Using recycled coffee grounds for the synthesis of ZIF-8@BC to remove Congo red in water

• Published in: Ecotoxicology and environmental safety Vol. 236; p. 113450
• Main Authors: Liang, Yixuan, Li, Hanbing, Li, Xiaotong, Zhang, Qiyu, Fei, Jiaying, Li, Sumei, Chen, Sha
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.05.2022; Elsevier
• Subjects: Adsorption; Charcoal; Coffee; Congo red; Congo Red - analysis; Kinetics; Metal-organic framework; Spent coffee grounds; Water; Water Pollutants, Chemical - analysis; Metal-organic framework; Congo red; Adsorption; Spent coffee grounds
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2022.113450

Around 6.6 million tons of spent coffee is produced per year, resulting in resources loss and potential environmental risks. Hence, a green technique is required to reuse the spent coffee grains. In this study, coffee grounds were burnt at 900 °C to generate the biochar (BC) for the synthesis of the porous adsorbent (ZIF-8 @BC) by growing ZIF-8 on the surface of BC. We applied the well-prepared ZIF-8 @BC to remove Congo red (CR) in water. The maximum adsorption capacity of ZIF-8 @BC on Congo red in water was up to 1080.4 mg/g, which was significantly higher than that of many different types of BCs reported in previous studies. The reasons for its highly efficient adsorption of CR probably was attributed to metal ions and coordinatively unsaturated sites in the material. Also, BC enabled the less aggregation of ZIF-8 to provide sufficient specific surface area for CR adsorption. From the analysis of the pseudo-second-order kinetic model and Langmuir model, the adsorption of ZIF-8 @BC on CR was a homogeneously chemical adsorption process regulated by electrostatic interaction, π-π stacking and metal coordination. [Display omitted] •Successful using SCGs to synthesis a novel adsorbent ZIF-8 @BC.•Powerful adsorption performance of ZIF-8 @BC for CR.•Strong regeneration and recyclability of ZIF-8 @BC for practical use.