Manganese-modified lignin biochar as adsorbent for removal of methylene blue

Methylene blue, a prevalent cationic type dye, has been extensively utilized in textile industry. Lignin generates as a byproduct and its utilization is required to add a potential economic benefit of a biorefinery process. Lignin-derived porous biochar, as a promising adsorbent, was propitiously prepared by chemical modification with different oxidation number manganese compounds (KMnO4, MnSO4, and MnO2). The adsorption capacity of MnO2-loaded biochar to methylene blue dye was substantially higher relative to original biochar. The maximum adsorption capacity was 248.96 mg/g and removal rate was 99.73%, as compared to 234.65 mg/g and 94.0% for unmodified biochar. In comparison, the decolorization rate of the modified biochar exceeded 95%. Substantial results showed that methylene blue has a strong binding affinity with MnO2 modified biochar. Adsorption kinetics was described by a quasi-second order model and methylene blue adsorption isotherm was better fitted by Langmuir model. The research provides a promising way for the removal of methylene blue from wastewater through the manufacture of adsorbent from byproduct of biorefinery process.