Preparation Of Ti-pillared Montmorillonite Particles And Their Adsorption To Cadmium Ions

In order to overcome the shortcomings of powdery montmorillonite which is easy to form mud and solid-liquid separation in the presence of water,this study takes montmorillonite as the main raw material,and studies its pillar modification,molding and adsorption effects.Paper is divided into three parts:1.Na-MMT is used as the matrix material.Tetrabutyl titanate was used as the titanium source to prepare titanium pillared montmorillonite?Ti-MMT?.Then using polyvinyl alcohol?PVA?as the adhesive and sodium alginate?SA?as the cross-linking agent,extruded and granulated to obtain Ti-MMT particles,and inspect the adhesive,cross-linking agent and Ti-MMT.The effects of the amount and other factors on the properties of Ti-MMT particles,the molding conditions of powdery Ti-MMT were studied.On this basis,the removal performance of Ti-MMT particles on simulated cadmium ion wastewater was discussed.In this paper,through static adsorption experiments,the adsorption mechanism of Ti-MMT particles on cadmium ion simulated wastewater is discussed from the adsorption isotherm model,kinetics and thermodynamics.The relevant model parameters are calculated,and the dosage,p H and initial concentration of cadmium ions are studied.The influence of adsorption temperature and adsorption time on the treatment effect.The results show that the optimal preparation conditions for Ti-MMT particles are:PVA:SA:Ti-MMT=0.6:1.0:20.0?mass ratio?.The adsorption capacity of Cd²⁺was 15.99 mg/g,the removal rate was 79.61%,and the loss rate was 7.48%.Under the conditions of dosage M=0.25 g,initial p H=6,initial concentration C=100 mg/L,adsorption temperature T=40?,and adsorption time t=120 min,the Cd²⁺adsorption capacity of the particles was 7.89 mg/g,and the removal rate reached 98.63%.And at 20?,the adsorption conforms to the Langmuir isotherm model.It is speculated that the adsorption of particles on Cd²⁺belongs to monolayer adsorption,and the RL value is between 0?1,indicating that the adsorption process is a preferential adsorption,and the adsorption reaction is easy to occur.The thermodynamic parameters?H,?G,and?S of Ti-MMT particles adsorbing Cd²⁺indicate that adsorption is an endothermic entropy increasing process.The adsorption process is affected by the hydrogen bonding force and the interaction force between dipoles.There is physical adsorption and complexation.The adsorption equilibrium time is 120 min,and the adsorption process conforms to the quasi-second-order kinetic equation.The adsorption process is controlled by multiple processes such as liquid membrane diffusion and intra-particle diffusion.2.In order to further improve the mechanical properties of Ti-MMT particles,the extrusion granulated Ti-MMT particles were roasted,and investigate the effects of roasting temperature,roasting time,preheating temperature and preheating time on the pores of particles and the effect of removing Cd²⁺,and The roasted particles were tested for recycling performance.The results of the study indicate that the adsorption capacity of Ti-MMT particles decreases after roasting.The best roasting conditions:The roasting temperature is 600?,the roasting time is90 min,the preheating temperature is 400?,and the preheating time is 20 min.The prepared Ti-MMT particles have good adsorption capacity and particle strength,and the removal rate is 67.95%,The loss rate is 4.65%.After three cycles,the particles remained stable,with a removal rate of approximately 67%and a loss rate of approximately 4.21%.3.Characterization of Ti-MMT particles.XRD analysis showed that the interlayer structure of montmorillonite was destroyed during granulation and roasting.FTIR analysis shows that there is a certain bonding relationship between PVA,SA and Ti-MMT.SEM image analysis revealed that PVA bonded fine flaky montmorillonite to form a large number of small network channels.After roasting,PVA blackens and carbonizes,and the rigidity of the amorphous material between the pore structures is enhanced.BET shows that after granulation of Ti-MMT,the specific surface area and total pore volume decrease and the pore size increases.After firing,the specific surface area,pore size and pore volume further increase.The adsorption-desorption isotherm of powdered Ti-MMT belongs to category II,and the adsorption isotherm curve belongs to the B-type adsorption loop.The shape of the adsorption-desorption isotherms before and after calcination is similar,and the hysteresis loops belong to the type IV in the BDDT classification.TG-DSC analysis shows that compared with powdered Ti-MMT,the particle mass loss is less,the added PVA has a certain effect on the shape of the curve,and the calcination process has no significant effect on the structural changes of the particles at high temperature?>600??.