Loading Of TiO2 Nanoparticles Research Articles

Self-cleaning PDMS films with durable superhydrophobicity and photocatalytic capability based on TiO2-modified nanopillar array

Self-cleaning films with superhydrophobicity and photocatalytic capability have attracted considerable interest in recent years for the synthetical chemical and physical self-cleaning performance to overcome individual inherent limitations. In the present work, a dual-functional self-cleaning film is proposed through the design of polydimethylsiloxane (PDMS) nanopillar array, swelling absorption of anatase-typed TiO2 nanoparticles, and final low-surface-energy modification of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (PFDTS). Benefiting from the hierarchically mountain-like structure constructed by the PDMS nanopillar array and swelling absorbed TiO2 nanoparticles, the self-cleaning film presents a robust superhydrophobicity to resist chemical and mechanical damages (e.g. solvent/acid/alkali immersion, stretching, water impact, and sand abrasion). Combining the photocatalytic activity with adequate loading of TiO2 nanoparticles, the self-cleaning film demonstrates a great degradation capability of organic pollutants with a degradation efficiency over 98 %. Importantly, owing to the superhydrophobicity repairability induced by the migration of fluorocarbon chains, the self-cleaning film can highly recover the water repellency with a water contact angle (WCA) of 155o even after long-term irradiation under UV light. The findings conceivably promote the development and application of the self-cleaning materials with superhydrophobic and photocatalytic properties.

Using predictive models unravel the potential of titanium oxide-loaded activated carbon for the removal of leachate ammoniacal nitrogen.

The TiO2 nanocomposite efficiency was determined under optimized conditions with activated carbon to remove ammoniacal nitrogen (NH3-N) from the leachate sample. In this work, the facile impregnation and pyrolysis synthesis method was employed to prepare the nanocomposite, and their formation was confirmed using the FESEM, FTIR, XRD, and Raman studies. In contrast, Raman phonon mode intensity ratio ID/IG increases from 2.094 to 2.311, indicating the increase of electronic conductivity and defects with the loading of TiO2 nanoparticles. The experimental optimal conditions for achieving maximum NH3-N removal of 75.8% were found to be a pH of 7, an adsorbent mass of 1.75mg/L, and a temperature of 30°C, with a corresponding time of 160min. The experimental data were effectively fitted with several isotherms (Freundlich, Hill, Khan, Redlich-Peterson, Toth, and Koble-Corrigan). The notably elevated R2 value of 0.99 and a lower ARE % of 14.61 strongly support the assertion that the pseudo-second-order model compromises a superior depiction of the NH3-N reduction process. Furthermore, an effective central composite design (CCD) of response surface methodology (RSM) was employed, and the lower RMSE value, precisely 0.45, demonstrated minimal disparity between the experimentally determined NH3-N removal percentages and those predicted by the model. The subsequent utilization of the desirability function allowed us to attain actual variable experimental conditions.

Survey of catalytic performance of TiO2 via coupling with ZSM-5 Zeolite under UV light for activation of peroxymonosulfate Applied towards Orange II (OII) degradation

Background: The widespread presence of organic dyes in the various industries’ effluent such as paper, textile, and clothing has led to significant environmental pollution. Titanium oxide (TiO2 ) nanoparticles immobilized on zeolite (ZSM-5) were investigated under UV light for activation of peroxymonosulfate (PMS) for photocatalytic degradation of Orange II (OII) dye in aqueous solutions. Methods: In this study, the photocatalyst used was prepared by immobilizing different amounts of TiO2 nanoparticles on ZSM-5. Characterization analyses including X-ray diffractometer (XRD), Fourier transform infrared (FTIR), BET, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) were performed on the synthesized samples. Then, the effect of various parameters, such as TiO2 nanoparticles loading onto the ZSM-5, pH, contact time, dye concentration, and TiO2 / ZSM-5 dosage, is investigated for the removal of OII as a model molecule under the UV irradiation with 15 W power. Results: The highest removal percentage of OII dye (97.44%) was obtained in the optimal operating conditions of pH=3, the initial dye concentration=5 ppm, amount of TiO2 /ZSM-5=10 mg/L, amount of PMS=50 mg/L, and reaction time=120 minutes. The Langmuir–Hinshelwood kinetics model fitted with the experimental data. Conclusion: The obtained results of this research showed that PMS can be used as a suitable oxidant activated with ZSM-5/TiO2 nanocomposite in OII degradation in different water environments, by optimizing the effective operating factors.

Effect of TiO2 concentration in PVDF-TiO2-PVP mixed matrix membrane performance using ultrafiltration process

This study investigated how the addition of hydrophilic TiO2 to a porous asymmetric polyvinylidene fluoride (PVDF) Ultrafiltration (UF) membrane altered its properties and performance. The hydrophilicity and flux of PVDF and polyvinylpyrrolidone (PVP) combinations will be lower, and TiO2 will significantly impact raising those values. By mixing titanium dioxide (TiO2) nanoparticles with a pore-forming agent in a dope solution, PVDF-TiO2-PVP membranes were prepared via non-solvent-induced phase inversion method. Experiments using PVDF membranes with varying concentrations of TiO2 (0, 0.25, 0.5, 1, 1.5, and 2% wt) were applied to evaluate pure water flux and Bovine Serum Albumin (BSA) flux. The functional group composition of membranes was investigated by Fourier transform infrared spectroscopy. The wettability of porous membranes was determined by measuring contact angles. Results demonstrated that membranes constructed from PVDF/PVP/TiO2 with a lower loading of TiO2 nanoparticles had a smaller mean pore size, more apertures inside the membrane, and better membrane hydrophilicity. The highest flux of pure water (121 L/m2h) was achieved by the PVDF-TiO2-PVP mixed-matrix membrane at a TiO2 concentration of 2 wt%.

Chitosan and TiO2 functionalized polypropylene nonwoven fabrics with visible light induced photocatalytic antibacterial performances

Chitosan/TiO2 functionalized polypropylene (CS/TiO2/PP) nonwoven fabrics were fabricated through crosslinking of chitosan with glutaraldehyde followed by loading of TiO2 nanoparticles. The functionalized CS/TiO2/PP has super hydrophilicity and excellent visible light induced photocatalytic antibacterial properties owing to the synergistic effects of CS and TiO2. The photocatalytic degradation performance was determined by assessing the degradation of methyl blue under simulated visible light irradiation and its recyclability was also evaluated. In addition, SEM images demonstrated that TiO2 nanoparticles were distributed evenly on the surface of the 2 g/L CS/TiO2/PP. Meanwhile, the polypropylene surface showed a significant increase in hydrophilicity after being treated with chitosan and TiO2. The photocatalytic degradation results revealed that CS/TiO2/PP had higher photocatalytic properties than those of pure PP under visible light, and the degradation rate of methylene blue reached 96.4 % after 90 min of light exposure. Compared to pure PP, the antibacterial properties of CS/TiO2/PP significantly increased, and the bacterial reduction percentages were increased to 98.7 % and 96.3 %, against E. coli and S. aureus, respectively. The functionalized CS/TiO2/PP composites exhibited promising potential in environmentally friendly antibacterial materials.

CO2 absorption enhancement in low transition temperature mixtures-based nanofluids: Experiments and modeling

The enhancement of gas–liquid mass transfer in the CO2 absorption process by Low Transition Temperature Mixtures (LTTMs) based nanofluids was investigated. The effects of loading and size of TiO2 nanoparticles on the CO2 absorption rate were studied experimentally. The absorption rate was found to be improved significantly after adding nanoparticles. The maximum enhancement factor of 1.35 was observed when using nanoparticles with a particle size of 10 nm and a concentration of 0.6 kg/m3. The maximum absorption enhancement factor and mass transfer coefficient were observed when the loading of nanoparticles increased, hence there was an optimal concentration of TiO2 nanoparticles in the CO2 absorption process. For the size of nanoparticles, the CO2 absorption rate was higher when the diameter of nanoparticles decreased. Furthermore, a three-dimensional unsteady mathematical model of gas–liquid mass transfer, which was based on the mechanisms of grazing effect and hydrodynamic effect in the gas–liquid boundary layer, was developed to describe the CO2 absorption enhancement. The model predictions were well consistent with the experimental results, with a maximum deviation of less than 5%, which proved the reliability of the model. Finally, Molecular dynamics simulations were conducted on the absorbent-CO2 system. The results showed that the addition of TiO2 nanoparticles led to a reduction in the simulation box size at the same simulation time, but it did not significantly alter the interaction between LTTMs and CO2. Therefore, it can be inferred that TiO2 nanoparticles enhance CO2 absorption capacity by modifying the mass transfer rate. Through the aforementioned study, this paper explores the experimental and mechanistic aspects of nanoparticle-enhanced absorption of CO2 in LTTMs systems. The research demonstrates the feasibility of nanoparticle-enhanced absorption of CO2 in LTTMs solvents, providing insights into studying nanoparticle-enhanced gas–liquid mass transfer and offering a new research approach for CO2 capture.

Modulating the Conduction Band of MOFs by Introducing Tiny TiO2 Nanoparticles for Enhanced Photocatalytic Performance: Importance of the Loading Position.

The preparation of TiO2 and metal-organic framework (MOF) into composite photocatalysts has been proven to be a mature and effective strategy to achieve stronger catalytic activity. In this work, we focus on exploring the significant effects and mechanisms of the relative positions of decorated titanium oxide nanoparticles and MOFs on the final catalytic activity. We first used a simple in situ method to encapsulate tiny TiO2 nanoparticles into a Zr-MOF (PCN-222), where Zr-Ti bonds were created at the interface of the two components. Thanks to the strong interfacial interaction forces, band bending occurred in TiO2@PCN-222 and a more negative conduction band (Δ = 0.26 V) with better electron transport properties was obtained. The results of photocatalytic CO2 reduction experiments under visible light showed a 78% increase (142 μmol g-1 h-1) in the production rate of HCOO-. Surprisingly, the loading of TiO2 nanoparticles on the MOF surface (TiO2@PCN-222) resulted in a significant decrease of 56% in the catalyst yield activity due to poor adsorption and electron transfer properties. This work demonstrates the possibility of tuning the band structure and catalytic activity of MOFs with the help of changing the position of the dopant and shows the importance of the rational design of MOF-based composites.

Understanding the interfacial interaction of TiO2 nanoparticles filled glass fiber/epoxy composites through dynamic mechanical analysis

ABSTRACT In a multi-component system, the interfacial interactions between the various components trigger the behavior of the composite under external loading and thus determine the bulk properties of the material. In the present work, composite laminates made from TiO2 modified epoxy reinforced with glass fiber are subjected to thermal loading and the effort is made to analyze the interfacial interactions through the experimental values of storage modulus, loss modulus and tan delta. The loading of TiO2 nanoparticles in the epoxy resin is varied to also understand the effect of nanoparticle addition on the interfacial interactions through DMA. The addition of TiO2 nanoparticles helped to increase the storage and loss modulus by improving the rigidity of the polymeric chain. To understand the effect of varying the loading of TiO2 nanoparticles and to gauge the optimum wt.% addition of such nanoparticle, Tan delta, the degree of entanglement and the coefficient of the effectiveness of the nanofiller is found and the results indicate that the laminates successfully withstand the applied thermal load when the TiO2 loading is kept at 2 wt.%. This optimum nanoparticle loading wt.% is further validated through the adhesion factor which is found with the help of Tan delta values.

Hydroxyapatite-based catalysts for CO2fixation with controlled selectivity towards C2 products. Phenomenal support or active catalyst?

The loading of TiO2nanoparticles onto p-HAp has been studied for the selective fixation of CO2into C2 products.

Simulation of forward osmosis and pressure retarded osmosis membrane performance: Effect of TiO2 nanoparticles loading on the semi-permeable membrane

Forward osmosis (FO) has made significant progress in recent years as an emerging membrane technology for the treatment of water and wastewater. Differential osmotic pressure is used to extract pure water across a semi-permeable membrane in this process. CFD simulations were used to investigate the performance of flux changes in membrane systems in this study. This paper simulates the performance of a thin film composite (TFC) membrane with a titanium dioxide (TiO2) modified substrate in terms of FO and pressure retarded osmosis (PRO). The results showed how the simulation results (CFD) can be used to detect flux changes with additive particles. It was discovered that even a small amount of TiO2 nanoparticles can alter water flux. In the FO and PRO systems, adding 1 wt% TiO2 to the membrane matrix increased water flux by about 15% and 14%, respectively. Nevertheless, the increased solute flux was insignificant in simulation, which indicates the positive effect of adding TiO2 nanoparticles. Finally, a comparison of the results for different membranes indicated the best correlation between the simulation and experimental results, when 0.75 wt% TiO2 was used, and a relative error of 0.3% has been recorded in PRO process. Also, the maximum pure water flux rate (8·974×10−4molm2·s)obtained in the simulation of thin film nanocomposite (TFN) 1 and PRO process.

Exploring the bone regeneration potential of bio-fabricated nano-titania reinforced polyvinyl alcohol / nano-cellulose based composite film

A significant rise in bone-related defects affects the quality of life which impels researchers to facilitate the new approaches for bone regeneration. Herein, we have explored the bioactive nature of nano-titania for its utilization in bone tissue engineering. The titania-doped ternary nanocomposite film (PVA/NC-TiO2) was prepared by the fusion of Polyvinylalcohol (PVA), nano-cellulose (NC), and TiO2 (0.01 wt%) nanoparticles via sol-gel casting and compared with its binary nanocomposite film (PVA/NC). The simple and low-cost synthesis of these nanocomposite films, together with remarkable bioactive and thermo-mechanical properties, makes them a good candidate for their applications in human bone regeneration. The fabricated nanocomposite films were characterized through Fourier transform infra-red, Ultra-violet spectroscopy, and X-ray diffraction analysis to study complex formation and intermolecular interactions between the molecular entities.The SEM and TEM micrographs revealed the smooth surface of the developed binary and ternary nanocomposite films along with homogenous particle distribution. The thermo-mechanical stability was significantly improved when the nanocomposite film was modified with TiO2 nanoparticles indicating an enhancement of intermolecular interactions in PVA/NC-TiO2 film as compared to PVA/NC film. The Dynamic mechanical analysis results show higher storage modulus and glass transition temperature for PVA/NC-TiO2 film (9131.26 MPa, 74.3 °C) than PVA/NC film (7588 MPa, 64.3 °C). A comparative analysis of nanocomposite films revealed that PVA/NC-TiO2 film exhibited a thick and more uniformed layer of Ca–P mineral on its surface than PVA/NC film when incubated in Simulated Buffer Saline. The low loading of TiO2 nanoparticles resulted in a positive reinforcement effect on the bioactivity of the PVA/NC-TiO2 film (cell viability higher than 80%, hemolysis less than 1.7%) which provides an effective gateway for polymer nanocomposites in the dynamic orthopedic application by serving a better bone template for the regeneration of bone tissue.

TiO2 Nanoparticle Filler-Based Mixed-Matrix PES/CA Nanofiltration Membranes for Enhanced Desalination.

Mixed-matrix nanocomposite (PES/CA/PVP) membranes were fabricated for water desalination by incorporating varying amount of titanium dioxide nanoparticles (TiO2 NPs) ranging from 0 and 2 wt. %. Efficient dispersion of nanoparticles within polymeric membranes was achieved using the chemical precipitation method for uniform surface generation, and an asymmetric morphology was achieved via phase inversion method. Finally, membranes were characterized by Fourier Transform Infrared (FTIR) spectroscopy, Thermo Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), porosity and contact angle analysis. FTIR confirmed chemical composition of membranes in terms of polymers (PES/CA/PVP) and TiO2. TGA analysis confirmed an increase in thermal stability of membranes with the increase of TiO2 nanoparticles loading. The addition of TiO2 nanoparticles also resulted in an increase in porous structures due to an increase in mean pore size, as shown by SEM results. An increase in the hydrophilicity of the membranes was observed by increasing the concentration of TiO2 nanoparticles. The present study investigated pristine and mixed-matrix nanocomposite NF membrane performance while filtering a NaCl salt solution at varying concentration range (from 1 to 4 g/Lit 6 bar). The prepared membranes demonstrated significant improvement in water permeability and hydrophilicity. Further, to optimize the water flux and salt rejection, the concentration of Polyvinylpyrrolidone (PVP) was optimized along with TiO2 nanoparticles. Both the water flux and salt rejection of the fabricated membranes were observed to increase with an increase inTiO2 nanoparticles to 2 wt. % loading with optimized PVP concentration, which demonstrated the improved desalination performance of resultant membranes.

Stability evaluation and formula optimization of cellulose-based scaffold for the air-liquid interface cultivation of Navicula incerta

Culture scaffolds allow microalgae cultivation with minimum water requirement using the air-liquid interface approach. However, the stability of cellulose-based scaffolds in microalgae cultivation remains questionable. In this study, the stability of regenerated cellulose culture scaffolds was enhanced by adjusting TiO2 loading and casting gap. The membrane scaffolds were synthesized using cellulose dissolved in NaOH/urea aqueous solution with various loading of TiO2 nanoparticles. The TiO2 nanoparticles were embedded into the porous membrane scaffolds as proven by Fourier transform infrared spectra, scanning electron microscopic images, and energy-dispersive X-ray spectra. Although surface hydrophilicity and porosity were enhanced by increasing TiO2 and casting gap, the scaffold pore size was reduced. Cellulose membrane scaffold with 0.05 wt% of TiO2 concentration and thickness of 100 μm attained the highest percentage of Navicula incerta growth rate, up to 37.4%. The membrane scaffolds remained stable in terms of weight, porosity and pore size even they were immersed in acidic solution, hydrogen peroxide or autoclaved at 121 °C for 15 min. The optimal cellulose membrane scaffold is with TiO2 loading of 0.5 wt% and thickness of 100 μm, resulting in supporting the highest N. incerta growth rate and and exhibits good membrane stability.

Composite polydopamine-based TiO2 coated mesh with restorable superhydrophobic surfaces for wastewater treatment

Various pollutants in wastewater including water-insoluble oils and water-soluble toxic organic pollutants, have been threatening ecosystems and human health, making wastewater purification difficult. Inspired by the hierarchical structures and chemical compositions of lotus leaf, we combined the usage of polydopamine (PDA) chemistry and photocatalytically active TiO2 to develop a facile approach toward composite PDA-based TiO2 coated mesh with restorable superhydrophobicity. In this procedure, PDA assisted loading of TiO2 nanoparticles onto stainless steel mesh with a result of micro/nanoscale hierarchical surface was achieved via a single-step solvothermal method. After modified with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, this mesh became superhydrophobic. The TiO2 coated mesh exhibited enhanced superhydrophobicity, excellent environmental stability, robust chemical resistance and high mechanical durability. Moreover, it has been demonstrated the high separation capacity and extraordinary recyclability for various oils collection from water due to its special surface superhydrophobicity. Importantly, such a mesh possessed photocatalytic activity due to the embedded TiO2, which allowed for the effective degradation of organic pollutants under UV irradiation, representing a plausible way to restore superhydrophobic surface by photocatalytically decomposing the attached contaminants. This investigation suggests a green and facile way to prepare superhydrophobic materials with restored surface wetting property, which will be useful for wastewater purification.

Development of TiO2/RT–35HC based nanocomposite phase change materials (NCPCMs) for thermal management applications

This experimental study covers the development of novel nanocomposite phase change materials (NCPCMs) based on RT–35HC as a phase change material (PCM) and titanium oxide (TiO2) as thermal conductivity enhancement material, for thermal management applications. The TiO2 loadings were varied from 0.0 to 2.0 wt.% in pure RT–35HC samples and characterized for their chemical, physical and thermal properties by different characterization methods. The microstructures, chemical structures, lattice structures showed the presence of TiO2 nanoparticles onto the surface of NCPCMs. The results revealed that thermal properties including phase–change temperature, melting/solidifying latent–heat enthalpies, specific heat capacity and thermal conductivity were decreased by the introduction of TiO2 nanoparticles. This study confirmed that NCPCMs based on TiO2/RT–35HC revealed the phase–change enthalpies and thermal conductivities of 238.33-227.74 J/g and 0.238-0.341 W/m.K, respectively. In addition, significant chemical and thermal stability and no phase segregation were observed with the increase in loading of TiO2 nanoparticles. The newly developed TiO2/RT–35HC base NCPCMs revealed acceptable chemical stability, thermal reliability, and efficient conjugate heat transfer performance. Thereby, NCPCMs exhibit the potential application for thermal energy storage and thermal management of electronic devices, Li-ion batteries and photovoltaic (PV) modules.

Optimized Loading of TiO2 Nanoparticles into Electrospun Polyacrylonitrile and Cellulose Acetate Polymer Fibers

Polyacrylonitrile (PAN), cellulose acetate (CA), PAN-TiO2, and CA-TiO2 nanofibers were prepared using the electrospinning technique under varying the loading of the TiO2 nanoparticles. The latter TiO2 nanoparticles were prepared using the sol-gel method by varying the calcination temperatures. The absorption and emission spectra illustrated the formation of TiO2 nanoparticles with an increase in absorption band edges with smaller particles. The TEM results showed the spherical morphology of the nanoparticles calcined at 500°C with an average diameter of 12.2±3.3 nm. XRD analysis revealed anatase phase as the dominant crystalline phase of the nanoparticles. TiO2 nanoparticle loadings of 0.2 and 0.4 wt% were incorporated into 16 wt% CA solutions while 1, 2, and 3 wt% of TiO2 nanoparticles were incorporated into 10 wt% PAN solutions. The SEM results illustrated the lowering in diameter and morphology of the nanofibers upon incorporation of nanoparticles. Their respective average diameters are 220, 338, 181, and 250 nm for PAN, CA, PAN-TiO2, and CA-TiO2 polymer fibers, respectively. The morphology of the nanofibers improved while the diameter increased with an increase in polymer concentration. Different loadings of TiO2 nanoparticles improved the electrospinnability and morphology and further decreased the size of the nanofibers. FTIR spectroscopy signifies the formation of nanocomposites and the presence of TiO2 nanoparticles which corresponded to the Ti-O stretching and Ti-O-Ti bands on the FTIR spectra.

Mechanical and microscopical characterisation of bilayer hydrogels strengthened by TiO2 nanoparticles as a cartilage replacement candidate

Bilayer hydrogels are suggested as a candidate for cartilage replacement due to their similarity to the native cartilage structure. While their water retention in the lubricious layer is an advantage over other counterparts, their mechanical properties have remained under-explored. In this study, indentation, compression and stress relaxation tests were conducted to evaluate mechanical responses of the bilayer hydrogels. Scanning electron microscope was also utilised to visualise the formation of the porous layer with varying TiO2 nanoparticle (NP) loadings. Our results show that an optimum TiO2 NPs concentration, improved elastic modulus and hardness of the bilayer hydrogels threefold. 0.2wt% TiO2 loading in the polyacrylamide/alginate/ acrylic acid hydrogel exhibited the best material stiffness and stress-strain responses. Viscoelastic responses improved for 0.2wt%, 0.4wt% and 0.6wt% NPs loadings compared to the non-reinforced hydrogel. A unique string-like pore on the surface of 0.2wt% NPs sample was observed, and swelling ratio of this sample was at a moderate level (300 %) compared to other concentrations. The NP loaded bilayer hydrogel demonstrated mechanical features similar to those of articular cartilage, hence could be considered as a cartilage replacement candidate.

Chitosan biopolymer based nanocomposite hydrogels for removal of methylene blue dye

Nanocomposite hydrogels were synthesized by γ-radiation-induced copolymerization and crosslinking of Chitosan biopolymer (CS), acrylic acid (AAc) and TiO2 nanoparticles (CS-PAAc/TiO2). The structure, morphology, and properties of the nanocomposites were investigated using Fourier-transform infrared spectroscopy, X-Ray Diffraction, Scanning electron microscopy, Transmission electron microscopy, and thermogravimetric analysis techniques. The nanocomposites hydrogel was used for the removal of methylene blue dye (MB) from wastewater. It was found that the presence of TiO2 in the copolymeric matrix enhances the adsorption by increasing the physical interaction between the dye molecules and the adsorbent surface. The removal percentage increases with the increase in pH of the medium of all investigated samples and the maximum value is obtained at the solution pH is 10. The maximum adsorbent dosage for CS-PAAc/TiO2 nanocomposites is 0.20 g and for CS-PAAc hydrogel is 0.15 g per liter of the adsorbate. This study revealed that the loading of TiO2 nanoparticles into the polymeric matrix of CS-PAAc does a remarkable increase in the removal parentage of MB dye from its aqueous solution.

Heterostructured TiO2@HKUST-1 for the enhanced removal of methylene blue by integrated adsorption and photocatalytic degradation

ABSTRACT Aiming at exploring an effective photocatalytic adsorbent for organic dye removal, a series of heterostructured TiO2@HKUST-1 photocatalysts, by incorporating HKUST-1 with different TiO2 nanoparticles loading, were prepared by single-step hydrothermal method. The morphology and surface characteristics of the as-prepared TiO2@HKUST-1were analyzed using SEM, HRTEM, XRD, FTIR, UV–vis DRS, and Photoluminescence techniques. The adsorption-photocatalytic degradation of the model dye methylene blue (MB) on the catalysts was investigated. It was indicated that the introduction of a certain amount of TiO2 on the surface of HKUST-1 could improve the transfer and separation of the photogenerated charge carriers, resulting in the enhanced photocatalytic activity. The optimal 0.02TiO2@HKUST-1 exhibited the highest MB removal rate with about 4.4 and 19.3 times as high MB removal efficiency as that of HKUST-1 and TiO2, respectively. Heterostructured TiO2@HKUST-1 materials for the removal of MB involved the integrated adsorption and visible light photocatalysis. Meanwhile, the composite exhibited good reusability in the process of cyclic experiments. Therefore, this work provides a potential MOF-based photocatalytic adsorbent for organic dye removal.

Freezing-Induced Loading of TiO2 into Porous Vaterite Microparticles: Preparation of CaCO3/TiO2 Composites as Templates To Assemble UV-Responsive Microcapsules for Wastewater Treatment.

The photocatalytic degradation of organic molecules is one of the effective ways for water purification. At this point, photocatalytic microreactor systems seem to be promising to enhance the versatility of the photoassisted degradation approach. Herein, we propose photoresponsive microcapsules prepared via layer-by-layer assembly of polyelectrolytes on the novel CaCO3/TiO2 composite template cores. The preparation of CaCO3/TiO2 composite particles is challenging because of the poor compatibility of TiO2 and CaCO3 in an aqueous medium. To prepare stable CaCO3/TiO2 composites, TiO2 nanoparticles were loaded into mesoporous CaCO3 microparticles with a freezing-induced loading technique. The inclusion of TiO2 nanoparticles into CaCO3 templates was evaluated with scanning electron microscopy and elemental analysis with respect to their type, concentration, and number of loading iterations. Upon polyelectrolyte shell assembly, the CaCO3 matrix was dissolved, resulting in microreactor capsules loaded with TiO2 nanoparticles. The photoresponsive properties of the resulted capsules were tested by photoinduced degradation of the low-molecule dye rhodamine B in aqueous solution and fluorescently labeled polymer molecules absorbed on the capsule surface under UV light. The exposure of the capsules to UV light resulted in a pronounced degradation of rhodamine B in capsule microvolume and fluorescent molecules on the capsule surface. Finally, the versatility of preparation of multifunctional photocatalytic and magnetically responsive capsules was demonstrated by iterative freezing-induced loading of TiO2 and magnetite Fe3O4 nanoparticles into CaCO3 templates.