Study On Adsorption Of Hg²⁺ In Wastewater By Biomass Adsorbent Smilax Glabra Roxb

With the development of industrialization,many industries will be accompanied by the production of mercury pollution in the process of production,such as chlor-alkali manufacturing industry,chemical industry,mining and mineral processing industry,metallurgical electroplating industry,cement production and other industries,there will be mercury emissions in the production process.Mercury,as a global pollutant,poses a great threat to water,soil,air and human health.The advantages of Biomass adsorbent in the treatment of heavy metal pollution,such as high efficiency,economy,simple operation and environmental protection,are concerned by many researchers.At present,finding suitable adsorbents raw materials has become the main hot spot of biomass adsorption.Smilax glabra Roxb?SGR?is a widely distributed and easy to obtain biomass material in China.A large number of traditional Chinese medicine literature has proved that it has the effect of mercury toxicity.In this paper,the performance of biomass material SGR in the treatment of mercury-containing waste was studied.The effects of single factors on the adsorption properties of SGR were studied by controlling the particle size,p H,the initial concentration of Hg²⁺,temperature and reaction time.The significant influencing factors were selected and the response surface optimization test was used to study the effect of the two factors on the removal rate of Hg²⁺.Through the optimization of the model,the test conditions of the maximum removal rate of Hg²⁺were obtained.The study of biology was carried out by combining SGR characterization analysis?SEM,EDS,XRD,FTIR?with kinetic model,isotherm model and thermodynamic calculation.The process of adsorption of Hg²⁺in wastewater by material material SGR and the Mechanism involved in the adsorption process.The main results are as follows:?1?The results of single factor test of Hg²⁺adsorption by SGR showed that the adsorption of Hg²⁺reached equilibrium at 5 h,the removal rate of mercury ions was the best at around p H 4,the higher adsorption efficiency at SGR dosage 2.0 g/L and particle size80?100,35?and the initial concentration of Hg²⁺was 1.0 mg/L,which met the requirements of the test.When K⁺,Na⁺,Ca²⁺,Mg²⁺,Zn²⁺coexist in the solution,the inhibition effect on the removal efficiency of mercury ion order is Zn²⁺>Mg²⁺>Ca²⁺>K⁺>Na⁺.Increasing temperature is favorable for adsorption.?2?The response surface optimization test showed that the quadratic multivariate regression equation model has significant F value,p value and correlation coefficient R²?F?30.78,P<0.000 1,R²?0.968 5?,which indicated that the model has the higher credibility on Hg²⁺adsorption test.The order of significant influence was p H>Hg²⁺initial concentration>reaction temperature>dosage.The model predicted that the maximum removal rate of Hg²⁺could reach 92.28%when the initial concentration of Hg²⁺was 1.3 mg/L,p H=3.86,the dosage was 4.96 g/L,and the reaction temperature was 45?.?3?The adsorption kinetics fitting showed that the quasi-secondary kinetic model?R²=0.999?can describe the process of adsorption of mercury ions by SGR.Both the Bangham model and the W-M model indicated that the internal diffusion is the main reason for speed limitation.Langmuir adsorption isotherm model indicated that the adsorption of mercury ions by SGR is monolayer adsorption,and the maximum adsorption capacity of monolayer can reach about 1.8mg/g.The thermodynamic parameters?G<0,?H=11.25k J/mol,?S=56.75 J/?mol·k?showed that the adsorption of mercury ions is a spontaneous,endothermic and entropy increase process.?4?Analysis of SGR characterization and mechanism.The results of SEM,EDS,XRD and FTIR analysis showed that there were abundant tubular bundles on the surface of SGR.It was found that the tubular bundles were filled with spherical particles before and after adsorption,which indicated that SGR could be used to adsorb mercury ions,and a small amount of K⁺,Ca²⁺was released during the adsorption process,and exchanged with Hg²⁺took place in the adsorption process.XRD analysis showed that the phase composition of SGR contained not only crystal structure but also amorphous structure,and the crystal structure did not change obviously before and after adsorption,and the results of FTIR showed that the peak position and absorption intensity of surface active functional groups such as-COOH,,-NH₂and-OH adsorbed Hg²⁺changed to a certain extent,which indicated that there was complexation reaction between these functional groups and Hg²⁺.As a biomass adsorbent for the first time,Smilax glabra Roxb has shown a good effect on mercury removal in the treatment of mercury containing wastewater,which provides a new idea for the comprehensive utilization of Smilax glabra Roxb.