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Biomass Chemical Engineering ›› 2020, Vol. 54 ›› Issue (4): 1-8.doi: 10.3969/j.issn.1673-5854.2020.04.001

• Research Report •     Next Articles

Preparation and Characterization of Activated Carbon from Coffee Grounds and Its Adsorption Mechanism for Cr(Ⅵ)

Jie REN1,2(),Li WAN1,2,Nanwei CHEN1,2,Fan YANG1,2,Shuiyu SUN1,2,3,Suizhou REN1,2   

  1. 1. Guangdong Polytechnic of Environmental Protection Engineering, Foshan 528216, China
    2. Guangdong Engineering and Technology Research Center of Solid Waste Resource Recovery and Heavy Metal Pollution Control, Foshan 528216, China
    3. School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
  • Received:2019-07-16 Online:2020-07-30 Published:2020-08-06


The preparation conditions of activated carbon from coffee grounds, including activation temperature, activation time and impregnation ratio, were studied by using the response surface methodology with iodine adsorption value as evaluation index. And the effects of adsorption time, initial pH value and temperature on the Cr(Ⅵ) removal by the obtained activated carbon were investigated. In addition, the kinetic data were fitted by pseudo-first-order equation, pseudo-second-order equation and infra-particle diffusion model, and the equilibrium data was analyzed by using Langmuir and Freundlich isotherm models. The experimental results showed that the activated carbon had the best performance under the optimum conditions of activation time 1 h, activation temperature 498℃ and impregnation ratio 1.72. Under these conditions, the yield of activated carbon was 30.4%, and the iodine adsorption value got up to (799±16) mg/g, the relative surface area could reach 1 006 m2/g, the total pore volume was 0.799 cm3/g, the t-Plot micropore volume was 0.051 cm3/g and the average pore size was 3.088 nm. The adsorption data fitted Langmuir isotherm model. Higher temperature and lower pH could promote the adsorption of Cr(Ⅵ) on activated carbon. The adsorption of Cr(Ⅵ) on activated carbon was divided into three stages:fast adsorption stage, slow adsorption stage and adsorption equilibrium stage, the total adsorption of 79% was completed in 10 min, the adsorption process could reach equilibrium in 360 min, and the pseudo-second-order equation generated the best agreement with the experimental data for the adsorption systems. The results showed that the adsorption of Cr(Ⅵ) on the obtained activated carbon was chemical adsorption with monomolecular layer.

Key words: coffee grounds, response surface methodology, activated carbon, Cr(Ⅵ), adsorption properties

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