Preparation Of Modified Bentonite And Study On Its Adsorption

Bentonite is a clay mineral with expandable layer structures that primary constituent of montmorillonite. Modification of bentonite can be prepared by exchanging the cation interbedded with simple metal cation, quaternary ammoniumcanons. The physical and chemical capability of the modified bentonite improved obviously, such as d₀₀₁, adsorb hydrophobic contaminants after the modification. And the modified bentonites are used as sorbents to treat various wastewater and have a lot of applications in environmental protection.There is little research on exploitation and application of Ezhou bentonite. In allusion to the actuality, this dissertation studies the basis physical and chemical characters and the types of Ezhou bentonite particularly. Special attention is paid to the best technical condition of Na-modification and organ-intercalation. And modified bentomtes are used as sorbents to treat Cu(II) wastewater and oily wastewater. The adsorption capability of Ezhou bentonite is discussed detailedly.The montmorillonite content of nature bentonite in Ezhou is low, only 73.8%. It is obviously important to purify the bentonite as the require content is above 90% in the modification and farther process of bentonite. This article uses sedimentation technics to purify bentonite. The montmorillonite content increases to 93.4%.The best technic conditions of Na-modification are ascertained via single factor experiment: selecting Na₂CO₃ as modifying addition, amount 5%, pulp density 15%, and stirring time 15min. The physical and chemical capability enhanced evidently, after the Na-modification. The colloid index and expansive capacity arrive to 500mL/15g, 72.0mL/g from the primary 100mL/15g, 11.0mL/g. It indicates that the Ca-bentonite changes into Na-bentonite as the d₀₀₁ decreases to 1.24nm from 1.53nm and Ca²⁺ are changed by Na⁺ in the X-ray diffraction patterns.Diversified factors are studied the modification of octadecyl trimethyl ammonium chloride (1831) on Na-bentonite in the research of organ-modification. This dissertation prepares a series of organ-bentonite. It takes the size of interlayer field as estimate index to evaluate the preparation effect, combing with the intensity, the acuity and the symmetry of diffraction apices. The best technic conditions of organ-modification are: pulp density 5%, wash the sample for 3 times before organic intercalation, amount 30%, temperature 65℃, and stirring time 7h. The d₀₀₁ increases to 4.167nm.Systematic research of adsorption experiment is carried to study the each adsorption behavior of Cu(II) and oily wastewater on the three sorbents: purified Ca-bentonite, Na-bentonite and organobentonite. Comparer with the adsorption capacity of Cu(II) and oily wastewater through adsorption kinetic curve and isothermal absorption curve. Results show, the best adsorbent of Cu(II) is Na-bentonite while the best adsorbent of oily wastewater is organobentonite. Modification model is proposed to explain the modification mechanism and show the change process inside. Using FTIR, they show the adsorption process of oily wastewater on organobentonite, explain the inner structure change, and indicate that it includes physical adsorption and chemical adsorption for organobentonite to adsorb oily wastewater, and chemical adsorption takes advantage.