Study On Preparation And Performance Of Metal Ion (Pb²⁺、Cd²⁺、Mg²⁺、Ca²⁺) Adsorbent

With the rapid development of industry,agriculture and the continuous expansion of human activities,many wastewater containing heavy metal ions is discharged into natural water bodies.The heavy metal ions in the water can not only be biodegraded,but also enter the human body through the food chain,posing a serious threat to human health.Therefore,removing heavy metal ions in water is of great significance.This article aims to efficiently absorb heavy metal ions in water,three kinds of heavy metal ion adsorbents were prepared and their adsorption properties were systematically studied,the main tasks are as follows:1.Using biocompatible sodium alginate and carboxylated chitosan as raw materials,carboxylated chitosan is linked to sodium alginate through classical carboxyl and amino-condensation reactions.After gelling in calcium ion solution,the calcium alginate-chitosan composite aerogel(first-generation adsorbent)was prepared by vacuum freeze-drying.The adsorbent has good selectivity for lead and copper ions,the adsorption capacities of lead and copper ions are higher than those reported in most of the current literature(the adsorption capacity for lead ions is 468.5 mg/g,and the adsorption capacity for copper ions is 110.7 mg/g).At the same time,it has good acid resistance and can be recycled,and can effectively remove lead and copper ions in environmental water.2.Using sodium alginate and sodium ethylenediaminetetraacetate as raw materials,the ethylenediamine linkage agent was first modified to the surface of sodium alginate through carboxyl and amino group condensation reactions.After the amino and carboxyl condensation reaction is modified on the sodium ethylenediaminetetraacetate,the mixed droplets are then gelled in the calcium ion solution,and the cadmium ion adsorbent(second generation adsorbent)is finally obtained after vacuum freeze-drying.The cadmium ion adsorbent is highly selective to cadmium ions and has a maximum adsorption capacity of 172.8 mg/g for cadmium ions.The cadmium ion adsorbent is easy to recycle,and has stable performance after repeated adsorption/desorption cycles.The treatment of various types of wastewater containing cadmium ions has broad application prospects.3.Using sodium alginate and sodium citrate as raw materials,the carboxyl group was activated and ethylenediamine was used as a connecting agent.The two were connected by a carbamide condensation reaction,and then dropped into an alkaline earth metal ion solution to gelate.After washing with ultrapure water and freeze-drying,three generation adsorbents are obtained.The adsorbent has simple preparation process,large adsorption capacity,convenient recovery,high green efficiency and friendly environment.It has a high adsorption rate for most heavy metal ions and has strong adsorption efficiency for calcium and magnesium ions,and the adsorbent is not damaged after many cycles.It can be effectively used for the purification and softening of the environmental water body.