Review of the use of mesoporous silicas for removing dye from textile wastewater

The textile industry is a major user of dyes and hence an important source of water pollution, which poses a threat to aquatic as well as human life. Adsorption is a widely used technique for separating and removing dye from wastewater. Recently the use of mesoporous silica (MPSs) as an adsorbent in wastewater treatment has received considerable attention. MPSs are emerging as potential adsorbents because of their surface area, tunable and uniform pore structure, high pore volume, ordered pore structure, thermal and mechanical stability, and extraordinarily wide possibilities for functionalization to increase their adsorption capacity. In this paper the ability of MPSs to absorb dyes from aqueous solutions is reviewed. This article provides information on adsorption studies carried out under different operational conditions such as contact time, solution pH, temperature, agitation speed, etc. This review also summarizes and attempts to compare the equilibrium isotherm and kinetic models, and the thermodynamic studies that report the adsorption of dyes onto MPSs. The literature reviewed, indicate that SBA-MPSs have a higher adsorption capacity than MCM-MPSs and functionalized MPSs a better adsorption capacity than MPSs. It is evident from the literature that the potential of MPS based nano-sorbents being used for removing dyes from aqueous solution is very high. However, still more research work is needed on developing cost effective and more efficient MPS based nano-sorbents for use commercially.