Synthesis of Titanium Dioxide/Silicon Dioxide from Beach Sand as Photocatalyst for Cr and Pb Remediation

Abstract

Heavy metals are non-biodegradable and have a high toxicity effect on microorganisms which makes their presence in the environment extremely dangerous. The method of handling heavy metal waste by photocatalysis techniques using TiO2/SiO2 composite showed a good performance in reducing harmful pollutants. In this study, SiO2 from Bengkulu beach sand, Indonesia, was used as a support material for TiO2 photocatalyst to remove Cr(VI) and Pb(II). SiO2 was obtained through leaching techniques using NaOH as a solvent. The TiO2/SiO2 composite photocatalyst was synthesized using a solvothermal method at 130 °C and then characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and a particle size analyzer (PSA). Based on the XRD diffractogram, the synthesized TiO2 showed the anatase structure while the SiO2 showed the amorphous structure. The Ti–O–Si bond is defined in the infrared (IR) spectra, which indicates that the relationship between TiO2 and SiO2 is a chemical interaction. The results of SEM and PSA characterizations show agglomerated spherical (round) particles with a mean particle size of 616.9 nm. The TiO2/SiO2 composite of 7:1 ratio showed the highest photocatalytic activity after 180 min of ultraviolet (UV) irradiation, with a concentration-decrease percentage of 93.77% and 93.55% for Cr(VI) and Pb(II), respectively.

Recent Improvement Strategies on Metal-Organic Frameworks as Adsorbent, Catalyst, and Membrane for Wastewater Treatment

“…Alternatively, combining two materials to create a composite system has been receiving major attention in catalysis. In this scenario, one material will act as a structural support for anchoring the catalytically active second material in order to enhance its stability and ensuring reusability [82]. Huge efforts to combine MOFs with other functional materials in order to enhance its catalytic properties have been attempted, which can be confined inside the MOFs' structure thanks to its permanent porosity [83,84].…”

Block Copolymer and Cellulose Templated Mesoporous TiO2-SiO2 Nanocomposite as Superior Photocatalyst

“…This could be avoided by incorporating silica (SiO 2 ) into the titania matrices [14,[23][24][25]. Silica insertion into the TiO 2 nanostructure not only increases the thermal stability of the highly photoactive anatase phase but also helps to prevent the mesoporous structure from collapsing [2,[26][27][28]. Introducing cellulose matrix as the second templating media to the triblock copolymer-TiO 2 -SiO 2 composite could further enhance the specific surface area and support the mesoporous structure with a higher degree of dispersibility in aqueous media that would enhance the photocatalytic efficiency [29].…”

Photocatalytic Phenol Degradation by Silica-Modified Titanium Dioxide

“…This synthesis was performed in three separate TiO 2 :SiO 2 mole ratios (1:1, 3:1, and 7:1) through the impregnation method [19,22]. To prepare a composite with a mole ratio of 1:1, 1.3258 g of TiO 2 P25 Degussa was mixed with 80 mL of ethanol and subjected to sonication for 30 min.…”

“…In addition, it may be synthesized using a variety of methods, which includes solvothermal [17,18], sol-gel [15,17], impregnation [19,20], and microwave radiation [21]. In our previous study [22], the synthesis of this composite photocatalysts was carried out using the solvothermal method, which was applied to reduce the concentration of inorganic waste, specifically a solution of Cr(VI) and Pb(II) metal ions. The results showed a fairly good percentage reduction of 93.77% and 93.55% for Cr(VI) and Pb(II), respectively.…”

“…In addition, the SiO 2 source used was natural silica extracted from the Bengkulu beach [24]. TiO 2 and SiO 2 were composited using the impregnation method, different from the previous literature [22], and which used the solvothermal method. The physical properties of the TiO 2 /SiO 2 composites were investigated by XRD, FTIR, SEM, BET analysis, PSA, and UV-vis spectroscopy.…”