Treatment of Heavy Metal Wastewater by Electroplating and Crosslinking Modified Chitosan with Electric Heating Tube

Treatment of Heavy Metal Wastewater by Electroplating and Crosslinking Modified Chitosan with Electric Heating Tube

Crosslinking modification can effectively improve the stability of chitosan by forming a network structure of linear chitosan molecules. In addition, crosslinking modification can improve the adsorption selectivity of chitosan. However, due to crosslinking modification, the number of amino groups in chitosan molecules is reduced, which may reduce the adsorption capacity of chitosan. Due to the influence of the properties of heavy metal ions and crosslinking agents, the adsorption capacity of crosslinked chitosan for heavy metals may not necessarily be higher than that of chitosan. Therefore, in order to achieve better adsorption effects, it is necessary to choose appropriate crosslinking agents. Commonly used crosslinking agents include epichlorohydrin, glutaraldehyde, glyoxal, and formaldehyde; There are two cross-linking methods: direct method and template method.

In recent years, template synthesis has become a new method for preparing polymer adsorption chelating resins with certain "memory" functions. Due to the retention of "holes" within the molecules that exactly accommodate template ions, it has strong recognition ability (i.e. "memory" ability) for template ions. Huang Xiaojia et al. found that the synthesis of glutaraldehyde crosslinked chitosan resin using zinc ions as a template not only affected the+[ ρ (Zn2+) has a strong "memory" ability at a concentration of 1g/L, and has a high adsorption capacity for Cd2+and Hg2+at the same mass concentration. Moreover, it does not soften or dissolve during regeneration under acidic conditions, and has good regeneration performance. Sun Shengling et al. studied the adsorption performance of glutaraldehyde crosslinked resins synthesized using copper salts [CuSO4 · 5H2O, Cu (Ac) 2 · H2O, Cu (NO3) 2 · 6H2O, CuCl2 · 2H2O] as templates for metal ions. The results showed that the adsorption capacity of CTS (chitosan) crosslinked by each copper salt template for Cu2+, Co2+, Ni2+, and Zn2+sulfate was similar to that of Co2++

Han Deyan et al. studied crosslinked chitosan magnetic microspheres, which have adsorption capacities of 72.0mg/g and 48.3mg/g for Pb2+and Cu2+, respectively. The magnetic microspheres have the characteristics of being difficult to lose and easy to regenerate. Li Jiping used chitosan with high deacetylation degree to encapsulate a self-made magnetic fluid, and crosslinked it with glutaraldehyde to produce magnetic chitosan (MCG) with good adsorption effect on rare earth ions (La3+, Nd3+, Eu3+, Lu3+). The highest adsorption rate can reach over 99%, and it has good reusability; Its adsorption behavior satisfies the Langmuir isotherm.

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