Application of Modified Lignocellulosic Biomass for Sorption of Anionic Dye Reactive Black 5 in an Air-Lift and Column Reactor

The study presents research on the use of modified lignocellulosic biomass as a waste sorbent for the removal of anionic dyes from aqueous solutions. The sawdust used as sorption material was subjected to an acid-base modification and further functionalised by introducing amino groups into the biomass structure. Dynamic sorption experiments were carried out in two reactor types (airlift and column) with two sorbents: sawdust treated under acid-base conditions (S-AB) and sawdust aminated with epichlorohydrin after acid-base treatment and preactivation (S-AB-EA). The anionic dye Reactive Black 5 (RB5) was used as a sorbate. The experiments were carried out at two flow rates (0.1 and 0.5 dm3/h) and two feed concentrations (10 and 50 mg/dm3), maintaining the pH of the solution at 3, as determined in previous studies. The experimental data allowed the maximum sorption capacities of the tested sorbents to be determined under dynamic conditions and were described using the Thomas, Adams-Bohart and Yoon-Nelson models. The results showed that the flow rate, the dye concentration and the reactor type strongly influence the efficiency of dye removal. The highest capacity, 73.89 mg/g, was achieved in the airlift reactor for aminated sawdust and preactivation with epichlorohydrin (S-AB-EA) at a feed concentration of 50 mg/dm3 and a flow rate of 0.1 dm3/h.