Microwave treated activated carbon from industrial waste lignin for denitrification of surface water

Highly porous adsorbent materials were developed from industrial waste lignin for denitrification of surface and groundwater. The effect of microwave treatment and zinc ion impregnation on denitrification capacities of the material was investigated. The denitrification efficiencies of prepared materials were investigated by performing batch and continuous column adsorption experiments. The effect of different experimental parameters, including initial nitrate ion concentration, solution pH, and contact time, was also investigated. Adsorption kinetic follows the pseudo-second-order kinetic mechanism. Adsorption isotherm follows the monomolecular adsorption and experimental data best fitted into the Langmuir isotherm model. Continuous column denitrification experiments were performed with granulated adsorbent at different experimental conditions to understand its applicability in the household water treatment unit. Thomas model breakthrough time and the nitrate removal efficiency increase with increasing bed depth, whereas it declines with flow rate and nitrate concentration. The economic viability and environmental friendliness were understood by conducting adsorption–desorption experiments with loaded materials. The performance of adsorbent did not alter significantly even after four consecutive adsorption–desorption cycles. Graphic abstract