Biomass-Based Biochar as Adsorbent: A Mini Review of Production Methods, Characterization, and Sustainable Applications

Abstract

Biochar is a carbonaceous material derived mainly from lignocellulosic biomass through thermochemical conversion processes such as conventional pyrolysis and hydrothermal carbonization. The review was conducted by screening and analyzing literature articles from Google Scholar and Scopus from 2012 to 2024. The operating temperature for conventional pyrolysis is 300 ºC to 1000 ºC and 180 ºC to 300 ºC for hydrothermal carbonization (HTC). The hemicellulose, cellulose, and lignin undergo different levels of degradation due to process conditions, which will lead to varying characterizations of the final product. The adsorption ability of biochar toward different pollutant types depends on the initial biomass feedstock. The surface functional group, surface area, porosity, and surface morphology are mainly affected by the production method and feedstock, which affects the adsorption ability of biochar. This mini-review aims to compare the biochar production method and adsorption ability of biochar toward different dye components to study its potential in wastewater treatment. Due to the varying properties of dye components, to effectively remove a specific dye through a specific biochar, it needs to be developed to obtain an optimized biochar for the adsorption of a particular dye. This manuscript concludes that pyrolysis at 700 ºC temperature and 240 minutes could produce biochar with the highest adsorption capacity; however, the optimized condition for HTC will be at a temperature of 180 ºC, and a time of 900 minutes with post-modification required.