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Degradation of paraquat from contaminated water using green TiO2 nanoparticles synthesized from <i>Coffea arabica</i> L. in photocatalytic process
摘要： The TiO2 nanoparticles synthesized from the extract of Coffea arabica L. (or TiO2/C) were used to remove paraquat from contaminated water in heterogeneous photocatalysis process. In this work, the sol-gel process using Coffea arabica L. as the solvent chemical were performed to obtain the TiO2 nano-catalyst. The value of pHpzc of TiO2/C was 2.9 which cause a highly acidic surface of catalyst. The paraquat is effectively removed in alkaline medium due to the adsorption ability of paraquat on the surface of TiO2/C. The paraquat degradation followed the pseudo-?rst-order model with the apparent rate constants as of 5.84 × 10?2, 4.08 × 10?2, and 2.28 × 10?2 min?1 for TiO2/C, TiO2, and without TiO2, respectively, under the presence of UV and H2O2. The combined TiO2/C with UV and H2O2 was the most ef?cient process, exhibiting a maximum 66.3% degradation of 50 mg/L over 90 min at pH 10.
关键词： green TiO2 nanoparticles,paraquat,Coffea arabica L.,water treatment,photocatalytic process
更新于2025-09-09 09:28:46
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A Novel Green Stabilization of TiO2 Nanoparticles onto Cotton
摘要： Facile embedding of TiO2 nanoparticles onto cotton fabric has been successfully attained by ultraviolet light irradiations. The adhesion of nanoparticles with fibre surface, tensile behaviour and physicochemical changes before and after ultraviolet treatment were investigated by scanning electron microscopy, energy dispersive X-ray and inductive couple plasma-atomic emission spectroscopy. Experimental variables i.e. dosage of TiO2 nanoparticles, temperature of the system and time of ultraviolet irradiations were optimised by central composite design and response surface methodology. Moreover, two different mathematical models were developed for incorporated TiO2 onto cotton and tensile strength of cotton after ultraviolet treatment and used further to testify the obtained results. Self-clean fabric through a synergistic combination of cotton with highly photo active TiO2 nanoparticles was produced. Stability against ultraviolet irradiations and self-cleaning properties of the produced fabric were evaluated.
关键词： Nanoparticles,Self-stabilization,Self-cleaning,TiO2,UV fixation
更新于2025-09-09 09:28:46
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Nanoscale Materials in Water Purification || Recent Progress in TiO2- and ZnO-Based Nanostructured Hybrid Photocatalysts for Water Purification and Hydrogen Generation
摘要： Energy and clean environmental conditions are the two basic requirements for the survival and progress of human civilization. The Industrial Revolution was a prime factor in the rapid development of human society. However, the industrial malpractices of waste disposal and extensive use of fossil fuels have led human society to face a number of challenges such as global warming, and water and air pollution. Also, the extensive use of pesticides in agriculture has led to high toxicity in soil and ground water, which can pose a big threat to human and wildlife [1]. A recent WHO report shows that about 3.7 million people globally die each year in the 21st century from the hazards of water and air pollution, and 92% of the world’s population still does not have access to pure water [2]. The fossil fuel resources are limited in their ability to cater to the energy demands of the growing world’s population and are on the verge of exhaustion in the near future. This has led to the fear of energy crises, which can prove fatal for human society. Hence, the search for an ultimate and clean energy source, as well as the development of technologies for the remediation of hazardous materials from the environment have become topics of high international concern. There have been several attempts to harness alternative energy sources such as wind, water tides, biomass and solar energy, etc., as well as to design methods for the remediation of environmental pollutants. Hence, the development of cleaner, low carbon, and sustainable technologies is a bigger challenge for scientists and engineers worldwide [3]. Some technologies have been developed to harness alternative energy sources, but these have proven either inefficient or too expensive. Also, efforts toward the removal of harmful environmental pollutants are either inefficient or have their own side effects [4]. Among renewable energy sources, solar energy is available in abundance and has the potential for overcoming current environmental impacts. However, its unavailability at night, and during rainy and foggy seasons make it difficult to properly harness. Hence, transforming energy from sunlight to the chemical energy of hydrogen through photocatalytic water splitting could be a more promising approach [5]. Solar energy is also gaining attention for water treatment. There have been a number of metal oxide-based photocatalysts prepared for degrading organic pollutants such as dyes and pesticides. This chapter stresses H2 generation through photocatalytic and photoelectrochemical water splitting and photocatalytic water treatment using two well-known photocatalysts, ZnO and TiO2.
关键词： ZnO,water purification,nanostructured hybrid photocatalysts,hydrogen generation,TiO2
更新于2025-09-09 09:28:46
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The role of adsorbed water on TiO <sub/>2</sub> particles in the electrorheological effect
摘要： TiO2 particles prepared by the hydrolysis of titanium butoxide adsorb water molecules with different adsorption energies. The electrorheological (ER) ?uid composed of TiO2 particles behaves as the polar-molecule giant electrorheological (GER) ?uid at 25?C even after thermal treatment at 75?C. After thermal treatment at 125?C and 175?C, the water molecules with low adsorption energy are removed and the ER ?uid behaves as traditional ER ?uid at 25?C. However, at 175?C, the ER ?uid treated at 175?C behaves as a polar-molecule GER ?uid when the external electric ?eld is larger than 2 kV/mm. These results show that the water molecules with low adsorption energy act as polar molecules responsible for the GER effect and, with the help of thermal energy, water molecules with high adsorption energy can work as those with low adsorption energy, resulting in the GER effect.
关键词： TiO2 particles,electrorheological effect,polar-molecule GER ?uid,adsorbed water,thermal treatment
更新于2025-09-09 09:28:46
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Degradation of tartrazine and hydrogen production simultaneously with combination of photocatalysis-electrocoagulation
摘要： Degradation of tartrazine dye and the production of hydrogen simultaneously with a combination of photocatalysis and electrocoagulation has been investigated. The photocatalytic process was performed by using a catalyst of TiO2 nanotubes that had been synthesized by anodizing method. In electrocoagulation process used Al-SS 316 electrode with variation of voltage: 5V, 10V, and 15V. The structure of TiO2 catalyst with nanotubes morphology was characterized by SEM-Mapping, FTIR, XRD, and UV-Vis DRS. The optimum condition obtained from the electrocoagulation process is at a voltage of 15V with a test time of 4 hours. From the results of photocatalysis with TiO2 nanotubes obtained percent degradation of tartrazine dye equal to 48.86% and simultaneously produced 0.87 ml of H2 with concentration 3.46%. The use of aluminum plate as anode and 316 stainless steel plate as cathode in electrocoagulation process has also succeeded degrading tartrazine dye by 82.45% and produced 3.88 ml of H2 with concentration 12.14%. The result of the combination of photocatalysis and electrocoagulation process obtained degradation conversion of tartrazine dye by 90.68% with final dye concentration to 1.93 ppm and simultaneously H2 products as much as 5.97 ml with a concentration of 12.41% can be produced. The final concentration of tartrazine dye waste from combination of photocatalysis-electrocoagulation process is safe to be disposed into the environment because it meets the quality standard. In addition, the production of H2 has potential as a renewable energy source.
关键词： electrocoagulation,tartrazine,hydrogen production,TiO2 nanotubes,photocatalysis
更新于2025-09-09 09:28:46
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Effects of fulvic acids and electrolytes on colloidal stability and photocatalysis of nano-TiO2 for atrazine removal
摘要： The colloidal stability and photocatalysis of nano-TiO2 particles were investigated in the presence of fulvic acids (FA) and electrolytes (NaNO3, Na2SO4, Na3PO4) at different pH. Results showed that increasing FA concentration, the absolute value of zeta potential of nano-TiO2 increased and particle size decreased at all pH which promoted the colloidal stability of nano-TiO2. Particle size of nano-TiO2 was larger with the coexistence of FA and electrolytes than with FA only as the concentration of electrolytes was greater than or equal to 0.01 mol/L. The largest particle size occurred in the presence of Na3PO4, followed by Na2SO4 and NaNO3. Particle size of nano-TiO2 decreased with higher pH and stability further increased in the presence of FA and/or electrolytes. Nano-TiO2 stabilization was enhanced by increasing FA concentration when the solution pH was 7.0. However, the removal efficiency of atrazine by nano-TiO2 decreased with the increase in FA concentration. Adding electrolytes (0.01 mol/L), atrazine removal by nano-TiO2 further decreased, albeit slightly. The inhibitory effect of electrolytes on nano-TiO2 removal of atrazine was highest for Na3PO4, followed by Na2SO4, and NaNO3, which were consistent with the results of colloidal stability of nano-TiO2. These findings help to better understand the mechanisms and correlation between colloidal stability and photocatalysis of nano-TiO2 in the presence of FA and electrolytes.
关键词： Atrazine,Fulvic acids,Photocatalysis,Colloidal stability,Electrolytes,Nano-TiO2
更新于2025-09-09 09:28:46
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Photoelectrochemical Performance of TiO <sub/>2</sub> /Ti Electrode for Organic Compounds
摘要： Photoelectrochemical performance of TiO2/Ti electrode was investigated by using organic compounds. The TiO2/Ti electrode was prepared by anodic oxidation at a potential bias of 25 V for 4 h then calcined for 450 °C to obtain the anatase polymorph. Subsequently, it was characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX). The XRD pattern showed that TiO2 has anatase phase as confirmed by 2θ peaks at 37.93°; 63.00°, and 83.00°. Using SEM-EDX data the TiO2 layer was formed on Ti plate with the composition of Ti (4.5 keV) and O (0.5 keV) elements. Furthermore, the photoelectrochemical sensing on the three organic compounds (ascorbic acid, glucose, and titan yellow) with the electrolyte addition showed that the linearity of TiO2/Ti electrode were 0.937, 0.968, and 0.938, meanwhile without the electrolyte were 0.998, 0.989, and 0.923, respectively.
关键词： TiO2/Ti,organic compounds,photoelectrochemical,Electrode
更新于2025-09-09 09:28:46
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Effect of NO2 and NO3-/HNO3 adsorption on no photocatalytic conversion
摘要： A study was undertaken of the adsorption and photocatalytic conversion of NO, NO2 and NO3-/HNO3 using two photocatalysts (P25 and HT-ET). The HT-ET is a catalyst synthesized in our laboratory comprised only of anatase phase and with a surface area three times larger than that of the P25. In powder form, the catalyst was introduced into and extended along the length of a tube with no type of compaction on the part of the solid (pressure drops are negligible under these conditions). This tubular photoreactor arrangement operates as a continuous reactor system enabling FTIR analysis of the surface of the catalysts during the conversion process. NO adsorption was negligible, though the FTIR studies revealed the formation of nitrites on the surface after 18 h of reaction. Overall NO conversion efficiency rates were above 68% with both catalysts in that reaction time. However, selectivity to NO2 was very high with both catalysts. It was also found with both catalysts that the number of NOx moles eliminated during NO photocatalytic conversion coincided with the number of adsorbed NO2 moles observed in the adsorption studies performed with this molecule, indicating that the NO2 molecule is not efficiently converted photocatalytically. It was observed that most of the NO2 undergoes disproportionation on the surface of the catalysts, giving rise to nitrates and NO. The FTIR studies showed that a significant proportion of the NO2 interacts with surface nitrates resulting in [(NO3-)-(H2O) n-NO2] complexes which are stable on the catalyst surface in an NO atmosphere.
关键词： NO2,TiO2,NOx,Photocatalysis,Nitrates,FTIR,NO
更新于2025-09-09 09:28:46
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Facial construction of defected NiO/TiO2 with Z-scheme charge transfer for enhanced photocatalytic performance
摘要： Here we report a defected NiO/TiO2 composite (NiO/TiO2-OV) fabricated by a two-step hydrothermal method with the followed one-step calcination, which induced the in situ generation of Ti3+ and oxygen vacancies, coupled with the construction of a direct Z-scheme band structure. The NiO/TiO2-OV catalyst exhibited a substantially improved performance in the photodegradation of organic pollutant and photocatalytic hydrogen evolution reaction (HER). The sensitization by narrow bandgap semiconductor of NiO enhanced the light response of catalysts. More importantly, the intrinsic defects, the Ti3+ and oxygen vacancies, acted as the mid-gap state in TiO2, and resulted in the direct Z-scheme charge transfer between the Ti3+/oxygen vacancies state and the valance band (VB) of NiO to suppress the recombination of photogenerated electrons and holes. Meanwhile, the realignment of band structure caused by constructing NiO/TiO2 heterojunction made the photogenerated carries more active in the photocatalytic reduction and oxidation reactions.
关键词： Z-scheme charge transfer,NiO/TiO2 hybrid,Photocatalysis,Surface defects,Self-doping of Ti3+
更新于2025-09-09 09:28:46
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Transformation of Commercial TiO <sub/>2</sub> into Anatase with Improved Activity of Fe, Cu and Cu–Fe Oxides Loaded TiO <sub/>2</sub>
摘要： In the present study copper and iron oxides loaded TiO2 catalysts are prepared by the deposition-precipitation method (DP) and the photocatalytic efficiency of these catalysts are tested for the degradation of Rose Bengal dye (Acid Red 94) under sunlight. The catalysts are characterized by XRD, TEM and UV-vis diffuse reflectance spectral analysis. It is interesting to note that the rutile form of commercial TiO2 is competently converted into anatase after loading oxides of Cu, Fe and Cu–Fe on TiO2 as evident from XRD analysis. This result is consistence with the result obtained in UV-vis diffuse reflectance spectra. TEM analysis confirms the nano particles of Cu and Fe deposited on TiO2. Photocatalytic studies were performed in a batch reactor under solar radiation. Preliminary studies are performed to understand the photocatalytic degradability of the dye and optimization of catalyst weight and dye concentration. Kinetic studies were done at different dye concentrations and it was found that the rate equation followed first order kinetics and obeyed Langmuir–Hinshelwood model. The comparison of the activity of blank TiO2, copper or/and iron oxides loaded TiO2 catalysts showed that the Cu and Fe oxide loaded catalysts are more active than pure TiO2 and also the Cu–Fe oxides co-loaded TiO2 catalysts showed much best activity. The order of activity of the catalysts is in the following order: Cu–Fe/TiO2 > Cu/TiO2 > Fe/TiO2 > TiO2. The enhanced activity of metal oxide loaded TiO2 is attributed to the presence of TiO2 in anatase form after loading, which enhanced the charge transfer from the TiO2 to adsorbed molecules for reaction.
关键词： Sunlight,TiO2,Rutile into Anatase,Photocatalyisis,Cu/Fe Loading,Rose Bengal Dye
更新于2025-09-09 09:28:46