A new valorization of sotol bagasse waste

Sotol bagasse is an increasing waste. This is due to the growing demand for sotol liquor in Mexico. By now, it pollutes the environment with no other use. In terms of sustainable development, the safe reuse of waste and biomass is expected. Additionally, the overexploitation of aquifers and natural leaching processes have caused an increase in the concentration of arsenic in drinking water. This work aims to characterize sotol bagasse and its conversion into a biochar. Additionally, it assesses the biochar´s suitability for removing arsenic from water. Ash, extractives, and lignin content of sotol bagasse were 7.40, 11.57, and 29%. Scanning electron microscopy revealed a fibrous structure with carbon, oxygen, calcium, and potassium. Bagasse was pyrolyzed from 300 to 900 °C. Infrared spectroscopy analysis indicated biopolymer degradation according to temperature. The highest biochar yield was 46.69%. The largest surface area was 77.59 m²/g. The biochar efficiently removed arsenic (97% at eight h) from Chihuahua’s city tap water, with an initial concentration of 0.026 mg/L. X-ray photoelectron spectroscopy showed calcium within the biochar framework is essential for arsenic removal.