Synthesis of Porous Biochar Containing Graphitic Carbon Derived From Lignin Content of Forestry Biomass and Its Application for the Removal of Diclofenac Sodium From Aqueous Solution

• Published in: Frontiers in chemistry 2020-04, Vol.8, p.274
• Main Authors: Tam, Nguyen Thi Minh, Liu, Yun-Guo, Bashir, Hassan, Zhang, Peng, Liu, Shao-Bo, Tan, Xiaofei, Dai, Ming-Yang, Li, Mei-Fang
• Format: Article
• Language: English
• Subjects: adsorption; Chemistry; diclofenac sodium; graphitic carbon; lignin content; porous biochar; potassium ferrate
• ISSN: 2296-2646; 2296-2646
• DOI: 10.3389/fchem.2020.00274

Porous biochar containing graphitic carbon materials have received great attention from various disciplines, especially for environmental pollutant treatment, due to their cost-effective and specific textural properties. This study exhibited a two-step strategy to compose lignin-porous biochar containing graphitic carbon (LPGC) from pitch pine sawdust and investigated its adsorptive removal for diclofenac sodium (DCF) from an aqueous solution. Sulfuric acid (H SO ) was utilized to obtain lignin content from biomass and potassium ferrate (K FeO ) and was adopted to fulfill the synchronous carbonization and graphitization of LPGC. Through slow pyrolysis in atmospheric N (900°C - 2 h), the structure of the as-prepared sample was successfully modified. Using SEM images, a stripped layer structure was observed on the H SO -treated sample for both one-step and two-step activated samples, indicating the pronounced effect of H SO in the layering of materials. K FeO acted as an activator and catalyst to convert biomass into the porous graphitic structure. The BET surface area, XRD and Raman spectra analyses demonstrated that LPGC possessed a micro/mesoporous structure with a relatively large surface area (457.4 m g ) as well as the presence of a graphitic structure. Further adsorption experiments revealed that LPGC exhibited a high DCF adsorption capacity (q = 159.7 mg g at 298 K, pH = 6.5). The effects of ambient conditions such as contact time, solution pH, temperature, ionic strength, electrolyte background on the uptake of DCF were investigated by a batch adsorption experiment. Results indicated that the experimental data were best fitted with the pseudo second-order model and Langmuir isotherm model. Furthermore, the adsorption of DCF onto the LPGC process was spontaneous and endothermic. Electrostatic interaction, H-bonding interaction, and π-π interaction are the possible adsorption mechanisms. The porous biochar containing graphitic carbon obtained from the lignin content of pitch pine sawdust may be a potential material for eliminating organic pollutants from water bodies.