Dual Valorization of Potato Peel (Solanum tuberosum) as a Versatile and Sustainable Agricultural Waste in Both Bioflocculation of Eriochrome Black T and Biosorption of Methylene Blue

Current research has developed an effective and economical technique for the double valorization of potato peel (PP), a very abundant and accessible waste material. It was subjected to the extraction of starch which was further used without any modification as a coagulant aid for the removal of Eriochrome Black T (EBT). Unmodified PP starch was proven to be an effective plant-derived material for the reduction of EBT in aqueous solution by coagulation-flocculation, increasing EBT removal efficiency from 63.66% to 80.98% when 4 g/L of PP starch were used together with 0.5 g/L of alum. Although PP starch alone was found inefficient for removing EBT, its usage as a flocculant produced larger flocs than alum alone, resulting in a quicker and more efficient decantation. The remaining PP residue from starch extraction process was used as a biosorbent for the removal of Methylene Blue (MB) in aqueous solution, then characterized by Fourier Transform Infrared Spectroscopy for the determination of functions involved in the MB uptake, the point of zero charge (pH(pzc)) was also determined. The findings indicate that the initial dye concentration, biosorbent dosage, and pH all have a beneficial effect on the biosorption. However, increasing the ionic strength and particle size has a detrimental impact on dye removal. Adsorption kinetics and isotherms were studied: according to investigations, the adsorption of MB dye onto PP residue adsorbent followed the pseudo-second order kinetic model. The equilibrium sorption research found that the Langmuir isotherm model best matched the experimental results with a q(max) of 25.00 mg/g.