Study On Adsorption Of Cr(?) To Montmorillonite Modified By CPB And Tetra-n-butyl Titanate For Postgraduate

Montmorillonite(MMT)is a kind of excellent performance inorganic nano-particles,which is rich in mineral resources.It has widely used in industrial fields because of its low price.Montmorillonite has a layered structure,so it has good adsorbility,and it is easily be modified.In this article,montmorillonite was used as raw material,the hexadecylpyridine bromide(CPB)and Tetra-n-butyl Titanate was used as pillared agents.The adsorbent(CPB-Ti-MMT)'s preparation conditions and adsorption process conditions were optimized by analyzing the results of experimental data.The potassium dichromate solution was used as Chromium-containing wastewater.Combining the experimental data and the results of characterization which concluded X-ray diffraction(XRD),Braunuer-Emmett-Teller(BET),Fourier transform infrared(FT-IR),and Zeta potential,the preparation optimal conditions showed that: if CPB was intercalated before Titanium pillared agent,the adsorption capacity was better than that of intercalated simultaneously or Titanium pillared agent pre-intercalated;the optimal preparation temperature is 40 ?;the optimal montmorllonite solution concentration is 1g/200 m L;the optimal ratio of Ti/CPB is 25mmol/g;the optimal ultrasonic power was 90 W.The characterization results of CPB-Ti-MMT showed that CPB and Titanium pillared agent was intercalated into MMT's layer successfully and made the interlayer spacing of MMT increase to 2.92 nm,total pore volume and average pore diameter were increased as well.According to the date of experiments,the adsorption process conditions show that: the optimal adsorption temperature is 20?;the optimal initial Cr(?)concentration is 10mg/L;the optimal dosage ratio of adsorbent is 0.2g/100 m L;the optimal p H is 6.0.Under the above conditions,CPB-Ti-MMT exhibited the best adsorbility,the removal of Cr(?)reached97.60%,the adsorption capacity was 49.5mg/g.The experimental data was fitted by pseudo-first-order reaction kinetics equation,pseudo-second-order reaction kinetics equation,particle diffusion model.The results demonstrated that pseudo-second-order reaction kinetics equation could describe the adsorption process better.It revealed the exist of chemical adsorption.Correspondingly,the results of diffusion experiments showed that the control step is boundary layer diffusion infirst parts,and in second parts,the control step is intraparticle diffusion.The experimental date was as also fitted by Langmuir adsorption isotherm equation and Freundlich adsorption isotherm equation.The results showed Langmuir adsorption model could describe the adsorption process better.The experimental data of adsorbent was fitted by intraparticle diffusion equation,it showed that the process of adsorption has two parts,the quick adsorption and the unsaturated adsorption,and the rate of the adsorption process was not intraparticle diffusion,but co-determined by the boundary layer diffusion and intrapaticle diffusion.