“…Numerous researchers have worked on different sources for biochar production, such as rice straw, Korean cabbage, wood chip, pine wood biochar, pig manure biochar, paper-derived biochar, peels of oranges, peels of bananas, coir pith, date pith, peanut shells, almond hulls, Citrullus lanatus rind, ZnO/cotton stalk biochar, cow dung biochar, litchi peel biochar, sludge biochar, low-rank coal (leonardite), coffee waste-activated biochar, oil palm waste biochar, waste palm shell biochar, wet-torrefied microalgal biochar, and green biochar/iron oxide, for the adsorption of various dyes (congo red, crystal violet, methylene blue, aid violet, basic blue 9, reactive dye, acid yellow 36, rhodamine B, malachite green, etc.) [ 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 ]. From the thermodynamic parameters as reported by Zhang et al, physical sorption is the primary adsorption mechanism through which methylene blue adsorbs biochar/Fe x O y [ 80 ].…”