TiO2 Chitosan Research Articles

Synthesis and characterization of ZnO–TiO2–chitosan–escin metallic nanocomposites: Evaluation of their antimicrobial and anticancer activities

Abstract This work intended to formulate bio-nanocomposites of zinc oxide (ZnO), titanium oxide (TiO2), chitosan, and escin, characterize their physical properties, and evaluate their antimicrobial and anticancer properties. X-ray diffractometers (XRD) and scanning and transmission electron microscopes were applied to characterize the morphology and ultrastructure of chemically synthesized bio-nanocomposites. To investigate the functional groups of bio-nanocomposites, we used Perkin–Elmer spectrometers for Fourier transform infrared (FTIR) analysis and photoluminescence (PL) spectroscopy for PL spectrum analysis. Antimicrobial activities against bacterial and fungal strains were tested with agar well diffusion. Bio-nanocomposites were tested for anticancer effects on a MOLT4 blood cancer cell line using morphological analysis, methyl thiazole tetrazolium assay, apoptosis by acridine orange/ethidium bromide, and mitochondrial membrane potential (ΔΨm). In XRD, FTIR, and PL, the active compounds of ZnO–TiO2, chitosan, and escin peaks were observed. Our bio-nanocomposites demonstrated antimicrobial activity against bacterial and fungal pathogens. The bio-nanocomposite was cytotoxic to MOLT4 cells at an IC50 concentration of 33.4 µg·mL−1. Bio-nanocomposites caused cytotoxicity, changes in cell morphology, and mitochondrial membrane potential degradation, all of which resulted in apoptotic cell death. MOLT4 cells were found to be responsive to bio-nanocomposites based on ZnO–TiO2–chitosan–escin.

Experimental and modeling analyses of COD removal from industrial wastewater using the TiO2–chitosan nanocomposites

In the present study, titanium oxide (TiO2) nanoparticles, chitosan, and several nanocomposites containing different mass dosages of TiO2 and chitosan have been applied as the adsorbent for COD removal from the industrial wastewater (Bouali Sina Petrochemical Company, Iran). The FESEM, XRD, and FTIR tests have been employed to characterize TiO2 nanoparticles, chitosan, and fabricated nanocomposites. Then, the effect of adsorption parameters, including TiO2–chitosan mass ratio (1:1, 1:2, and 2:1), adsorbent content (0.25–2.5 g), temperature (20–50 °C), pH (3–11), solution volume (100–500 mL), and contact time (30–180 min) on the COD reduction has also been monitored both experimentally and numerically. The Box–Behnken design of the experiment approves that TiO2–chitosan (1:1), adsorbent content of 2.5 g, temperature = 20 °C, pH 7.4, solution volume of 100 mL, and contact time = 180 min are the condition that maximizes the COD removal (i.e., 94.5%). Moreover, the Redlich–Peterson and Pseudo-second order models are the best isotherm and kinetic scenarios to describe COD removal’s transient and equilibrium behaviors. The maximum monolayer COD adsorption capacity of the TiO2–chitosan nanocomposite is 89.5 mg g−1. The results revealed that the industrial wastewater COD is better to remove using the TiO2–chitosan (1:1) at temperature = 20 °C.

Potential Use of Chitosan-TiO2 Nanocomposites for the Electroanalytical Detection of Imidacloprid.

The detection of toxic insecticides is a major scientific and technological challenge. In this regard, imidacloprid is a neonicotinoid that is a systemic insecticide that can accumulate in agricultural products and affect human health. This work aims to study the properties of chitosan–TiO2 nanocomposites in which nanoparticles with high surface area serve as molecular recognition sites for electroanalytical imidacloprid detection. We show that the best sensitivity to imidacloprid was obtained using a modified electrode with a chitosan–TiO2 nanocomposite with a 40 wt.% of TiO2 nanoparticles. By using a three-phase effective permittivity model which includes chitosan, TiO2, an interface layer between nanoparticles and a matrix, we showed that nanocomposites with 40 wt.% of TiO2 the interface volume fraction reaches a maximum. At higher nanoparticle concentration, the sensitivity of the sensor decreases due to the decreasing of the interface volume fraction, agglomeration of nanoparticles and a decrease in their effective surface area. The methodology presented can be helpful in the design and optimization of polymer-based nanocomposites for a variety of applications.

Synthesis of modified chitosan TiO2 and SiO2 hydrogel nanocomposites for cadmium removal

Heavy metals removal from wastewaters and surface waters using low cost and eco-friendly adsorbents is one of the best ways to eliminate these impurities. In the current study, the nanocomposites based on chitosan-g-(acrylamide-co-itaconic acid) and titanium dioxide or silicon dioxide nanoparticles, were synthesized and their antibacterial property and the removal of Cd2+ from an aqueous solution have been investigated. The hydrogel and nanocomposites were synthesized via in situ polymerization within TiO2 and SiO2 nanoparticles separately. The products were characterized using FTIR, TGA, SEM, BET and EDX techniques. These analyses proved the synthesized nanocomposites and dispersion of nanoparticles with desirable properties. Nanocomposites were shown as porous structures with the average pore diameter of 4.40 and 5.05 nm for TiO2 and SiO2 composite, respectively. In addition, water absorption results indicated that by increasing the amount of nano particles, the water absorption decreases from 28 to 15 g/g for SiO2 nanocomposite and from 21 to 11 g/g for TiO2 nanocomposite. The effect of initial pH, initial concentration and time has been studied. Highest cadmium adsorption capacity for TiO2 and SiO2 nanocomposites respectively are 303, and 291 mg/gr. In addition, the equilibrium data and kinetics are described perfectly by pseudo second order kinetics and Freundlich isotherm. Freundlich isotherm has fitted the experimental data with the R2 of 0.96 and 0.91 for SiO2 and TiO2 nanocomposite, respectively. Antibacterial results showed that the synthesized nanocomposite inhibits the growth of E. coli and S. aureus.

Photocatalytic Degradation of Tartrazine Dyes Using TiO2–Chitosan Beads under Sun Light Irradiation

Photocatalytic Degradation of Tartrazine Dyes Using TiO2–Chitosan Beads under Sun Light Irradiation

Modeling the photocatalytic oxidation of carboxylic acids on aqueous TiO2 suspensions and on immobilized TiO2-chitosan thin films in different reactor geometries irradiated by UVA or UVC light sources

Photocatalytic reactor models incorporating radiation transport parameters and intrinsic kinetic parameters of photocatalytic decomposition of single-compound and mixtures of oxalic (OA) and formic acid (FA), in both slurry suspensions and immobilized photocatalytic thin films, were validated in two well-mixed annular photoreactors geometries irradiated with either UVA or UVC radiation. The six-flux absorption scattering model (SFM) predicted the radiation field in a titanium dioxide (TiO2 P25) catalyst suspension, the local volumetric rate of photon absorption (LVRPA) at each point of the reactor and, after volumetric integration, the lumped VRPA. The model combining the lumped VRPA, the kinetics models describing the adsorption and photocatalytic decomposition of OA and FA and the material balance of the reacting species was fitted to the experimental results of photocatalytic decomposition of OA and FO in a slurry TiO2 suspension, to determine the OA and FA intrinsic reaction kinetics parameters. Such intrinsic parameters were then used with the average surface rate of photon absorption (SRPA) to model and predict the photocatalytic oxidation of OA and FA on non-porous TiO2–chitosan films immobilized on glass plates immersed in the photoreactor. The models for both slurry suspensions and immobilized photocatalysts predicted the degradation and mineralization of OA and FA and of a mixture of them under diverse experimental conditions. This study demonstrates a systematic methodology for determining intrinsic reaction kinetics rate parameters of water contaminants that can also be used to represent the photocatalytic oxidation of such contaminants in irradiated slurries and in immobilized photocatalytic thin films and in any photoreactor geometry.

Novel antimicrobial bioplastic based on PLA-chitosan by addition of TiO2 and ZnO.

The purpose of this study was to develop antimicrobial bioplastics based on Poly Lactic Acid (PLA) with the addition of chitosan-ZnO, and chitosan-TiO2 to improve antimicrobial properties. For the preparation of the bioplastics, PLA with chitosan-ZnO or chitosan-TiO2 were used. The antimicrobial activity, mechanical and thermal properties, and water vapor permeability of bioplastics were evaluated. PLA-chitosan-ZnO indicated a robust antimicrobial activity against bacteria such as Salmonella typhi, Bacillus subtilis, Escherichia coli, Staphylococcus aureus, yeast such as Candida albicans, and fungus Aspergillus niger. No formation of new functional groups in PLA-chitosan-ZnO composites. In comparison to other PLA-based bioplastics, this bioplastic has medium tensile strength, tensile modulus, and elongation percentages with low barrier ability to water vapor. Chitosan-ZnO itself has a greater tensile strength compared to chitosan-TiO2. These two compounds undergo 2 stages of decomposition in a temperature range of 43°C to 265°C. The addition of PLA into chitosan-ZnO or chitosan TiO2 causes the bioplastics decomposed in a single stage. It also increases the decomposition temperature of bioplastic. However, compared to chitosan-ZnO or TiO2, the PLA-chitosan-ZnO or TiO2 bioplastics tend to produce a fragile composite indicating by decrease in their tensile strength. In general, the addition of chitosan-ZnO into in PLA-based bioplastic produces better antimicrobial properties compared to TiO2.

Investigations on Amphoteric Chitosan/TiO2 Bionanocomposites for Application in Visible Light Induced Photocatalytic Degradation

The present investigation reports the greener synthesis and characterization of novel acrylic acid grafted amphoteric chitosan/TiO2 (CAT) bionanocomposites using ultrasonic radiations. This was done by grafting of acrylic acid onto chitosan in the presence of potassium persulfate by free radical polymerization reaction. The uniform distribution of metal oxide in CA/TiO2 nanocomposites was achieved on grafted acrylic acid/chitosan which contains a weak anionic group (-COOH) using ultrasonication technique. Physiochemical techniques such as X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), Fourier Transform Infra-Red spectroscopy (FT-IR), Energy Dispersive X-ray spectroscopy (EDX), and Thermal Gravimetric Analysis (TGA) were employed to characterize synthesized CAT. Nanocomposite CAT was applied for degradation of industrial dye. Malachite green (MG) often presents in the waste waters. The degradation kinetics were studied by monitoring the photocatalytic reaction for degradation of MG under visible light, and the rate constant of the reaction was found to be 7.13x10−3min−1. The current research work opens vistas for the new dimensions in the area of water treatment by solving the issues related to degradation reaction efficiency in visible light and cost effectiveness.

Enhanced Antibacterial Activity of Silver Doped Titanium Dioxide-Chitosan Composites under Visible Light.

Nano titanium dioxide (TiO2) with photocatalytic activity was firstly modified by diethanolamine, and it was then doped with broad spectrum antibacterial silver (Ag) by in situ method. Further, both Ag doped TiO2-chitosan (STC) and TiO2-chitosan (TC) composites were prepared by the inverse emulsion cross-linking reaction. The antibacterial activities of STC composites were studied and their antibacterial mechanisms under visible light were investigated. The results show that in situ doping and inverse emulsion method led to good dispersion of Ag and TiO2 nanoparticles on the cross-linked chitosan microsphere. The STC with regular particle size of 1–10 μm exhibited excellent antibacterial activity against E. coli, P. aeruginosa and S. aureus under visible light. It is believed that STC with particle size of 1–10 μm has large specific surface area to contact with bacterial cell wall. The increased antibacterial activity was attributed to the enhancement of both electron-hole separations at the surface of nano-TiO2 by the silver ions under the visible light, and the synergetic and sustained release of strong oxidizing hydroxyl radicals of nano-TiO2, together with silver ions against bacteria. Thus, STC composites have great potential applications as antibacterial agents in the water treatment field.

Active papers coated with chitosan and containing TiO2 and Ag/TiO2 nanoparticles for increasing the shelf-life of walnut kernels

Three active cellulose-based papers coated with chitosan (P–CH), chitosan–TiO2 nanocomposite (P–CH–TiO2) and chitosan–Ag/TiO2 nanocomposite (P–CH–Ag/TiO2), respectively, were subjected to real-time ageing for 6 months at 25 °C and 45% re humidity and characterized from a physical–chemical–antimicrobial perspective in relation to plain paper (P). Scanning electron microscopy pictures indicate a smooth morphology in the active papers, while the structure of P is rough with large pores. The fresh papers containing nanocomposites displayed enhanced barrier properties against water vapor, air and grease. The photocatalytic action of TiO2 during ageing results in the deacetylation of the chitosan layer and the degradation of cellulosic fibers with a reduction of barrier properties. Fresh P–CH–Ag/TiO2 displayed the highest value of inhibition index against yeasts and molds (95.65%), its value decreasing to 79.25% after 6-month storage. Walnut kernels were stored for 6 months at 25 °C and 45% RH in packages made of investigated papers and analyzed. It was found that P–CH–Ag/TiO2 is the most effective in the prolongation of the shelf-life of kernels. They are assessed to be safe in terms of peroxide value and yeasts and molds count for 11.6 and 15.1 months when stored in P–CH–Ag/TiO2 filled with 25 and 50 g kernels, respectively, as compared to 1.8 and 3.4 months, respectively when they are stored in P. The appearance of packages containing nanocomposites was clean without grease spots in opposition with that of P and P–CH and proves the self-cleaning property of P–CH–TiO2 and P–CH–Ag/TiO2. Cluster diagrams indicate a strong correlation between the quality and safety of kernels and properties of paper sheets in a paper type-depending manner.

The sensitization effect of waste toner powder in the photocatalytic degradation of surfactant sodium dodecylbenzene sulfonate over immobilized TiO2–chitosan layer under UVC and solar irradiation

The application of dye sensitized photocatalysis for the degradation of surfactant in the model wastewater has been studied. The aim was to explore the possibility of the photocatalytic activity enhancement by introducing the waste toner powder in the photocatalytic films. The development and a partial characterization of the supported catalyst were described within this study. Waste toner and commercial TiO2 powder (AEROXIDE® P25) were integrated within the matrix of chitosan molecules as a thin layer films. The developed films contain the high amount of the TiO2 (approx. 90%) which structure appeared to be intact. The efficiency of the photocatalytic films for the oxidation of the anionic surfactant dodecylbenzene sulfonate (SDBS) has been evaluated. Preliminary experiments were performed in an annular batch reactor using UVC lamp. Photocatalytic films were supported on the glass, stainless steel and waste offset printing plates. Support was made in a form of plates or rings. Further experiments were performed under artificial and natural solar irradiation whereby photocatalytic films were fixed at the bottom of reaction cell (boat shaped flow reactor). In order to estimate the reaction rate constant for SDBS degradation over irradiated photocatalytic films and to evaluate the effects of photon absorption under different irradiation conditions, a detailed kinetic model was developed. The sensitization effect of the components in toner powder due to the visible light absorption for the photocatalytic oxidation of SDBS under solar irradiation was quantified.

Physicochemical Characteristics of Chitosan–TiO2 Biomaterial. 1. Stability and Swelling Properties

The surface and electrokinetic properties of chitosan–TiO2 biomaterial have been investigated. Both carbohydrate polymer and titanium dioxide demonstrate unique physicochemical properties appropriate for biotechnological applications. However, the changing stability of such systems restricts its usage. Improved stability can be controlled by environmental parameters, process conditions, or modifying TiO2 structure. Antibacterial chitosan was used because its protective barrier can retard ripening, water loss, as well as destruction of products. The concentrations of compounds and solution pH were varied. Static and dynamic light-scattering measurements make evident the relationship between the state of aggregation of the suspensions and the stability. The chitosan–TiO2 system is characterized by improved physicochemical properties in comparison with base TiO2 as an effect of electrosteric stability. Stable material was obtained with the precisely selected compounds ratio, proved by Fourier transform infra...

The Effect of pH and Aging Time on the Synthesis of TiO2 – Chitosan Nanocomposites as Photocatalyst by Sol-Gel Method at Room Temperature

The synthesis of TiO2–chitosan nanocomposite photocatalyst using Titanium(IV)-Isopropoxide (TTIP) as precursors and chitosan as host material has been conducted. The synthesis was carried out using sol-gel method at room temperature and aging to grow crystal seeds and generate nanoparticles. The success of forming nano-sized anatase phase TiO2 nanocrystal was strongly influenced by the sol pH system during hydrolysis and the aging time. The effect of sol pH system and aging time to the crystallinity level and particle size were examined using X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Diffuse Reflectance UV-Spectroscopy (DR-UV). The results showed that TiO2 produced in acidic pHs (pH 2-4) tended to have higher crystallinity level than that produced in weakly alkaline (pH > 6), which prone to be amorphous. The longer aging time (> 14 days) also tended to produce the amorphous phase. Furthermore, chitosan as a host material had a notable influence in determining the crystallinity level and particle size of TiO2 in TiO2–chitosan nanocomposite.

Simulation and scale-up study for a chitosan–TiO2 nanotubes scaffold production

The use of TiO2 nanotubes as implant coating has gained good attention in the past decade. Their potential as regenerative materials for promoting new bone formation has recently been reported. In this paper, a novel chitosan–TiO2 nanotubes (CTNTs) scaffold production pathway was analyzed for its potential for commercial production. The production pathway was simulated using a commercial batch process simulation software, based on previously reported laboratory experimental results. An optimum production scale was then determined from the simulation study and subjected to sensitivity analysis. The sensitivity analysis was carried out to identify seven parameters that would affect the profitability of the process. The cost of TiO2 and autoclave reaction time were identified as the most dominant technical parameters which affected the main product cost and annual number of batches respectively.

Chitosan-modified TiO2 as photocatalyst for ethanol reforming under visible light

This work reports the reforming of bio-ethanol on chitosan–TiO2 hybrid photocatalysts at ambient temperature. The influence of chitosan composition on the photocatalytic performance of chitosan–TiO2 hybrid was studied. The hybrids were characterized by CHN elemental analysis, nitrogen adsorption–desorption isotherms, thermogravimetric analysis, diffuse reflectance spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the preparation variables used for the incorporation of chitosan on TiO2 promoted changes in the morphology, superficial area, crystal size and porosity of the photocatalyst, affecting the band gap of this semiconductor and consequently the reactivity of the chitosan–TiO2 hybrids. The catalysts were evaluated for hydrogen production from ethanol under visible light. It was demonstrated that the calcination temperature of 623 K and a chitosan content of 20% were the most appropriate preparation conditions and the resulting product displays a pore size of 1.9 nm, crystal size of 11.3 nm, BET area of 178 m2 g−1 and band gap of 2.92 eV. The calcination temperature of 623 K and incorporation of 20% of chitosan obtained the same results in the conversion rate of hydrogen in comparison to the pure TiO2 P25.

Incorporation of chitosan and glass substrate for improvement in adsorption, separation, and stability of TiO2 photodegradation

It is demonstrated that single titanium dioxide (TiO2) has high potential for photodegradation of pollutants. However, it is still far from becoming an effective photocatalyst system, due to issues of adsorption process, separation, as well as dissolution. Therefore, this study highlights the high adsorption capacity, simplified separation, and the promising stability of TiO2(SY) (synthesized via sol–gel method) photocatalyst, fabricated using chitosan–TiO2(SY) and supported by glass substrate (Cs–TiO2(SY)/glass substrate) photocatalysts. Chitosan (Cs), with abundant –R–NH and NH2 groups, promotes the adsorption sites of methyl orange (MO) and OH groups for major attachment to TiO2(SY). Meanwhile, the glass substrate increases stability and assists separation of the photocatalysts. Initially, nano-TiO2(SY) has been characterized using high-resolution transmission electron microscope. Cs–TiO2(SY)/glass substrate was fabricated via dip-coating. The distribution and interface between the photocatalytic components were characterized by Fourier transform infrared absorption spectroscopy, UV–Vis diffuse reflectance spectroscopy, field emission scanning electron microscopy, and energy-dispersive spectrometer. UV–Vis analysis of the multilayer photocatalyst (2, 4, 6, and 8 layers) was further carried out by the adsorption–photodegradation, with MO as model of pollutant. Seventy percent of the total removal of MO via optimized eight layers of photocatalyst was achieved within 1 h of UV irradiation. The adsorption photocatalyst achieved 50 % with no exposure to UV light for 15 min of irradiation. It is concluded that suitable photocatalytic conditions and sample parameters possessing the multilayer photocatalyst of Cs–TiO2(SY) are beneficial toward the adsorption–photodegradation process in wastewater treatment.

Purification of household greywater loaded with hair colorants by solar photocatalysis using TiO2-coated textile fibers coupled flocculation with chitosan

This study reports a possibility of the household greywater treatment by solar photocatalysis followed by flocculation with special emphasis on hair colorants and accompanying chemicals. The greywater of concern (hereafter: GW) was collected from the bathroom after hair dyeing, washing and rinsing. Its tentative composition was determined taking into account listed ingredients of used hair colorant, dyeing chemistry and measured values of surface tension, light absorption and scattering. In order to assess the quality of the effluent, TOC, COD, BOD5 and toxicity toward yeast and Vibrio fischeri were determined. Greywater was treated in the hand-made reactor system, with a constant recirculation over photocatalytic layer exposed to direct sunlight. Photocatalytic layer consisted of TiO2-coated textile fibers prepared by applying TiO2–chitosan pasteous dispersion on polyester/wool blend textile (75% polyester, 25% wool). Results showed the significant decrease in organic content, COD and toxicity over a period of 4h. UV–vis spectra of treated samples indicate the complete degradation of dye molecules and certain aromatic compounds. Emulsifying compounds and surfactant concentrations were reduced significantly. Preliminary kinetic study involving chitosan dissolution kinetics and pollutant mineralization was presented. It was observed that chitosan dissolved at certain extent during photocatalytic treatment, thus acted as an efficient flocculant in treated wastewater; flocs were observed shortly after photocatalytic treatment, followed by complete sedimentation over a period of 12h in dark. Additionally, surface of the photocatalytic layer was analyzed by TGA, FTIR, ESR and Raman spectroscopy, SEM and contact angle measurements. Evidence of Ti (III) species was presented.

Ultrasonic fabrication of TiO2/chitosan hybrid nanoporous microspheres with antimicrobial properties

We report a sonochemical method for the fabrication of stable TiO2–chitosan hybrid microspheres possessing nanoporous structure and antimicrobial properties.

Synthesis of core–shell bioaffinity chitosan–TiO2 composite and its environmental applications

Based on the coupling of molecular imprinting, chitosan biosorption, and nano TiO2 photocatalysis technologies, a novel core–shell organic–inorganic hybrid material of surface imprinted chitosan–TiO2 composite (SICT) was prepared with methyl orange as the template. SEM, EDS, AFM, pore size analysis, and FTIR characterization results illustrated that TiO2 nano powder was successfully coated on the surface of chitosan microparticles via intermolecular hydrogen bonds to form the core–shell organic–inorganic composites with rough and porous surface morphology. SICT showed enhanced photocatalytic selectivity for methyl orange (M.O.) compared with the non-imprinted chitosan–TiO2 composites because of the existing of more suitable sites generated by surface molecular imprinting. The removal of M.O. by SICT was mainly from the photocatalytic degradation rather than simple adsorption. SICT could be reused directly without further desorption and regeneration for 10 cycles with preserving 60% of its photocatalytic efficiency. The reusability of SICT would be beneficial for the simplification of the operating steps and the cost reduction which facilitated its practical applications in wastewater treatment concerning environmental organic pollutants.

Nitroaldol condensation catalyzed by topologically modulable cooperative acid–base chitosan–TiO2hybrid materials

Chitosan–TiO2 shaped as macroporous aerogels, lamellar cryogels or electrospun films act synergistically as acid–base bifunctional catalysts. Depending on the topology of the material, a marked difference in the selectivity for nitroaldol condensation is observed.