A study on adsorption characteristics of iron-modified hemp root biochar for phosphate in water

doi:10.16535/j.cnki.dlhyxb.2022-270

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Journal of Dalian Fisheries University ›› 2023, Vol. 38 ›› Issue (3) : 464-473. DOI: 10.16535/j.cnki.dlhyxb.2022-270

A study on adsorption characteristics of iron-modified hemp root biochar for phosphate in water

WANG Nana，WANG Jing*，LI Yang，LI Jing

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Abstract

In order to effectively control eutrophication of water bodies and improve the resource utilization of agricultural waste, hemp root was used as a precursor to prepare biochar (RHY) using dilute sulfuric acid catalyzed hydrothermal method, and iron modification was carried out using immersion method to obtain iron modified hemp root biochar (RHY-Fe). The modified biochar was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, etc. The adsorption isotherm model and kinetic model were used to fit the phosphorus adsorption characteristics of biochar, and the effects of adsorption time, phosphorus concentration, temperature, addition amount, coexisting ions, etc. on the adsorption of phosphorus by biochar were analyzed. The results showed that the adsorption capacity of iron modified biochar was significantly improved, and the maximum phosphorus adsorption capacity of iron modified biochar Langmuir was 6.9 mg/g; An ideal adsorption effect was achieved at an initial phosphorus concentration of 40 mg/L and a RHY-Fe addition of 6.67 g/L; The adsorption reaction basically reached adsorption equilibrium within 60 minutes; When the temperature rised from 15 ℃ to 25 ℃, the adsorption capacity of modified biochar significantly increases to the highest level; Cl- and

have significant interference, with adsorption capacities decreasing by 3.1 and 2.7 mg/g, respectively. The adsorption mechanism of RHY-Fe on phosphate may mainly involve ion exchange, surface chemical precipitation, etc.; The modified biochar (addition amount 0.2 g/L) was used to treat the actual aquaculture waste water, a good phosphorus removal effect was observed with a removal rate of 71%. All results obtained in this research indicate that iron modified hemp root biochar has a good adsorption effect on phosphate in water, and has good reusability. It can not only achieve the resource utilization of agricultural waste, but also has the potential for efficient removal of phosphate in wastewater treated plants.

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hemp root / phosphate / ferric chloride / biochar / adsorption

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WANG Nana, WANG Jing, LI Yang, LI Jing. A study on adsorption characteristics of iron-modified hemp root biochar for phosphate in water[J]. Journal of Dalian Fisheries University, 2023, 38(3): 464-473 https://doi.org/10.16535/j.cnki.dlhyxb.2022-270