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Metal salt-modified biochars derived from agro-waste for effective congo red dye removal


Dang Le Tri Nguyen, Quach An Binh, Xuan Cuong Nguyen, Thi Thanh Huyen Nguyen, Quang Nha Vo, Trung Duong Nguyen, Thi Cuc Phuong Tran, Thi An Hang Nguyen, Soo Young Kim, Thang Phan Nguyen, Jaehan Bae, Il Tae Kim, Quyet Van Le

Source title: 
Environmental Research, 200: 111492, 2021 (ISI)
Academic year of acceptance: 

Anionic Congo red dye (CR) is not effectively removed by conventional adsorbents. Three novel biochars derived from agro-waste (Acacia auriculiformis), modified with metal salts of FeCl3, AlCl3, and CaCl2 at 500 °C pyrolysis have been developed to enhance CR treatment. These biochars revealed significant differences in effluents compared to BC, which satisfied initial research expectations (P < 0.05). The salt concentration of 2 M realized optimal biochars with the highest CR removal of 96.8%, for AlCl3-biochar and FeCl3-biochar and 70.8% for CaCl2-biochar. The modified biochars were low in the specific surface area (137.25–380.78 m2 g−1) compared normal biochar (393.15 m2 g−1), had more heterogeneous particles and successfully integrated metal oxides on the surface. The CR removal increased with a decrease in pH and increase in biochar dosage, which established an optimal point at an initial loading of 25 mg g−1. Maximum adsorption capacity achieved 130.0, 44.86, and 30.80 mg g−1 for BFe, BCa, and BAl, respectively. As magnetic biochar, which is easily separated from the solution and achieves a high adsorption capacity, FeCl3-biochar is the preferred biochar for CR treatment application.