Abstract

The environmental impact of water contamination has driven the search for sustainable materials for wastewater treatment, especially in the textile industry. The production of carbonaceous materials from biomass stands out as a low-cost and accessible alternative, promoting sustainable development and environmental preservation. This study aimed to produce biochar from leucaena (Leucaena leucocephala) pods and seeds impregnated with Black Liquor and evaluate its performance in removing methylene blue as a model cationic dye. The materials (original and carbonized) were characterized using several techniques, including thermogravimetry, infrared spectroscopy, X-ray diffraction, scanning electron microscopy, ammonia desorption, specific surface area analysis, point of zero charge determination, and Raman spectroscopy, and tested as adsorbents for methylene blue removal. The original materials exhibited a residual mass of 25-54% after pyrolysis up to 600 degrees C and maintained thermal stability in the range of 400 and 1000 degrees C. Regarding the total acidity, the results of ammonia desorption at programmed temperature showed that the samples obtained from the leucaena and liquor mixture exhibited higher acidity. The leucaena-black liquor mixture materials efficiently removed methylene blue at alkaline pH (>7.0-9.0), achieving removal efficiencies of 94.08% (pod) and 87.17% (seed). The adsorption kinetics followed a pseudo-second order model, with adsorption capacities of 3.64 mg center dot g(-1) (seed-liquor) and 4.40 mg center dot g(-1) (pod-liquor).