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| Adsorption of tetracycline hydrochloride by KOH modified peanut shell biochar and its mechanism |
| Received:May 06, 2023 Revised:June 20, 2023 |
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| KeyWord:peanut shell;biochar;alkali treatment;tetracycline hydrochloride;adsorption mechanism |
| Author Name | Affiliation | | ZHONG Laiyuan | College of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China | | LIAO Rongjun | College of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China | | LIU Fuyujie | College of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China | | LUO Zhangyi | College of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China |
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| Abstract: |
| In this study, peanut shell was used as raw material and KOH as a modifier to investigate the effects of parameters in the process of alkali modification, such as pyrolysis temperature, alkali-carbon ratio, and the alkali treatment procedure, on the adsorption properties of modified biochar to tetracycline hydrochloride(TCH). The adsorption experiments were carried out using pristine biochar(BC600)as a control, and the effect of parameter changes in the process of modification on adsorption performance was studied. The biochar was characterized by SEM, EDS, specific surface area and pore size analysis, FTIR, and pHpzc to unravel the adsorption mechanism of TCH by biochar. The results showed that modified biochar(Post-MBC)prepared by alkali post-treating-melting method at 600℃ with alkali-carbon ratio of 2:1 exhibited excellent TCH removal capacity. The removal rate of TCH in 40 mL solution of 0.06 mg·mL-1 reached 99.07% using 0.1 g Post-MBC at 25℃ and pH of 4. The theoretical maximum adsorption capacity of Post-MBC to TCH reached 240.94 mg·g-1 (45℃). The specific surface area and total micropore volume of Post-MBC reached 863.56 m2·g-1 and 0.26 cm3·g-1, respectively. The hydrophilicity of biochar modified by KOH was reduced, and the biochar carried negative charges on its surface. Consequently, its adsorption capacity was improved for hydrophobic and positively charged pollutants. The kinetic model of biochar accords with the McKay equation, and the fitting results of Langmuir, Freundlich, and Temkin isotherm models showed that all three models had high correlation coefficients. Chemisorption was the primary adsorption mode of modified biochar removing TCH, and the adsorption process was endothermic and spontaneous. The adsorption mechanism of modified biochar included pore filling, π-π interaction, hydrogen bonding, electrostatic interaction, and hydrophobic interaction. |
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