Preparation And Adsorption Of Heavy Metal Cr(?) On Copper Slag-based Alkali-activated Cementitious Materials

In recent years,in the development of human civilization,metallic copper,as a modern engineering material full of vitality and vitality,has made an indelible contribution to our development.However,a large amount of copper slag is produced in the process of producing metallic copper.The accumulation of copper slag not only takes up a lot of land resources,but also causes a waste of resources.At the same time,with the rapid development of our human society,we are also facing serious heavy metal pollution problems.For this reason,the state has put forward relevant environmental governance policies,requiring heavy metal pollution control methods to be transformed into environmentally friendly development.Therefore,it is particularly important to research and develop green and environmentally-friendly methods for comprehensive utilization of copper slag and methods for treatment of heavy metal pollution.Aiming at the comprehensive utilization of copper slag and the treatment of heavy metal Cr(?)in wastewater,this paper proposes to use alkali activator to stimulate the activity of copper slag to prepare copper slag-based alkali-activated cementitious material(CS-ACM),and use it as an adsorbent for adsorption Liquid phase heavy metal Cr(?).Detailed research work are as follows:(1)A more comprehensive study of the alkali solubility characteristics of copper slag will lay a certain foundation for the subsequent preparation of CS-ACM.The research results show that the dissolution of Si during the alkali dissolution of copper slag belongs to the internal diffusion control process,and the apparent activation energy of the alkali dissolution of copper slag is Ea=24.47 KJ/mol.XRD,FT-IR,SEM-EDS analysis showed that the phase composition before and after the alkali dissolution of the copper slag did not change significantly,and no new substances were formed.The intensity of the diffraction peaks of each phase increased with the extension of the dissolution time and the alkalinity of the dissolution lye The increase of the dissolution temperature and the rise of the dissolution temperature continue to weaken;the microscopic morphology after dissolution has a network structure similar to corrosion before dissolution.(2)A preparation method of CS-ACM was proposed,and the formation mechanism of CS-ACM was studied.The research results show that the optimal preparation conditions of CS-ACM are:water-cement ratio of 0.18,composite activator modulus of 1.6,dosage of 8%,curing constant temperature of 40?;CS-ACM prepared under these conditions,The compressive strengths of,3,7,and 28 days are 41.3 MPa,71.8 MPa,and 113.4 MPa,respectively.The analysis of XRD,FT-IR,SEM-EDS,XPS and M?ssbauer spectroscopy shows that the formation process of CS-ACM and ordinary alkali-excited gelling materials is not much different,but the Fe³⁺in CS-ACM is forming CASH gel When it partially replaces Al³⁺to form a ferrite tetrahedron,the CASH gel in the final system contains not only an aluminum oxide tetrahedron and a silicon oxygen tetrahedron,but also a ferrite tetrahedron,which promotes the pressure of the material.It is CS-ACM An important reason for the higher compressive strength.(3)The use of CS-ACM to adsorb Cr(?)in wastewater provides a new method for the treatment of heavy metals and the cleaning of water resources.The research results show that the adsorption rate of Cr(?)increases with the increase in the amount of adsorbent used,and the adsorption capacity continues to decrease until the adsorption equilibrium;with the increase of the p H value of the solution,the adsorption rate of Cr(?)decreases significantly.The p H of the solution is about 1 is the best;the adsorption temperature is 25?.Studies on adsorption kinetics and thermodynamics show that the adsorption of Cr(?)by CS-ACM can be described by a pseudo-first-order kinetic model and a Langmuir adsorption isotherm model.