Removal of copper and cadmium from aqueous solution using switchgrass biochar produced via hydrothermal carbonization process

• Published in: Journal of environmental management Vol. 109; pp. 61 - 69
• Main Authors: Regmi, Pusker, Garcia Moscoso, Jose Luis, Kumar, Sandeep, Cao, Xiaoyan, Mao, Jingdong, Schafran, Gary
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 30.10.2012; Elsevier; Academic Press Ltd
• Subjects: Activated carbon; Activation; Adsorption; Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Aqueous solutions; Biochar; Biological and medical sciences; Biomass energy; Cadmium; Cadmium - chemistry; Carbon emissions; Charcoal - chemistry; Chemistry; Conservation, protection and management of environment and wildlife; Copper; Copper - chemistry; Emissions trading; Environmental management; Fundamental and applied biological sciences. Psychology; General aspects; Hydrothermal; Particular ecosystems; Sorption; Switchgrass; Synecology; Water Purification - methods; Activation; Adsorption; Biochar; Hydrothermal; Switchgrass; Hydrothermal vent; Cadmium; Aqueous solution; Copper; Environmental management
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2012.04.047

Biochar produced from switchgrass via hydrothermal carbonization (HTC) was used as a sorbent for the removal of copper and cadmium from aqueous solution. The cold activation process using KOH at room temperature was developed to enhance the porous structure and sorption properties of the HTC biochar. The sorption efficiency of HTC biochar and alkali activated HTC biochar (HTCB) for removing copper and cadmium from aqueous solution were compared with commercially available powdered activated carbon (PAC). The present batch adsorption study describes the effects of solution pH, biochar dose, and contact time on copper and cadmium removal efficiency from single metal ion aqueous solutions. The activated HTCB exhibited a higher adsorption potential for copper and cadmium than HTC biochar and PAC. Experiments conducted with an initial metal concentration of 40 mg/L at pH 5.0 and contact time of 24 h resulted in close to 100% copper and cadmium removal by activated HTCB at 2 g/L, far greater than what was observed for HTC biochar (16% and 5.6%) and PAC (4% and 7.7%). The adsorption capacities of activated HTCB for cadmium removal were 34 mg/g (0.313 mmol/g) and copper removal was 31 mg/g (0.503 mmol/g). ► Biochar prepared via hydrothermal carbonization can be an effective adsorbent. ► Cold alkali activation enhanced the adsorption capacity for copper and cadmium. ► Adsorption by activated biochar was higher than by unactivated biochar and PAC.