Preparation and Characterization of ZnO Nanoparticles Supported on Amorphous SiO₂

Conversion of Phosphogypsum into Porous Calcium Silicate Hydrate for the Removal and Recycling of Pb(II) and Cd(II) from Wastewater

The discharge of lead and cadmium wastewater, along with the pollution caused by phosphogypsum, represents a particularly urgent environmental issue. This study employed a straightforward hydrothermal method to convert phosphogypsum into porous calcium silicate hydrate (P-CSH), which was then used to remove and recover Pb(II) and Cd(II) from wastewater. The adsorption capacities of P-CSH for Pb(II) and Cd(II) were notably high at 989.3 mg/g and 290.3 mg/g, respectively. The adsorption processes adhered to the pseudo-second-order kinetics model and the Langmuir isotherm model. Due to identical adsorption sites on P-CSH for both Pb(II) and Cd(II), competitive interaction occurred when both ions were present simultaneously. Additionally, the adsorption efficacy was minimally impacted by the presence of common coexisting cations in wastewater. The dominant mechanisms for removing Pb(II) and Cd(II) via P-CSH were chemical precipitation and surface complexation. Moreover, the adsorbed heavy metals were efficiently separated and reclaimed from the wastewater through a stepwise desorption process. The primary components of the residue from stepwise desorption were quartz and amorphous SiO2. Following dissolution via pressurized alkaline leaching, this residue could be recycled for synthesizing P-CSH. This research offered a new strategy for the resourceful use of phosphogypsum and heavy metal wastewater.

Comparative Study of ZnO-and-TiO2-Nanoparticles-Functionalized Polyvinyl Alcohol/Chitosan Bionanocomposites for Multifunctional Biomedical Applications

This study aimed to synthesize chitosan/polyvinyl alcohol (CS/PVA)-based zinc oxide (ZnO) and titanium dioxide (TiO2) hybrid bionanocomposites (BNCs) and observe their comparative accomplishment against the skin cancer cell line, A431, and antioxidant potential. CS was blended with PVA to form polymeric films reinforced with the immobilization of ZnO and TiO2 nanoparticles (NPs), separately. The optimization of the BNCs was done via physicochemical studies, viz. moisture content, swelling ratio, and contact angle measurements. The free radical scavenging activity was observed for 1,1-diphenyl-2-picryl-hydrazyl, and the antibacterial assay against the Escherichia coli strain showed a higher zone of inhibition. Furthermore, the anticancer activity of the synthesized BNCs was revealed against the skin cancer cell line A431 under varying concentrations of 50, 100, 150, 200, and 300 μg/mL. The anticancer study revealed a high percent of cancerous cell inhibition (70%) in ZnO BNCs as compared to (61%) TiO2 BNCs in a dose-dependent manner.

Greener design and characterization of biochar/Fe3O4@SiO2-Ag magnetic nanocomposite as efficient catalyst for synthesis of bioactive benzylpyrazolyl coumarin derivatives

The study aimed to develop an efficient catalyst, biochar/Fe₃O₄@SiO₂-Ag magnetic nanocomposite, to synthesize bioactive benzylpyrazolyl coumarin derivatives through a one-pot multicomponent reaction. The catalyst was prepared using Ag nanoparticles synthesized with Lawsonia inermis leaf extract and carbon-based biochar obtained through pyrolysis of Eucalyptus globulus bark. The nanocomposite contained a silica-based interlayer, highly dispersed Ag nanoparticles, and a central magnetite core, which responded well to external fields. The biochar/Fe₃O₄@SiO₂-Ag nanocomposite showed excellent catalytic activity and could be easily recovered using an external magnet and reused five times without significant loss of performance. The resulting products were tested for antimicrobial activity and showed significant activity against various microorganisms.

Zinc oxide nanoparticles coated urea enhances nitrogen efficiency and zinc bioavailability in wheat in alkaline calcareous soils

Nitrogenous fertilizers have low efficiency in alkaline calcareous soils due to volatilization and denitrification. These losses cause economic environmental constraints. Coating of urea with nanoparticles (NPs) is an innovative strategy to improve crop yields by sustaining N availability. In the current study, zinc oxide nanoparticles (ZnO NPs) were synthesized by precipitation method and characterized for morphology and configuration, bond formation, and crystal assemblage using the X-ray diffraction and scanning electron microscope (SEM). The SEM results confirmed the size of ZnO NPs in the size range of 25 nm with cuboid shape. Urea fertilizer, coated with ZnO NPs, was applied to wheat crop in a pot trial. Two rates of ZnO NPs at 2.8 and 5.7 mg kg^-1 were selected to coat the commercial urea. A batch experiment was conducted to ensure the ammonium (NH₄⁺) and nitrate (NO₃^-) ions release by amending the soil with ZnO NPs coated urea and comparing with non-amended soil. The gradual release of NH₄⁺ was observed for 21 days from the ZnO NP-coated urea. In the second part of trial, seven different treatments of coated and uncoated urea were tested on wheat crop. Urea coated with ZnO nanoparticles at 5.7 mg kg^-1 improved all growth attributes and yields. The ZnO NP coated urea increased the N content shoot (1.90 g 100g^-1 DW) and potentially biofortified Zn content (47.86 mg kg^-1) in wheat grain. The results are indicative of viability of a novel coating for commercial urea that will not only reduce N losses but also supplement Zn without additional cost of labor.

Degradation of Epoxy–Particles Composites Exposed to UV and Gamma Radiation

In the design and fabrication of any structural system for space application, balance between mass, stiffness and strength is crucial. Structures in space environments are exposed to high radiation levels and thermal shock, due to the sun irradiance and rotation around Earth. Therefore, accurate determination of the thermal and radiation properties is a key issue for the materials used in such applications. This study reports the thermal and mechanical performance of particle composites (epoxy resin and ZnO particles) after gamma and UV radiation. Composites are exposed to gamma and UV radiation at rates of 1 kGy and 10 kGy and characterized after exposure. For the evaluation, DMA, TGA and three-point bending mechanical test are performed to determine thermal properties and possible material degradation after radiation exposure. The incorporation of the filler in the thermal, radiation and mechanical response of the epoxy system improves as a function of its concentration. Then, epoxy resin reinforced with ZnO particles can be a potential candidate as a polymeric matrix for fiber-reinforced composites for nanosatellites.

Influence of Cerium and Nickel Co-Doping on ZnO Nanostructures for Electrochemical Behavior of H2O2 Sensing Applications

The present paper reports facile synthesis by simple chemical precipitation method for Zinc Oxide (ZnO) nanoparticles with cerium (Ce) and nickel (Ni) co-doped ZnO nanocrystals. The different optimum conditions are analyzed in dual metallic (Ce/Ni) nanoparticles doped with ZnO nanoparticles. Successful incorporation of cerium and nickel is predicted with X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Additionally, optical effects were studied as-prepared active materials by UV-Visible reflectance (UV-Vis-DRS) and photoluminescence (PL) measurements at room temperature. In addition, morphology investigations of the scanning electron microscope (SEM) and transmission electron microscope (TEM) are conducted. The results of electrochemical studies reveal that the co-doped product exhibits a higher H2O2 sensing response, with 46.21 μA/μM.cm2 for Ce/Ni-doped ZnO, which can use potentially for future biomedical applications.

Fast-Charging Anode Materials and Novel Nanocomposite Design of Rice Husk-Derived SiO2 and Sn Nanoparticles Self-Assembled on TiO2(B) Nanorods for Lithium-Ion Storage Applications

A novel microstructure of anode materials for lithium-ion batteries with ternary components, comprising tin (Sn), rice husk-derived silica (SiO2), and bronze-titanium dioxide (TiO2(B)), has been developed. The goal of this research is to utilize the nanocomposite design of rice husk-derived SiO2 and Sn nanoparticles self-assembled on TiO2(B) nanorods, Sn-SiO2@TiO2(B), through simple chemical route methods. Following that, the microstructure and electrochemical performance of as-prepared products were investigated. The major patterns of the X-ray diffraction technique can be precisely indexed as monoclinic TiO2(B). The patterns of SiO2 and Sn were found to be low in intensity since the particles were amorphous and in the nanoscale range, respectively. Small spherical particles, Sn and SiO2, attached to TiO2(B) nanorods were discovered. Therefore, the influence mechanism of Sn-SiO2@TiO2(B) fabrication was proposed. The Sn-SiO2@TiO2(B) anode material performed exceptionally well in terms of electrochemical and battery performance. The as-prepared electrode demonstrated outstanding stability over 500 cycles, with a high discharge capacity of ∼150 mA h g-1 at a fast-charging current of 5000 mA g-1 and a low internal resistance of around 250.0 Ω. The synthesized Sn-SiO2@TiO2(B) nanocomposites have a distinct structure, the potential for fast charging, safety in use, and good stability, indicating their use as promising and effective anode materials in better power batteries for the next-generation applications.

Analysis of herbicide and its applications through a sensitive electrochemical technique based on MWCNTs/ZnO/CPE fabricated sensor

The electrochemical performance of linuron (LNR) was studied by fabricating the carbon paste electrode (CPE) using multiwalled carbon nanotubes (MWCNTs) along with zinc oxide (ZnO) nanoparticles (MWCNTs/ZnO/CPE). The influence of electro-kinetic specifications involving steady heterogeneous rate, pH, sweep rate, temperature effect, transfer coefficient, accumulation time, activation energy, as well as the total number of protons and electrons participating in electro-oxidation of LNR has been established using voltammetric techniques like cyclic voltammetry (CV) and square wave voltammetry (SWV). These techniques were applied to investigate LNR in real samples such as soil including water samples. Over the 0.02 μM-0.34 μM ranges, a linear relationship was confirmed along with the limit of detection and quantification (LOD and LOQ) of the LNR. The synthesized ZnO nanoparticles were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) analysis. The MWCNTs/ZnO/CPE sensor was considered sensitive for LNR detection because the sensor exhibited enhanced catalytic qualities with peak current in the involvement of 0.2 M phosphate buffer solution (PBS) of pH 6.0, attributed to the ultimate sensing performance of the sensor.

Bacterial chitinase biochemical properties, immobilization on zinc oxide (ZnO) nanoparticle and its effect on Sitophilus zeamais as a potential insecticide

It has been planned to minimize the yield and quality impairment of the seed corn, which is strategically important in the world, by pests under storage conditions with a biological product produced with a biotechnological approach. In this context, the present study aimed to control the maize weevil Sitophilus zeamais, known as a warehouse pest, using a nanoformulation. In the study, the chitinase enzyme from Lactobacillus coryniformis was purified first using ammonium sulfate precipitation and then by using the HiTrap Capto DEAE column, and the molecular mass of the purified enzyme was determined to be ~ 33 kDa, and the optimum pH and the values as pH 6.0 and 65-75 °C, respectively. Five different doses of nanoformulation (2, 4, 6, 8 and 10 mg/L) were applied to corn grains by the spraying method with three repetitions so that the insect can ingest the formulation through feeding. The effects of the applications on the death rate and mean time of death of Sitophilus zeamais were determined. According to these findings, it was concluded that the best practice was nanoformulation with 6 mg/L, considering both the mortality rate (100%) and the average death time (2.4 days). Chitinase from L. coryniformis is a promising candidate for corn lice control and management.

Photocatalytic Degradation of Rhodamine B and Methylene Orange Using TiO2-ZrO2 as Nanocomposite

The present research reports the synthesis of ZrO2-doped TiO2 photocatalysts at different ZrO2 contents (1, 3 and 5% wt.) synthesized by the sol–gel method. The samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction, attenuated total reflectance-Fourier transform infrared, ultraviolet–visible, X-ray photoelectron spectroscopy and N2 adsorption–desorption analysis. The photocatalytic activity of the ZrO2-doped TiO2 was investigated against the dyes methyl orange and rhodamine B through mineralization studies. The ZrO2-doped TiO2 samples presented a semiglobular-ovoid agglomerate shape around 500–800 nm. The samples presented high crystallinity of the TiO2 anatase phase, XPS suggested the formation of Zr–O–Ti bonds and the samples were classified as mesoporous materials with slight changes in the optical features in comparison with pure TiO2. Our study shows that the ZrO2-doped TiO2 composites exhibited a higher photocatalytic activity than just utilizing the synthetized TiO2 and a commercial P25. The different degradation behaviors are attributed to differences in the textural properties, and to the different optical absorptions of the samples due to structural defects created by the level of doping of Zr4+ ions into the TiO2 lattice. Reaction kinetics parameters were calculated by the Langmuir–Hinshelwood model, and a third run cycle of the ZrO2-doped TiO2 at 1% wt. achieved a photocatalytic degradation of 78.1 and 75.5% for RhB and MO, respectively.

A comparison of the removal efficiencies of Myriophyllum spicatum L. for zinc oxide nanoparticles (ZnO NP) in different media: a microcosm approach

The phytoremediation potential of Myriophyllum spicatum L. has been well documented for bulk-sized heavy metals, including zinc (Zn). However, there is no information on the removal efficiencies of this aquatic macrophyte for zinc oxide nanoparticles contaminated waters. Therefore, the present study was aimed to compare the removal efficiency of M. spicatum in two different media: tap water and pond water. Results were evaluated by comparing percentage (%) removal and goodness-of-fit to regression models. Plants were exposed to 0.8 and 2 ppm nano-sized Zn for 1, 4, and 7 days. The zinc concentrations were monitored using ICP-MS. The %removal in tap water ranged between 29.5 and 70.3%, and slightly higher in pond water. Modeling results confirmed that there was a strong relationship between removal performance and exposure duration. Time-dependent removal shows that %removal shows no further progress after 4 days. Our results also indicate that planktonic communities in pond water might play an important role in the fate of ZnO NPs.

Green Synthesis of Highly Dispersed Zinc Oxide Nanoparticles Supported on Silica Gel Matrix by Daphne oleoides Extract and their Antibacterial Activity

Background:

ZnO nanoparticles (ZnO-NPs) are one of the most popular metal oxide nanoparticles, which exhibit significant antibacterial properties against various pathogens. Among nanoparticle synthesis methods, the green synthesis using plant extract is considered as an eco-friendly and cost-effective method for ZnO-NPs production, compared to the chemical procedures.

Background:

This study aimed to evaluate the green synthesis of ZnO-NPs loaded on silica gel matrix (ZnO/SG nanocomposite) by using methanol leaf extract of Daphne oleoides as a new extract and a cost-effective method. Furthermore, the antibacterial activity of the synthesized structure is evaluated against some pathogenic bacteria and the results are compared with unsupported ZnO-NPs.

Materials and Methods:

For ZnO/SG nanocomposite synthesis, a solution of Zn (NO₃)₂ was stirred with silica gel. Then the Daphne oleoides extract was added and stirred continuously until white precipitate was formed. The precipitate was heated at 200 ˚C for calcination, and ZnO/SG nanocomposite was obtained. The phytochemical constituents of leaf extract were then analyzed by gas chromatography–mass spectrometry (GC-MS). Afterwards, the structure of ZnO-NPs on SiO₂ matrix (ZnO/SG nanocomposite) was characterized by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). Surface area measurement was also determined by Brunauer-Emmett-Teller (BET) techniques. Furthermore, the antibacterial activity of ZnO/SG nanocomposites against pathogenic bacteria was evaluated using agar-based disk diffusion method standardized by clinical and laboratory guidelines.

Results:

The leaf extract of Daphne oleoides encompassed five major polyphenolic components. The results of the nanocomposite structure showed that ZnO-NPs with an average particle size of 38 nm were obtained and stabilized on the silica gel matrix. The BET surface area measurement of ZnO/SG nanocomposite was compared with unsupported ZnO-NPs, and the results indicated that the surface area of ZnO/SG nanocomposite was increased. Furthermore, the structure showed more powerful antibacterial activity against pathogens than unsupported ZnO-NPs.

Conclusions:

Green synthesis of ZnO-NPs supported on the silica gel matrix with the leaf extract of Daphne oleoides is a benign and effective procedure for ZnO/SG nanocomposite synthesis. Embedding ZnO-NPs in silica gel matrix prevents the agglomeration of nanoparticles and prepare homodispersed nanoparticles. This structure revealed great antibacterial activity against many pathogens.

Synthesis of ZnO/SiO2-modified starch-graft-polyacrylate superabsorbent polymer for agricultural application

A bio-based superabsorbent polymer (SAP) for agricultural application was synthesized from modified starch (MS) to enhance its antibacterial property and biodegradability. The starch was modified by zinc oxide and tetraethyl orthosilicate via a sol-gel reaction under an acidic condition. Structural and morphological examinations were used to confirm the modification. The MS showed a good antibacterial activity against Staphylococcus aureus and Escherichia coli with 61.9 % and 99.9 % reduction in viable cells, respectively, after a 1 h exposure. The MS was then graft copolymerized with potassium acrylate monomer to synthesize a new MS-g-polyacrylate (PA) SAP. The grafting reaction was confirmed and the main factors for agricultural applications along with its biodegradation and antibacterial properties were achieved. The MS-g-PA SAP exhibited an excellent reusability and biodegradation. Importantly, the MS-g-PA SAP did not impose growth inhibition of mung bean (Vigna radiata), but provided some transient drought relief.

The role of kaolin and kaolin/ZnO nanoadsorbents in adsorption studies for tannery wastewater treatment

In the present study, comparative studies of kaolin and kaolin/ZnO nanocomposites for the adsorption of Cr(VI), Fe(III), COD, BOD, and chloride from tannery wastewater were investigated. ZnO nanoparticles and kaolin/ZnO nanocomposites were prepared by sol-gel followed by wet-impregnation methods. The prepared adsorbents were characterized using different analytical tools such as X-ray diffraction, Fourier transforms infrared, high-resolution transmission electron microscopy, energy dispersive spectroscopy, selective area electron diffraction and Brunauer Emmett-Teller (BET) and X-ray Photoelectron Spectroscopy (XPS). The HRSEM/EDS/XPS analysis confirmed successful immobilization of clay structural network on the lattice layers of zincite hexagonal structure of ZnO nanoparticles. BET measurement showed an increase in the surface area of kaolin/ZnO nanocomposites (31.8 m²/g) when compared to kaolin (17 m²/g). Batch adsorption studies were carried out by varying the parameters such as contact time, adsorbent dosage and temperature. The maximum removal of Cr(VI) (100%), Fe(III) (98%), COD (95%), BOD (94%) and Chloride (78%) was obtained at 15 min by kaolin/ZnO composites. While 78% Cr(VI), 91% Fe(III), 91% COD, 89% BOD and 73% Chloride were removed by kaolin under the same conditions. The kaolin/ZnO nanocomposites exhibited better adsorption performance than kaolin due to higher surface area of the former than the latter. It was found that the Jovanovic isotherm model fitted the adsorption experimental data most with the highest correlation (R² > 0.99) for both nanoadsorbents and indicate the occurrence of adsorption on monolayer and heterogeneous surfaces. The mechanism for the adsorption of metal ions in tannery wastewater onto the nano-adsorbents was examined using Weber Morris intra-particle diffusion model and Boyd plot which showed that the adsorption process was both intra-particle and film diffusion controlled. The thermodynamic parameters such as enthalpy change showed that that adsorption of metal ions and other parameters was feasible, spontaneous and endothermic. The ZnO/clay nanocomposites exhibited excellent recyclable and re-useable properties even after six repeated applications and can, therefore, be applied in wastewater treatment for removal of heavy metals and other physicochemical parameters.

Loading and release of doxorubicin hydrochloride from iron(iii) trimesate MOF and zinc oxide nanoparticle composites

A significant amount of work has been done in recent years for the development of metal organic framework (MOF) based drug delivery vehicles. Often, nanomaterials such as iron oxide (Fe3O4), zinc oxide (ZnO), and other metal oxides like graphene oxide etc. are incorporated into the structures to impart additional functionality. In this work, an iron(iii) trimesate metal organic framework i.e. MIL-100(Fe) and its composites with ZnO nanoparticles i.e. ZnO@MIL-100(Fe) were investigated as delivery agents for anticancer drug doxorubicin hydrochloride (DOX). The synthesis of the composites was done by two routes viz. a conventional HF route (in the presence of HF as a crystallizing agent) and another one in the absence of HF. The resultant MOF and its composites significantly differ in DOX loading capacity and release rates. The results obtained in this work indicate that the DOX loading capacity increases upon addition of nanoparticles when the original MOF has lower mesopore volume (as in the sample obtained via the HF route). Surprisingly, this increase in the DOX loading was comparable to that of Fe3O4@MIL-100(Fe), although the two pure nanoparticles (ZnO and Fe3O4) have widely different loading capacities. On the other hand, the addition of ZnO nanoparticles reduces the DOX loading capacity, if the MOF has higher mesopore volume (as for the sample obtained via the HF free route). The composites synthesized by the HF route with enhanced loading capacity exhibit slower DOX release rates due to the stronger interaction of the drug with the composite.

Effective hydrogenation of carbonates to produce methanol over a ternary Cu/Zn/Al catalyst

Methanol synthesized from carbonate hydrogenation is of great importance for CO₂ utilization indirectly. Herein, a series of Cu/Zn/Al heterogeneous catalysts were prepared by co-precipitation with a synchronous aging step, and were applied for hydrogenation of diethyl carbonate (DEC) to produce methanol. Furthermore, the catalysts were characterized by physicochemical methods, such as N₂ adsorption, ICP-OES, N₂O titration, SEM, TEM, XRD, H₂-TPR and XPS in detail. Higher copper concentration led to a higher ratio of bulk CuOx species in the calcined samples, which resulted in different copper species distribution after the reduction process. Structure activity relationship analysis indicated that the balance of surface Cu⁰ and Cu⁺ species influenced the formation rate of methanol. A higher proportion of Cu⁺ to (Cu⁺ + Cu⁰) was conductive to methanol formation, while excessive Cu⁰ site density played a negative influence on the methanol synthesized from DEC. Cu/Zn/Al with a 45.2% weight fraction of copper showed better performance with a total methanol formation rate of 131.0 mg g_cat.⁻¹ h⁻¹. The reaction temperature and reaction time could obviously affect the reaction performance and the results suggested that 200 °C and 6 h were suitable. Furthermore, the long-term stability and activity of the catalyst was also studied on a fixed bed, and the yield of total methanol reached to 88.5% and the selectivity of total methanol gradually decreased to 74.0% within 200 h, which could be attributed to the detrimental influence derived from the increase of Cu⁰. The reaction pathways involved in the hydrogenation of DEC process were proposed. The substance scope was also extended to other carbonates and the catalyst exhibited superior catalytic performance toward linear carbonates. This work provided insights into carbonate hydrogenation over an effective Cu/Zn/Al catalyst, which could be utilized into upgrading CO₂ indirectly to produce commodity methanol under relatively mild reaction conditions.

The valence distribution of copper species in ternary Cu/Zn/Al catalysts have significant influence on diethyl carbonate hydrogenation to produce methanol.

Electrospun Gelatin Fibers Surface Loaded ZnO Particles as a Potential Biodegradable Antibacterial Wound Dressing

Traditional wound dressings require frequent replacement, are prone to bacterial growth and cause a lot of environmental pollution. Therefore, biodegradable and antibacterial dressings are eagerly desired. In this paper, gelatin/ZnO fibers were first prepared by side-by-side electrospinning for potential wound dressing materials. The morphology, composition, cytotoxicity and antibacterial activity were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), particle size analyzer (DLS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetry (TGA) and Incucyte™ Zoom system. The results show that ZnO particles are uniformly dispersed on the surface of gelatin fibers and have no cytotoxicity. In addition, the gelatin/ZnO fibers exhibit excellent antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) with a significant reduction of bacteria to more than 90%. Therefore, such a biodegradable, nontoxic and antibacterial fiber has excellent application prospects in wound dressing.

Preparation of Nano-TiO₂-Coated SiO₂ Microsphere Composite Material and Evaluation of Its Self-Cleaning Property

In order to improve the dispersion of nano-TiO₂ particles and enhance its self-cleaning properties, including photocatalytic degradation of pollutants and surface hydrophilicity, we prepared nano-TiO₂-coated SiO₂ microsphere composite self-cleaning materials (SiO₂–TiO₂) by co-grinding SiO₂ microspheres and TiO₂ soliquid and calcining the ground product. The structure, morphology, and self-cleaning properties of the SiO₂–TiO₂ were characterized. The characterization results showed that the degradation efficiency of methyl orange by SiO₂–TiO₂ was 97%, which was significantly higher than that obtained by pure nano-TiO₂. The minimum water contact angle of SiO₂–TiO₂ was 8°, indicating strong hydrophilicity and the good self-cleaning effect. The as-prepared SiO₂–TiO₂ was characterized by the nano-TiO₂ particles uniformly coated on the SiO₂ microspheres and distributed in the gap among the microspheres. The nano-TiO₂ particles were in an anatase phase with the particle size of 15–20 nm. The nano-TiO₂ particles were combined with SiO₂ microspheres via the dehydroxylation of hydroxyl groups on their surfaces.