TiO2 Loading Research Articles

Physical and structural properties of whey protein concentrate - Corn oil - TiO2 nanocomposite films for edible food-packaging

Interest in polymer technology based on biodegradable and edible films has increased dramatically, in hopes of creating a circular economy with little to no environmental impact. In this study nanocomposite films with a glycerol/WPC ratio of 4/5 were prepared from emulsions containing 2.5, 5.0, or 7.5 wt.% WPC and 2 wt.% corn oil. Films also contained a load of 0.5 wt.% TiO2. Emulsions were prepared with two different droplet sizes: conventional (from 300 to 700 nm) and nano (from 60 to 80 nm). Films were analyzed for color, water vapor permeability, thermogravimetric, mechanical/tensile properties, infrared behavior, and structure. Advanced X-ray microscopy based on small and wide-angle scattering contrast was used to investigate the nanocomponents in the films, allowing the identification of the main scattering species. Film that was prepared from starting systems with nano droplets (60 nm), the highest protein concentration (7.5 wt.% WPC), and TiO2 loading had the greatest E’ (elastic modulus, 19.2 MPa), E (Young modulus, 19.4 MPa), and εb (elongation at break, 119 %) values. This nano-based film had suitable physical properties for cheese packaging and other similar applications. In all films, data showed a close correlation between film structure and mechanical/tensile properties.

Flexible bacterial cellulose-based BC-SiO2-TiO2-Ag membranes with self-cleaning, photocatalytic, antibacterial and UV-shielding properties as a potential multifunctional material for combating infections and environmental applications

This research study reports the formation of flexible and multifunctional organic-inorganic hybrid membranes (BC-SiO2-TiO2/Ag) based on bacterial cellulose (BC) that contain photoactive (TiO2) and antibacterial (Ag) components, rendering them photocatalytic, self-cleaning and UV-shielding properties (due to TiO2) as well as antibacterial activity. Coating of BC with sol-gel derived silica and titania particles was achieved through hydrolysis-polycondensation of tetraethyl orthosilicate and titanium (IV) isopropoxide, respectively, and a soft hydrothermal treatment (140 °C, 20 h) was used to obtain well-crystalline TiO2. The prepared BC-SiO2-TiO2/Ag photoactive membranes were characterized by an array of analytical techniques including XRD, XRF, SEM-EDS, electronic absorption spectroscopy and vibrational spectroscopy. The morphology of TiO2 coatings changes from a homogenous film-like smooth one to a rougher one consisting of randomly oriented titania particles (170 ± 35 nm) upon increasing the TiO2 loading of the membranes. These prepared photoactive BC-SiO2-TiO2 membranes exhibited excellent TiO2-loading dependent photocatalytic/self-cleaning activity towards crystal violet dye deposited as an over-layer on the surface of the membranes, degrading 97 % of the dye within 50 min of UV illumination. In addition to good photoactivity, the BC-SiO2-TiO2/Ag membranes demonstrated reasonable antibacterial activity against five different bacterial strains under dark conditions. These flexible BC-based hybrid membranes with photocatalytic, self-cleaning, antibacterial properties have the potential to be used in the design of self-cleaning and antibacterial surfaces, filters and facemasks that could be easily disinfected under UV irradiation from a lamp or natural sunlight and safely discarded and even recycled.

Utilization of Nano-TiO2 as an Influential Additive for Complementing Separation Performance of a Hybrid PVDF-PVP Hollow Fiber: Boron Removal from Leachate.

The continuous increase in anthropogenic activities resulting in an increase in boron concentration in the environment is becoming a serious threat to public health and the ecosystem. In this regard, a hybrid polyvinylidene fluoride (PVDF)-polyvinyl pyrrolidone (PVP) hollow fiber was synthesized with hydrophilic nano-titanium oxide (TiO2) at varied loadings of 0, 0.5, 1.0, 1.5, and 2.0 wt% using the phase inversion technique. The resultant membranes were characterized in terms of Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), contact angle, porosity, and zeta potential. The permeability flux was assessed using both pure water and leachate; also, rejection performance was evaluated based on boron removal from the leachate. The results revealed that the membrane with 1.0 wt% loading had the highest flux alongside an upturn in boron rejection percentage of 223 L/m2·h and 94.39%, respectively. In addition, the lowest contact angle of 50.01° was recorded with 1.0 wt% TiO2 loading, and this implies that it is the most hydrophilic. Throughout the experiment cycles, the fiber with 1.0 wt% TiO2 loading demonstrated a high flux recovery varying between 92.82% and 76.26% after 9 h filtration time. The physicochemical analysis of the permeate revealed that the boron concentration was significantly reduced to 0.43 mg/L, which is far lower than the discharge limit of 1.0 mg/L.

Strategic Surface Modification for the Enhanced Photocatalyic Activity: Synergistic Promotion for Energy Utilization in TiO2–Cu2O–Au

A ternary nanocomposite structure of TiO2–Cu2O–Au was successfully synthesized by the hydrothermal method to explore the light trapping mechanism of Au nanoparticles in photoelectrochemical water splitting. The photocurrent curve of TiO2–Cu2O–Au quickly arrived at saturation and increased to 1044 μA/cm2 at 1.23 V (vs RHE), which was 10.4 times higher than the TiO2 only. This attributed to the positive synergistic effect of Au plasmon and TiO2–Cu2O heterojunction, in which Au act as a light absorber extended the optical path while Cu2O promoted the separation of photogenerated electron–hole pairs in semiconductors. These intriguing results expanded the comprehensive understanding of the plasmon-assisted photocatalyic reactions and gave a better manipulation in the design of efficient artificial photosynthesis systems. TiO2–Cu2O–Au nanorod arrays were successfully synthesized by the hydrothermal method. TiO2–Cu2O–Au nanorod arrays photoanode were strategically designed to improve photoelectrocatalytic (PEC) performance by Au plasmon loading and building TiO2–Cu2O heterojunction. The Au in TiO2–Cu2O–Au nanorod array act as a light absorber extended the optical path, and the Cu2O promoted the separation of photogenerated electron–hole pairs. On the merits of such a synergistic effect, TiO2–Cu2O–Au nanorod array shows higher light-harvesting ability, lower carrier recombination rate, and resultant improved PEC performance than the contrast of TiO2, TiO2–Cu2O and TiO2–Au.

Organic Degradation Potential of Real Greywater Using TiO2-Based Advanced Oxidation Processes

In keeping with the circular economy approach, reclaiming greywater (GW) is considered a sustainable approach to local reuse of wastewater and a viable option to reduce household demand for freshwater. This study investigated the mineralization of total organic carbon (TOC) in GW using TiO2-based advanced oxidation processes (AOPs) in a custom-built stirred tank reactor. The combinations of H2O2, O3, and immobilized TiO2 under either dark or UVA irradiation conditions were systematically evaluated—namely TiO2/dark, O3/dark (ozonation), H2O2/dark (peroxidation), TiO2/UVA (photocatalysis), O3/UVA (Ozone photolysis), H2O2/UVA (photo-peroxidation), O3/TiO2/dark (catalytic ozonation), O3/TiO2/UVA (photocatalytic ozonation), H2O2/TiO2/dark, H2O2/TiO2/UVA, H2O2/O3/dark (peroxonation), H2O2/O3/UVA (photo-peroxonation), H2O2/O3/TiO2/dark (catalytic peroxonation), and H2O2/O3/TiO2/UVA (photocatalytic peroxonation). It was found that combining different treatment methods with UVA irradiation dramatically enhanced the organic mineralization efficiency. The optimum TiO2 loading in this study was observed to be 0.96 mg/cm2 with the highest TOC removal (54%) achieved using photocatalytic peroxonation under optimal conditions (0.96 mg TiO2/cm2, 25 mg O3/min, and 0.7 H2O2/O3 molar ratio). In peroxonation and photo-peroxonation, the optimal H2O2/O3 molar ratio was identified to be a critical efficiency parameter maximizing the production of reactive radical species. Increasing ozone flow rate or H2O2 dosage was observed to cause an efficiency inhibition effect. This lab-based study demonstrates the potential for combined TiO2-AOP treatments to significantly reduce the organic fraction of real GW, offering potential for the development of low-cost systems permitting safe GW reuse.

Synthesis of high-efficient TiO2/clinoptilolite photocatalyst for complete degradation of xanthate

Acid leaching clinoptilolite-based composite photocatalyst coated with TiO2 nanoparticles was prepared by a hydrothermal method. Photocatalytic properties of the obtained TiO2/clinoptilolite were evaluated through the degradation of sodium isopropyl xanthate (SIPX) under UV light irradiation. The as-prepared samples were characterized by XRD, SEM, TEM, TG-DSC, N2 adsorption-desorption, XPS, FTIR, and UV–vis DRS in detail. Compared with pure TiO2, TiO2/clinoptilolite significantly enhanced the photodegradation efficiency of SIPX due to the synergistic effect of the composite. Over 90% of SIPX could be removed within 30 min with a TiO2/clinoptilolite dosage of 1.0 g/L under neutral condition. The influences of some parameters such as the TiO2 loading amount, H2O2 dosage, calcination temperature, and initial SIPX concentration on removal efficiency were investigated systematically. The results indicated that all the photocatalytic degradation process of SIPX followed a pseudo-first-order reaction kinetic model. Moreover, the stability and applicability of TiO2/clinoptilolite were also studied. The possible degradation pathway and mechanism of improved photocatalytic activity were proposed. It showed that the novel catalyst would have a promising application prospect in the field of flotation effluent treatment.

Z‐scheme 3 D g‐C3N4/TiO2−x Heterojunctions with High Photocatalytic Efficiency

AbstractThe 3D network structure composed of g‐C3N4 nanorods was prepared via treatment of bulk g‐C3N4 with hot HNO3 followed by adjustment the pH and lyophilization. Then the 3D g‐C3N4/TiO2−x heterojunctions with a strong interface was constructed via loading TiO2−x nanoparticles onto the 3D g‐C3N4 networks under hydrothermal conditions. The structure and morphology of the 3D g‐C3N4/TiO2−x heterojunctions was characterized by infrared spectrum (FTIR), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and field emission transmission electron microscope (TEM). The photo‐degradation rate of Doxycycline HCl for 3D g‐C3N4/TiO2−x heterojunction is about 4 times of that original bulk‐C3N4 and 2.75 times of 3D g‐C3N4. The improved photocatalytic efficiency is attributed to 3D g‐C3N4 networks, which provides the more transfer channel to accelerate the electron transportation and the strong heterointerface between g‐C3N4 and TiO2−x which promotes the separation of the electron‐holes. Besides, more adsorption capacity of the pollutant onto the 3D g‐C3N4/TiO2−x also contributed to this high efficiency.

Applicability of TiO2(B) nanosheets@hydrochar composites for adsorption of tetracycline (TC) from contaminated water

We test the feasibility of TiO2(B)@carbon composites as adsorbents, derived from wheat straws, for tetracycline (TC) adsorption from aqueous solutions. Hydrochar (HC), biochar (BC), and hydrochar-derived pyrolysis char (HDPC) are synthesized hydrothermally from the waste and then functionalized with TiO2(B), named as ‘Composite-1′, ‘Composite-2′, and ‘Composite-3′, respectively. A higher loading of TiO2(B) into the HC was also synthesized for comparison, named as ‘Composite-4′. To compare their physico-chemical changes before and after surface modification, the composites are characterized using FESEM-EDS, XRD, BET, FRTEM, and FTIR. The effects of H2O2 addition on TC removal are investigated. Adsorption kinetics and isotherms of TC removal are studied, while TC adsorption mechanisms are elaborated. We found that the Composite-4 has the highest TC removal (93%) at pH 7, 1 g/L of dose, and 4 h of reaction time at 50 mg/L of TC after adding H2O2 (10 mM). The TC adsorption capacities of the Composite-1 and Composite-4 are 40.65 and 49.26 mg/g, respectively. The TC removal by the Composite-1 follows the pseudo-second order. Overall, this suggests that converting the wheat straw into HC and then functionalizing its surface with TiO2(B) as a composite has added values to the waste as an adsorbent for wastewater treatment.

A green, and eco-friendly bionanocomposite film (poly(vinyl alcohol)/TiO2/chitosan/chlorophyll) by photocatalytic ability, and antibacterial activity under visible-light irradiation

In this study, using the chitosan (Chi), and poly(vinyl alcohol) (PVA) as a matrix for loading TiO2 nanoparticles (NPs), and the chlorophyll (Chl) as a natural light photocatalyst, provided the new, and efficient photocatalyst (PVA/TiO2/Chi/Chl). The TiO2 NPs and chlorophyll were applied to modify the PVA/Chi, and use as an effective nano-photocatalyst for degradation of methylene blue (MB), 4-chlorophenol (4-CP), and Congo red (CR) for the first time which shows efficiently promoted the separation of electron-hole pairs to enhance the photocatalytic activity. The degradation of MB was examined in the presence and absence of visible light. Also, the various contact time and the synergic effect of the different components of the bionanocomposite were studied. The high efficiency (96%) was achieved under visible-light irradiation (LED lamp 70 W by λ is 425 nm) at 60 min. The present bionanocomposite was identified by Fourier-transform infrared (FT-IR) spectra, field-emission scanning electron microscopy (FE-SEM) image, X-ray diffraction (XRD) pattern, and energy-dispersive X-ray (EDX), and photoluminescence (PL) analyses. Also, the antibacterial properties of PVA/TiO2/Chi/Chl as a distinctive feature were examined by the agar disk diffusion and colony counter method. The zone of inhibition for both S. aureus and E. coli bacteria were around 2.08 (±0.02), and 1.98 (±0.02), respectively. The colony counter was checked in the presence and the absence of visible light. Bacterial contamination presents serious risks to human health, therefore the prominent antimicrobial capability bionanocomposite inhibits the growth of both S. aureus, and E. coli bacteria under LED light irradiation. The use of green, and available materials, easy synthetic process, simple extraction method, eco-friendly protocol, high removal efficiency, and noticeable antibacterial properties are advantageous of the present work.

Integration of machine learning-based prediction for enhanced Model’s generalization: Application in photocatalytic polishing of palm oil mill effluent (POME)

In predicting palm oil mill effluent (POME) degradation efficiency, previous developed quadratic model quantitatively evaluated the effects of O2 flowrate, TiO2 loadings and initial concentration of POME in labscale photocatalytic system, which however suffered from low generalization due to the overfitting behaviour. Evidently, high RMSE (131.61) and low R2 (−630.49) obtained indicates its insufficiency in describing POME degradation at unseen factor ranges, hence verified the fact of poor generalization. To overcome this issue, several models were developed via machine learning-assisted techniques, namely Gaussian Process Regression (GPR), Linear Regression (LR), Decision Tree (DT), Supported Vector Machine (SVM) and Regression Tree Ensemble (RTE), subsequently being assessed systematically. To achieve high generalization, all models were subjected to ‘train-all-test-all’ strategy, 5-fold and 10-fold cross validation. Specifically, GPR model was furnished with high accuracy in ‘train-all-test-all’ strategy, judging from its low RMSE (1.0394) and high R2 (0.9962), which however menaced by the risk of overfitting. In contrast, despite relatively poorer RMSE and R2 (1.7964 and 0.9886) obtained in 5-fold cross validation, GPR model was rendered with highest generalization, while sufficiently preserving its accuracy in development process. Besides, SVM and RTE models were also demonstrated promising R2 (0.9372 and 0.9208), which however shadowed by their high RMSEs (4.2174 and 4.7366). Furthermore, the extraordinary generalization of GPR model was coincidentally verified in 10-fold cross validation. The lowest RMSE (2.1624) and highest R2 (0.9835) obtained with feature number of 36 asserted its sufficiency in both generalization and accuracy prospect. Other models were all rendered with slight lower R2 (> 0.9), plausibly due to the higher RMSE (> 4.0). According to GPR model, optimized POME degradation (52.52%) can be obtained at 70 mL/min of O2, 70.0 g/L of TiO2 and 250 ppm of POME concentration, with only ∼3% error as compared to the actual data.

Effects of operational parameters on bacterial inactivation in Vis-LEDs illuminated N-doped TiO2 based photoreactor

Titanium dioxide (TiO2) based photocatalysis has been widely investigated for several applications in the past. The major challenges related to this catalyst have also been successfully tackled through doping and immobilization techniques. For the practical application of the TiO2 photocatalyst in environmental remediation, the selection and design of proper types of photoreactors are also mandatory. The present study focuses on the investigation of operational parameters of a new type of Vis-LEDs illuminated N-doped TiO2 based photoreactor developed from immobilized visible light active nitrogen-doped titanium dioxide on the surface of glass beads. Advanced instruments, such as HR-TEM, XRD, BET, XPS, UV-Vis, FE-SEM, FT-IR, and TGA-DSC were employed to characterize the prepared catalyst. The performance of the photoreactor has also been investigated under different operational parameters (such as TiO2 load, initial E. coli concentration, bacterial solution feed flow rate, and light incident photon flux). Results showed that the inactivation efficiency of the reactor was found to increase with increasing TiO2 load and incident photon flux. However, the efficiency of the reactor decreased with increasing E. coli concentration and bacterial solution flow rate. The results indicate that initial E. coli concentration of 106 CFU mL-1, TiO2 concentration of 0.6 g, a flow rate of 40 mL min-1 and light incident photon flux of 5.23 × 1016 photons/s demonstrated higher inactivation efficiency in comparison to other study parameters. The photocatalytic inactivation kinetics also best fitted to Modified-Hom model with R2 0.9998.

Investigations on effect of graphitic carbon nitride loading on the properties and electrochemical performance of g-C3N4/TiO2 nanocomposites for energy storage device applications

The g-C3N4/TiO2 nanocomposites samples have been prepared by thermal spreading method. The effects of carbon nitride loading on the physical and electro-chemical properties of g-C 3N4/TiO2 have been studied. The surface of Titania (TiO2) could be progressively covered with amorphous carbon nitride effectively for different loads. The consequent changes in the structure, morphology and optical properties were probed by spectroscopic techniques. The resulting changes in the electrochemical behaviour also analysed. The combined results of X-ray Diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), Ultra Violet-Visible (UV–Vis), Raman studies showed that, the structure of g-C3N4/TiO2 changes from highly dispersed to bulk-like form with increasing loading. EDAX results were analysed to understand the proportions and loading variations of g-C3N4/TiO2 and optimum loading for electrochemical enhancements. The consequent changes in the electrochemical behaviour were revealed. Among different loadings, the 33% g-C3N4/TiO2 composite exhibited high specific capacitance. It exhibited good electrochemical performance in the cycling tests of charge-discharge analysis too. The prepared g-C3N4/TiO2 nanocomposite was examined in terms of supercapacitor behaviour from the charge-discharge curve and found the higher the specific capacitance of about 864.5 F/g. The cyclic performance test was examined to the g-C3N4/TiO2 nanocomposite for 2000 cycles and found excellent retention.

A citizen science approach estimating titanium dioxide released from personal care products.

Titanium dioxide (TiO2) is a common component in personal care products (PCP), which through use enters the wastewater treatment plant (WWTP) and ultimately the environment. A citizen science approach is utilized here to inform the prevalence and usage of TiO2 containing PCP on a household scale, which generates information as to the quantity of TiO2 entering the WWTP, and the portion ultimately discharged to the environment. Meanwhile, citizen science sourced inventories were generated to estimate the quantity of TiO2, and potentially nanoscale TiO2 entering the WWTP from consumer products and to determine which products had the greatest contribution. The estimated values were compared with water samples from the WWTP which quantified the amount of total titanium present using ICP-AES. These values were at a similar level with other top-down estimation approaches and suggest that a citizen science approach is valid to estimate the loading of TiO2, and potentially other emerging contaminants, while at the same time engaging with community stakeholders.

Factors affecting the degradation of remazol turquoise blue (RTB) dye by titanium dioxide (TiO2) entrapped photocatalytic membrane

This study investigated the photocatalytic degradation of remazol turquoise blue (RTB) dye using titanium dioxide (TiO2) entrapped polyvinylidene fluoride (PVDF) membrane synthesized by non-solvent induced phase separation method. Numerous experiments were conducted to investigate the effects of catalyst loading in membranes, the concentration of dye, feed temperature, pH of the solution, and the addition of H2O2 to the dye solution on the removal of dye. Results were compared with the performance of virgin PVDF and modified PVDF/TiO2 membranes. The experimental results indicated that the optimum TiO2 loading in the membrane was 2 wt%, which enhanced the membrane morphology, permeability, and dye removal performance. The rate of photocatalytic degradation dropped with the increase in dye concentration. The photocatalytic efficiency of the membrane depends on the pH and the temperature of the solution.

Sonophotocatalytic degradation of lignin: Production of valuable chemicals and kinetic analysis

Lignin, a key by-product of paper and pulp industry, and second-generation bioethanol refinery, is a potential source of platform chemicals due to its aromatic-rich structure. This study aims to demonstrate the synergism achieved by combining photocatalysis with ultrasound to depolymerize lignin into low molecular weight compounds. Sonophotocatalysis of lignin in alkaline aqueous medium using commercial TiO2 catalyst resulted in higher rate of degradation of lignin compared to photocatalysis. The increase in ultrasound frequency from 58 kHz to 58 + 132 kHz resulted in four-fold increase in lignin degradation rate. Upto 93 % degradation of lignin was achieved within 180 min via sonophotocatalysis. The molecular weight distribution of lignin was monitored using gel permeation chromatography to determine the change in number average and weight average molecular weights with time. At 2 g L−1 of TiO2 loading, 58 + 132 kHz ultrasound frequency, and initial lignin concentration of 100 mg L−1, the rate constant of lignin depolymerization, determined using the continuous distribution kinetics model with random scission, was 2.5 × 10-6 min−1 for sonophotocatalysis, while it was 0.93 × 10-6 min−1 for photocatalysis. The products obtained from sonophotocatalysis of lignin were 3,4-dihydroxy benzaldehyde, cinnamyl alcohol, 4-methyl-3-hexanone and succinic acid. The total yield of products from sonophotocatalysis of lignin was higher compared to that from photocatalysis. Overall, sonophotocatalysis is demonstrated to be a promising technique to degrade lignin and convert it to valuable chemicals.

Electro-catalytic membrane anode for dye removal from wastewater

A TiO2 loaded carbon membrane termed, “TiO2/carbon electro-catalytic membrane” as anode (dead-end mode) and a stainless-steel mesh as cathode articulated an electrocatalytic membrane reactor (ECMR) to treat methylene blue (C16H18ClN3S.3H2O) wastewater. TiO2/carbon membrane was characterized by field emission scanning electron microscope, high resolution transmission electron microscope and atomic force microscope. Elemental analysis was done by energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy to ascertain TiO2 loading on the carbon membrane. A synthetic 200 ppm methylene blue (MB) solution with electrolyte (Na2SO4) of 15 g/L concentration was used as the feed. Novel electro-desorption effect was discovered in a fully adsorbed membrane. Another novel finding regarding the ECMR was the acidic pH of permeate. When ECMR applied voltage was set to 2.5 V and current to 8 mA, the current density was calculated as 0.56 mA/cm2. While the porosity of the carbon membrane was 32.6 % and the flow rate was set to 200 μL/min, the residence time was calculated as 5.74 min. The result showed that the chemical oxygen demand (COD) removal rate of 83.65 % and color removal rate of 99.94 % were obtained. Electric consumption of the ECMR setup for MB solution was 5.87 kW h/Kg COD. The difference between the effect of adsorption and electro-catalysis was also calculated. The degradation mechanism of MB was proposed by using high performance liquid chromatography – mass spectroscopy. The excellent performance of ECMR was attributed to the synergetic effect of electro-catalytic oxidation and membrane separation which increases its economic feasibility by reducing the costs associated with cleaning the membrane at industrial scale. The ECMR proved a good stability as well.

The role of seashell wastes in TiO2/Seashell composites: Photocatalytic degradation of methylene blue dye under sunlight

This paper proposes a sustainable and facile approach for the synthesis of photocatalysts in which shell waste is used as support material. The synthesized photocatalysts exhibited a significant performance in the mineralization of organic substances under solar irradiation or artificial lighting. Calcined abalone shell with a TiO2 loading of 23.4% led to a significant improvement in optical absorption: the degradation efficiencies of methylene blue (MB) after 140 min under UV light, vis light, UV–vis light, and natural sunlight were 93%, 96%, 100%, and 100%, respectively. Notably, the byproducts obtained after the degradation by commercial P25 TiO2 disappeared with the utilization of shell waste as support material. The Na, Sr, S present in the calcined abalone shell were doped into the substitutional sites of TiO2 and were indispensable to achieve the desired band-gap narrowing and photocatalytic performance; moreover, the Ti and Zn oxides in the calcined abalone shell acted as semiconductors and improved the charge separation efficiency of TiO2. Above all, this paper describes a green synthesis based on the use of waste seashell. This material acts as an excellent photocatalyst support for environmental pollution treatments, leading to the ‘control of waste by waste’ and opening up new possibilities for shell waste reutilization and sustainable chemistry.

Improving the thermal conductivity of ethylene glycol by addition of hybrid nano-materials containing multi-walled carbon nanotubes and titanium dioxide: applicable for cooling and heating

In this research, thermal conductivity of a hybrid nanofluid containing multi-walled carbon nanotubes (MWCNTs) and titanium dioxide (TiO2) has been examined. Many samples were prepared by loading MWCNTs and TiO2 at 50:50 mass% into the ethylene glycol (EG) to measure the thermal conductivity at temperatures within 25–50 °C and solid volume fractions of 0–1%. The amount of positive nanoparticles incorporation efficacy on the thermal conductivity was influenced by the volume fraction as well as the temperature. As the temperature augmented from 25 to 50 °C, the EG thermal conductivity was intensified by 9.6%, while this figure for nanofluid at 1 vol.% was 18.2%. Therefore, it is concluded that the loading nanoparticles amplified the thermal conductivity sensitivity to temperature. Statistical analysis showed that the positive effects of loading nanoparticles on thermal conductivity are amplified by rising temperature. At 25 °C, loading nanoparticles (1 vol.%) can amplify the thermal conductivity by 16%, while at 50 °C, this figure was 25.18% (maximum thermal conductivity enhancement). A correlation was developed using response surface methodology (RSM), and the input parameters significance was specified applying analysis of variance (ANOVA). Finally, using 28 machine learning-based algorithms, the hybrid nanofluid thermal conductivity has been predicted and compared with the RSM outputs.

Hydroxymethylation of xylenol over micro/mesoporous TiO2‐containing bifunctional catalyst: Effect of the Y zeolite incorporation with MCM‐41

AbstractThe hydrodemethylation reaction of 3,4‐xylenol on micro/mesoporous catalysts with active component TiO2 was studied. TiO2/YM‐m and TiO2/YM‐c micro/mesoporous materials were, respectively, derived by loading TiO2 with the composition and mechanical mixing of Al‐MCM‐41 and HY zeolite. The effect of the bifunctional catalysts on the catalytic performance of hydroxymethylation of xylenol before and after the introduction of Al‐MCM‐41 into HY was investigated in this study. Compared with TiO2/Y catalyst, TiO2/MCM‐41, TiO2/YM‐m, and TiO2/YM‐c have higher selective dealkylation products, especially the selectivity of cresol. This is attributed to the addition of Al‐MCM‐41 mesoporous molecular sieve to eliminate diffusion limitation. Compared with TiO2/YM‐m catalyst, the TiO2/YM‐c composite with Al‐MCM‐41 coated structure grown on the surface of HY crystals has better catalytic conversion activity and ability to inhibit secondary reactions. This is because of the existence of the special “coating” of HY zeolite, which eliminates the diffusion limitation and prevents the product and the reaction intermediate from entering the micropores for multiple reactions, thereby reducing the occurrence of side reactions. Meanwhile, TiO2/YM‐c catalyst has the best demethylation performance under the optimal reaction conditions, the conversion of 3,4‐xylenol, the selectivity to phenol, and m‐cresol were 52.15%, 62.17%, and 36.32%, respectively. And the TiO2/YM‐c catalyst has good stability within 80 h of reaction.

Reinforce of hydrotalcite-like loaded TiO2 composite material prepared by Ti-bearing blast furnace slag for photo-degradation of tetracycline

In this study, a composite material of hydrotalcite-like loaded TiO2 (TiO2@Mg-Al LDH) was prepared from Ti-bearing blast furnace slag (Ti-BFS) and used for photo-catalytic degradation of tetracycline (TC) in aqueous solution. The results of SEM, XRD, XRF, FT-IR, BET and UV-Vis DRS showed that photocatalytic TiO2@Mg-Al LDH was layered double hydroxide loading TiO2 structure and doped with metal elements, which could effectively induce the excitation wavelength of TiO2 to extend from UV to visible region. At the initial TC of 20?mg/L, the removal rate of TC and TOC were more than 90% and 72% within 120?min using UV in combination with TiO2@Mg-Al LDH. The radical quenching tests and EPR analysis indicated that TC degradation and mineralization were attributed to production of abundant OH• radicals, •O2- and h+ under UV conditions, which performed different proportion of removal, compared with adsorption experiment under non-light irradiation. Qualitative analysis of the by-products showed the aromatic ring of TC was opened, which effectively reduced the virulence of by-products. It indicated that the synergistic effect of hydrotalcite-like structure and photocatalysis could achieve efficient photodegradation of TC by TiO2. TiO2@Mg-Al LDH synthetized by high Ti-bearing blast furnace slag presented a good prospect of removing trace organic pollutants under synergistic effect of adsorption and UV photo-catalytic.