-cost sorbent for Cr(VI) sorption: Fuzzy logic modeling

•Hydrous iron oxide/aluminium hydroxide composite was loaded on CFA.•XRD, XRF, FT-IR, SEM, LPS and BET were used to characterize the sorbent.•The sorbent showed considerable potential for sorption of Cr(VI).•Sorption process was controlled by pseudo-first-order model.•Removal efficiency of Cr(VI) was predicted using the developed fuzzy logic model.