Photocatalytic Decolorization Research Articles

Construction of two isomorphic multifunctional MOFs via a dual-ligand strategy for aromatic compounds detection and photocatalytic degradation performance

The development of multifunctional and structurally unique metal−organic frameworks (MOFs) presents a highly attractive yet challenging endeavor for chemists. In this study, we employ a dual-ligand strategy to synthesize two isomorphic Co/Zn MOFs, {[Co4(BMIP)3(MIP)4]·3DMF·H2O}n (SNUT-35-Co) and {[Zn4(BMIP)3(MIP)4]·2DMF·2H2O}n (SNUT-35-Zn). The photocatalytic performance of SNUT-35-Co and SNUT-35-Zn was evaluated using methylene blue (MB). Under UV/visible-light irradiation, the photocatalytic decolorization rates of MB for SNUT-35-Co and SNUT-35-Zn reached 95% within 140 min and 120 min, respectively, indicating their superior degradation. Notably, SNUT-35-Zn demonstrated exceptional detection capabilities for aromatic compounds, such as aniline and nitrobenzene, at lower concentration range without interference from other components. The detection limits for these two small molecules were found to be 0.430 and 0.431 μM, respectively. Additionally, both MOFs exhibited larger transient photocurrents and lower impedance in electrochemical measurements. The results suggested that the photocatalytic activities of MOF are influenced by their three-dimensional structures, which facilitate electrons passing due to the inherent semiconductor properties.

Standardization of silver nanoparticle synthesis: Photocatalytic application (immobilized with chitosan complex) with textile dyes and antibacterial activity against Staphylococcus aureus using banana pseudo stem

The purpose of the study is to standardize the silver nanoparticle (BP-AgNPs) synthesis and its antibacterial activity and photocatalytic application with the selected dyes using the banana pseudo stem extract. “One-factor analysis (OFTA)” was carried out for the standardization of silver nanoparticle synthesis and nanoparticle-chitosan complex immobilization. The parameters were identified with plant quantity (20 g), silver nitrate concentration (1 mM), the ratio of plant extract and silver nitrate solution (2:8), pH (12), temperature (37 °C), dispersed light conditions, shaking conditions (120 rpm), and time (6 h) were analysed. The photocatalytic decolorization efficiency of the standardized BP-AgNPs (immobilized with chitosan complex) has shown 96.92% for methylene blue (10 ppm) at 3 h and 97.55% for safranin (100 ppm) at 15 h. The antibacterial activity for the synthesised BP-AgNPs was determined. MIC value of the BP-AgNPs was determined to be 15.62 μg. mL−1 for S. aureus. The synthesised BP-AgNPs treated with 0.5×, 1× and 2× MIC concentration (x = 15.62 μg. mL−1) showed decreased viable counts of S. aureus (99.6% at 2× concentration having viable count of 22.6 × 102 CFU. mL−1) at 24 h incubation when compared with the control culture. The structural characteristics of the BP-AgNPs were identified as spherical with SEM and the size was identified as 12.19 ± 1.62 nm with TEM and as 37.23 ± 17.89 nm with XRD. The parameters such as FTIR, Zeta potential, EDS further supports the nanoparticle synthesis with banana pseudostem extract. The current result suggested that, the silver nanoparticles (BP-AgNPs) synthesised using the extract of the banana pseudo stem could be used as an alternative source for dye decolorization and antibacterial activities.

Optimization of Rhizoclonium hieroglyphicum extract for enhanced synthesis of nickel oxide nanoparticles using response surface methodology and its potential exploration in biological application.

The study investigates the potential of Rhizoclonium hieroglyphicum as a novel source for synthesizing nickel oxide nanoparticles (RH-NiONPs) and evaluates its biological applications. Phytochemicals in the algal extract serve as capping, reducing and stabilizing agent for nickel oxide nanoparticles. The process variables were optimized using BBD based RSM to obtain maximum RH-NiONPs. Characterization of RH-NiONPs using UV-Vis and FT-IR spectroscopy reveals the plasmon resonance peak at 340 nm and the functional groups responsible for reduction and stabilization. XRD confirmed the crystalline nature while the stability and size of the RH-NiONPs were determined by DLS and zeta potential. Toxicity assessments demonstrated the effect of RH-NiONPs against Vigna radiata, Allium cepa and Artemia salina was low. RH-NiONPs revealed significant zone of inhibition against the selected bacteria and fungi. The results of larvicidal activity showed that RH-NiONPs are toxic to 4th instar larvae of Daphnis nerii. Also, RH-NiONPs efficiently decolorized Reactive Violet 13 (92%) under sunlight irradiation and the experimental data well fits to Langmuir isotherm along with pseudo second order kinetic model. The thermodynamic studies enunciate the exothermic and non-spontaneous photocatalytic decolorization of reactive violet 13. Thus, the current study assesses the eco-friendly and cost-effective nature of RH-NiONPs along with its biological applications.

Preparation of Au-MoS2 photocatalyst with a green synthesis method and its application in water contaminant degradation

In the current research, a successful and fast synthesis of gold nanoparticles (AuNPs) by utilizing the leaf extract of Eryngium planum is reported. In order to analyze the influential synthesis parameters, the Plackett-Burman (PB) design was utilized, while the response surface methodology (RSM) was employed for optimization purposes. Furthermore, the achieved AuNPs were applied in the production of the Au-MoS2 nanocomposite. The efficiency of the visible-light photocatalyst was examined in the photocatalytic decolorization of the refractory azo dye, Acid Blue 113 (AB113). A high dye removal efficiency (94%) was observed under the optimal conditions of pH 7.6 using 15.5 mg of Au-MoS2, and 14 min. These results proved that the fabricated Au-MoS2 photocatalyst using biogenic AuNPs was more efficient than pure MoS2 and could be used as a promising catalyst for the degradation of dye-containing effluents.

Degradation of Methyl Orange from Aqueous Solution Using Fe-Ni-Co-Based Trimetallic Nanocomposites: Optimization by Response Surface Methodology

Effluent-containing dye molecules is a significant environmental hazard. An economical and energy-saving solution is needed to combat this issue for the purpose of environmental sustainability. In this study, Fe-Ni-Co-based trimetallic nanocomposite was synthesized using the coprecipitation method. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infra-Red spectroscopy were conducted to explore the physical morphology, phase structure and functional groups of the synthesized catalyst. Among dyes, methyl orange is considered as a major contaminant in textile effluent. The current study focused on the degradation of methyl orange using a trimetallic Fe-Ni-Co-based nanocomposite. A central composite design in response surface methodology was employed to analyze the independent variables including dye concentration, catalyst dose, temperature, hydrogen peroxide, irradiation time, and pH. Dye degradation has been achieved up to 81% in 20 min at the lowest initial concentration (5 mg/L) in optimized conditions. Based on ANOVA, the predicted values were in great agreement with the actual values, signifying the applicability of response surface methodology in the photocatalytic decolorization of dyeing effluents. The results gained from this research demonstrated that the synthesis method of trimetallic nanocomposite (Iron Triad) is a cost-effective and energy efficient method that can be scaled up to a higher level for industrial application.

Investigation of the mechanism and stability of highly efficient photocatalytic degradation of Methylene blue using Ni doped CdS photocatalyst

Methylene blue (MB) is commonly utilized in chemical indicators, dyes, biological colors, and pharmaceuticals. Its aqueous solution is poisonous and carcinogenic, posing a significant threat to the ecological environment. The wurtzite-phase NixCd1−xS was synthesized using the hydrothermal technique in this study. Ni doped CdS enhanced its photocatalytic efficiency and resistance to photocorrosion, enabling its application in the photocatalytic destruction of MB. The incorporation of Ni did not change the crystal structure and microstructure of CdS, but increased the visible light absorption range and decreased the band gap width slightly, which promoted the migration of photogenerated electrons and reduced their recombination with holes, resulting in higher photogenerated carrier separation efficiency of NixCd1−xS. The photocatalytic decolorization rate of Ni0.06Cd0.94S for 100 mL of 10 mg/L MB at 240 min is 91.3 %, and the reaction rate constant is 0.01102 min−1, which is 4.42 times that of wurtzite-phase CdS. The photocatalytic mechanism of NixCd1−xS and its composite was analyzed using trap experiments in conjunction with the band structure of the sample. Additionally, the stability of NixCd1−xS was evaluated. The results indicated that the stability was superior to that of CdS. The findings demonstrate that Ni0.06Cd0.94S exhibits good catalytic activity and stability, making it a viable catalyst for the photocatalytic degradation of organic pollutants in water.

Biosynthesis of copper nanoparticles using Bacillus flexus and estimation of their potential for decolorization of azo dyes and textile wastewater treatment

In many underdeveloped countries, textile industries discharge their effluents without any treatment. The untreated textile wastewater consists of both azo dyes and heavy metals which not only change the physicochemical and biological properties of soil and water but also affect human health. In recent years, copper-based nanomaterials have attained worldwide attention because of their unique properties and potential for decolorization of azo dyes and wastewater treatment. The present study demonstrates the bacterial synthesis of copper nanoparticles (Cu-NPs) using Bacillus flexus strain isolated from a textile wastewater followed by their application for photocatalytic degradation of various azo dyes and treatment of actual wastewater. The FT-IR analysis confirmed the presence of various functional groups including proteins on Cu-NPs which improved their stability. The scanning electron microscopy (SEM) images revealed the spherical shape of Cu-NPs with a size of range between 17–34 nm. Similarly, the XRD analysis of biosynthesized Cu-NPs showed various diffraction peaks at 44.5°, 51.5°, 74.75 which confirmed the crystalline nature of nanoparticles. While studying the photocatalytic decolorization of azo dyes by Cu-NPs, it was observed that 88.164 ± 0.19 %, 88.452 ± 1.89 %, 90.433 ± 1.81 %, 64.770 ± 1.02 %, 46.774 ± 1.61 %, and 67.274 ± 2.89 % of reactive black-5, congo red, malachite green, methylene blue, reactive red-2 and blue direct, respectively, were decolorized after 4 h of solar irradiation at 50 ppm concentration. Additionally, the biosynthesized nanoparticles also resulted in reduction of various parameters like EC, pH, TDS, COD, color intensity, sulphates, and phosphates in the textiles wastewater. The reduction of COD, sulfates, and phosphates was about 39.659 %, 43.157 %, and 49.493 %. The results of current work suggest that biosynthesized copper nanoparticles might serve as a potential green solution for the decolorization of various dyes including wastewater treatment.

Biomineralization induced synthesis and self-assembly of photocatalyst-enzyme hybrid system for highly efficient environmental remediation

The photocatalyst-enzyme hybrid systems (PEHSs) provided a promising method for environmental remediation by simultaneously harnessing the power of solar-energy conversion and biocatalysis. However, the use of PEHSs for environmental remediation was restricted by a complicated synthesis and assembly process. This work explored a simple one-pot biomineralization approach to fabricate PEHS. It was found that the cytochrome enzyme could be directly self-assembled onto the biosynthesized CdS during biomineralization by Shewanella oneidensis MR-1. More strikingly, those attached cytochrome enzymes could efficiently receive the photoelectrons from the CdS and serve as the photoreduction center which formed a typical PEHS. Impressively, this bio-CdS-cytochrome PEHS exhibited an extremely high photocatalytic decolorization rate of 69.4 mg/g/min, which was the highest record ever reported for procion red H-E3B. This work provided a simple and facile approach for PEHSs fabrication, which would be promising for practical application in environmental remediation.

Facile fabrication of MoS2 and MoSe2 layered structures on Mo foil for the efficient photocatalytic dye degradation and electrocatalytic hydrogen evolution reaction

The rapidly growing necessity for sustainable materials in fields such as energy, environmental science, and medicine, two dimensional-based photo- and electro-catalysts has obtained mounting consideration. A simple methodology was employed to fabricate MoSe2 and MoS2 layered structures on flexible Mo foil as heterogeneous catalysts for the electrocatalytic hydrogen evolution reaction (HER) and the photocatalytic decolorization of chromic red (CR) and methylene blue (MB) dyes. The structural characteristics confirm the formation of the multi-layer thick MoSe2 and MoS2 nanofilms. The toxic MB and CR dyes were rapidly and effectively decolorized in polluted water by the photocatalysts within 30 min of UV-light irradiation. The fabricated layered structures exhibited favorable HER electrocatalytic activities along with low overpotentials, small Tafel slopes, and excellent 24-h stability performances. The strong catalytic behavior of these structures fabricated on Mo foil in relation to the HER reaction and the dye decolorization process make them suitable candidates for the catalyst industry.

Green synthesis and characterization of silver nanoparticles from sandalwood (Santalum album L.) extract for efficient catalytic reduction, antioxidant and antibacterial activity

Metal nanoparticles that have been manufactured in a green environment have been recognized as potentially useful materials for the development of nanomedicine due to the fact that they are eco-friendly, non-toxic, and durable. Silver nanoparticles (AgNPs) have been demonstrated to be beneficial in a variety of applications, including those in the fields of biomedicine and environmental protection, according to research. Our study aims to prepare AgNPs using sandalwood (Santalum album L.) extract. Sandalwood-based silver nanoparticles (SW-AgNPs) that were characterized using a variety of techniques, including UV–Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray (SEM-EDS) analysis. The antioxidant activity of the produced SW-AgNPs was examined in relation to the radical scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and showed a maximum of 80.21 ± 0.91% after the concentration of SW-AgNPs was set at 500 μg/mL. The antibacterial efficiency of SW-AgNPs was tested against infection causing bacteria (Staphylococcus aureus and Pseudomonas aeruginosa) with zones of inhibition of 17.2 and 12.3 mm, respectively. The SW-AgNPs showed photocatalytic decolorization efficiency of around 71.3% and 92.14% for the Malachite green (MG), methylene blue (MB) dyes respectively, after a 150 min incubation. The results that were obtained therefore present a potential way for the green synthesis of SW-AgNPs utilizing S. album L. extract, which has significant applications in the fields of biopharmaceuticals and catalysis.

Efficient photocatalytic decolorization of textile wastewater using Fe-Mo LDH/ZnO nanocomposite: A sustainable approach for environmental remediation

The efficient treatment of dye-contaminated wastewater using environmentally friendly technologies holds considerable significance. This study delves into the synthesis of Iron-Molybdenum Layered Double Hydroxide/Zinc Oxide (Fe-Mo LDH/ZnO) nanocomposite using a hydrothermal technique and evaluating its performance in adsorption and photocatalysis for decolorizing textile wastewater under ultraviolet (UV) irradiation. The synthesized photocatalyst was characterized through various analytical techniques, including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDX), Elemental mapping, Vibrating sample magnetometer (VSM), Diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET), Photoluminescence spectroscopy, and Transient photocurrent density analyses. Additionally, the study investigated the impact of different parameters such as pH, contact time, photocatalyst amount, and oxidant amount on dye removal efficiency using central composite design (CCD) experiments. Optimal conditions resulted in an impressive 97.50 % dye removal efficiency, achieved with 0.75 g/L of Fe-Mo LDH/ZnO, 0.095 M of sodium persulfate as the oxidizing agent, 156 min of contact time, and adjustment the pH of the wastewater to 3.1. The dye removal process followed pseudo-first-order kinetics, with a maximum adsorption capacity at 25 °C of 28.33 mg/g. Moreover, the photocatalyst maintained its efficiency over 5 cycles, showing no significant reduction in dye removal efficiency, which indicates its reusability and cost-effectiveness for practical applications. This research demonstrates the desirable potential of Fe-Mo LDH/ZnO nanocomposite as a highly efficient and environmentally friendly photocatalytic adsorbent for the treatment of dye wastewater, providing valuable insights for sustainable water resource management and pollution control strategies.

Photocatalytic decolorization of textile effluent over ZnO nanoparticles immobilized on eucalyptus bark biochar: Parametric optimization, kinetic and economic analyses

Heterogeneous photocatalysis via combination of semiconductor-based material and light is considered one of the most promising advanced oxidation processes for degradation of non-biodegradable contaminants of drinking water and industrial effluents into harmless species. This work delves into the preparation and photocatalytic evaluation of ZnO nanoparticles doped with eucalyptus bark biochar (ZnO@EB) developed via sol-gel-hydrothermal method. Varying amounts (10–50 wt %) of ZnO nanoparticles were incorporated into the eucalyptus biochar (EB) framework, followed by hydrothermal treatment at 110 °C for 24 h, and 1.5 g of ZnO immobilized on 3.5 g of EB (30%ZnO@EB) exhibited excellent activity for photocatalytic degradation of dye in textile industry effluent. The photocatalytic decolorization of textile effluent under solar light irradiation using the 30%ZnO@EB composite was optimized. Influence of operational parameters on the decolorization efficiency of textile effluent was evaluated by the Box-Behnken design. Optimization results showed that the maximum decolorization efficiency of 94.8 ± 1.09% was achieved at the optimum conditions of 2.99 g/L photocatalyst dosage, 3.04 effluent pH and 101.7 min irradiation time. The pseudo-first-order Langmuir-Hinshelwood model with apparent rate constants of 0.029± 0.44, 0.027± 0.71 and 0.023± 0.08 min−1 (at effluent pH of 3, 7 and 11, respectively) excellently predicted the photocatalytic degradation kinetic. Additionally, the spent 30%ZnO@EB composite was easily separated from the treated solution and reused up to ten times for decolorization process without significant activity loss.

Removal of acid violet 7 from aqueous solution with polymer matrix composite particles by adsorption and photocatalytic decolorization methods: isotherms, kinetics, and thermodynamic studies

ABSTRACT A stable and efficient [m-poly(EGDMA-2-VP)]-TiO2 photocatalyst with magnetically separable UV light activated is synthesised and evaluated for the photodegradation and adsorption of Acid Violet 7 (AV7) dye. The polymer particles synthesised were analysed via Scanning electron microscopy ;(SEM) and energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer – Emmett – Teller (BET) and Electron spin resonance (ESR) techniques. The pH (3, 5, 7 and 9), polymer amount (0.01–0.09 g), initial dyestuff concentration (30, 50, 100, 200, 300, 400 and 500 mg/L), and temperature (277, 293, 318 and 338 K) parameters affecting the adsorption were investigated. The residual dye concentration was read at 517 nm by using a UV-vis spectrophotometer. The best adsorption efficiency (97%) was achieved with 30 mg/L dyestuff solution and 0.01 gram of the polymer at pH 3 at 65°C. The Langmuir isotherm model and the second-order kinetic model were found to agree very well with the experimental data. According to thermodynamic parameters, the adsorption is endothermic and spontaneous. The photocatalytic decolorization was carried out under 395 nm UV light to increase the remaining dyestuffs in the solution. As a result, 99% efficiency was obtained from the removal of dyestuffs from the aqueous solution. The decolorization mechanism is described by The Langmuir-Hinshelwood (L-H) model. The degradation of AV7 has also been confirmed by COD measurements. A slight, gradual decrease (from 93.03% to 75.93%) in the photocatalytic activity is observed during repeated cycles of degradation experiment. Thus, the [m-poly(EGDMA-2-VP)]-TiO2 polymer particles possesses efficient adsorptivity and photocatalytic property for AV7 degradation. The magnetic properties of the polymer particles eliminate the risk of secondary pollution and easy recovery of the catalyst.

A performance comparison of photo-fenton decolorization of methylene blue by using bentonite/iron composites prepared by liquid phase and solid phase ion exchange method

Nowadays, there is a wide range of pollutants present, which requires the treatment of wastewater. The photo-Fenton method has been recognized as valuable in this area. In this study, iron/bentonite composites were created using both liquid phase and solid phase iron exchange techniques, and they were utilized as a photocatalyst for the degradation of methylene blue through photo-Fenton process. Various factors affecting the photocatalytic decolorization were investigated, including the initial concentration of the dye, weight of the catalyst, pH of the solution, and concentration of hydrogen peroxide. The decolorization efficiency of the iron/bentonite composites prepared using the solid phase and liquid phase ion exchange approaches was found to be 99% and 95%, respectively. Based on the data, it can be concluded that the performance of both catalysts was almost equally influenced by the initial dye concentration, catalyst weight, solution pH, and hydrogen peroxide concentration. Moreover, the solid phase ion exchange method demonstrated greater reusability compared to the liquid phase ion exchange method. Consequently, it can be stated that the solid phase ion exchange approach is a suitable and straightforward alternative to the conventional liquid phase ion exchange method for producing a photo-Fenton catalyst.

Synthesis and characterization of 1-vinyl-1,2,4-triazole, m-poly(EGDMA-VTA)-TiO2 polymer composite particles and the using of Reactive Orange 16 dye in adsorption and photocatalytic decolorization

Synthesis and characterization of 1-vinyl-1,2,4-triazole, m-poly(EGDMA-VTA)-TiO2 polymer composite particles and the using of Reactive Orange 16 dye in adsorption and photocatalytic decolorization

Effect of the Magnetostriction Induced on the Crystalline Structure of Nanoparticulate TiO2 Films Supported on Stainless Steel Mesh Electrodes and Their Relationship with the Photocatalytic Decoloration of Aqueous Orange G Solutions

The study of ferromagnetism (FM) in non-cubic semiconductor oxides such as defective TiO2 is attractive due to their applications in photocatalysis [1]. FM can be activated in TiO2 nanomaterials by promoting oxygen vacancies (VO) located in paramagnetic defected sites Ti3+VOTi4+. In this context, the VO can induce in Ti3+-doped TiO2 structures remarkable magnetic anisotropy energy (MAE) of 6.51x106 erg/cm3, thus indicating the magnetic saturation should be achieved at magnetic fields (MFs) of ~425 gauss [2,3]. Therefore, magnetostriction can be observed in ferromagnetic TiO2 films as a phenomenon in which their dimensions and shapes are changed when they are magnetized. In this work, stainless steel mesh electrodes (ss) were modified by nanoparticulate TiO2 films (ssTiO2) enriched by Ti3+VOTi4+ sites, to gain an understanding of the effects of magnetostriction on the photocatalytic properties of ferromagnetic TiO2 electrodes. In this way, MFs having intensities (H) of 125, 250, 500, 1000, and 2000 gauss were applied to the ssTiO2 electrodes for 80 min under UV light illumination for increasing the number of Ti3+VOTi4+ sites. Our results revealed that the magnetic lines promoted compression of the TiO2 structure when achieving pressures p>4.67 GPa for H>425 gauss in p=1/2(MAE/4p gauss2)H 2. Consequently, the degree of disorder (0<b<1) of the electron traps at the intra-bandgap state's distribution along the thickness-axis(i.e. the x-axis) of TiO2 films decreased significantly because the fraction of trapped electrons f trap(x) at the quasi-Fermi level EF(x) was maximized according to f trap(x)=m[em (E F (x)-E F (0))-1], where m=kT/b (k and T are the Boltzmann constant and the absolute temperature) [4,5]. Later, it was observed a significant increase of trapped holes able to carry out the direct photocatalytic oxidation of aqueous orange G (without electron scavenger’s assistance, e.g. gaseous O2). On the other hand, the photogeneration of oxidant •OH radicals decreased dramatically while H increased [6].[1] Y. Bian et al., RCS Adv., 11(2021)6284.; [2] D. Kim et al., J. Phys.: Condens. Matter,21(2009)195405.; [3] B. Shao et al., J. Appl. Phys.,115(2014)17A915. [4] N. Kopidakis et al., J. Phys. Chem. B, 107(2003)11307. [5] J. van de Lagemaat et al., J. Phys. Chem. B,104(2000)4292. [6] K.-I Ishibashi et al., J.Photochem.Photobiol.A,134(2000)139-142. Acknowledgements The authors thank the National Council for Science and Technology (CONACyT) Mexico for the funding support (grants CB No. 258789 and FOINS No. 3838). JIVN thanks CONACyT for his doctoral fellowship support (grant No. 893260).

Novel biocomposite (Starch/metal–organic framework /Graphene oxide): Synthesis, characterization and visible light assisted dye degradation

Herein a new efficient biocomposites containing Starch metal–organic framework (MIL88A) and graphene oxide (Starch/MIL88A/GO) with different amounts of starch (0.05 0.1 and 0.2 g denoted as SMGO-0.5 SMGO-1 and SMGO-2) was synthesized characterized and used to degrade Acid Blue 92 (AB92). Decolorization efficiency was 7.4 % for Starch 19.4 % for GO 86 % for MIL88A and 90–98.5 % for Starch/MIL88A/GO composites (90 % for SMGO-0.5 96 % for SMGO-1 and 98.5 % for SMGO-2) using visible light. SMGO-2 composite showed the highest degradation ability. The effect of catalyst dosage and contaminant concentration on decolorization percentage was investigated. The efficiency of photocatalytic decolorization using 0 4 6 8 and 10 mg of Starch/MIL88A/GO are as follow: 10 55 89 93 and 98.5 % respectively. The results indicate that the decolorization by Starch/MIL88A/GO decreases as the initial pollutant concentration increases. Different decolorization kinetics (zero-order first-order and second-order) were studied. The reaction followed the zero-order kinetics. The zero-order decolorization rate constant for 0 4 6 8 and 10 mg of Starch/MIL88A/GO were 0.0134 0.1086 0.1182 0.1308 and 0.1727 respectively. The Starch/MIL88A/GO had high reusability (95 % after five cycles). The results indicated that the synthesized biocomposite (Starch/MIL88A/GO) could be used as an efficient photocatalyst to remove dye from the colored wastewater.

NH&lt;sub&gt;2&lt;/sub&gt;-modification Copper Metal-organic Framework as a Sunlight Photocatalyst for the Removal of Organic Dyes from Aqueous Solution

Dyes present in wastewater pose a threat to aquatic organisms and cannot be effectively eliminated by conventional biochemical treatment methods. As an alternative, the photocatalytic decolorization of dyes has emerged as a cost-effective and environmentally friendly approach. Two 1,3,5-benzenetricarboxylate (BTC)-based metal-organic frameworks (MOFs), CuBTC and CuBTC-NH2, were synthesized and used for the removal of two anionic dyes, namely Reactive Blue 171 and Acid Blue 1, from wastewater under sunlight irradiation. The structural and morphological characteristics of the MOFs were identified using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Compared to CuBTC, CuBTC-NH2 exhibited excellent photocatalytic activity. The successful degradation of 90% of the dyes was observed within 24 h of sunlight exposure using CuBTC-NH2, while only 70% degradation was achieved with CuBTC. The weak basic nature of the dye wastewater (pH 8-10) was found to facilitate the degradation process. CuBTC-NH2 was not only efficient in the removal of dyes but could also be recycled and reused for at least five cycles. In the process of photocatalytic degradation, the diazo bond of dyes in ortho-position to the amino substitution on the aromatic ring was attacked first. These results provide insights into the design of MOF catalysts for dye removal under visible-light irradiation.

TiO2-functionalized biochar from pistachio nutshells: adsorptive removal and photocatalytic decolorization of methyl orange

Pistachio nutshells-derived biochar (PNS-BC) was utilized as a cost-effective adsorbent for competently removing a model dye, methyl orange (MO) from wastewater. Three concentrations of TiO2; 1%, 2%, and 3% were used to decorate the biochar. Analysis of morphology, stability, and structure of the three adsorbents (PNS, PNS-BC, and the TiO2 functionalized biochar; TiO2@PNS-BC) was extensively explored using various characterization techniques. The synergistic photocatalytic-adsorptive efficiency of the three adsorbents was compared. In this regard, a Box-Behnken (BB) design-based multivariate scheme was inaugurated with the target of maximizing MO removal (%R) while using the minimum possible of chemicals and resources. The impact of five variables; %TiO2, dose of TiO2-PNS, reaction time, dye concentration, and pH on the magnitude of %R was investigated. Results show that 97.69% removal of MO could be recognized over 120 min using adsorption compared to 99.47% removal over 30 min using 3% TiO2@PNS-BC as a photocatalyst. A 3% TiO2@PNS-BC was the best catalyst (compared to 1% and 2%) with a decolorization rate constant of 0.12741 min−1, ~ 1.5 × faster compared to the decolorization of MO using adsorption alone. Adsorption of MO conformed well to Langmuir isotherm. A maximum adsorption capacity (qmax) of 142.38 mg/g was achieved. Adsorption kinetics fitted well with the pseudo-second order (PSO) model. Results obtained indicated that biochar of PNS is a promising, cost-effective, and economical adsorbent.

Facile auto-flash-combustion synthesis and characterization of visible-light-driven photocatalytic active Mn (II, III) loaded NiO nanoparticles

The opto-photocatalytic applications of Mn-doped NiO nanoparticles (NPs) are discussed. A facile synthesis of NiO doped with different Mn contents is performed and studied using experimental techniques. The structural properties and microstructural parameters of Mn:NiO NPs were examined by X-ray diffraction patterns. The average crystallite sizes of the pure NiO and 1.0-, 2.5-, 5.0-, 10-wt.% Mn-doped NiO NPs were found to be 25–19 nm by Williamson–Hall plots and 23–18 nm by the Debye–Scherer method. The crystallite size decreases with increasing doping concentration in the NiO host lattice. The optical bandgaps are found to be 3.53, 3.46, 3.39, 3.24, and 3.12 eV for pure NiO and 1.0-, 2.5-, 5.0-, and 10-wt.% Mn:NiO NPs, respectively, using the Kubelka–Munk function. X-ray photoelectron spectroscopy spectra of 2.5-wt.% Mn:NiO NPs were recorded for Mn, Ni, and O to determine the oxidation states. The photocatalytic performances of pure NiO and Mn:NiO NPs are examined. The 2.5-wt.% Mn:NPs exhibit the best photocatalytic performance owing to the greatest activation sites. The mechanism of the photocatalytic decolorization reaction is also investigated. The results demonstrate the high ability of Mn:NiO NPs as photocatalysts for methylene blue dye degradation, with 92% removal.