Characterizations of TiO2/SiO2/Ni–Cu–Zn Ferrite Composite for Magnetic Photocatalysts

The TiO₂/SiO₂/Ni–Cu–Zn ferrite composite for magnetic photocatalysts with high photocatalytic activity is successfully prepared in this study. The composite are composed of spherical or elliptical Ni–Cu–Zn ferrite nanoparticles about 20–60 nm as magnetic cores, silica as barrier layers with thickness of 15 nm between the magnetic cores and titania shells with thickness approximately 1.5 nm. Photodegradation examination of TiO₂/SiO₂/ Ni–Cu–Zn ferrite composite was carried out in methylene blue (MB) solutions illuminated under a Xe arc lamp with 35 W and color temperature of 6000 K. The results indicated that about 47.1% of MB molecules adsorbed on the TiO₂/SiO₂/Ni–Cu–Zn ferrite composite within 30 min mixing due to it higher pore volume of 0.034 cm³/g, and after 6 h Xe lamp irradiation, 83.9% of MB 16.1% was photodegraded. Compared with the TiO₂ /Ni–Cu–Zn ferrite composite, the TiO₂/SiO₂/Ni–Cu–Zn ferrite composite with silica barrier layer prohibited the photodissolution and enhanced the photocatalytic ability. The magnetic photocatalyst shows high photocatalytic efficiency that the apparent first‐order rate constant k_obs is 0.18427 h^?1, and good magnetic property that the saturation magnetization (M_s) of is 37.45 emu/g, suggesting the magnetic photocatalyst can be easily recovered by the application of an external magnetic field.     

Effects of poly (vinyl alcohol) (PVA) content on preparation of novel thiol-functionalized mesoporous PVA/SiO2 composite nanofiber membranes and their application for adsorption of heavy metal ions from aqueous solution

Thiol-functionalized mesoporous poly (vinyl alcohol)/SiO₂ composite nanofiber membranes and pure PVA nanofiber membranes were synthesized by electrospinning. The results of Fourier transform infrared (FTIR) indicated that the PVA/SiO₂ composite nanofibers were functionalized by mercapto groups via the hydrolysis polycondensation. The surface areas of the PVA/SiO₂ composite nanofiber membranes were >290 m²/g. The surface areas, pore diameters and pore volumes of PVA/SiO₂ composite nanofibers decreased as the PVA content increased. The adsorption capacities of the thiol-functionalized mesoporous PVA/SiO₂ composite nanofiber membranes were greater than the pure PVA nanofiber membranes. The largest adsorption capacity was 489.12 mg/g at 303 K. The mesoporous PVA/SiO₂ composite nanofiber membranes exhibited higher Cu²⁺ ion adsorption capacity than other reported nanofiber membranes. Furthermore, the adsorption capacity of the PVA/SiO₂ composite nanofiber membranes was maintained through six recycling processes. Consequently, these membranes can be promising materials for removing, and recovering, heavy metal ions in water.     

Evaluation of the Mn(II) adsorption potential of SiO2 obtained by different wet chemical methods

This paper describes the development of SiO₂ by 2 different wet chemical methods: polymeric precursor (PP) and sol-gel (SG). These samples were used as adsorbents of Mn(II) metal ions. Physicochemical characteristics of the 2 adsorbents were established, while zeta potential, Scanning Electron Microscopy, and Brunauer-Emmett-Teller (BET) surface area methods were further employed for characterization. Efficiencies of the prepared adsorbents in the adsorption of Mn(II) from aqueous solutions were investigated. The BET surface areas of the prepared adsorbent were 171 and 7 m² g⁻¹ for SiO₂ PP and SiO₂ SG, respectively. Optimal adsorption occurred at pH 8.5, 5g L⁻¹ of adsorbent concentration, and 90 minutes of contact time for both adsorbents. The Langmuir and Freundlich isotherms models fitted the experimental data of SiO₂ PP and SiO₂ SG, respectively, and SiO₂ PP showed the highest adsorption capacity due, probably, to its greater specific area.     

On the structure-sensitivity of 2-butanol dehydrogenation over Cu/SiO2 cogelled xerogel catalysts

Cu/SiO₂ cogelled xerogel catalysts were synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of Cu with 3-(2-aminoethylamino)-propyltrimethoxysilane (EDAS). The resulting catalysts are composed of metallic crystallites with a diameter of about 3 nm located inside microporous silica particles and larger metallic particles with a diameter of 8–30 nm located outside silica network. Cu/SiO₂ catalysts were tested for 2-butanol dehydrogenation. This reaction over Cu/SiO₂ cogelled xerogel catalysts is a structure-sensitive reaction: large metallic particles located outside silica particles are responsible for the dehydrogenation reaction, while small metallic particles located inside silica particles do not participate to the reaction.     

Solid acidities of SiO2–TiO2/montmorillonite composites synthesized under different pH conditions

SiO₂–TiO₂/montmorillonite composites were prepared under acidic, neutral and basic conditions and the solid acidity of the resulting composites were determined. All the SiO₂/TiO₂ ratio of the colloidal particles was set at 10 but the resulting SiO₂/TiO₂ ratios were significantly richer in TiO₂. The XRD patterns of the acidic composite showed expanding and broadening of the (001) reflection by intercalation of colloidal SiO₂–TiO₂ particles, but the neutral and basic composites showed only broadening of the reflections and no intercalation. The specific surface areas of the acidic, neutral and basic composites (375, 237 and 247 m²/g, respectively) were much larger than of montmorillonite (6 m²/g). The average pore sizes were about 4, 15 and 50 nm, and the amounts of solid acidic sites measured by the NH₃-TPD were 178, 95 and 86 µmol/g for the acidic, neutral and basic composites, respectively. The solid acid amount of the acidic composite was twice that of a commercial catalyst, K-10, (85 µmol/g) and much higher than the guest phase SiO₂–TiO₂ gel (16 µmol/g) or the host phase montmorillonite (6 µmol/g). The TPD peak temperatures reflect the acid strength, and were similar in all the samples, ranging from 175° to 200 °C.     

Efficient preparation of hybrid nanocomposite coatings based on poly(vinyl alcohol) and silane coupling agent modified TiO2 nanoparticles

In the present investigation, at first, the surface of titanium dioxide (TiO₂) nanoparticles was modified with γ-aminopropyltriethoxy silane as a coupling agent. Then a new kind of poly(vinyl alcohol)/titanium dioxide (PVA/TiO₂) nanocomposites coating with different modified TiO₂ loading were prepared under ultrasonic irradiation process. Finally, these nanocomposites coating were used for fabrication of PVA/TiO₂ films via solution casting method. The resulting nanocomposites were fully characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), thermogravimetric analysis/derivative thermal gravimetric (TGA/DTG), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TEM and SEM results indicated that the surface modified nanoparticles were dispersed homogeneously in PVA matrix on nanoscale and based on obtained results a possible mechanism was proposed for ultrasonic induced nanocomposite fabrication. TGA confirmed that the heat stability of the nanocomposite was improved. UV–vis spectroscopy was employed to evaluate the absorbance and transmittance behavior of the PVA/TiO₂ nanocomposite films in the wavelength range of 200–800 nm. The results showed that this type of films could be used as a coating to shield against UV light.     

Adsorption and photocatalytic properties of TiO<Subscript>2</Subscript>/mesoporous silica composites from two silica sources (acid-leached kaolinite and Si-alkoxide)

Two different mesoporous silicas (MPS) were synthesized by hydrothermal treatment in NaOH solution of two SiO₂ sources. These were microporous silica (MicroPS) derived from selectively acid leached metakaolinite and tetraethylorthosilicate (TEOS). The hydrothermal syntheses of the MPSs were performed at a ratio of SiO₂/cetyltrimethyl- ammonium bromide (CTABr)/NaOH/H₂O = 1/0.1/0.3/150. The specific surface areas (S _BET) of the MPSs from MicroPS (MPS(M)) and TEOS (MPS(T)) were 1070 and 1020 m²/g, respectively. Composites of MPS (75 mass%) with TiO₂ (25 mass%) were prepared using both SiO₂ and two commercial TiO₂ powders, P25 and ST-01. The adsorption–desorption behavior of methylene blue (MB) by the four resulting composites and the two MPSs alone was unique in showing partially reversible behavior. The maximum MB adsorption, observed in the composite of ST-01 with MPS(M), designated (S/M), was 0.034 mmol/g. The rates of MB adsorption in the dark and photodecomposition under UV illumination were considerably different for the four composites and two TiO₂ powers, and followed the order ST-01 < S/T < P25 < P/T ≈ P/M ≪ S/M. The removal rate of MB by the composite S/M by adsorption and photodecomposition was further enhanced by heating at 700 °C. Direct photodecomposition of MB without adsorption in the dark was greatly enhanced in the composites, especially in that composed of MPS(M) and ST-01.     

Micro-mesoporous TiO2/SiO2 nanocomposites: Sol-gel synthesis,characterization, and enhanced photodegradation of quinoline

Micro-mesoporous TiO₂/SiO₂ nanocomposite powders have been successfully synthesized by the sol-gel process with different TiO₂/SiO₂ molar ratios and were applied in the UV-photodegradation of quinoline (λ = 254 nm). The structural, morphological, and textural characterization of the powders showed a homogeneous distribution of TiO2 nanoparticles within a porous amorphous SiO2 matrix. Due to the micro-mesoporous character of the materials, their textural characteristics were evaluated by the N2 adsorption method, by comparing BET, DR, Langmuir, and DFT theories. Si₆₀Ti₄₀ powders (60%SiO₂/40%TiO₂) presented the highest specific surface area (SSA) obtained from BET (SSA = 363 m²g^-1), DR (SSA = 482 m²g^-1), and Langmuir (SSA = 492 m²g^-1) due to the adequate particle size of TiO₂ and its high dispersion in the porous matrix. A higher degradation of quinoline in the presence of H₂O₂ (66%) was achieved using Si₈₀Ti₂₀ powders (80%SiO₂/20%TiO₂), as compared to pure sol-gel TiO₂ powders, (51%) under the same reaction conditions (1 UVC lamp - 250W, t = 180 min). The better performance of the Si₈₀Ti₂₀ nanocomposite could be attributed to the small TiO₂ anatase crystallite size (<5.7 nm), high dispersion of these crystallites in the SiO₂ matrix, great specific surface area (DR SSA = 342 m² g^?1), and the formation of Ti–O–Si bond, which is associated with new catalytic sites in TiO₂/SiO₂ composite.     

Effect of SiO2 in situ cross-linked CS/PVA on SrFe12O19 scaffolds prepared by 3D gel printing for targeting

The design of magnetic composite scaffolds with superior properties has the potential to construct a targeted delivery platform with hyperthermia. In this study, strontium hexaferrite (SrFe₁₂O₁₉, SrM) magnetic nanoparticles (MNPs) were obtained by the chemical precipitation method. Non-toxic cross-linked biogels were prepared for adhesive ceramic scaffolds, and chitosan/polyvinylalcohol (CS/PVA)-bonded SrM magnetic nanoscaffolds were successfully prepared by 3D gel printing (3DGP) method. The effects of PVA physical cross-linking and in situ formed SiO₂ on the properties of CS-bonded scaffolds were evaluated, and the compressive strengths were increased from 6.13 ± 2.45 MPa to 8.80 ± 2.02 MPa and 17.18 ± 2.15 MPa, respectively. The results showed that the saturation magnetization of SiO₂/CS/PVA/SrM composite scaffolds was 59.96 emu/g. In vitro immersion experiments showed that the degradation rates of SiO₂/CS/PVA/SrM scaffolds were 4.90% after 28 days, and the in situ SiO₂ improved the deposition of calcium salts on the scaffolds. The experiments showed that the SrM magnetic scaffolds could not only concentrate magnetic fields to improve the efficiency of targeting deposition but also achieve a weak targeting process without external magnetic field assistance. In vitro cell proliferation test showed that MC3T3-E1 cells had good adhesion and proliferation on the surface of SiO₂/CS/PVA/SrM scaffolds, which indicated that the scaffolds may be used for bone repairing.     

Fe2O3/TiO2/Activated Carbon Nanocomposite with Synergistic Effect of Adsorption and Photocatalysis

Fe₂O₃/TiO₂/activated carbon (FT/AC) nanocomposites supported on silica gel beads were synthesized using a sonochemical method and fully characterized. The response surface method was applied to optimize the removal of Pb(II) ions by nanocomposites under visible light. The experiments were conducted by adjusting three parameters, i.e., initial concentration of Pb(II) ions, dosage of Fe₂O₃/TiO₂ (FT) photocatalyst, and pH. The FT/AC nanocomposite showed higher efficiency for Pb(II) ion removal in comparison with FT due to the synergistic effect of activated carbon combined with Fe₂O₃/TiO₂.     

Synthesis, characterization and enhanced photocatalytic activity of TiO2/SiO2 nanocomposite in an aqueous solution and acrylic-based coatings

In this study, TiO₂/SiO₂ nanocomposites were synthesized via a sol-gel route by adding tetraethylorthosilicate (TEOS) to a solution containing different molar ratios of Degussa P25 TiO₂ nanoparticles. FTIR, TGA, EDAX and XRD techniques were used to characterize the modified nanoparticles. Photocatalytic activity of the nanoparticles in an aqueous solution and into the acrylic based coating was evaluated using colour coordinate data measurements, SEM analysis, gloss measurements and FTIR spectroscopy, in the presence of Rhodamine B (Rh.B) dyestuff, as a pollutant model, before and after exposure to the UVA (340 nm) irradiation and compared to their unmodified counterparts.The results showed that silica grafting effectively reduced the photocatalytic activity of the TiO₂ nanoparticles as evidenced by absorption spectra and colour changes of Rh.B aqueous solutions during the UVA irradiation. The results revealed the effectiveness of sol-gel route for preparation of TiO₂/SiO₂ nanocomposites. The optimum result was obtained with 1% molar ratio of TiO₂:TEOS. Addition of TiO₂/SiO₂ nanocomposites into the acrylic based coating revealed reduction of photo-degradation of Rh.B compared to untreated nanoparticles. Finally, inclusion of TEOS treated TiO₂ nanoparticles into the aqueous organic coatings, provides photocatalytic property and as a result, it can possibly be considered for self-cleaning coatings.     

Preparation of waste-based Cu–Cu2O/SiO2 photocatalyst from serpentine tailings and waste printed circuit boards and photoreduction of Cr(VI)

In China, a large amount of serpentine tailings and waste printed circuit boards (WPCBs) are produced every year. Serpentine tailings contain about 43% SiO₂ and WPCBs contain about 20% Cu. Reusing their resources can not only solve the problem of environmental pollution, but also produce certain economic benefits. In this study, waste-based SiO₂ support, waste-based Cu–Cu₂O and Cu–Cu₂O/SiO₂ photocatalyst were prepared using serpentine tailings and WPCBs as Si and Cu sources. The waste-based SiO₂ of 750 nm particle size was obtained by precipitation of 0.7 mol/L Na₂SiO₃ solution from the serpentine tailings and its specific surface area reached 57.72 m²/g after 600 °C calcination. Cu and the waste-based Cu–Cu₂O were loaded on the waste-based Cu₂O and SiO₂ support, respectively, and the phase structure of the catalysts has not changed by the characterization of SEM, XRD and XPS. The activity of the photocatalytic reduction of Cr (VI) with the waste-based catalysts showed in the following order: Cu₂O < Cu₂O/SiO₂<Cu–Cu₂O < Cu–Cu₂O/SiO₂, inferring by the investigation of photoelectric properties that Cu prevented the recombination of Cu₂O electron-hole pairs, the Cu–Cu₂O dispersed on SiO₂ support surface to obtain a higher specific surface area. The waste-based Cu–Cu₂O/SiO₂ photocatalyst showed no obvious deactivation after 5 cycles. The mechanism revealed that photogenerated electrons are the major reactive species for the photodegradation of Cr (VI). The study indicates that the waste-based Cu–Cu₂O/SiO₂ is potentially a developed, low-cost catalyst from sustainable resources. The production of Cu–Cu₂O/SiO₂ photocatalyst by using WPCBs and serpentine tailings represents the potential usage of waste into valuable material.     

Enhanced copper removal from aqueous solution by hydrous TiO2/zeolite composite

ABSTRACT

Hydrous titanium dioxide was impregnated on the surface of zeolite to obtain a kind of hydrous TiO₂/zeolite (HTiO₂/ZFA) adsorbent using the hydrothermal method. HTiO₂/ZFA was characterised by scanning electron microscopy combined with energy-dispersive spectrometer, X-ray diffraction, Fourier transform infrared, particle size distribution; and the pH of zero point charge measurement and its performance for Cu(II) adsorption were investigated. It was shown that Ti was not inserted into the skeleton of ZFA and hydrous TiO₂ loaded on the surface was amorphous. The pHzpc of HTiO₂/ZFA decreased to pH 5.5 from pH 6.5 of ZFA. Cu(II) adsorption was favoured in a pH range of 3.0–6.0, and 90% copper could be removed in first 30?min for 60?mg?L^–1 Cu(II) solution. The Langmuir isotherm model could well describe the adsorption isotherm data and the maximal Cu(II) adsorption capacity reached 251.9?mg?g^–1. Moreover, the HTiO₂/ZFA could be desorbed by HCl solution for further use, which implied an effective application in wastewater treatment.     

Density functional theory study on adsorption of thiophene on TiO2 anatase (0 0 1) surfaces

In order to develop a fundamental understanding of the adsorption mechanism of thiophenic compounds on TiO₂-based adsorbents for ultra-deep desulfurization of liquid hydrocarbon fuels, a density functional theory (DFT) study was conducted on the adsorption of thiophene over the TiO₂ anatase (0 0 1) surface. The perfect, O-poor (with oxygen vacancies), and O-rich (with activated O₂ on the surface) anatase (0 0 1) surfaces were built, and the interaction of thiophene molecule with these surfaces was examined. The adsorption configuration and adsorption energy on the different surfaces and sites were estimated. The results showed that thiophene may be adsorbed on both the perfect and O-poor surfaces through an interaction between the Ti cations on the surface and the S atom in thiophene, whereas on the O-rich surface through an interaction of the activated O atoms (the dissociatively or associatively adsorbed O₂) on the surface with the S atom in thiophene to form a sulfone-like surface species. The adsorption of thiophene on the O-rich surface is significantly stronger than adsorption on the perfect and O-poor surfaces on the basis of the calculated adsorption energies. The results indicate that the activated O₂ on the TiO₂ anatase (0 0 1) surface may play an important role in the adsorption desulfurization over the TiO₂-based adsorbents, and increased concentration of the activated O₂ on the surface may result in improvement of the adsorption capacity of the adsorbents.     

Ag/SiO2, Cu/SiO2 and Pd/SiO2 cogelled xerogel catalysts for benzene combustion: Relationships between operating synthesis variables and catalytic activity

The aim of this work is to explore the applicability of the sol–gel method for the preparation of Ag/SiO₂, Cu/SiO₂ and Pd/SiO₂ catalysts and to see whether such a method can yield silver, copper and palladium species stabilized by the carrier in the case of benzene oxidation. So Ag/SiO₂, Cu/SiO₂ and Pd/SiO₂ xerogel catalysts were synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of Ag, Cu and Pd with 3-(2-aminoethylamino)-propyltrimethoxysilane (EDAS). The resulting catalysts are composed of completely accessible metallic crystallites with a diameter of about 3 nm located inside silica particles.     

Optimized synthesis of novel hydroxyapatite/CuO/TiO2 nanocomposite with high antibacterial activity against oral pathogen Streptococcus mutans

The main issue of using hydroxyapatite (HA) in dentistry is accumulation of microorganisms on it that causes tooth decay. The use of nanoparticles can decrease the accumulation of microorganisms, including Streptococcus mutans on HA, and increase its antibacterial effect. The present study aimed to determine the optimal conditions to synthesize HA/CuO/TiO₂ nanocomposites with the highest antibacterial properties. Utilizing the Taguchi method, nine experiments were designed to fabricate nanocomposites using 3 factors of hydroxyapatite, CuO and TiO₂ nanoparticles. The antibacterial activity of the synthesized nanocomposites was evaluated by the colony forming units (CFU) method against S. mutans. Nanocomposite synthesized under experimental conditions 2 (hydroxyapatite 20 mg/ml, CuO 1.50 mg/ml and TiO₂ 1.60 mg/ml) had the highest effect on reducing the growth of S. mutans (1.24 CFU/ml). The results demonstrated the improvement of structural properties, antibacterial activity, and thermal stability by formation of nanocomposite. Owing to the desirable antibacterial properties of the HA/CuO/TiO₂ nanocomposite, it can be used to improve performance in various dental fields.     

Role of promoters on Rh/SiO2 in CO hydrogenation: A comparison using DRIFTS

La, V, Zn, Cu, Fe, Li and Ag promoted Rh/SiO₂ catalysts were investigated for the synthesis of ethanol during CO hydrogenation at 230 °C and 1.8 atm. As is well known, the activity and selectivity depend heavily on the choice of promoter. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to probe the effects of La, V, Zn and Cu on CO adsorption and hydrogenation. From the IR study, it was found that the behavior of CO adsorbed on the differently promoted catalysts was very different. While La enhanced total CO adsorption, the addition of V, Zn and Cu suppressed CO adsorption to different extents. The doubly promoted Rh-La/V/SiO₂ showed only moderate CO adsorption. Results from DRIFTS suggest that the higher catalytic activity (compared to the non-promoted catalyst) observed for the La singly promoted Rh/SiO₂ catalyst may primarily be caused by an increase in the concentration of the adsorbed CO species in the presence of H₂, possibly due to the formation of new active sites at the LaO_x-Rh interface. The higher catalytic activity of the V singly promoted Rh/SiO₂ catalyst could be ascribed to an increased desorption rate/reactivity of the adsorbed CO species. The La and V doubly promoted catalyst showed both new adsorbed CO species and increased desorption rate/reactivity of the adsorbed species during CO hydrogenation due to a synergistic promoting effect of La and V. The addition of Zn or Cu promoters significantly reduced the desorption rate/reactivity of the adsorbed CO species on Rh/SiO₂, leading apparently to the much reduced activities for CO hydrogenation observed.     

Synthesis and characterization of sol–gel derived PVA-titanium dioxide (TiO<Subscript>2</Subscript>) nanocomposite

Novel PVA/TiO₂ polymer nanocomposites have been prepared at low temperature via sol–gel route. XRD analysis showed the particles to be elongated along a- and b-direction but contracted along c-direction. PVA-assisted TiO₂ nanocomposite samples dried at a temperature of 35 °C were found to have ~12 nm particle size. It was found that the composite nanoparticles had an increased degree of crystallinity in comparison to pure TiO₂ dried at 80 °C. TEM analysis depicted the formation of highly dense nanorods (and prism)-like structure of increasing length and diameter depending on PVA concentration. Our studies revealed that by increasing the concentration of PVA in TiO₂ the band gap was lowered from 3.55 to 1.65 eV. The photoluminescence studies showed that emission shifts towards higher wavelength (417–457 nm) accompanied by a reduction in impurity centres with increasing concentration of PVA in TiO₂.     

SnS2/TiO2 nanocomposites with enhanced visible light-driven photoreduction of aqueous Cr(VI)

SnS₂/TiO₂ nanocomposites have been synthesized via microwave assisted hydrothermal treatment of tetrabutyl titanate in the presence of SnS₂ nanoplates in the solvent of ethanol at 160 °C for 1 h. The physical and chemical properties of SnS₂/TiO₂ were studied by XRD, FESEM, EDS, TEM, XPS and UV–vis diffuse reflectance spectra (DRS). The photocatalytic activity of SnS₂/TiO₂ nanocomposites were evaluated by photoreduction of aqueous Cr(VI) under visible light (λ>420 nm) irradiation. The experimental results showed that the SnS₂/TiO₂ nanocomposites exhibited excellent reduction efficiency of Cr(VI) (~87%) than that of pure TiO₂ and SnS₂. The SnS₂/TiO₂ nanocomposites were expected to be a promising candidate as effective photocatalysts in the treatment of Cr(VI) wastewater.     

Impact of supercritical drying and heat treatment on physical properties of titania/silica aerogel monolithic and its applications

TiO₂–SiO₂ monolithic aerogels were homogeneously prepared using sol–gel method. Critical point of drying of TiO₂–SiO₂ gels with ethanol was studied for 30, 60, 90 and 120 min. Subsequently, the gels were dried with supercritical ethanol, resulting in amorphous aerogels that crystallized following heat treatment at 550 °C from 1 to 5 h. The TiO₂–SiO₂ aerogels were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and surface area measurements. The molar ratio of SiO₂:TiO₂ was 6 and the synthetic strategy revealed that TiO₂–SiO₂ aerogel, had a surface area 868 m²/g, particle size 40 nm, density 0.17 g/cm³ and 80% porosity. The finding indicated that from economic point of view, TiO₂–SiO₂ gel should be supercritical dried for 30 min and heat-treated for 5 h. The TiO₂–SiO₂ aerogel monoliths photocatalyst synthesized using sol–gel method provided insight into the characteristics that make a photocatalyst material well-suited for photodegradation of phenol and cyanide in an industrial waste stream containing Cl⁻, S²⁻ and NH₄⁺. Interestingly, after multiple reuse cycles (i.e. ≥7), photodegradation systems with regenerated photocatalyst showed a slightly decreasing of photoactivity 2–4%. The overall kinetics of photodegradation of either phenol or cyanide using TiO₂–SiO₂ aerogel photocatalyst was found to be of first order.