Biochar production from tannery waste pyrolysis as a circular economy strategy for the removal of emerging compounds in polluted waters

The tanning industry is of major interest for generating water and soil pollution in developing countries. Tannery wastes usually contain hair mixed with inorganic substances, being hazardous and difficult for use, treatment, and valorization. Tanner hair waste is a profitable material to produce biomaterials as biochar for agriculture and environment management. This study explores the potential use of biochar as a bio-adsorbent for emerging compounds like drugs. A fixed-bed pyrolysis activated with KOH was developed to produce the biochar, the KOH activation process increased the surface area and removal yields of the biochar. The study conducted adsorption tests with the single and mixed drugs amoxicillin-AMOX, diclofenac-DFC, azithromycin-AZM, and erythromycin-ERY. All biochar tested reached drug removal rates higher than 80%: AZM with the highest removal rate (94%), AMOX (91%), and DFC (83%). The tannery activated biochar was effective in removing all tested drugs. All the models tested have shown that the adsorption isotherms fit a Langmuir isotherms model.

Automated summary

The tanning industry in developing countries is a major source of water and soil pollution. Tannery wastes containing hair mixed with inorganic substances are hazardous and difficult to use, treat, and valorize. This study explores the potential use of tanner hair waste as biochar for the removal of emerging compounds like drugs. The biochar, produced through fixed-bed pyrolysis activated with KOH, showed high removal rates (over 80%) for all tested drugs, with azithromycin exhibiting the highest removal rate (94%).