Production of activated carbon from corn (Zea mays L.) cobs cultivated in the Black Sea region,characterization, and investigation of use for removal of various pollutants from wastewaters

Tons of waste by-products arise during the production process in many food and agriculture industries around the world. While these wastes can be recycled into the economy through recycling processes in developed countries, these studies have not yet reached an industrial scale in Turkey. In this study, four different activated carbons were produced by chemical activation from corn (Zea mays L.) cobs, which arise as a waste by-product as a result of agricultural activities, and their adsorption performance from aqueous solution was tested on some pollutant species. Planning the recycling of agricultural wastes to the economy by producing activated carbon from corn cobs can be considered as an alternative biotechnological waste utilization process. Four different activated carbons were obtained with micropore structure by K2CO3 (AK-PK) activation, micro-mesopore structure by H3BO3 (AK-BA) activation, mesopore structure by H3PO4 (AK-FA) activation, and improved surface structure by H2SO4 (AK-SA) activation. Characterization analysis includes volatile matter content, fixed carbon content, moisture content, ash content determination, pH-pHpzc and determination of surface acidic functional groups (Boehm titration), elemental analysis (C, H, N, S and O determinations), iodine and methylene blue numbers analysis, BET surface area, SEM images, micro-mesopore areas, pore volume and distributions, FT-IR analysis were performed. It has been determined that AK-FA has the highest BET surface area with 959.8 m2/g, AK-PK is 671.7 m2/g and AK-BA is 598.6 m2/g. For the adsorption performance of activated carbons from aqueous solution, Cu, Pb, Cd, and Cr metals were selected as inorganic contaminants, methylene blue, remazol brilliant blue, rhodamine 6G, phenol red, and indigo carmine dyestuffs, and phenol as organic pollutants. According to the dyestuff adsorption results from aqueous solution, it was determined that AK-FA had the highest capacity and according to the adsorption results of metal ions, AK-SA had the highest capacity. The activated carbon with the highest phenol adsorption capacity was found to be AK-PK with 205,2 mg/g. From the adsorption tests obtained, it was determined that the activated carbons removed pollutants from the aqueous solution with high performance. Thanks to this study, by producing activated carbon from corn cobs that do not have economic value, they gained an economic value and in addition, the possibility of waste causing environmental pollution was eliminated.