Photocatalytic Degradation Of Rhodamine B Dye Research Articles

Ni-Doped LaFeO3 Microspheres Composed of Nanoparticles for the Photocatalytic Degradation of Organic Dye

Ni-doped LaFeO3 (LFO) microsphere consisting of nanoparticles are synthesized by the hydrothermal route and used for the degradation of Rhodamine B (RhB) organic dye. The structural, morphological, and optical analysis is confirmed by the various characterization techniques, i.e., X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV-Visible spectroscopy. The all Ni-doped LFO catalyst shows excellent efficiency towards the photocatalytic degradation of RhB dye. LFNO-0.2 catalyst shows the highest degradation efficiency of 89.44% with rate constant (k) and correlation coefficient (R2) of 0.013304 min-1 and 0.989, respectively. The radical scavenging suggests the active involvement of O2- and h+ participates in the efficient degradation. Moreover, the material possesses excellent cyclic stability for the continuous Xenon lamp exposure of 540 min. Overall, the Ni-doped LFO can serve as one of the finest materials for wastewater remediation by means of photocatalytic dye degradation.

Eco-friendly Synthesis of γ-Fe2 O3–Ag–ZnO Nanocomposite with Antibacterial and RhB Dye Degradation Properties Using Leaf Extract

In this study, the photocatalytic degradation of RhB dye in an aqueous solution using ZnO nanoparticles (NPs), [Formula: see text]-Fe2O3, [Formula: see text]-Fe2O3–ZnO, Ag–ZnO, and [Formula: see text]-Fe2O3–Ag–ZnO nanomaterials generated using poinciana leaf extract is presented. The nanomaterials were prepared utilizing environmentally friendly methods and poinciana leaf extract. The properties of the originally generated nanomaterials, analyzed through techniques such as atomic force microscopy (AFM), UV–visible spectroscopy, X-ray, electron microscopy, and FE-SEM, have been described. The hexagonal structure of ZnO wurtzite was also discovered to align with the XRD findings. Additionally, EDX mapping was employed to analyze the composition of the [Formula: see text]-Fe2O3–Ag–ZnO nanocomposite. A topological investigation confirmed the roughness of the created nanostructures. Regarding the photocatalytic Rhodamine B (RhB) dye degradation studies, the [Formula: see text]-Fe2O3–Ag–ZnO nanocomposite demonstrated superior performance compared to pure ZnO in breaking down dye molecules under visible light exposure. Employing an ideal configuration of 1.0 g/L of photocatalyst, pH 10, and 10 ppm of RhB, an impressive photodegradation effectiveness of nearly 99% was achieved in just 45 min of light exposure. An analysis of reactive species was conducted to determine the photodegradation efficiency of [Formula: see text]-Fe2O3–Ag–ZnO. To investigate the impact of the microorganisms Escherichia coli and Staphylococcus aureus on the [Formula: see text]-Fe2O3–Ag–ZnO nanocomposite, the results indicated that the [Formula: see text]-Fe2O3–Ag–ZnO nanocomposite achieved a high rate of success in neutralizing and eradicating these bacteria.

Aminated graphene quantum dots/CdS nanobelts for enhanced photocatalytic degradation of RhB dye under visible light.

CdS nanoparticles have wide applications as photocatalysts for degradation of organic pollutants, but due to their limited turnover number and off-pathway charge recombination processes, their degradation efficiency is low. Herein, aminated graphene quantum dots/CdS (GQDs/CdS) nanobelts were successfully fabricated by solvothermal and hydrothermal processes. The prepared GQDs/CdS were characterized by physical methods to investigate their structure, morphology, optical properties, specific surface area, element composition, and chemical state. GQDs/CdS materials promoted efficient charge separation, and showed high efficiency in the photocatalytic degradation of the organic dye Rhodamine B (RhB) under visible light. The degradation efficiency of RhB samples over 0.05 g of catalysts reached 97.40% after 150 min, a much higher efficiency in comparison to pure CdS. Electron paramagnetic resonance (EPR) spectroscopy provided direct evidence for ˙OH and ˙O2- as the reactive oxidative species using DMPO as a spin trap. Consistent with the experimental results, a possible mechanism of RhB photocatalytic degradation by GQDs/CdS under visible light was proposed. This work may provide environmentally friendly photocatalysts for degrading organic dyes and purifying water.

Fabrication of ZnxMn1-xFe2O4 metal ferrites for boosted photocatalytic degradation of Rhodamine-B dye

The use of dyes increased with the development of Iraq's textile industry. Synthetic dyes are still widely used because of the various benefits they provide. However, synthetic colors do not biodegrade; therefore, their release into the environment could be harmful. In this study, simple coprecipitation was used to produce multi metal ferrites (ZnxMn1-xFe2O4) as photocatalysts for the degradation of the synthetic dye Rhodamine B (Rh B). The XRD, EDX, SEM, BET, DRS, and VSM”techniques were used to analyze the produced materials. Photodegradation efficiencies were tested by varying reaction parameters such pH, catalyst dosage, H2O2 addition, dye concentration, and irradiationtime. It was found that the Zn0.7Mn0.3Fe2O4 sample decomposed more rapidly under some conditions. A 99% degradation was achieved after 180 min of radiation exposure in a mixture with a pH of 3.0, a catalyst dose of 1 g/L, a Rh B concentration of 20 mg/L, and 1 mL of hydrogen peroxide. Also analyzed were processes for removing “total organic carbon” (TOC) and “chemical oxygen demand” (COD). Rh B at a concentration of 20 ppm was most effective at removing both TOC (75%) and COD (80%).

Visible light-driven photocatalytic degradation of Rhodamine B dye onto TiO2/rGO nanocomposites

In the current study, a series of reduced graphene oxide coated titanium dioxide nanocomposites (TiO 2 /rGO) were fabricated via a simple hydrothermal synthetic route using graphite flakes and titanium (IV) oxysulfate - sulfuric acid hydrate as precursors for rGO and TiO 2 synthesis, respectively. The TiO 2 /rGO nanocomposites were fabricated with various weight ratios of rGO (5, 10, and 15%) and their photocatalytic activity against Rhodamine B (RhB) dye removal was investigated. The composition, optical activity, morphology, and porosity of the obtained nanomaterials were determined using different techniques, including X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), UV-Vis diffuse reflectance spectroscopy (DRS) and Raman spectroscopy. Hence the XRD results showed that the TiO 2 /rGO nanocomposites were successfully fabricated. The TEM images exhibited the efficient distribution of TiO 2 NPs on the rGO nanosheets. The significant structural changes in TiO 2 /rGO nanocomposites were reflected in the Raman spectra, indicating nanocomposite hybridization. The optical bandgap of the as-synthesized nanomaterials was slightly shifted from 3.14 eV (bare TiO 2 ) to 2.75 eV (TiO 2 /rGO 15%). Based on the photocatalytic degradation results, the best removal percentage of RhB dye was approached by TiO 2 /rGO (5%) at optimum conditions ([RhB]= 15 ppm, pH 9, catalyst dose= 1.2 g/L, and irradiation time= 120 min). The highly efficient TiO 2 /rGO (5%) nanocomposite showed enhanced photocatalytic behavior for the degradation of RhB dye, with a maximum removal percentage of (∼94.55%). Various reactive oxygen species (ROS) scavengers were employed to study the mechanism of photocatalytic degradation of RhB dye. The TiO 2 /rGO (5%) nanocomposite showed good cycling stability for five cycles. • The TiO 2 /rGO nanocomposites were fabricated with various weight ratios of rGO (5, 10, and 15%) • The morphological images exhibited the efficient distribution of TiO 2 NPs on the rGO nanosheets. • The UV-Vis spectra showed that the bandgap values of the nanocomposites decreased with increasing the concentration of the reduced graphene oxide. • The highly efficient TiO 2 /rGO (5%) nanocomposite showed enhanced photocatalytic behavior for the degradation of RhB dye, with a maximum removal percentage of (∼94.55%).

BiOBr/ZnWO4 heterostructures: An important key player for enhanced photocatalytic degradation of rhodamine B dye and antibiotic ciprofloxacin

We report a facile synthesis of p-BiOBr/n-ZnWO4 heterostructures by hydrothermal/precipitation method as an important key player to enhance the photocatalytic degradation of Rhodamine B (RhB) dye and ciprofloxacin antibiotic. The structural and microstructural features confirm that p-BiOBr/n-ZnWO4 heterostructures display a mixed tetragonal/monoclinic phase with the presence of several n-ZnWO4 nanocrystals on the surface of petals of flower-like p-BiOBr microcrystals. X-ray photoluminescence (XPS) analysis of BiOBr exhibits the existence of Bi, O, and Br, whereas BiOBr/ZnWO4-5%, in addition to Bi, O, and Br, consist of signature of Zn and W. UV–Visible spectra of p-BiOBr/n-ZnWO4-5% showed better absorption than p-BiOBr and n-ZnWO4, which displayed an enhanced collection of photons in the heterojunction. An intense photoluminescence emission at room temperature was observed for p-BiOBr microcrystals as compared to p-BiOBr/n-ZnWO4. We observed the best photocatalytic activity for p-BiOBr/n-ZnWO4-2.5% in the degradation of RhB dye at 99.4% in 25 min and CIP antibiotic at 58.2% in 170 min, which is assigned due to high surface area SBET (13 m2/g), pore size, providing active catalytic sites for bonding chemical and surface interaction and bonding chemical between the bromide/oxides. Finally, we have investigated the use of scavengers for isopropanol, benzoquinone, and sodium azide, which proves that the hydroxyl (•OH) and superoxide (O2′) radicals as the foremost reactive oxygen spicies (ROS) in photocatalytic degradation of RhB dye and antibiotic CIP.

Uv Photocatalytic Degradation of Rhodamineb Dye Using Sol-Gel Mediated Ultrasonic Hydrothermal Synthesized Zno Nanoparticles

Uv Photocatalytic Degradation of Rhodamineb Dye Using Sol-Gel Mediated Ultrasonic Hydrothermal Synthesized Zno Nanoparticles

Enhanced photocatalytic degradation of RhB dye from aqueous solution by biogenic catalyst Ag@ZnO

In the present work, ZnO and Ag@ZnO nanoparticles based photocatalyst were synthesized via green route by using the leaves extract of pecan nuts (Carya illinoinensis) for the first time. The phytochemicals present in leaf of extract pecan nuts (Carya illinoinensis) such as methyl gallate and kaempferol act as capping and reducing agents. The obtained photocatalyst were analyzed via various techniques such as XRD (X-ray diffraction), TEM (transmission electron microscopy), SEM (scanning electron microscopy), FTIR (Fourier transform infrared spectroscopy), PL (Photoluminescence spectroscopy), XPS (X-ray photoelectron spectroscopy) and UV (UV–visible spectroscopy). The activity of biogenic photocatalyst were investigated against RhB (Rhodamine B) dye and the results demonstrated that the catalytic properties become enhanced significantly after Ag doping as compared to bare ZnO. The effect of various parameters were also investigated such as pH, catalyst dose, initial concentration of dye. The obtained results showed highest efficacy of catalyst at pH 10, further the photo-degradation of Rhodamine B (RhB) dye followed pseudo first order kinetic model. The reusability test of biogenic photocatalyst revealed that the catalyst was an excellent option for practical use with high stability even after 5 cycles. The mechanism for, ZnO and Ag@ZnO synthesis and degradation pathway of RhB dye was proposed.

Energy band gap tuning of LaNiO3 by Gd, Fe and Co ions doping to enhance solar light absorption for efficient photocatalytic degradation of RhB dye: A mechanistic approach

A series of Gd, Co and Fe substituted LaNiO3 perovskite oxides were synthesized via microemulsion approach. The influence of dopants was investigated on the basis of ferroelectric, dielectric and photocatalytic properties. X-ray diffraction, Raman spectroscopy, scanning electron microscopy and UV–Visible spectroscopic techniques were employed for the characterization of prepared samples. XRD analysis confirmed the distorted rhombohedral phase with space group R3¯c and the grain size was in 65–48 nm range. The ferroelectric and dielectric parameters including AC conductivity were increased except AC resistivity with dopant contents. The band gap energy was reduced significantly in doped samples from 3.01 to 2.43 eV. A decrease in PL (photoluminescence) intensity was also observed in doped samples. The PCA (photocatalytic activity) of pure and substituted LaNiO3 was studied by photodegradation of RhB (rhodamine B) dye under visible light exposure. The LNGCF5 (x = y = 0.25) composition exhibited superior PCA of 97% within 120 min irradiation time in comparison to pure LaNiO3. The rate constants for LaNiO3 and LNGCF5 were 0.006 min−1 and 0.0096 min−1, respectively. Furthermore, effect of catalyst load and pH on kinetics of PCA was also studied, which affected the RhB dye degradation significantly. The enhanced dielectric constant and AC conductivity of LNGCF (1–5) introduce these materials as potential candidates for dielectric resonator and memories devices. The increased ferroelectric polarization along with low band gap energy improved their ferroelectric photovoltaic response, which makes their feasibility in photovoltaic devices. Superior PCA of LNGCF5 under visible illumination in comparison to pure LaNiO3 introduces this material as promising photocatalyst for the removal of hazardous and toxic dyes in effluents under solar light irradiation.

Preparation of titanium dioxide modified biomass polymer microspheres for photocatalytic degradation of rhodamine-B dye and tetracycline

Photocatalysis, in which carcinogenic compounds are decomposed into harmless products, is the most promising method for the eco-friendly degradation of wastewater pollutants. This study investigated a novel bio-based polymeric microsphere photocatalyst produced via the precipitation polymerization of widely available biomass-derived phenylpropenes trans-anethole (ANE) and N-phenylmaleimide (N-PMI). Amino-modified TiO2 nanoparticles were grafted onto the surfaces of the microspheres, thereby producing Poly[ANE+N-PMI]-TiO2 microspheres using photocatalysis. The microspheres were used as photocatalysts for the degradation of rhodamine B (RhB) dye and tetracycline (TC) antibiotics in wastewater, where 95% and 97% degradation rates were achieved for 50 mg·L-1 RhB and 100 mg·L-1 TC, respectively. The microsphere photocatalyst exhibited high stability and recyclability, and maintained excellent photocatalytic performance during continued cycling. Kinetic studies demonstrated that the photocatalytic degradation of RhB and TC proceeded according to a pseudo-first-order kinetics model. Furthermore, superoxide free radicals (·O2−) and hydroxyl radicals (·OH) were the primary and secondary reactive species during photo-degradation. Overall, the excellent performance of the simple TiO2-based photocatalyst was clearly demonstrated, and its numerous advantages, such as low energy consumption, low cost, non-toxicity, and environmental friendliness, highlight its promising practical applications.

Fabrication and characterization of B/Sn-doped ZnO nanoparticles via mechanochemical method for photocatalytic degradation of rhodamine B

Undoped and B/Sn-doped ZnO nanoparticles are successfully produced by a simple mechanochemical method, and are characterized by XRD, FTIR, EDX, SEM, XPS and BET techniques. The XRD studies reveal that the prepared nanoparticles possess the hexagonal wurtzite structure of ZnO. The presence of various functional groups (–OH, –CH, Zn–O) are observed by FTIR. It is clear from EDX analysis that B, Sn, Zn and O elements are present in the nanoparticles. SEM images confirm the relatively smooth surface of B/Sn-doped ZnO nanoparticles. XPS results indicate that B and Sn are successfully doped into ZnO matrix. The photocatalytic performances of undoped and B/Sn-doped ZnO nanoparticles are investigated for the degradation of aqueous solution of Rhodamine B (RhB) dye in natural sunlight irradiation. The photocatalytic degradation of RhB dye in 1 h with B/Sn-doped ZnO nanoparticle is about 70.2%, which is significantly enhanced compared with the undoped ZnO (51.8%).

Reusability of metals/metal oxide coupled zinc oxide nanorods in degradation of rhodamine B dye

Purpose This paper aims to investigate the reusability of metal/metal oxide-coupled ZnO nanorods (ZnO NRs) to degrade rhodamine B (RhB). Design/methodology/approach ZnO NRs particles were synthesized by precipitation method and used to remove various types of metal ions such as Cu2+, Ag+, Mn2+, Ni2+, Pb2+, Cd2+ and Cr2+ ions under UV illumination. The metal/metal oxide-coupled ZnO NRs were characterized by scanning electron microscope, X-ray diffraction and UV-Vis diffuse reflectance. The photodegradation of RhB dye by these metal/metal oxide-coupled ZnO NRs under UV exposure was assessed. Findings The metal/metal oxide-coupled ZnO NRs were successfully reused to remove RhB dye in which more than >90% of RhB dye was degraded under UV exposure. Furthermore, the coupling of Ag, CuO, MnO2, Cd and Ni particles onto the surface of ZnO NRs even enhanced the degradation of dye. The dominant reactive species involved in the degradation of RhB dye were •OH- and •O2−-free radicals. Research limitations/implications The coupling of metal/metal oxide onto the surface of ZnO NRs after metal ions removal could affect the photocatalytic performance of ZnO NRs in the degradation of organic pollutants in subsequent stage. Practical implications A good reusability performance of metal/metal oxide-coupled ZnO NRs make ZnO NRs become a desirable photocatalyst material for the treatment of wastewater, which consists of both heavy metal ions and organic dyes. Originality/value Metal/metal oxide coupling onto the surface of ZnO NRs particles improved subsequent UV-assisted photocatalytic degradation of RhB dye.

Study of the Photocatalytic Activity Using Silica-Based Materials Doped with Silver Nanoparticles for Degradation of Rhodamine B Dye

Rhodamine B (RhB) is a cationic organic dye widely used industrially, mainly in the textile and food industries. Then, the work aims to study on the photocatalytic degradation of RhB dye, under UV and visible radiation, using photocatalyst silica-based materials synthesized by sol-gel route with different solvents (ethanol and n-propanol) and catalysts (C12H27N, HNO3, NH4OH, and NaOH) to the hydrolysis and condensation of tetraorthosilicate (TEOS). In addition, the effect of doping with silver nanoparticles (AgNPs) was evaluated on the photocatalytic activity. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), N2 porosimetry, zeta potential measurements (ZP), and Fourier transform infrared spectroscopy (FTIR). To evaluate the photocatalytic activity, photocatalytic tests were carried out in a stirred batch reactor, with the photocatalyst in suspension, under ultraviolet and visible radiation, and the target molecule chosen was the Rhodamine B dye (RhB). The photocatalyst Si–HNO3–AgNPs showed the best photocatalytic activity with a degradation of the RhB dye of 90.16% (k = 0.0198 min−1, under ultraviolet radiation) and 82.79% (k = 0.0148 min−1, under visible radiation), after 120 min of reaction; while under the same conditions, the commercial catalyst TiO2 (P25) showed a degradation of 50.02% and 42.14%, respectively.

Synthesis of Spin Coated Tungsten Oxide for Photocatalytic Degradation of Rhodamine-B Dye

Optical properties including band gap of many wide band gap semiconductor oxides like TiO2, ZnO and SnO2 has limitations over their bare use in photocatalytic applications. Thus, in view of above, tungsten oxide (WO3), an intermediate band gap metal oxide has been selected to explore for photocatalytic degradation application. Present work deals with the preparation of WO3 using a simple chemical solution based spin coating method. The prepared sample has been characterized for structural, morphological and photocatalytic properties. Degradation experiment of dye was carried out systematically at the optimized conditions of pH 4 and contact time (120 min) between dye and catalyst. For optimized conditions, WO3 showed about 75% of degradation of rhodamine-B. This suggests that a huge scope to optimize preparative parameters for WO3 to explore it as an alternative to conventional metal oxides.

Visible-light-induced enhanced photocatalytic degradation of Rhodamine-B dye using BixSb2-xS3 solid-solution photocatalysts

The present work examines binary solid solutions of BixSb2-xS3 [x = 0.536, 1.09, 1.68] toward photocatalytic degradation of Rhodamine-B (RhB) under visible light. Phase and microstructural analysis confirmed the formation of Bi0.536Sb1.464S3, Bi1.09Sb0.91S3, and Bi1.68Sb0.32S3 solid-solution phase with nanorods (~25–50 nm average diameter) morphology. The synthesized products show outstanding photocatalytic degradation of RhB with ~95–99.5% degradation achieved within 30 min. The kinetic study finds the high degradation efficiency (~98%) of BixSb2-xS3 photocatalysts stems from the amenable band gap (~2.3 eV, confirmed from DRS study), and higher separation efficiency of photogenerated electron-hole pairs (established from PL studies). The complete detoxification of RhB dye was confirmed by quantitative estimation of CO2 post photodegradation through GC analysis. Moreover, due to the solid and hard nature of the photocatalysts, it was easily recovered from the reaction mixture and reused multiple times without losing the degradation behavior. The parallel comparison with other active photocatalysts demonstrates BixSb2-xS3 [x = 0.536, 1.09, 1.68] have higher catalytic efficiency with similar dosing hitherto reported in the literature and possibly can be used for degradation of other organic dyes using the visible spectrum.

Investigation on antibacterial and photocatalytic degradation of Rhodamine-B dye under visible light irradiation by titanium molybdate nanoparticles prepared via microwave method

Titanium molybdate (TM) nanoparticles were synthesized by two different methods using titanium tetrachloride and ammonium molybdate as starting precursor. The obtained nanoparticles were examined by various analytical techniques such as powder XRD, FESEM, HRTEM, UV–visible spectroscopy, PL spectroscopy and FTIR analysis. The tetrahedral phase and crystallite size were determined using powder XRD. The morphology of the samples was examined by FESEM and HRTEM techniques. Titanium molybdate prepared via precipitation method (TM1) shows irregular and unclear morphology whereas titanium molybdate prepared thru microwave method (TM2) exhibits pores and sphere like structure. The elemental composition (EDX) confirms the presence of elements in the order of O > Ti > Mo for TM1 and Mo > Ti > O for TM2 samples. The functional groups were determined using FTIR analysis it exhibits lower frequencies for TM2 than TM1. UV–vis spectra show the optical energy gap of 3.0 eV and 2.78 eV for TM1 and TM2 samples respectively. The antibacterial effect of titanium molybdate (TM2) sample prepared via microwave method was studied in Staphylococcus aurous, Escherichia coli and Pseudomonuas aeruginosa. The obtained results states Staphylococcus aurous has noteworthy antibacterial activity than other two bacterial species. The photocatalytic activity of Rhodamine-B (RhB) under visible light irradiation expounded about 96% of dye was degraded after 150 min for titanium molybdate (TM2).

Effect of organic capping agents on the optical and photocatalytic activity of mesoporous TiO2 nanoparticles by sol–gel method

In this work, the effect of capping agent effects on the structural, morphological, optical properties and photocatalytic removal of Rhodamine B (RhB) dye has been investigated. TiO2 nanoparticles were synthesized by a simple, fast and eco-friendly sol–gel method, in the presence of various capping agents, including ethylenediamine, polyvinyl alcohol (PVA), ethylene glycol, glucose and valine. The obtained TiO2 nanoparticles have been characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis, high resolution scanning electron microscopy and transmission electron microscopy, UV–visible absorption and photoluminescence (PL) spectroscopy. XRD pattern reveals the polycrystalline nature of TiO2 with anatase structure. The results revealed that the optical absorption band of TiO2 nanoparticles varied by capping agents. PL spectra exhibited visible emissions due to the formation of defects in the band gap region of TiO2 nanoparticles. The photocatalytic degradation of RhB dye by synthesized TiO2 nanoparticles using different capping agents was investigated under UV irradiation and the results demonstrated that TiO2 nanoparticles have appreciable photocatalytic activity for decomposing RhB dye when PVA was used as a capping agent. The results explained that the preparation of TiO2 nanoparticles showed a high efficiency in the removal of organic dyes.

Tetragonal to Monoclinic Crystalline Phases Change of BiVO4 via Microwave-Hydrothermal Reaction: In Correlation with Visible-Light-Driven Photocatalytic Performance.

Explicit control of the crystalline phases and morphology of semiconducting BiVO4 crystals has been successfully synthesized via microwave-hydrothermal condition (MW-HT) without requiring any template/surfactant, doping of metal ions, and altering pH of reaction solution. Unambiguously, the crystalline phase of BiVO4 crystal has transformed from tetragonal zircon type ( tz) to monoclinic scheelite ( m) via mixed-phase ( m- tz) by altering microwave-irradiation time at fixed microwave-irradiation power (800 W) without changing any precursor concentrations throughout the reaction. X-ray diffraction and Rietveld refinement studies confirmed the phase transformation of BiVO4 crystals that occurs by controlling the irradiation time (10-22 min) and temperature (116-195 °C). The changes in VO43- tetrahedron bond strength and bond length attributed to phase transitions in BiVO4 crystals were corroborated by Raman spectra. Field emission scanning electron microscope revealed the sequential growth and rational morphological evolution of spherical-shaped zircon type tz-BiVO4 particles to preferentially oriented (010) and (110)-faceted decahedron-shaped scheelite m-BiVO4 crystals. The UV-reflectance and photoluminescence analyses revealed reduction in the optical bandgap and efficient charge separation with tunneling of excitons through interfaces, owing to phase transitions from tetragonal to monoclinic in BiVO4 crystals. High-resolution transmission electron microscopy images revealed the formation of heterojunctions between both the phases of BiVO4 crystals. The photocatalytic degradation of Rhodamine-B dye under natural sunlight showed maximum efficiency of 95% with highest rate kinetics (κavg = 0.0718/min) using mixed-phase BiVO4 ( m: tz-60:40) crystals, whereas under simulated sunlight, monoclinic phase BiVO4 crystals showed high degradation efficiency of 87% with low rate kinetics (κavg= 0.0436/min) for 200 min. The free-radical trapping tests revealed that superoxide radical (•O2) and hydroxyl radical (•OH) are active radicals during photocatalysis. Significantly, the MW-HT synthesized mixed-phase BiVO4 retained photocatalytic activity and structural stability even after three cycles. These findings open possibilities for innovative design of highly efficient semiconductor photocatalyst for environmental remediation applications.

Synergistic effect of organic-inorganic hybrid nanocomposite ion exchanger on photocatalytic degradation of Rhodamine-B dye and heavy metal ion removal from industrial effluents

Present work reports the synthesis of Chitosan-Gelatin @ zirconium (IV) selenophosphate nanocomposite (CH-GEL/ZSPNC) ion exchanger. CH-GEL/ZSPNC was characterized by different characterization techniques using Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopic studies (EDX), High resolution-transmission electron microscopy (HRTEM), powdered X-ray diffraction (PXRD) and Thermal gravimetric analysis (TGA). Physicochemical properties like ion exchange capacity (IEC), thermal stability, elution behaviour, eluent concentration, pH titration, chemical stability and distribution coefficient (Kd) of (CH-GEL/ZSPNC) ion exchanger were investigated. The ion exchange capacity of the synthesized nanocomposite was improved by one and half order (2.4 mequiv/g) as compare to its inorganic moiety (1.6 mequiv/g) and highest among a number of nanocomposite ion exchangers already reported in the literature. CH-GEL/ZSPNC ion exchanger was found to be thermally stable and retained 58.3% ion exchange capacity (IEC) of its original IEC value at 400 °C. Pb (II) and Cu (II) was found to possess the highest values of Kd. Binary separation of divalent heavy metal ions has been conducted on the basis of Kd values. Photocatalytic degradation of the Rhodamine-B (RD-B) dye was explored with CH-GEL/ZSPNC in the solar radiations. It has been investigated that 84% of the RD-B dye was degraded after 160 min of photo exposure. Photodegradation of the RD-B follows the pseudo-first-order kinetics. Thus, the synthesized CH-GEL/ZSPNC ion exchanger is found to be a superior advanced nanocomposite photocatalyst for environmental remediation of dye pollutants, heavy metal ion removal, the binary separations and possessed tremendous reusability potential.

Photocatalytic degradation of Rhodamine-B dye by stable ZnO nanostructures with different calcination temperature induced defects

For developing ZnO as an efficient photocatalyst it needs to embrace a suitable architecture to promote simultaneous maximum photon absorption and minimum charge carrier recombination. In this regard, presently ZnO nanoparticle and nanorod morphologies with embedded pit like structures possessing enriched surface defects, as demonstrated by X-ray diffraction as well as electron microscopic studies, have been prepared using a rapid one-pot co-precipitation technique. Further characterization by electron paramagnetic resonance (EPR), Raman and PL spectroscopy reveal the origin of bulk and surface defects within the nanostructures. Prominent EPR signals with different g-factors e.g., g = 1.93, 1.97, 2.01 etc., indicate EPR-active defect regions on the bulk and surface of the material. These defect states lower the fast recombination of electron and hole, increase charge transport and accelerate the photocatalytic activity. In the present study most efficient ZnO nanostructures have been obtained at calcination temperature (TC) ∼500 °C. Formation of metallic zinc through surface reduction of Zn2+ centers promotes narrowing of the optical band gap and endorses efficient absorption of light, additionally via enhanced surface area of the pitted structures. These surface defects reduce recombination of the photogenerated charge carriers and enhance photo-degradation efficiency to ∼97.75% and rate constant to ∼0.042 min−1 under the exposure of UV light.