Commercial Textile Dye Research Articles

Microwave-Assisted Hydrothermal Synthesis of Photocatalytic Truncated-Bipyramidal TiO2/Ti3CN Heterostructures Derived from Ti3CN MXene.

TiO2/MXene heterostructure has garnered significant interest as a photocatalyst due to its large surface area and efficient charge carrier separation at the interface. However, current synthesis methods produce TiO2 without clear crystal faceting and often require complicated postprocessing step, limiting its practical applications. We demonstrate a facile and controlled microwave-assisted hydrothermal synthesis for transforming multilayered Ti3CN MXene to a truncated-bipyramidal TiO2/Ti3CN heterostructure. The resulting TiO2 nanocrystals at the Ti3CN surface exhibited crystalline anatase truncated bipyramids, exposing {001} and {101} facets. We further tailored an indirect optical band gap of the TiO2/Ti3CN heterostructure in the range of 3.17-3.23 eV by varying the hydrothermal synthesis time from 15 min to 5 h at a fixed temperature of 160 °C. Efficient charge separation allowed us to decompose 97% of methylene blue (MB) within 30 min of ultraviolet (UV) light irradiation, ∼3.9-fold faster than the benchmark P25, higher than any other TiO2/MXene heterostructures. With simulated white light, we achieved over 60% efficiency of the dye decomposition within 2 h of irradiation, which resulted in 1.5-fold faster kinetics than P25. We also observed a similar excellent performance of Ti3CN-derived TiO2 in decomposing various persistent synthetic dyes, including commercial textile dye, methyl orange, and rhodamine B. In conclusion, our study provides a strategy for utilizing MXene chemical reactivity to produce highly crystalline optically active TiO2/Ti3CN heterostructure. The developed heterostructure can serve as an efficient photocatalyst for the degradation of organic pollutants.

Properties of hydrogel for adsorbent textile dye waste based cellulose-carboxymethyl sago starch

Abstract The use of a single natural polymer in hydrogel preparations is considered insufficient to produce hydrogels that are more durable, more stable, and stronger. Blends of various natural polymers can improve each sago other’s lack of physicochemical characteristics and produce new properties. This research combines two natural polymers, cellulose and starch. Cellulose isolation from Gracilaria verrucosa seaweed using acid hydrolysis and alkaline autoclaving method produced 14.01% cellulose. This study combined the results of cellulose isolation with carboxymethyl sago starch at 0.09; 0.14 and 0.24 mol/mol AGU. The isolated cellulose-carboxymethyl sago starch has the potential as a hydrogel material with the addition of crosslinkers such as epichlorohydrin (ECH). This study aims to synthesize hydrogels from cellulose-carboxymethyl sago starch with application as a textile dye waste absorbent with a concentration of epichlorohydrin (ECH) at 7.5%. Analysis of carboxymethyl sago starch is degrees of substitution, water-soluble index (WSI), and swelling power (SP). The hydrogel properties are characterized by the degree of swelling, degree of polymerization, FTIR, and SEM, and the hydrogel adsorption ability is characterized by adsorption efficiency using a microplate reader. The research results show that hydrogel can be synthesized optimally by adding carboxymethyl sago starch (CMSS) at 0.24 mol/mol AGU. The results of FTIR analysis are also by chemical measurements (swelling and gel fraction). In contrast, for maximum colour absorption, the addition of carboxymethyl sago starch is 0.09 mol/mol AGU for purple, yellow, and black and 0.14 mol/mol AGU for green color absorption. In conclusion, the adsorption ability of hydrogel in commercial textile dyes is maximum when the carboxymethyl sago starch (CMSS) is added at 0.09 mol/mol AGU with the best adsorption efficiency at purple 86.22%, yellow 77.40%, black 73.70% and at the addition of CMSS 0.14 mol/mol AGU the best adsorption efficiency in green is 73.46%.

Removal of Commercial Textile Dye DRMD from Wastewater Using Two-Dimensional Mesoporous Graphene Oxide Adsorbent

Environmental toxins from textile effluents, including organic contaminants, heavy metals, and dyes, pose significant health risks such as renal illness, allergies, dermatitis, and cancer when released into the aquatic environment. While various dye removal methods exist, adsorption is highlighted as a potentially effective solution due to its low cost, simplicity, and ease of use. An adsorbent of two-dimensional mesoporous Graphene Oxide (GO) was produced using Hummer’s method from cost-effective graphite powder. This was then utilized to eliminate the Doracryl Red MD (DRMD) textile dye from the aqueous system. To characterize the synthesized material, XRD, FTIR, and SEM analyses were performed. Zeta Potential and AFM analysis were used to determine surface charge and roughness, respectively. BET analysis was performed to obtain information regarding the surface area and porosity of the mesoporous GO. The highest adsorption capacity for the adsorption of the dye DRMD was found at 917.62 mg/gm. A variety of factors, including the influence of solution pH, adsorbent dosage, adsorption temperature, concentration of dye solution, and contact time, were thoroughly investigated. Adsorption data best fit the Langmuir model and demonstrated pseudo-second-order reaction kinetics. After repeatedly washing used adsorbents with 2% HCl solution, 88.62% of its initial adsorption capacity was retained after the 4th cycle. Hence, the enhanced adsorption capacity and recyclability of Graphene Oxide (GO) render it a promising candidate for the treatment of wastewater polluted with organic dyes.

Biodegradation of commercial textile reactive dye mixtures by industrial effluent adapted bacterial consortium VITPBC6: a potential technique for treating textile effluents.

Textile industries release major fraction of dyestuffs in effluents leading to a major environmental concern. These effluents often contain more than one dyestuff, which complicates dye degradation. In this study ten reactive dyes (Reactive Yellow 145, Reactive Yellow 160, Reactive Orange 16, Reactive Orange 107, Reactive Red 195, Reactive Blue 21, Reactive Blue 198, Reactive Blue 221, Reactive Blue 250, and Reactive Black 5) that are used in textile industries were subjected to biodegradation by a bacterial consortium VITPBC6, formulated in our previous study. Consortium VITPBC6 caused single dye degradation of all the mentioned dyes except for Reactive Yellow 160. Further, VITPBC6 efficiently degraded a five-dye mixture (Reactive Red 195, Reactive Orange 16, Reactive Black 5, Reactive Blue 221, and Reactive Blue 250). Kinetic studies revealed that the five-dye mixture was decolorized by VITPBC6 following zero order reaction kinetic; Vmax and Km values of the enzyme catalyzed five-dye decolorization were 128.88mg L-1day-1 and 1003.226mg L-1 respectively. VITPBC6 degraded the dye mixture into delta-3,4,5,6-Tetrachlorocyclohexene, sulfuric acid, 1,2-dichloroethane, and hydroxyphenoxyethylaminohydroxypropanol. Phytotoxicity, cytogenotoxicity, microtoxicity, and biotoxicity assays conducted with the biodegraded metabolites revealed that VITPBC6 lowered the toxicity of five-dye mixture significantly after biodegradation.

Kinetics of three commercial textile dyes decomposition by UV/H2O2 and UV/acetone processes: An experimental comparative study and DFT calculations

Acetone photolysis was investigated and compared with the UV/H2O2 process for the removal of three commercial textile dyes, Reactive Red 184 (RR184), Reactive Orange 4 (RO4), and Direct Red 80 (DR80), in aqueous solution at 254 nm, pH = 6.5–6.8, and T = 20 ± 2 °C. The removal efficiency of RR184, RO4, and DR80 by UV/H2O2 was 35 %, 59 %, and 69 %, respectively, whereas UV/acetone exhibited a removal efficiency of 81 %, 99 %, and 88 %, within 30 min ([Dye]0 = 0.1 mM and [acetone]0 = [H2O2]0 = 50 mM). However, as the initial doses of H2O2 and acetone were increased, the decolorization increased, and the experimental kinetic data always agreed with the pseudo-first-order reaction model (R2 = 0.94–0.99). Additionally, UV/acetone was consistently shown to be significantly more efficient than UV/H2O2 under all conditions tested. For instance, the rate constant ratios kUV/acetone/kUV/H2O2 are 3.19, 1.95, and 1.67 for RR184, RO4, and DR80, respectively ([Dye]0 = 0.1 mM and [acetone]0 = [H2O2]0 = 50 mM). Scavenging tests using specific probes revealed that •OH and •CH3 radicals were the main responsible for dyes degradation (greater than80 %) in the UV/H2O2 and UV/acetone processes, respectively. In both systems, the dyes' reactivity order was found to be RO4 > DR80 > RR184, indicating that chemical structure is an important factor in evaluating the efficiency of the degradation process. This reactivity order was supported by the density functional theory (DFT)-based thermodynamic calculations used to explain the HO•-initiated degradation of the studied azo dyes in the UV/H2O2 process.

Tailoring of Ag3PO4-Anchored Hydroxyapatite Nanophotocatalyst with Tunable Particle Size by a Facile Ion-Exchange Method for Organic Textile Dyes Photodegradation

Silver phosphate (Ag3PO4) exhibits excellent photocatalytic performance but has limitation in its stability and reusability. To overcome the issue of reusability, composites of silver phosphate nanostructures are tailored. This paper elucidates the photocatalytic study of silver phosphate-anchored hydroxyapatite (HA) (Ca10(PO4)6(OH)2) on the degradation of commercial textile dye, Sunfix Red (SR) S3B 150% by changing the experimental parameters such as catalyst concentration, dye concentration, and pH of the dye solution under the sunlight. Silver phosphate-anchored HA (HA_Ag3PO4(x)) was prepared via a two-step process. HA was synthesized by a simple wet chemical precipitation and silver phosphate-anchored HA (HA_Ag3PO4(x)) via in situ ion-exchange method. The synthesized photocatalysts were subjected to characterization studies such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). All the synthesized composites exhibited the bandgap of 2.34 eV and degraded SR in 45 min with the rate constant 0.07168 min−1 under sunlight. The trapping tests for radicals were done to study the role of free radicals in the degradation of the dye, SR, and the possible degradation mechanism was proposed. The postphotocatalytic analysis of XRD showed that the structure of Ag3PO4 remained intact declaring its structural stability. It was observed that the concentration of AgNO3 precursor influenced the number of nucleation over the surface of HA and the particle size of Ag3PO4. The applicability of the synthesized material was extended to other organic dyes such as Sunzol Black (SB) DN conc., methylene blue (MB), and rhodamine B (RhB) by the prepared composite and the findings were presented.

Facile Synthesis and Characterization of Magnetic Calcium Alginate-Graphene Oxide Composite for Removal of a Commercial Textile Dye Doracryl Red MD

Facile Synthesis and Characterization of Magnetic Calcium Alginate-Graphene Oxide Composite for Removal of a Commercial Textile Dye Doracryl Red MD

Adsorption of textile dyes from aqueous solutions onto clay: Kinetic modelling and equilibrium isotherm analysis.

The commercial activated carbon commonly uses to reduce of dye amount in the textile industry effluents. In this study has focused on the use of a natural clay sample as low cost but potential adsorbent. For this purpose the adsorption of commercial textile dyes, Astrazon Red FBL and Astrazon Blue FGRL, onto clay was investigated. The physicochemical and topographic characteristics of natural clay sample were determined by scanning electron microscopy (SEM), X-Ray fluorescence spectrometry (XRF), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and cation exchange capacity measurements. It was determined that the major clay mineral was smectite with partial impurities. The effects of several operational parameters such as contact time, initial dye concentration, temperature, and adsorbent dosage on the adsorption process were evaluated. The adsorption kinetics was interpreted with pseudo-first order, pseudo-second order, and intra-particle diffusion models. The equilibrium adsorption data were analyzed using Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherm models. It was determined that the adsorption equilibrium was reached in the first 60min for each dye. The amount of adsorbed dyes onto clay decreased with increasing temperature, similarly, it decreased with increasing sorbent dosage. The kinetic data were well described by pseudo-second order kinetic model, and adsorption equilibrium data was followed both Langmuir and Redlich-Peterson models for each dyes. The adsorption enthalpy and entropy values were calculated as -10.7kJ.mol-1 and -13.21J.mol-1.K-1 for astrazon red and those for astrazon blue -11.65kJ.mol-1 and 37.4J.mol-1.K-1, respectively. The experimental results support that the physical interactions between clay particles and dye molecules have an important role for the spontaneous adsorption of textile dyes onto the clay. This study revealed that clay could effectively be used as an alternative adsorbent with high removal percentages of astrazon red and astrazon blue.

Photocatalytic Activity of the Oxidation Stabilized Ti3 C2 Tx MXene in Decomposing Methylene Blue, Bromocresol Green and Commercial Textile Dye.

Two-dimensional MXenes are excellent photocatalysts. However, their low oxidation stability makes controlling photocatalytic processes challenging. For the first time, this work elucidates the influence of the oxidation stabilization of model 2D Ti3 C2 Tx MXene on its optical and photocatalytic properties. The delaminated MXene is synthesized via two well-established approaches: hydrofluoric acid/tetramethylammonium hydroxide (TMAOH-MXene) and minimum intensive layer delamination with hydrochloric acid/lithium fluoride (MILD-MXene) and then stabilized by L-ascorbic acid. Both MXenes at a minimal concentration of 32mg L-1 show almost 100% effectiveness in the 180-min photocatalytic decomposition of 25mg L-1 model methylene blue and bromocresol green dyes. Industrial viability is achieved by decomposing a commercial textile dye having 100 times higher concentration than that of model dyes. In such conditions, MILD-MXene is the most efficient due to less wide optical band gap than TMAOH-MXene. The MILD-MXene required only few seconds of UV light, simulated white light, or 500nm (cyan) light irradiation to fully decompose the dye. The photocatalytic mechanism of action is associated with the interplay between surface dye adsorption and the reactive oxygen species generated by MXene under light irradiation. Importantly, both MXenes are successfully reused and retained approximately 70% of their activity.

A Combination of UV-Vis Spectroscopy and Chemometrics for Detection of Sappanwood (Caesalpinia sappan) Adulteration from Three Dyes

Sappan wood (Caesalpinia sappan) is very well known as a natural dye for traditional food and beverage in many countries. Recently, there are many reports of sappan wood adulteration by adding synthetic or natural dyes to obtain quality color and better appearance. In this study, UV-Vis absorption spectra coupled with chemometrics were used to develop rapid detection of sappan wood raw material adulteration (authentication) from three dyes, i.e., sudan III, commercial textile dyes, and red yeast rice. Absorption spectra of 13 sappan wood raw material and adulterated sappan wood with the three dyes in two different concentrations which resulted about 78 adulterated samples were measured with UV-Vis spectrophotometer at a wavelength range of 200-800 nm. A principal component analysis followed by discriminant analysis was used to construct a model for the authentication of sappan wood from the three dyes used in this study. The combination of both methods was successfully classified sappan wood as non-adulterated and adulterated with the dyes. Cross-validation results of the authentication model of sappan wood from sudan III, commercial textile dyes, and red yeast rice were 94.12%, 94.12%, and 92.16% correctly classified into their groups, respectively.

Screening for a more sustainable solution for decolorization of dyes and textile effluents using Candida and Yarrowia spp.

Dyed effluents from textile industry are toxic and difficult to treat by conventional methods and biotechnological approaches are generally considered more environmentally friendly. In this work, yeast strains Candida parapsilosis, Yarrowia lipolytica and Candida pseudoglaebosa, isolated from wastewater treatment plants, were tested for their ability to decolorize textile dyes. Both commercial textile synthetic dyes (reactive, disperse, direct, acid and basic) and simulated textile effluents (a total of 32 solutions) were added to a Normal Decolorization Medium along with the yeast (single strains and consortia) and the decolorization was evaluated spectrophotometrically for 48–72 h. Yeasts were able to perform decolorization through adsorption and biodegradation for 28 of the dyes and simulated effluents by more than 50%. Y. lipolytica and C. pseudoglaebosa presented the best results with a true decolorization of reactive dyes, above 90% at 100 mg l−1, and simulated effluents at 5 g l−1 of concentration. Enzyme production was evaluated: oxidoreductase was found in the three yeasts, whereas tyrosinase was only found in Y. lipolytica and C. pseudoglaebosa. Y. lipolytica and C. pseudoglaebosa are a potential biotechnological tool for dye degradation in textile wastewaters, especially those containing reactive dyes and a promising tool to integrate in bioremediation solutions, contributing to circular economy and eco sustainability in the water sector since the treated water could possibly be reused for irrigation.

Improvement in photocatalytic activity of titanium dioxide nanoparticles through doping and calcination for textile wastewater treatment under visible light

The photocatalytic degradation of commercial textile azo dye, namely C.I Acid red 2 also called as methyl red has been studied. TiO2 nanoparticles doped with zinc nitrate were made by sol–gel technique and calcined at higher temperature that leads to the formation of mixed phases and improved photocatalytic action of nanoparticles underneath visible light. The obtained nanoparticles are characterized by SEM, XRD and FTIR techniques along with zeta potential measurement. The nanoparticles were found to be crystalline with a size of around 58 nm to 192 nm. The effect of visible light irradiation time on photodegradation was investigated. Optimum pH for degradation of the dye solution was determined. The reusability of the photocatalyst was analyzed by recycling experiments. The degradation of the chosen dye was monitored using UV–Vis spectroscopy. Maximum degradation of 85 % was obtained for a time duration of 180 min. From kinetics studies it was noticed that degradation of methyl red followed pseudo second order kinetics. The results suggest that using a suitable photocatalyst and choosing the right operational settings can readily result in complete decolorization of azo dye solutions.

Oxidative Stress and Toxico-Pathic Branchial Lesions in Cyprinus carpio Exposed to Malachite Green.

Gill is the frontier tissue to come in direct contact with aquatic toxicants. Malachite green (MG) commercial textile dye was assessed for its impact on the gill cytoarchitecture. Cyprinus carpio were exposed to 0.087 and 0.146mg/L of MG for 60days. The tissue was processed, and HE stained slidesrevealed histo-pathic lesions such as lamellar curling, edema, necrosis, telangiectasia, aneurysm, and vacuolization. Scanning electron microscopy reported aberrations in lamellae and microridges of the epithelium. At the cellular level, transmission electron microscopy exhibited nuclear alterations in form of pyknosis and mitochondrial swelling followed by cristolysis. Pillar cells displayed cytoplasmic vacuolization and leukocyte infiltration, and goblet cell containing varied shaped and density mucous globules. The biochemical analysis supported the ultrastructural alterations and showed a negative impactof MG on the antioxidative enzymes (CAT, SOD, GSH), while levels of MDA were found to be significantly elevated. Thereby, concluding MG induced branchial toxicity in the fish.

Development of LaxCa1-xMnO3 materials for Bezaktiv Blue removal in aqueous media.

In this work, mixed oxides of LaxCa1-xMnO3 perovskite type (x = 0, 0.5 and 1.0) were synthesized through modified proteic method using collagen and calcination process at 700 °C/2 h in order to remove the commercial textile dye Bezaktiv Blue S-MAX from water. Oxides were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 physisorption, scanning electron microscopy (SEM) and point of zero charge (PZC) techniques while the dye only by the first two techniques. The XRD showed that perovskite monophase was obtained for x = 0.5 and 1.0. However, for x = 0, the low crystalline perovskite phase was obtained in the midst of precursor oxides. FTIR showed the adsorption process did not damage the adsorbents structure. The successful obtained materials have meso and macroporous with slit or cavity shape, rough surface and particles with varying sizes. The pseudo-second-order model was the one that best fit the kinetic data. The process must occur through electrostatic surface interactions between the adsorbent surface and the dye molecule. For the equilibrium study, Langmuir isotherm is the most suitable when using LaMnO3 adsorbent, while Freundlich isotherm was better suited when used the other two materials. The adsorbents were termally regenerated and reused five times. The best performance was exhibited by LaMnO3.

COD removal and colour degradation of textile dye effluents by locally isolated microbes

ABSTRACT Textile industry has been rapidly progressing over the years, leading to an increasing volume of water usage that contributes to the large production of textile wastewater. Biological treatment processes have been proven to be the most environmentally friendly, cost-effective and requiring reduced production treatment by-products. In this study, using microbial treatment was applied. Three potential local isolates of micro-organism had been isolated from textile wastewater. The treatment processes were studied under two conditions, namely aerobic and anaerobic. Decolourization of seven commercial textile dyes, namely Crystal Violet 3, Acid Black 1, Basic Blue 8, Acid Blue 147, Congo R, Chrysoiodine R and Yellow 2 G were studied. After seven days of incubation, a significant reduction of 92% for Yellow 2G (Y) and 73.73%for Chrysoiodine R was observed, indicating a high capability of the bacterial isolates indye-degrading activities. Highest chemical oxygen demand (COD) removal was achieved byisolate C3K (93.93%), followed by isolate C3W (90.5%) and isolate C1 (89.173%) in nineincubation days, highlighting the ability of these microbial isolates in removing COD from the individual textile dyes.

Colour and COD removal from aqueous solutions of direct yellow 86 textile dyestuff by electro-Fenton method

In this study, COD and colour removal were investigated by the electro-Fenton method from aqueous solutions of direct yellow 86 commercial textile dyes. The effects of electrolyte concentration (250-3,000 mg/L), H2O2 concentration (250-3,000 mg/L), the initial dye concentration (50-500 mg/L), the distance of anode-cathode (0.5-1.5 cm) on COD and colour removals were investigated. Under optimal experimental conditions (NaCl: 1,500 mg/L, H2O2: 1,500 mg/L, the initial dye concentration: 50 mg/L, the distance of anode-cathode: 1.5 cm), the maximum COD and colour removal efficiencies were 95.3% and 99.5%, respectively. It was determined that H2O2 concentration and dye concentration had the highest effect on the removal efficiencies. It was determined that pollutant removal efficiencies increased with increasing H2O2 concentration, and decreased with increasing initial dye concentration. The results showed that the electro-Fenton method can be effectively applied in COD and colour removal from aqueous solutions of direct yellow 86 commercial textile dyestuff.

Development of the N-Doped Cu-Carbon Composite as a Novel Catalyst for the Removal Reactive Black 5

In this study, two Cu-based catalysts with and without N doped carbon matrix, named N-Cu/CuO/C and Cu/CuO were synthesized via calcination of melamine-cupper acetate complex and cupper acetate at 500°C under an inert atmosphere. The catalysts were characterized by X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and CHNS elemental analyzer. The catalytic activity of both catalysts was evaluated through the NaBH4 associated reduction of commercial textile dye named reactive black 5 (RB5). The kinetics of the reduction of reactive black 5 was also described by the pseudo-first-order kinetic equation. For the studied reduction, N-Cu/CuO/C exhibited enhanced catalytic activity both in conversion and kinetics (97% conv. in 315 sec) compared to that of by Cu/CuO/C (25% conv. in 1500 sec). Besides, N-Cu/CuO/C also demonstrated good reusability up to four consecutive cycles.

Synthesis of cost-effective magnetic nano-biocomposites mimicking peroxidase activity for remediation of dyes

The present study describes preparation of cellulose incorporated magnetic nano-biocomposites (CNPs) by using cellulose as base material. The prepared CNPs were characterised by SEM, EDAX, TEM, XRD, and FT-IR and found to exhibit an intrinsic peroxidase-like activity with a Km and Vmax of 550 μM and 3.8 μM/ml/min, respectively. The CNPs exhibited higher pH and thermal stability compared to commercial peroxidase. These nanocomposites were able to completely remove (i) a persistent azo dye, methyl orange at a concentration of 50 ppm, within 60 min under acidic conditions (pH 3.0) and also (ii) decolourize commercial textile dye mixture under acidic conditions within 30 min. CNP-mediated degradation of dyes into simple products was further confirmed by UV-Vis and AT-IR spectroscopy The added advantage of CNPs separation after decolourization by simple magnet due to their magnetic properties and consequent reusability makes them fairy attractive system for dye remediation from environmental samples or textile industries effluents.

Photocatalytic Degradation of Textile Reactive Dyes-A Comparative Study Using Nano Silver Decorated Titania-Silica Composite Photocatalysts.

Photocatalytic degradation of commercial textile azo dyes such as Reactive Red 120 (RR 120), Acid Orange 20 (AO 20), Reactive Orange 16 (RO 16) and Congo Red (CR) was studied under UV light and visible light irradiations of wave length 365 nm and 420 nm respectively over bare and modified titania catalysts such as TiO2, 1% Ag/TiO2, 30% TiO2/SiO2 and 1% Ag/30% TiO2/SiO2. On comparison of the catalytic activity of all the synthesized catalysts under UV and Visible irradiations, it was found that the composite catalysts showed higher photocatalytic activity than bare TiO2. Among the catalysts 1% Ag/30% TiO2/SiO2 composite catalyst was the best catalyst for the decolourization of the chosen dyes. Results obtained showed that the time taken for the complete decolourization of dyes was found to be significantly different for different dyes under both UV and visible light irradiations. Among the four dyes, AO 20 decolourised completely (100%) in 2 hrs, whereas Congo Red (CR) decolourised to the least extent (35%) over 1% Ag/30% TiO2/SiO2 under UV light irradiation. Experiments carried out under dark condition in the presence of catalyst revealed very high adsorption of CR (≈60%) over titania catalysts and hence this could be reason for suppressed catalytic activity of 1% Ag/30% TiO2/SiO2. Various optimization studies such as effects of substrate concentration, weight of catalyst and substrate pH were carried out. TOC analysis revealed a very high mineralization of all the dyes.

Alternative support materials for titania photocatalyst towards degradation of organic pollutants

Stainless steel mesh and hemmed knitted fiber glass strips were coated with TiO2 sol to study the possibilities of the two materials as alternative supports for TiO2 in photocatalytic wastewater treatment process. Commercially available P25, P90 and PC500 powder catalysts were successfully immobilized on stainless steel mesh and fiber glass strips. The prepared photocatalysts were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The retention (stability) of as-prepared layers of photocatalyst on fiber glass strips was tested by sonication test. Best adhesion levels were achieved with P90; with only 17% of photocatalyst loss during the harsh sonication test. The photocatalytic activity was tested with degradation of phenol and commercial textile dye Reactive Blue 19 in flow-through photoreactor. After 240 min of irradiation, mineralization degree of pollutants ranged from 72 to 99% for RB-19 and 38 to 94% for phenol.