Preparation And Characterization Of Photocatalytic Cement Materials

TiO₂ and Bi₂WO₆ were loaded on the surface of Portland cement-based materials by sol gel method and one step hydrothermal method,respectively.Then,through hydrating and aging process,certain activity of TiO₂/cement-based and Bi₂WO₆/cement based composites were prepared.Formaldehyde gas,Rhodamine B solution and other pollutants were conducted on degradation experiment by using the two prepared photocatalytic cement based materials,which could evaluate the photocatalytic performance.Furthermore,antibacterial property was evaluated by the Escherichia coli antimicrobial experiment.This paper also intended to explore hydrated heat dynamics between photocatalyst and cementitious materials,in order to establish hydration kinetics model of photocatalytic cement based materials to explain the relationships of each hydrating stage.Make reasonable explanation on complex hydration mechanism of the photocatalytic cement based materials.1.The SEM of Silicate cement-based composite with different mass ratio of TiO₂and Bi₂WO₆ was obtained.It suggested that TiO₂ and Bi₂WO₆ as structural materials were mixed with Silicate cement,which can effectively compound with Silicate cement and involve in the hydration process of cement-based materials,playing the role on the content of C₃S in Silicate cement system.At the same time,the high activity of TiO₂ and Bi₂WO₆ can also react with the hydratded product of Ca?OH?₂,which can influence the structural properties of Silicate cement-based materials and adjust the interior and superficial structure of the composite.But there was an extreme value of mixed amount of the two compound.In a certain range,hydration process can be promoted by increasing the added amount.Beyond the best range,it was detrimental to hydration process with continuing to increase the mass ratio.2.TiO₂ and Bi₂WO₆ can be used as a micro aggregate,it can make Portland ceme-nt has photocatalytic performance when mixed each other.Also can be used as struct-ure materials add in the hydration process of cement base material,and adjust the mi-crostructure of hydration products.TiO₂ and Bi₂WO₆ can take the composite reaction with Ca?OH?₂ which hydration products of cement base material with appropriate ma-ss ratio.And then,we can get microstructure surface with loose structure and large g-ap.3.The results of SEM and EDS with TiO₂ content of 20%and 10%of the photocatalytic material suggested that TiO₂ content of 20%involved in the compound and hydration process of Portland cement which could produce a large amount of material of needles and rehydrated dense architecture,with more part of the local area big hole structure.Large Amount of H₂O was consumed in the reaction system because of the TiO₂ consumption of large quantities,thereby inhibiting hydration process which was not complete it would produce empty.The arrangement of Ca?OH?₂ crystals have a tendency,loose structure and larger gap with addition of10%TiO₂.It is benefit to improve property of catalysis and antibiosis for the surface is absorbed with the plenty of TiO₂.4.Formaldehyde and contaminants by photocatalysis experiments Rhodamine B solution is drawn:for the catalytic gas experiments,when the TiO₂ content at 15%,Bi₂WO₆ dosage of 5%,the degradation of formaldehyde gas is the best.Too much or too little of incorporation,are not conducive to the degradation of gaseous pollutants.For the degradation of rhodamine B liquid,with the increase Bi₂WO₆ and TiO₂content,the catalytic performance gradually increased,possibly because Mechanism of two different catalytic reactions caused.For the antibacterial experiments,quality Bi₂WO₆ the ratio of 5%and TiO₂ the ratio of 10%of the photocatalytic Portland cement-based composite materials for photocatalytic 4-6h.The results showed that both composite material of bacteria having a strong role in the destruction,so that the middle of escherichia coli appear sunken,subject to certain surface damage,Portland cement-based photocatalytic materials have some antibacterial properties.