Degradation Of Methyl Orange Dye Research Articles

Photodegradation of cationic and anionic dyes by ZnO and S/ZnO biosynthesized nano‐photocatalysts

Photocatalysis is considered a promising and efficient oxidation technique for wastewater treatment. Developing more environmentally biocompatible, simple, effective, and inexpensive photocatalysts enables photocatalysis technology to be at the forefront of wastewater treatments. As an alternative to harmful chemicals, this work focused on the biosynthesis of a variety of ZnO and doped ZnO based on the extract of the brown alga Cystoseira crinite. X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), Fourier transform‐infrared (FTIR) spectroscopy, and ultraviolet–visible (UV–vis) spectroscopy were used to characterize the structure, phase, morphology, and UV–vis properties of the biosynthesized samples. XRD showed the crystalline structure of ZnO and S‐doped ZnO. SEM analysis revealed agglomerated spherical particles of the prepared samples. EDX analysis confirmed the formation of S‐doped ZnO. FTIR spectra exhibited that phenolic compounds and protein molecules are present in the Cystoseira crinite extract. The photocatalytic efficiency of biosynthesized materials was examined by monitoring the degradation of crystal violet (CV) and methyl orange (MO) dyes, which serve as cationic and anionic dye models, respectively. The various factors that influence the efficacy of the photodegradation process were investigated. In total, 5% S‐doped ZnO decomposed 97.40% and 89.18% of CV and MO dyes, respectively. The dye degradation was most efficient in samples calcined at 500 °C. The photodegradation of CV dye was enhanced at high pH, while the highest photocatalytic activity of MO dye was observed at low pH values. The kinetic study confirmed that the photodegradation follows the first‐order reaction.

Sintesis dan Aplikasi CuSnO3 sebagai Katalis pada Proses Degradasi Zat Warna Methyl Orange dengan Metode Fotolisis

Research on the degradation of methyl orange dye using the photolysis method using a copper tin oxide (CuSnO3) catalyst has been carried out. The aim of this research is to see how catalyst activity influences variations in methyl orange degradation time, whether the addition of MEA (Monoethanolamine) is more effective for photocatalyst applications. In this research, a concentration of 10 ppm of methyl orange was used, 40 mL of which was degraded with a CuSnO3 catalyst of 0.05 grams. This degradation process involves treatments including CuSnO3 catalyst without MEA; 1 mL, 1.5 mL, and 2 mL MEA. The characterization used in this research is UV – VIS. The analysis results showed that the percentage of degradation without MEA at a time variation of 240 minutes was 64.43%, while at 1 mL it was 19.77%, 1.5 mL 16.92%, and 2 mL 20.91%.

Au9 clusters deposited as co-catalysts on S-modified mesoporous TiO2 for photocatalytic degradation of methyl orange

Au9 nanoclusters (Au9 NCs) were deposited onto S-functionalized mesoporous TiO2 (SMTiO2) to produce efficient photocatalysts for Methyl Orange (MO) dye degradation with UV light. The morphology, the surface composition and the size of the deposited Au9 NCs of the catalyst was analysed. SMTiO2 could adsorb more clusters with lesser Au9 cluster agglomeration than unmodified MTiO2. This finding is attributed to the capability of the thiol groups to form strong bonds with the Au9 clusters. To study Au9 NCs effect on dye degradation activity, the MO degradation reaction constants under UV-light irradiation for SMTiO2 nanoparticles (NPs) and Au9 NCs decorated SMTiO2 photocatalysts were studied, which were 0.07 min−1 and 0.149 min−1, respectively. Hence, it takes almost half the time to completely degrade MO using Au9 NCs decorated SMTiO2 photocatalysts compared to SMTiO2 substrate. Results were analysed using the response surface methodology (RSM) to study the interaction between the reaction parameters.

Intensifying heat using AgCu core-shell-based black titania with highly efficient photothermal conversion performance for solar-driven seawater desalination

A novel photoreceiver composed of black titania (BT) matrix with biochar for efficient steam production was investigated to measure the desalination efficiency under the illumination of one sun (1 kW m−2). The density of localized hotspots on the surface of the photothermal system is enhanced by the incorporation of AgCu core-shell that promotes photothermal activity and improves the degradation of methyl orange (MO) dye. Assemblages of AgCu nanoparticles on the surface of BT generated a strong stochastic plasmonic coupling and therefore broad-band absorption for much better solar energy consumption. The nanocomposite exhibited an excellent vaporization flux of 1.4 kg m−2 h−1 with high efficiency reaching 95.7 % under the illumination of one sun. AgCu@BT/BC exhibited an excellent surface temperature of 41 °C after only 5 min compared to other prepared photothermal systems. Furthermore, the prepared composites revealed superb degradation of MO dye under UV–vis light with a percentage of 96 %. The band gap energy of white titania decreased from 3.2 eV to 1.86 eV in the case of AgCu@BT/BC nanocomposite. Moreover, the crystalline AgCu@BT/BC demonstrates outstanding photocatalytic performance because of boosted charge migration, reduced electron-hole pair recombination rate, and identifiable shift to the red region.

Facile synthesis of an α-Bi2O3/BiO2 heterojunction for enhanced piezoelectric catalytic degradation of dye wastewater

This study employed a one-step microwave method to fabricate an α-Bi2O3/BiO2 heterojunction with a narrow bandgap which exhibited a high efficiency in the degradation of methyl orange dye.

Natural tea polyphenol functionalized graphene anode for simultaneous power production and degradation of methyl orange dye in microbial fuel cells.

The microbial fuel cell (MFCs) has dual functions, capable of achieving dye decolorization and synchronous power generation. Despite these advantages, the MFCs have faced challenges related to low electron transfer efficiencies and limited dye treatment capacity in wastewater applications. This work introduces an innovative approach by employing reduced graphene oxide-modified carbon cloth (TP-RGO@CC) anodes, utilizing tea polyphenols as the reducing agent. This modification significantly enhances the hydrophilicity and biocompatibility of the anodes. The MFC equipped with the TP-RGO@CC anode demonstrated a remarkable increase in the maximum power density, reaching 773.9 mW m-2, representing a 22% improvement over the plain carbon cloth electrode. The decolorization rate of methyl orange (50 mg L-1, pH 7) reached 99% within 48 h. Biodiversity analysis revealed that the TP-RGO@CC anode selectively enriched electrogens producing and organic matter-degrading bacteria, promoting a dual mechanism of dye decolorization, degradation, and simultaneous electro-production at the anode. This work highlights advanced anode materials that excel in effective pollutant removal, energy conversion, and biomass reuse.

Constructing of GQDs/ZnO S-scheme heterojunction as efficient piezocatalyst for environmental remediation and understanding the charge transfer mechanism

Highly efficient catalysts are challenging in the fields of environmental remediation. In this work, for the first time, we combined graphene quantum dots (GQDs) and piezocatalytic materials (ZnO) to construct a novel S-scheme GQDs/ZnO heterojunction via facile method. The obtained GQDs/ZnO heterojunction presented excellent piezocatalytic activity such as higher reaction kinetic rate constant (0.051 min−1) and degradation efficiency (96.1 % within 60 min) as well as superior stability toward methyl orange (MO) dye degradation, far exceeding those of pure ZnO and most reported other typical piezocatalysts. This superior piezocatalytic performance of GQDs/ZnO could be ascribed to S-scheme heterojunction facilitating charge carrier transfer and separation, and enhancing the redox ability as well as the formation atomic-level interfacial bridge of Zn–C–O bond at GQDs/ZnO interface. Furthermore, density functional theory (DFT) calculations demonstrated the charge transfer path of GQDs/ZnO S-scheme heterojunction and provided a novel understanding for S-scheme heterojunction mechanism in piezocatalytic field, which supports the experimental evidences of S-scheme heterojunction. This research provides an effective strategy to modulate charge transfer from the atomic level, highlighting an innovative insight for the practical application of highly efficient piezocatalysts in environmental remediation.

Plant Extract Mediated Biogenic Synthesis and Characterization of Nickel Oxide Nanoparticles and its Environmental and Antibacterial Applications

This research focuses on the green synthesis of Nickel Oxide nanoparticles (NiO NPs) using Musa paradisiaca, commonly known as banana plant, as a cost-effective and eco-friendly approach. Musa paradisiaca, utilized in traditional medicine, possesses various medicinal properties, including antioxidant, antibiotic, allogeneic, and hypoglycemic antimicrobial attributes. The peduncle extract of Musa paradisiaca serves as a reducing and capping agent for NiO nanoparticle synthesis. Characterization techniques such as XRD, EDX, and UV-vis spectroscopy were employed to analyze the properties of the synthesized NiO nanoparticles. XRD analysis confirmed an average grain size of 15.26nm, while SEM images revealed round cubic-shaped nanoparticles with a highly crystalline structure. The antibacterial activity of NiO nanoparticles was investigated against bacterial strains, including Escherichia coli, Staphylococcus aureus, Bordetella bronchiectasis, and Bacillus subtilis, demonstrating effective antibacterial properties. Furthermore, the catalytic power of the synthesized nanoparticles was evaluated through the degradation of methyl blue and methyl orange dyes under sunlight and UV light. The results indicated superior degradation efficiency under sunlight compared to UV light for both dyes. Additionally, the study explored the adsorption activity of NiO nanoparticles for chromium (VI) at various concentrations, with the best adsorption percentage recorded at 17.23% under pH 4.

Copper oxide nanoparticles fabricated by green chemistry using Tribulus terrestris seed natural extract-photocatalyst and green electrodes for energy storage device

Nanobiotechnology is a unique class of multiphase and recently become a branch of contemporary science and a paradigm shift in material research. One of the two main problems facing the field of nanomaterial synthesis is the discovery of new natural resources for the biological production of metal nanoparticles and the absence of knowledge about the chemical composition of bio-source required for synthesis and the chemical process or mechanism behind the production of metal nanoparticles presents the second difficulty. We reported template-free green synthesized copper oxide nanoparticles using Tribulus terrestris seed natural extract without any isolation process. XRD, TEM, SEM, UV–Vis, DLS, zeta potential, and BET evaluated the synthesized metal nanoparticle. The TEM analysis confirmed that the CuO NPs are well dispersed and almost round in shape with an average size of 58 nm. EDAX confirms that copper is the prominent metal present in the nanomaterial. The greener fabricated copper oxide nanoparticle was employed to degrade methyl orange dye, almost 84% of methyl orange was degraded within 120 min. The outcomes demonstrated the nanomaterial’s effective breakdown of contaminants, highlighting their potential for environmental rehabilitation. The electrochemical investigation of the CuO NPs was utilized for supercapacitor application. An appreciable value of specific capacitance is 369 F/g specific capacitances with 96.4% capacitance retention after 6000 cycles. Overall, the results of the current study show that the biologically produced copper oxide nanoparticles have intriguing uses as photocatalysts for treating water contaminants and are suitable for energy storage devices.

Synthesis and Characterization of Ag/CdO Nanocomposite for the Photocatalytic Degradation of Methyl Orange Dye

Well crystalline Ag/CdO nanocomposite has been synthesized via the solution combustion synthesis (SCS) route. The Ag/CdO nanocomposite has been characterized in term of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Raman spectroscopy. The crystallinity of the as-synthesized nanocomposite was obtained by using XRD technique. The crystallite size of the nanocomposite was calculated by the Scherrer equation and was found to be 47 nm. The surface morphology was obtained by FESEM spectroscopy. The particles appear to be porous in nature and wool-like morphology was obtained. Raman band at about 278 cm[Formula: see text] is because of the combination of transverse acoustic and optical phonon modes of cadmium oxide (CdO). Further, the Ag/CdO nanocomposite was used as a photocatalyst for the degradation of methyl orange (MO) dye. Results revealed that the photocatalytic activity of Ag/CdO nanocomposite for the degradation of MO dye increases with increasing the amount of photocatalyst. The rate constant, [Formula: see text] values for 100 mg, 150 mg and 200 mg of photocatalyst were 0.83, 2.21 × 10[Formula: see text] min[Formula: see text] and 3.81 × 10[Formula: see text] min[Formula: see text], respectively.

Synthesis of p-CuO/n-ZnO heterostructure by microwave hydrothermal method and evaluation of its photo and bio-catalytic performance

The use of photocatalysts without noble metals is of great interest in the industrial field for the degradation of organic pollutants. In this study, a CuO/ZnO heterostructure was synthesized using the microwave hydrothermal method and characterized using various analytical techniques. The synthesized CuO/ZnO photocatalyst exhibited a low bandgap energy of 2.4 eV, enabling efficient visible light absorption. The photocatalytic activity of the CuO/ZnO heterostructure was evaluated for the degradation of Methyl Orange (MO) dye and showed a high degradation efficiency of 99 % due to its excellent electron-hole charge separation. The biological activity of the synthesized CuO/ZnO catalyst was further investigated through protein docking studies, which showed promising results. The CuO/ZnO was also evaluated for its anticancer and antibacterial properties. It exhibited effective anticancer activity against prostate cancer cells (PC-3) in a dose-dependent manner, with an IC50 value of 6.87 ± 8. In addition, it demonstrated potent antibacterial activity against Escherichia coli, Staphylococcus aureus, Bacillus cereous and Pseudomonas aeruginola. The results of this study demonstrate the potential of CuO/ZnO heterostructures as promising materials for various applications in the fields of photocatalysis, biomedicine and antimicrobial materials. Future research in this area will focus on further optimizing the properties of the CuO/ZnO heterostructure to enhance its performance in these applications.

Carbon Dots from Tire Waste for the Photodegradation of Methyl Orange Dye, Antimicrobial Activity, and Molecular Docking Study.

In this study, solvothermal pathway was employed for the synthesis of P, N codoped C-dot using tire waste as a sustainable source of carbon and nitrogen. Comprehensive analyses encompassing X-ray diffraction (XRD) analysis, Transmission Electron Microscopy (TEM), FT-IR, cyclic voltammetry, and UV-Vis spectra were used to assess the crystalline structure, purity, size, fluorescence up-conversion, and morphological attributes of the nanomaterial. Subsequently, the produced C-dots were evaluated for their efficacy in the photocatalytic degradation of methylene blue and methyl orange dyes, demonstrating notable success in degrading methyl orange dye within eight hours in the visible region. Furthermore, the same nanomaterial was applied for carrying out agar disk-diffusion assays against a spectrum of microorganisms. Results revealed substantial inhibition zones against Methicillin-Resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa. Elucidating the antimicrobial mechanism, molecular-docking simulations were excuted using on AutoDock Vina with designated ligands. The results indicated a strong binding affinity of the C-dots with certain proteins associated with antibacterial activity. This observation suggests that the synthesized C-dots effectively engage with the active sites of these proteins, indicating their potential as promising antibacterial agents. Importantly, this study implies that C-dots do not induce protein denaturation, thereby warranting further investigation of their utility as antibacterial agents.

Synthesis and application of novel microporous framework of nanocomposite from trona for photocatalysed degradation of methyl orange dye.

Photocatalysed degradation of environmental contaminants is one of the most fashionable technologies in the purification of water because the method converts toxic products to nontoxic ones. In this study, a method has been developed to synthesize novel nanocomposites of Na-Ca-Al-Si oxides for the first time. The average surface area, pore volume and pore size for the novel product were 1742.55 m2/g, 0.3499 cc/g and 3.197 nm respectively. The crystal parameters were a = 7.1580 Å, b = 7.4520 Å, c = 7.7160 Å, α = 115.0600, β = 107.3220, γ = 100.4380, density (calculated) = 2.0 × 103g/cm3 and cell volume = 332.7 Å3 respectively. The average crystalline size deduced from the Scherrer equation (i.e. 6.9393 nm) was higher than the value of 1.024 nm obtained from the graphical method. The FTIR and UV spectra of the nanocomposites were unique and provided baseline information that characterises the new product. XRD profiling of the new product reveals the existent of a silica framework consisting of NaAlSi3O3 and CaAl2Si2O8 The synthesized nanocomposites is an effective photocatalyst for the degradation of methyl orange dye in water, with aoptimum efficiency of 96% at an initial dye concentration of 10 ppm, the adsorbent dosage of 0.5 g,contact time of 90 min and pH of 2.5. The Langmuir-Hinshelwood, modified Freundlich and pseudo-second kinetic models were significant in the description of the photocatalytic kinetics of the degraded dye molecules.

Enhancing Methyl Orange Degradation with Laser-Generated ZnO and Ce-Doped ZnO Nanoparticles

The presence of Methyl Orange, a hazardous organic compound typically found in industrial wastewater, presents a significant environmental challenge, necessitating the development of effective strategies for its removal to mitigate adverse impacts on aquatic ecosystems and human health. In this work, we utilized 60-watt continuous-wave (CW) and high-power CO2 laser with 10.6 μm wavelength to synthesize Zinc Oxide nanoparticles (ZnO NPs) doped with 1% Cerium (Ce) as photocatalyst at standard laboratory conditions through Laser-Assisted Chemical Bath Synthesis (LACBS) technique. The synthesized nanostructures were thoroughly characterized using UV–vis spectroscopy, field-emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD) techniques. Subsequently, their efficiency in degrading Methyl Orange (MO) dye was evaluated under UV and sunlight irradiation. The findings revealed that the 1% Ce-doped ZnO sample exhibited enhanced photocatalytic efficiency under both UV and sunlight irradiation, as well as active adsorption capabilities in the absence of light. Notably, the most effective photodegradation performance was achieved under solar radiation, with an impressive 95% of MO dye degradation observed after just 90 min of exposure.

Box-Behnken design for the optimization of the photocatalytic degradation of methyl orange using gold-platinum bimetallic nanoparticles doped-1D titania

The aim of this work is the study the degradation of methyl orange (MO) dye in the presence of materials based on titanate nanotubes (TNT). The nanotubes are synthesized hydrothermally followed by simultaneous deposition of gold and platinum nanoparticles at different content. The characteristics of the obtained materials are determined by: photoelectron spectroscopy (XPS), N2 Adsorption-desorption, X-Ray Diffraction (XRD), High-resolution transmission electron microscopy (TEM), UV–Visible in Reflection Diffuse (RD/UV–Vis) and Fourier-transform infrared spectroscopy (FTIR). The results of this part reveal the formation of nanotubes well decorated by metallic nanoparticles. However, the oxidation of MO is carried out under different conditions: UV, Visible irradiations, and/or in the presence of oxygenated water (H2O2) and at different concentrations of pollutants. The Au-Pt/TNT bimetallic catalyst shows interesting activity in a fairly short time and a mineralization rate that reaches 70 %. Based on ANOVA studies, the results show that the response of degradation rate (R) is considerably influenced by a positive individual effect of methyle orange concentration. However, the individual effect of catalyst weight and oxidant volume has an antagonist impact through the degradation process.

Synthesis and Characterization of a Nano‐Composite CuO@Zn−2‐PTZ {Zn−2‐PTZ=bis[5‐(2‐pyridyltetrazolato)]diaquazinc(II)} for Efficient Photo‐catalytic Degradation of Methylene Blue (MB), Methyl Orange (MO) and mixed(MB‐MO)Dyes in Sunlight

AbstractRemoval of organic contaminants such as azo dyes is highly desirable from the industrial waste waters because of their toxicity, stability, and mutagenic properties. Herein, the nano‐composite CuO@Zn−2‐PTZ has been synthesized by a simple hydrothermal method and characterized by a combination of techniques like Powder X‐Ray Diffraction (PXRD), UV‐Visible spectroscopy, Fourier Transform Infrared (FT‐IR) spectroscopy, Scanning Electron Microscopy‐Energy Dispersive X‐ray analysis (SEM‐EDX) etc. The band gap of the composite was found to be 2.07 eV, indicating the spread of absorption in to the visible region in comparison to the high (3.76 eV) band gap of the parent metal organic framework (MOF) Zn−2‐PTZ. The composite CuO@Zn−2‐PTZ exhibited much higher photo degradations, under natural sunlight, towards the decompositions of the cationic [Methylene Blue (MB)] and anionic [Methyl Orange (MO)] dyes as well as mixed MB and MO dyes taken in water. A comparative study was also undertaken by taking CuO nanoparticles and the parent MOF separately with the same set of dyes under same conditions to substantiate the above. The enhancement of photo‐catalytic activity has been caused by the formation of a p‐n hetero‐junction in the composite. The Langmuir‐Hinshelwood model showed that the degradation rates of the dyes follow pseudo‐first‐order kinetics.

Exploring the photo-catalytic degradation of methyl orange dye using Strontium doped Bismuth oxide nanoparticles

Low dimensional metal oxide Nps have garnered significant attention due to their distinctive characteristics and diverse application domains. This investigation can provide further elucidation regarding the synthesis of Strontium doped-Bi2O3 efficacious photocatalysts operating under visible light, thereby potentially addressing environmental quandaries. The photoactivity of Strontium doped-Bi2O3 Nps exhibits a significantly greater magnitude when compared to that of Bi2O3 nanoparticles lacking Strontium doping. The hydrothermal method shall be employed for the synthesis of Strontium-doped Bismuth oxide in the course of preparation. A solution of NH4OH will be introduced to Bismuth nitrate and Strontium chloride. The resulting mixtures shall be subjected to vigorous stirring for a duration of 1 hour, after which they will be transferred into 100 mL autoclaves made of stainless steel and equipped with Teflon liners. These autoclaves shall then be heated to a temperature of 180 °C for a period of 6 h. The prepared samples shall subsequently undergo collection and undergo multiple washes utilising de-ionized water. In order to synthesise Strontium doped-Bi2O3 is imperative to subject the resulting compound to a subsequent calcination process at a temperature of 450° C. Infra-Red spectroscopy (FT-IR), UV-Visible, scanning electron microscopy (SEM), X-ray diffraction (XRD), techniques shall be employed for the investigation of the crystalline structures and morphologies of the powder. The resultant specimen shall subsequently serve as a catalyst for the photolytic degradation of organic dye methyl orange under diverse illumination circumstances. UV-Visible spectroscopy shall subsequently be employed to monitor the extent of photocatalytic efficacy.

ZnO-based heterojunction catalysts for the photocatalytic degradation of methyl orange dye

In this study, a variety of ZnO-based heterojunctions with disparate wt.% doping of WO3 and BiOI have been prepared for the photodestruction of methyl orange (MO) dye in aqueous solution. The composites were analysed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, optical studies, and nitrogen adsorption-desorption isotherms. The SEM images revealed non-uniform surfaces of the ZnO–BiOI based composites while mostly nodular morphology was observed for all three samples of ZnO-WO3. As the WO3 loading increased, more clustering was detected. The analysed samples exhibited characteristic peaks representative of the triclinic phase of WO3 and the hexagonal wurtzite structure of ZnO, while the diffractogram observed from the materials displayed distinct peaks corresponding to the crystalline phases of both BiOI and ZnO in their pure forms. Further evidence of the samples' characteristics includes the presence of distinct crystalline patterns without any impurity peaks, a red shift in the absorption spectra of the heterostructure, the detection of only the reference elements, and mostly Type IV isotherm adsorption. This study identified the ZnO-[10%]BiOI and ZnO-[10%]WO3 heterojunctions as the best performing photocatalysts, as MO was completely destroyed in 120 and 90 min, respectively. Thus, confirming 10% wt. as the optimal doping concentration for the best photo-activity in this study. The impact of varying process parameters demonstrates that at an elevated photocatalyst mass of 40 mg, both heterojunctions effectively degraded MO. The photodegradation efficiency of MO was more pronounced in strong acidic conditions (pH 2) when compared to high alkaline conditions (pH 11) for the ZnO-[10%]BiOI heterostructure. However, a decrease in performance was observed for both strong acidic and high alkaline pH values when the ZnO-[10%]WO3 heterostructure was applied. The kinetic analysis of the photodegradation study reveals that all the photodegradation experiments can be represented by the pseudo-first-order kinetic model. The findings from this investigation propose that the ZnO-[10%]BiOI heterojunction photocatalyst holds significant potential for the effective treatment of dye-contaminated wastewater.

Fabrication of CN-HAp heterostructures from eggshells with improved photocatalytic performance in degrading of mixing dyes under sunlight

In this work, hydroxyapatite (HAp) and g-C3N4 (CN) heterostructures were synthesized by the microwave-assisted hydrothermal method (MAHM). The calcium precursor for HAp synthesis was obtained from white eggshells. The influence of increasing the CN mass percentage (60–95%) in the heterostructure was investigated through structural characterizations via XRD, morphological characterizations through FESEM, and optical properties by UV–Vis and PL. The XRD results indicated hydroxyapatite formation from the eggshells and the heterostructures showed high crystallinity. The morphological and optical characterizations indicate the interface region between the phases, leading to a decrease in the intensity of the photoluminescence (PL) of the heterostructures, as well as a widening of the wavelength absorption band in relation to the spectrum of emission from the CN evidencing the decrease in the recombination of the photogenerated charges. The photocatalytic performance of heterostructures was first studied in the degradation of crystal violet (CV) and methyl orange (MO) dyes under UV light irradiation, in which heterostructures containing 80% and 95% CN had better performance over a period of 120 min. The best heterostructures were tested in the degradation of CV, MO, and a mixture (MIX) of both dyes under sunlight irradiation. The results under solar irradiation showed that the heterostructures with 80% and 95% CN degraded the CV dye in more than 99%, the MO dye in more than 80% and the MIX in more than 80% in 120 min. Therefore, obtaining environmentally friendly and economically sustainable CN-HAp heterostructures is another interesting option for use in photocatalysis.

Synthesis and Characterization of CdO/CdS Nanocomposite for the Degradation of Methyl Orange Dye

CdO/CdS nanocomposites have been synthesized via the solution combustion route. These nanocomposites have been characterized in terms of XRD, FESEM, EDS, UV-visible and FTIR spectroscopy. The crystallinity and the crystallite size of the as-synthesized CdO/CdS nanocomposites were calculated from XRD, whereas the surface morphology and chemical purity were obtained from FESEM and EDS analysis. Further, all the samples were used as photocatalyst for the degradation of methyl orange (MO) dye under UV-Visible irradiation. The rate constant, [Formula: see text], was obtained by the Langmuir–Hinshelwood model. From [Formula: see text] values, it can be observed that the rate constant increases on increasing the amount of photocatalyst due to an increase in surface area. The rate constant value for CdO/CdS nanocomposite annealed at 615[Formula: see text]C was found to be very low, which may be largely due to loss in crystallinity at this higher temperature. Further, we compared our results with those reported in the literature and it was observed that CdO/CdS nanocomposites act as a better photocatalyst than others.