Speaker
Description
Congo red (CR) and methylene blue (MB) are considered to be two traditional synthetic dyes of organic provenance. The current study examines the dye removal capacity of the commingled food waste biochar (CFWB) prepared through Microwave-assisted Pyrolysis (MAP). The pristine CFWB has lower efficiency for CR (71.7 %) and MB removal (74.5 %) with initial concentration of 10 mg/L after 150 min, necessitating the implementation of certain modifications. Both the dye removal were assessed using acid and alkali modified CFWB, using 0.1 M HCl and 0.1 M NaOH respectively. Alkali-modified CFWB (Al-CFWB) showed encouraging results with 79.5 % and 83.7 % removal for CR and MB respectively for similar operating conditions. The applicability of Al-CFWB for dye removal in the mixed aqueous solution of CR and MB at 10 mg/L each, was also tested to replicate the actual industrial effluent which generally contains more than one dye. The MB removal efficiency dropped by around 20 % for mixed dye solutions with little effect on CR removal efficiency (71.3 %). Both individual dye and mixed dye removal processes followed Freundlich Isotherm (R2- 0.99) suggesting that the processes involved both monolayer and multilayer adsorption. Four different kinetic models were studied where pseudo-second order kinetic model deemed best fit with R2 values of 0.92 – 0.99, for all the adsorption systems suggesting chemisorption as the rate-limiting step. The regeneration studies shown that the biochar can be used for up to three adsorption-desorption cycles. Moreover the SEM analysis of Al-CFWB suggested its porous characteristic with an average pore size of 4.4 µm. FT-IR analysis determined the presence of oxygen-containing surface functional groups, which play an important role in adsorption of dyes.
