Caracterização e sorção do NH4+ em biocarvão de casca de banana e bagaço de laranja carbonizados a 400 e 600°C

Abstract

Biochar is a product of pyrolysis, under partial or total absence of biomass oxygen, usually organic waste from agricultural and forestry processes, for purposes of use as a soil conditioner or filter element. Research has shown the potential of using biochar in agriculture as a soil conditioner and its use for environmental recovery purposes, making it an alternative for both organic waste disposal and urban solid waste. Its use potential depends essentially on its physico-chemical properties, which vary according to the biomass used and the pyrolysis process used, therefore its characterization is necessary to verify its use and limitations. Biochars also present a potential for the treatment of urban landfill leachates due to their potential for sorption of ammoniacal nitrogen, a compound found at high concentrations in the Brazilian landfill leachate. The objective of this work is to characterize and verify the potential of ammoniacal nitrogen sorption of the biochars produced from banana peel and orange bagasse carbonized at 400 and 600 °C. For the physico-chemical characterization of the biochars, adapted methodologies for soil analysis and methodologies proposed by international organisms for charcoal analysis were used. In the sorption tests, batch equilibrium tests were used with monosolution of ammonium chloride prepared in the laboratory and crude leachate from the sanitary landfill of Seropédica-RJ. The results showed that the biochars have properties of interest for both agricultural application and environmental remediation, with high nutrient contents, especially the K for the banana peel biochar reaching 157 g kg -1, and C contents in around 50%. They also demonstrated good water retention capacity at low and high potentials, especially the banana peel biochars reaching 600%. The carbonization temperature and the biomass used demonstrated to have a great influence on the final properties of the studied biochars. Sorption tests using monounsaturated ammonia nitrogen monoxide solutions indicated a maximum sorption for banana peel biochars at 400 and 600°C of 14.57 mg g -1 and 9.63 mg g -1 respectively. For orange bagasse biochars at 400 and 600°C, the maximum sorption was 13.67 mg g -1 and 10.84 mg g -1. For the leachate, the maximum sorption was 12.43 mg g-1 for the biochar of banana peel at 600° C and 8.49 mg g-1 for the orange bagasse biochar at 600° C, with better adjustment to the Freundlich isotherm. Carbonization has been shown to be a sustainable alternative in the final destination of organic solid waste, reducing and controlling the impacts generated by them and may have an added value as a soil conditioner and use for the remediation of contaminants of the environment.