Study On The Preparation Of Mesoporous MCM-41Molecular Sieve And Its Adsorption Properties

Mesoporous molecular sieves have attracted much attention from the scientificresearches and technological applications due to the excellent properties such as uniform andtunable mosopores, extremely high surface areas and pore volume, good long-range orderingand good thermal and hydrothermal stability, etc. As far as ordered mesoporous materials areconcerned, they are of particular interest not only because of their important applications inchemical engineering, energy, information and biology, but also because of potentialapplications as hosts for a variety of technologically advanced materials such assemiconductor clusters, molecular wires with tailored electronic and optical properties,enzyme mimicking organic complexes.In the present dissertation, Mesoporous molecular sieves MCM-41with controlled shapeshave been synthesized using tetraethyl orthosilicate.(TEOS) as silica sources,cetyltriethylammonium bromide (CTAB) as templating agent and PPG, PVA, PVP as co-templating agent. The attained samples were characterized by XRD, N2adsorption-desorptionand TEM. The adsorption process conditions were studied including adsorption time, pHvalue of potassium bichromate solution, adsorbent dosage and adsorption temperature, usingMCM-41as adsorbent.The concrete results as follows:(1)The mesoporous silica MCM-41with spherical androd-like shapes could be easily synthesized under room temperature. The length of rod-likeMCM-41decreases with decreasing of the concentrations of reactant; the ratio of length todiameter of rod-like MCM-41decreases with increasing of pH.(2)We have studied theinfluences of polymers on the morphologies and structures of mesoporous silica sieves, theresults are as following: PVA can adsorbed on the surface of mesoporous silica sieves, thenprevent the growth and aggregation of the particles; PVP can increase the regularity of thesamples; PPG can make the particles grow along the direction of the pores, and longerrod-like particles are formed.(3)The optimum conditions are as follows:adsorption time was75min, pH value of potassium bichromate solution was6, adsorbent dosage was0.5g andadsorption temperature was30℃. The removal rate of Cr6+was67.22%under the aboveconditions.