Defatted algal biomass as a non-conventional low-cost adsorbent: Surface characterization and methylene blue adsorption characteristics

•Utilization of defatted algal biomass (DAB) as an adsorbent was studied.•Maximum adsorption capacity of DAB was found to be 7.73 mg g−1.•Specific surface area of DAB was estimated to be 18.94 m2 g−1.

The present study investigates the use of defatted algal biomass (DAB) as a non-conventional low cost adsorbent. The maximum adsorption capacity of biomass (raw, defatted and sulfuric acid pretreated DAB) was determined by liquid phase adsorption studies in batch mode for the removal of methylene blue present at various concentrations (1, 2, 3, 4, and 5 mg L−1) from aqueous solutions. The data was well fitted with Langmuir and Freundlich isotherms. The maximum adsorption capacity for raw, defatted and sulfuric acid pretreated DAB was found to be 6.0, 7.73 and 7.80 mg g−1, respectively. The specific surface area of raw, defatted and sulfuric acid pretreated DAB was estimated to be 14.70, 18.94, and 19.10 m2 g−1, respectively. To evaluate the kinetic mechanism that controls the adsorption process, pseudo-first order, pseudo-second order, intraparticle diffusion and particle diffusion has been tested. The data fitted quite well with pseudo-second order kinetic model.