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| Adsorption mechanism of Pb2+ in water by biochar derived from spent Agaricus bisporus substrate and its environmental application potential |
| Received:August 15, 2020 |
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| KeyWord:Agaricus bisporus substrate;biochar;lead pollution;pyrolysis temperature;adsorption mechanism;application potential |
| Author Name | Affiliation | E-mail | | ZHANG Guo-sheng | College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, China | | | CHENG Hong-yan | College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, China | ndchenghy@163.com | | ZHANG Hai-bo | College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, China | | | SU Long | College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, China | | | HE Xiao-fang | College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, China | | | TIAN Xin | College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, China | | | NING Rui-yan | College of Resources and Environment, Shanxi Agricultural University, Taigu 030801, China | |
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| Abstract: |
| To utilize the biochars from spent mushroom substrate for adsorbing Pb2+ in aqueous solutions effectively, they were prepared using spent Agaricus bisporus substrate(MS) as raw materials by limited oxygen pyrolysis under 350, 550℃, and 750℃(MS350, MS550, and MS750). The original and lead-loaded biochars were characterized using XRD and FTIR. The adsorption characteristics and removal mechanisms of Pb2+ on biochars were investigated by batch adsorption and sequential metal extraction tests. Results indicated that the biochar yield decreased while the pH and aromaticity increased with an increase in pyrolysis temperature. The adsorption kinetics of biochars were well-fit to the pseudo-second order model. The isothermal adsorption of MS350 and MS550 was better described using the Freundlich isotherm model, whereas MS750 was better described using the Langmuir model. Among the biochars, MS750 was the most effective adsorption biochar, and the maximum adsorption capacity reached 266.23 mg·g-1. The solution pH affected the adsorption performance of biochars, and the adsorption capacity increased with an increase in solution pH in the range of 2.0~7.0. The possible mechanisms of Pb2+ adsorption on the biochars included precipitation with minerals, ion exchange, complexation with surface oxygen-containing functional groups, and coordination with π electrons. Mineral precipitation(CO32-, SO42-) was the primary adsorption process, and its contribution rate increased with the increase of pyrolysis temperature. The results of sequential lead extractions showed that the Pb of biochars was mainly acid-soluble and non-available fractions, indicating that the majority of Pb immobilized by the biochars was stable. The order of total acid-soluble and non-available fractions of Pb in the total adsorption capacity was as follows:MS750(98.65%) > MS550 (95.91%) > MS350(86.51%). MS750 had a higher pH and adsorption capacity of Pb2+ and better stability after Pb2+ adsorption than those of other biochars. Therefore, it has great potential in environmental applications. |
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