Iron/Biochar-based Gel Pellet for Highly Efficient Phosphate Removal and Analysis on Approximate Site Eenergy Distribution
JIANG Baiguo
LI Huiping
ZHOU Baiqin
PANG Weihai
Abstract：The biochar prepared by use of organic solid-waste is applied to adsorbing excessive phosphate in water bodies for controlling eutrophication,and at same time,realizing organic solid-waste effective reuse;however,the biochar common-ly prepared without any surface modification is limited in terms of phosphate adsorption performance.In this experimental study,magnetic Fe3O4 is employed to modify the biochar,and then chitosan is used to make solid gel pellets,i.e.,the highly efficient phosphate adsorbent,and later testing of this iron/biochar-based gel pellets is conducted,which includes the employ-ment of several characterizations techniques as well as the theory of approximate site energy distribution to investigate the adsorption mechanism,and the elaborate analysis of the key to upgrading phosphate adsorption performance.As a result,the experimental study presents that it is by adding Fe3O4 that the gel pellets increase the adsorption capacity from 13.76 mg/g(with biochar)to 87.79 mg/g(with Fe3O4-modified biochar)at 293 K;phosphate adsorption onto the gel pellets is an endother-mic process,and the experimental data about phosphate adsorption behavior could be well described by the pseudo-second and Langmuir model;besides,the characterization techniques reveal that the surface precipitation formed between Fe and phosphate is the primary mechanism,on the other hand,porous filling,hydrogen bonding and electrostatic attraction also play a role in the adsorption. On the whole, chemisorption is regarded as the primary adsorption mechanism; moreover, according to the analysis of approximate site energy distribution, it is revealed that the improvement of adhesion between the phosphate and adsorbent and the intensive distribution of high-energetic adsorptive sites is a critical measure to boost phosphate adsorp-tion amount; besides, the iron/biochar-based gel pellet shows a certain flexibility against varied external ions in the water, maintaining high adsorption property in natural water body, and is easy to be recycled. So it is expected that the result of the study would provide a guideline for developing high-efficient phosphate removal adsorbent.
Keywords：biocharphosphateadsorptiongel pelletapproximate site energy distributionpractice
Publication Date：2023-11-28
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：12( 168-179 )