Perfluorooctanesulfonic acid (PFOS) removal from aqueous solution through N-doped porous copper-carbon composite derived from recycled copper obtained from fly ash incinerator: Water decontamination via municipal waste remnants.

Abstract

Invincible growth in waste production is the consequence of overpopulation, which should be addressed to reduce the occupied landfill surface needed for their disposal and to alleviate the leachate of extremely hazardous material into the soil and water bodies. In this study, copper (Cu) was extracted from fly ash of a municipal solid waste incinerator by an electro-chemical method, which was optimized to recover the highest amount of Cu, and then it was chelated with 4-aminobenzoic acid (AM) and terephthalic acid (TM) in an aqueous phase. The obtained composites were then heated to form a porous calcinated copper-carbon composite and utilized to adsorb the forever contaminant of PFOS from aqueous solutions. As the calcinated composite of Cu/AM with a ratio of 1:1 removed a greater amount of PFOS from the aqueous solution than Cu/TA, it was utilized as the ultimate adsorbent. The platform adsorbent was subjected to multiple characterizations, including XRD, FESEM, elemental mapping, TEM, BET, EDS, ICP-OES, FTIR, DLS, and point of zero charges, as well as optimization of several operational parameters involving pH, adsorbent dosage, initial PFOS concentration, and contact time. At the neutral pH, under the optimal conditions (adsorbent dosage of 1 g L^-1 and 5 h), 97.23% of PFOS was eliminated from the solution spiked with 5 mg L^-1 of PFOS. The equilibrium data were best fitted with Frundlich isotherm, and the maximum adsorption capacity of 402 mg g^-1 was achieved. The optimal conditions were also applied to PFOA, demonstrating high adsorption of different types of PFAS. The recovery tests of the adsorbent conducted 5 times on the solution spiked with 10 mg L^-1 of PFOS showed a slight decrease in PFOS removal at least for 5 regeneration cycles, demonstrating the high adsorption capacity and its reusability, thereby validating its feasibility for large-scale applications.