Chitosan-TiO2: A Versatile Hybrid Composite Anaya-Esparza, Luis Miguel; Ruvalcaba-Gómez, José Martín; Maytorena-Verdugo, Claudia Ivette ...
Materials,
02/2020, Letnik:
13, Številka:
4
Journal Article
Recenzirano
Odprti dostop
In recent years, a strong interest has emerged in hybrid composites and their potential uses, especially in chitosan–titanium dioxide (CS–TiO2) composites, which have interesting technological ...properties and applications. This review describes the reported advantages and limitations of the functionalization of chitosan by adding TiO2 nanoparticles. Their effects on structural, textural, thermal, optical, mechanical, and vapor barrier properties and their biodegradability are also discussed. Evidence shows that the incorporation of TiO2 onto the CS matrix improves all the above properties in a dose-dependent manner. Nonetheless, the CS–TiO2 composite exhibits great potential applications including antimicrobial activity against bacteria and fungi; UV-barrier properties when it is used for packaging and textile purposes; environmental applications for removal of heavy metal ions and degradation of diverse water pollutants; biomedical applications as a wound-healing material, drug delivery system, or by the development of biosensors. Furthermore, no cytotoxic effects of CS–TiO2 have been reported on different cell lines, which supports their use for food and biomedical applications. Moreover, CS–TiO2 has also been used as an anti-corrosive material. However, the development of suitable protocols for CS–TiO2 composite preparation is mandatory for industrial-scale implementation.
The effect on the physicochemical properties of aluminum salts on the synthesis of γ-AlOOH nanostructures has been investigated in detail using a hydrolysis-precipitation method. X-ray fluorescence ...(XRF), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), were used to characterize the synthesized samples. The specific surface area, pore size distribution and pore diameter of the different γ-AlOOH structures were discussed by the N2 adsorption-desorption analysis. According to the results of the nanostructure, characterization revealed that for synthesized γ-AlOOH nanostructures from AlCl3 and Al(NO3)3, obvious XRD peaks corresponding to the bayerite phase are found indicating an impure γ-AlOOH phase. Furthermore, the nitrogen adsorption-desorption analysis indicated that the obtained γ-AlOOH nanoparticles from Al2(SO4)3 of technical grade (95.0 % of purity) and low cost, possess a high BET surface area of approximately 350 m2/g, compared to the obtained nanostructures from aluminum sources reactive grade, which was attributed to the presence of Mg (0.9 wt.%) in its nanostructure.
TiO₂-ZnO-MgO mixed oxide nanomaterials (MONs) were synthetized via the sol-gel method and characterized by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), ...transmission electron microscopy (TEM), nitrogen physisorption analysis, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), Fourier transform infrared spectroscopy (FTIR), and color (Luminosity (
),
,
, Chrome, hue) parameters. Furthermore, the antimicrobial activity of the MONs was tested against
(EC),
(SP),
(SA), and
(LM). The MONs presented a semi globular-ovoid shape of ≤100 nm. Samples were classified as mesoporous materials and preserved in the TiO₂ anatase phase, with slight changes in the color parameters of the MONs in comparison with pure TiO₂. The MONs exhibited antimicrobial activity, and their effect on the tested bacteria was in the following order: EC > SP > SA > LM. Therefore, MONs could be used as antimicrobial agents for industrial applications.
The present research reports the synthesis of ZrO2-doped TiO2 photocatalysts at different ZrO2 contents (1, 3 and 5% wt.) synthesized by the sol–gel method. The samples were characterized by ...transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction, attenuated total reflectance-Fourier transform infrared, ultraviolet–visible, X-ray photoelectron spectroscopy and N2 adsorption–desorption analysis. The photocatalytic activity of the ZrO2-doped TiO2 was investigated against the dyes methyl orange and rhodamine B through mineralization studies. The ZrO2-doped TiO2 samples presented a semiglobular-ovoid agglomerate shape around 500–800 nm. The samples presented high crystallinity of the TiO2 anatase phase, XPS suggested the formation of Zr–O–Ti bonds and the samples were classified as mesoporous materials with slight changes in the optical features in comparison with pure TiO2. Our study shows that the ZrO2-doped TiO2 composites exhibited a higher photocatalytic activity than just utilizing the synthetized TiO2 and a commercial P25. The different degradation behaviors are attributed to differences in the textural properties, and to the different optical absorptions of the samples due to structural defects created by the level of doping of Zr4+ ions into the TiO2 lattice. Reaction kinetics parameters were calculated by the Langmuir–Hinshelwood model, and a third run cycle of the ZrO2-doped TiO2 at 1% wt. achieved a photocatalytic degradation of 78.1 and 75.5% for RhB and MO, respectively.
Photocatalysts of titanium dioxide (TiO2) doped with different percentages of iron were synthesized via microwave at 180 °C, with two different times, 2 min and 10 min. Temperature, pressure, and ...power change were analyzed. Important changes were mainly observed in the pressure conditions. The synthesized photocatalysts were characterized using: Scanning electron microscopy (SEM), X-ray diffraction (XRD), specific surface area (BET), and UV-vis diffuse reflectance spectroscopy. The presence of nanoparticles was observed; furthermore, anatase crystalline phase of TiO2 was the only found. A study of the photocatalytic activity for discoloration acid blue dye 9 (AB9) with UV light was performed, and it was compared with the commercial photocatalyst Degussa P-25, being the best result a total discoloration of dye at 45 min of reaction using the TiO2 photocatalyst undoped synthesized at 2 min. The iron doping did not show an improvement in the photocatalytic activity, and it was also observed that the time of synthesis considerably influences in the photocatalytic activity, with best efficiencies at minor synthesis time.
The high toxicity of arsenite and the difficulty to remove it is one of the main challenges for water treatment. In the present work the surface of a low cost zeolite was modified by chemical ...treatment with a ferrous chloride to enhance its arsenite adsorption capacity. The effect of pH, ions coexistence, concentration, temperature and dosage was studied on the adsorption process. Additionally, the Fe-modified W zeolite was aged by an accelerated procedure and the regeneration of the exhausted zeolite was demonstrated. The Fe-modified W zeolite was stable in the pH range of 3 to 8 and no detriment to its arsenite removal capacity was observed in the presence of coexisting ions commonly found in underground water. The studies showed that the adsorption of As (III) on Fe-modified W zeolite is a feasible, spontaneous and endothermic process and it takes place by chemical bonding. The exhausting process proved the adsorption of 0.20 mg g−1 of As (III) by the Fe-modified W zeolite and this withstand at least five aging cycles without significant changes of its arsenite adsorption capacity. Fe-modified W zeolite prepared from fly ash might be a green and low-cost alternative for removal of As (III) from groundwater.
This work aimed to evaluate the effect of time and two storage temperatures (25 °C and 4 °C) on the structural changes in chitosan (CS) films functionalized with titanium dioxide (TiO2) and a ternary ...mixed oxide-based TiO2 (TiO2-ZnO-MgO; TZM) by Fourier transform infrared (FTIR) spectroscopy and the in vitro release of TiO2 and TZM from the CS film to the medium. Changes in the FTIR spectra (mainly in the 1700 to 1250 cm–1 region) of the CS-based films during storage were dependent on the storage temperature. The film stored at 25 °C showed remarkable changes after 7 days of evaluation, indicating a dehydration process; however, films stored at 4 °C exhibited reduced changes after 21 days of storage. Moreover, the migration behavior of TiO2 (< 13%) and TZM (< 7%) from CS to the medium showed a first-order kinetic model (R2 > 0.93) in a temperature-dependent response. Further studies are needed to correlate the structural changes of CSTiO2 and CSTZM films during storage with their technological and functional properties, which could limit their potential applications.
Arsenic is a toxic element for human health. It persists in the environment as a result of natural and anthropic contamination, generating nocive effects for consumers. Some of them can be cancer, ...cardiovascular disorders, hypotension, metabolic disease and peripheral neuropathy. Adsorption is considered to be one of the most effective technologies widely used in global environmental protection areas. The objective of this study was to generate a low cost agglomerated alumina adsorbent (A-1) for the effective removal of arsenic (V) from water and its comparison with a commercial agglomerated alumina (A-2). Both of them of 5 mm of diameter. The physicochemical properties of the adsorbents were characterized by various techniques, such as: XRF, zeta potential, XRD, adsorption-desorption of N2 and FE-SEM/EDS. Batch experiments were performed to evaluate the efficiency of removal of As (V) from water by A-1 and A-2. The point of zero charge of A-1 and A-2 was at pH 8.5 and 8.1, respectively. The experimental results in batches indicated that agglomerate A-1 has a higher adsorption capacity than A-2 (1.212 mg∙g-1; 1.058 mg∙g-1) in similar conditions, concentration of 15 mg∙L-1 of As (V), temperature (20± 2 °C) and pH 7. The adsorption processes of As (V) in A-1 and A-2 followed the kinetics of Pseudo-first order kinetic and the Freundlich isotherm. The results showed that the agglomerate A-1 is an attractive adsorbent for the effective removal of As (V) from water.
This study reports the synthesis of mesoporous nano-fibrillar alumina prepared by hydrolysis-precipitation route from aqueous solution of aluminum sulfate analytical reagent (AR) compared to aluminum ...sulfate technical grade (TG) of low purity under similar conditions using ammonia as the precipitating agent. The phisicochemical properties of these samples was studied with the assistance of characterization techniques such as Thermogravimetric and differential thermal analysis (TG/DTGA–DTA), X-ray diffraction (XRD), N2 adsorption-desorption isotherms, Fourier transform infrared (FTIR) spectroscopy, particles size and Transmission electron microscopy with energy-dispersive X-ray analysis (TEM/EDAX). The TG-DTA and XRD results show greater stability and a slightly greater crystallinity in Al2O3-TG sample than Al2O3-AR. N2 adsorption-desorption results show for both materials greatly surface area of 311 m2/g for Al2O3-TG and 272 m2/g for Al2O3-AR exhibiting characteristics of mesoporous materials. The FTIR results show a lower percentage of surface OH groups for Al2O3-TG showing a lower acidity due to the lower concentration of Al-OH species (AlIV). TEM measurements confirmed fibers size ranged from 20 to 100 nm for Al2O3-TG and 20-80 nm for Al2O3-AR. EDAX shows the presence of 0.20 % atomic of Mg as an impurity in Al2O3-TG, is attributed that this amount is sufficient to generate structural defects and decrease slightly acidity, likewise, extended the fibrillar chain of the alumina.
In recent years, a strong interest has emerged in polysaccharide-hybrid composites and their potential applications, which have interesting functional and technological properties. This review ...summarizes and discusses the reported advantages and limitations of the functionalization of conventional and nonconventional polysaccharides by adding TiO2 nanoparticles as a reinforcement agent. Their effects on the mechanical, thermal, and UV-barrier properties as well as their water-resistance are discussed. In general, the polysaccharide–TiO2 hybrid materials showed improved physicochemical properties in a TiO2 content-dependent response. It showed antimicrobial activity against bacteria (gram-negative and gram-positive), yeasts, and molds with enhanced UV-protective effects for food and non-food packaging purposes. The reported applications of functionalized polysaccharide–TiO2 composites include photocatalysts (dye removal from aqueous media and water purification), biomedical (wound-healing material, drug delivery systems, biosensor, and tissue engineering), food preservation (fruits and meat), cosmetics (sunscreen and bleaching tooth treatment), textile (cotton fabric self-cleaning), and dye-sensitized solar cells. Furthermore, the polysaccharide–TiO2 showed high biocompatibility without adverse effects on different cell lines, indicating that their use in food, pharmaceutical, and biomedical applications is safe. However, it is necessary to evaluate the structural changes promoted by the storage conditions (time and temperature) on the physicochemical properties of polysaccharide–TiO2 hybrid composites to guarantee their stability during a determined time.
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