Preparation Of Titanium Modified Montmorillonite And Its Adsorption Properties For Cr (â…¥)

With the development of the society, mining activities and the using of heavy metals are becoming more and more frequently. Chromium pollution is increasingly serious. In this paper, we used montmorillonite as the carrier, used titanium and silicon as modified element, prepared the titanium pillared agent by sol-gel method and used the method of ion exchange to prepared the titanium modified montmorillonite clay adsorbent. Prepared the simulation wastewater by potassium dichromate and to select the best adsorbent from adsorbents which made under different preparation conditions use the evaluation index which was the removal rate of Cr (Ⅵ) in simulation wastewate.By investigating the preparation technology of titanium modified montmorillonite conditions, it is concluded the best preparation conditions were that:when the rate of titanium and soil was 20mmol/g, the join method of pillared agent was the method of direct addition, montmorillonite suspension concentration was 2%, the temperature of pillared was 80℃, the power of microwave-ultrasonic was 100 w and didn’t roasting. Uses XRD、BET、FT-IR、TG and SEM-EDX analysis methods to analyze samples and it was concluded that pillared agent successfully entered into the structure of montmorillonite and titanium ion replaced the structure of metal cation, adsorbent layer spacing of the maximum expansion until d(ooi)=1.8192 nm, the biggest specific surface area is 111.085 m2/g and thermal stability is also improved.In order to improve the adsorption performance of adsorbent, we chose two elements which were titanium and silicon to prepare the modified adsorbents. Used the removal rate of Cr(VI) in the waste water as the evaluation index, through screening the proportion of titanium and silicon, we selected the best ratio:Si:Ti:MMT= 20 mmol:30 mmol:1 g. Using XRD、BET、FT-IR、TG and SEM-EDX analysis methods to analyze the samples, it was concluded that pillared agent successfully into the carrier in the structure of montmorillonite, titanium and silicon replaced the structure of metal cation, adsorbent layer spacing of the maximum expansion until d(001)=1.9484 nm, specific surface area of 304.723 m2/g and the total entrance were also increased. Screening the adsorption conditionthe of the best adsorbent Si-Ti-3, it was concluded that when the pH is 5、6 or 7, temperature is room temperature, dosing quantity is 0.3g/100 mL, simulated wastewater concentration is 30 mg/L is the best adsorption conditions.By using two kinds of common isothermal adsorption equation (Langmuir adsorption isotherm equation and the Freundlich adsorption isotherm equation) and three kinds of dynamics equations (pseudo first order reaction kinetics equation, pseudo first order reaction kinetics equation and particle diffusion model) to fit the experimental data analysis, it is concluded that the Langmuir adsorption isotherm equation which represents single physical adsorption model than the Freundlich isothermal adsorption equation which represents the multi-layer chemical adsorption model is more suitable to describe Cr(Ⅵ) adsorb on the adsorbent; the second order reaction kinetics equation is suitable to describe the adsorption process of Cr(Ⅵ) and particle diffusion is not within the reaction rate control steps.