Synthesis and Characterization of Novel Nanomaterials for Removal of Textile Dyes in Industrial Wastewater

Abstract

Inefficient treatments and uncontrolled pollutants generation to the environment has been significantly affected the living standards in the ecosphere. The advancement in nanotechnology resulted in the effective treatment of all of the pollutants generated in the environment. In the field of textile dye removal, the special features of nanomaterials are gaining attention due to their enhanced physical, chemical and mechanical properties. Rice husk is an agricultural waste material that is used for the production of adsorbents in this study. Mesoporous silica nanoparticles were successfully synthesized by using rice husk as the raw material via a sol-gel pathway using cetyltrimethylammonium bromide (CTAB) as the structure-directing agent. The functionalization of silica nanoparticles was taken place in two pathways, such as in-situ and post functionalization methods by using 3-aminopropyltriethoxysilane (APTES) as the functionalization agent. Mesoporous silica nanoparticles were able to effectively adsorb methylene blue dye from aqueous solutions. The adsorption of MB could be best described by the pseudosecond-order model and well fitted to the Langmuir equation, with a maximum monolayer capacity of 19.26 mg/g. Photocatalytic decomposition of the organic pollutants gains emerging attention after the discovery of water splitting ability by TiO2. The high purity (98.8%, TiO2) rutile nanoparticles were successfully synthesized using ilmenite sand as the initial titanium source. This novel synthesis method was cost-effective and straightforward due to the absence of the traditional gravity, magnetic, electro statistic separation, ball milling and smelting processes. Also, highly corrosive environmentally hazardous acid leachate generated during the leaching process of ilmenite sand was effectively converted into highly efficient photocatalysts. The most efficient photocatalysts were composed of anataseTiO2/rutile-TiO2/Fe2O3, α-Fe2O3/Fe2TiO5/TiO2 and Fe2TiO5/TiO2. The synthesized nanocomposites were characterized by microscopic (SEM and TEM) and spectroscopic (XRD, Raman, XPS, FT-IR and DRS) analytical techniques. These nano heterostructures were catalytically active for the photodegradation of methylene blue upon irradiation by a light source (LED or sunlight). Efficient charge separation and limiting electron-hole recombination in photocatalyst surfaces resulted in the overall performance of synthesized material. Reduced iv graphene oxide (r-GO) has lately attracted a lot of attention to overcome limitations associated with photocatalysts. The honeycomb sp2 network structure of r-GO improves charge separation and transportation through the surface of the catalyst. The fabricated GO/Fe3O4 heterogeneous photocatalyst shows very efficient degradation performance by overcoming the limitations associated with the narrow bandgap of Fe3O4 (0.1 eV). Finally, the synthesis of graphene like materials by catalytic graphitization of sucrose by using Fe and Ti transition metals studied in this study. Herein, we reported that Fe and Ti metal oxides promoted to the graphitization process at low temperature. Sucrose mixed with only uncalcined Fe2O3 produced Fe3C, Fe, Fe3O4 dispersed on graphitic carbon, while sucrose mixed with only Fe2TiO5/TiO2 product, and mixed with uncalcined Fe2O3 and Fe2TiO5/TiO2 led to the production of TiO2, Fe3C, Fe, Fe3O4 dispersed on graphitic carbon. The most outstanding photocatalyst synthesized material composed with TiO2/Fe3C/Fe/Fe3O4–Graphitic carbon which is sun light sensing photocatalyst.