Marine macro algae-derived activated carbon an efficient bio-sorbent for Malachite green removal from wastewater

Extensive use of dyes by the textile industries poses a serious threat to the aquatic flora and fauna. Low-cost bio-sorbent derived from marine red, Gracilaria verrucosa (RAC), and green macroalgae, Enteromorpha intestinalis (GAC) have been used for effective removal of unsafe Malachite Green (MG) dye. Batch study was conducted to determine the different bio-sorption parameters such as biochar dosage, pH, initial concentration of MG, and contact time including MG bio-sorption capacities. The physicochemical characterization results show the presence of lower crystallite sizes, and active functional groups such as carbonyl, hydroxyl, carboxyl, sulfate and amine with the mesoporous morphology of the algal biochar. The FT-IR, XRD and SEM analyses were also performed to characterize the structural investigation of adsorbents. The kinetics of adsorption such as pseudo-first-order and pseudo-second-order were analyzed and pseudo-second-order confirms about the nature of process to be chemisorption. The bio-sorption test for 20 mg/L of initial MG at an equilibrium time of 90 min by RAC showed maximum removal efficiency of about 97.49% at pH 8 whereas GAC showed a removal efficiency of 93.37% at pH10. Thus, marine macroalgae RAC and GAC can be a substitute for the commercially available adsorbents for degradation of dyes from textile effluents.