Adsorption of methylene blue by activated carbon derived from Platycodon grandiflorus residue
Objective To prepare Platycodon grandiflorus residue activated carbon(PGAC)adsorbent with high specific surface area and develop pore structure to remove methylene blue(MB)in dye waste water,and to determine the adsorption performance and mechanism of MB in dye wastewater.Methods PGAC was obtained through a simple high-temperature pyrolysis process with Platycodon grandiflorus residue as raw material and KOH as activator.The surface morphology,internal structure,and functional group distribution of PGAC were characterized.By changing the concentration of the adsorbent,the mass concentration of MB,adsorption time,pH value,and the influence of various factors on the adsorption performance of MB were studied,and the experimental process fit the isothermal adsorption models and adsorption kinetic models.Results When the concentration of the adsorbent was 80 mg·L-1,the initial concentration of MB was 100 mg·L-1,the adsorption time was 1 hour,the pH was 6,and the removal rate of MB in waste water by PGAC was 99.5%.The adsorption process of PGAC on MB followed the Langmuir model and pseudo-second kinetic model.Conclusion The adsorption of MB by PGAC is mainly dominated by uniform monolayer adsorption,and the adsorption rate is mainly through chemical adsorption mechanism.The prepared PGAC efficiently adsorbs MB in the water due to its stable pore structure and large surface area.This study provides useful references for the resource utilization of traditional Chinese medicine residues and use of MB in the printing and dyeing waste water.
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