Methyl Orange Solution Research Articles

Controllable preparation and multifunctional application of high-strength porous anorthite ceramics

Porous anorthite ceramics, as emerging green materials, garner significant interest in applications such as catalyst carriers, thermal insulation, and sound absorption due to their distinctive structural and functional attributes. In the present study, porous ceramics with anorthite as the main phase were prepared using the natural minerals kaolin, calcite, and quartz as raw materials, combined with a simple and environmentally friendly foam gel-casting method. By adjusting the additive content, we optimized the viscosity and stability of the slurry, and further investigated the impact of the slurry's foaming capacity on the resulting porosity, pore size, mechanical strength, and other key properties of the ceramics. Notably, the porous anorthite ceramic with 15 g/L of foaming agent demonstrated a porosity of 70.57%, a bulk density of 0.81 g/cm3, and a thermal conductivity of 0.26 W/(mK), along with a commendable compressive strength of 8.85 MPa due to the homogeneous sub-spherical pore structure and plate-like anorthite grains. The suitability of these porous ceramics for catalyst carrier applications was confirmed through the effective photodegradation of a methyl orange solution.

Multifunctional hybrid films made from CoT3OTx4 and CoFeT2OT4 nanoparticles inside a poly 3-hydroxybutyrate matrix and study of their impact in methyl orange photodegradation.

This work aims to produce hybrid materials with potential applications in dye photodegradation. Therefore, hybrid films were obtained by incorporating cobalt (II, III) oxide (Co3O4) or cobalt ferrite (CoFe2O4) nanoparticles (NPs) with 18 ± 1.6 nm and 26 ± 1.3 nm, respectively, into a poly 3-hydroxybutyrate (P3HB) polymeric matrix. The Co3O4@P3HB and CoFe2O4@P3HB hybrid films were fabricated by solvent casting in a ratio of 85 mg to 15 mg (P3HB-NPs). Different spectroscopic and microscopy techniques characterized the Co3O4 and CoFe2O4 NPs and the P3HB, Co3O4@P3HB and CoFe2O4@P3HB films. The optical band gap for Co3O4 and CoFe2O4 NPs was estimated from their diffuse reflectance spectra (DRS) around 2.5 eV. X-ray diffraction (XRD) of the hybrid films revealed that the nanometric sizes of the Co3O4 and CoFe2O4 nanoparticles incorporated into the P3HB are preserved. The magnetic hysteresis curve of CoFe2O4 nanoparticles and CoFe2O4@P3HB film showed a ferromagnetic behaviour at 300 K. Transmission electron microscopy (TEM) confirmed the formation of nanocrystals, and scanning electron microscopy (SEM) provided evidence for the successful incorporation of the NPs into the P3HB matrix. The surface roughness and hydrophilicity of the hybrid films are increased compared to the P3HB film. The impact of the nanoparticles and the hybrid films on the photodegradation of methyl orange (MO) in its acidic form was studied. The photodegradation tests were carried out by direct sunlight exposure. The CoFe2O4@P3HB hybrid film achieved 85% photodegradation efficiency of a methyl orange solution of 20 ppm after 15 minutes of exposure to sunlight. After 30 minutes of exposure to sunlight, the nanoparticles and the hybrid films reached about 90% of the MO degradation. The results suggest that combining nanoparticles with the polymer significantly enhances photodegradation compared to isolated nanoparticles.

Insights into mixed dye pollutant degradation by oxygen and air plasma bubbling array

Abstract Synthetic organic dye pollutants pose a serious threat to the aquatic ecological environment due to their difficulty in complete degradation. This study employed a plasma bubble array reactor to degrade individual and mixed dye pollutant solutions of Sunset Yellow (SY), Methyl Orange (MO), and Methyl Violet (MV). The degradation efficiencies and mechanisms of the plasma were investigated under different working gas atmospheres. It was found that oxygen plasma degraded the target dyes and their mixtures more significantly than air plasma. Specifically, compared with air plasma, the removal of single dyes SY, MO and MV by oxygen plasma was increased by 76.6%, 13.8% and 3%, respectively, after 20 min of treatment. As for mixed dyes, after 25 min treatment, oxygen plasma removed 99.1%, which was 31.6% higher than air plasma. However, the degradation kinetic order in oxygen plasma was SY > MO > MV, while that in air plasma was MV > MO > SY. Combined with the detection of reactive oxygen-nitrogen species (RONS), the results showed that the reactive oxygen species (ROS) played an important role in the degradation of SY, and it was also important for the degradation of MO, whereas both the ROS and reactive nitrogen species (RNS) were important for the degradation of MV. Scavenger experiments revealed that hydroxyl (·OH) and superoxide anion (·O2-) played the most important roles in the degradation process. The three dyes were basically completely degraded within 14-20 minutes of treatment, with corresponding yields of 1.94-2.79 g/kWh. Possible degradation pathways for each dye were deduced based on LC-MS and the toxicities of solutions were evaluated by phytotoxicity tests and ion chromatography. The results showed that the biotoxicity of the intermediates was significantly reduced. This study may provide a feasible option for effective application of plasma technology in organic dye wastewater treatment.

Preparation of Composites Derived from Modified Loess/Chitosan and Its Adsorption Performance for Methyl Orange.

A modified loess/chitosan composite (ML@CS) was prepared via solution. The microstructure and physicochemical properties of ML@CS were characterised via scanning electron microscope (SEM), Zeta potential, X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), and thermogravimetric analysis (TGA). An aqueous solution of methyl orange (MO) was used as simulated wastewater from which the influence of the initial concentration and pH of MO, the dosage amount and regeneration performance of ML@CS, adsorption temperature, and time on the adsorption effect of MO were systematically investigated. The adsorption kinetics, isothermal adsorption, and adsorption mechanism were also analysed. The results indicate that ML@CS had a good adsorption effect on MO. When the initial concentration of MO was 200 mg/L, pH was 5.0, and ML@CS dosage was 1.0 g/L, the adsorption equilibrium could be reached within 180 min at room temperature, and the equilibrium adsorption capacity and removal rate reached 199.52 mg/g and 99.75%, respectively. After five adsorption-desorption cycles, the MO removal rate remained above 82%. The adsorption behaviour of ML@CS for MO conforms to the pseudo-second-order kinetic model and the Langmuir isotherm adsorption model. The spontaneous exothermic process was mainly controlled by monolayer chemical adsorption and the physical adsorption only played an auxiliary role. ML@CS efficiently adsorbed MO in water and can be used as a high-efficiency, low-cost adsorbent for printing and dyeing wastewater treatment.

Development of photoactive ZnS-SiO2 composites on biogenic silica matrix for organic pollutant degradation.

Sulfide ZnS-SiO2 composite photocatalysts with biogenic silica matrix were prepared by sol-gel method based on wet gel and xerogel. FT-IR, SEM, XRD, EDXRF, UV-Vis, and XPS methods were systematically used to characterize the obtained materials. The use of support allowed to obtain stable porous (SBET = 79-105 m2g-1; Vpore = 0.25-0.17 cm3·g-1) ZnS-SiO2 photocatalysts in aqueous solutions. Zn2+ content in methyl orange solution after its degradation was 0.4 MPC. ZnS-SiO2 composites had 3.68-3.70eV band gap. The obtained materials were photoactive under different irradiation conditions (sunlight, UV-light, Xenon light, visible light) due to effective separation of charge carriers (e- and h+). Methyl orange degradation degree under UV light excitation was 35-88%, under sunlight - 11-30%. ZnS-SiO2 composite synthesized using silica xerogel showed a greater photoactivity due to a presence of cone-shaped or cylindrical pores with one open end in its structure and a higher content of ZnS photoactive component. A comparative study of photocatalytic performance of methyl orange degradation by ZnS-SiO2 under UV irradiation was investigated using radical scavengers. •O2- was main active species during MO degradation under UV irradiation, and electrons played additional role during the photocatalytic process.

Reversible Color Loss in Aqueous Methyl Orange Solutions Induced by Freezing

Reversible Color Loss in Aqueous Methyl Orange Solutions Induced by Freezing

Fabrication of cobalt oxide nanosheets using Withania somnifera root extract for degradation of organic pollutants

In today’s scenario, material science emerges as pivotal players, as it is an emerging and fast-growing interdisciplinary field. Nanomaterials are increasingly popular among researchers due to their unique physicochemical properties and multifaceted applications. Recently, researchers are exploring more sustainable approaches for the synthesis of nanomaterials due to its numerous advantages. In this context, present investigation reports an approach for the synthesis of cobalt oxide nanosheets (Co3O4 NSs). This approach leverages environmentally friendly and sustainable methods, minimizing the use of hazardous chemicals and reducing energy consumption. Hence it involved Withania somnifera (ashwagandha) root extract as a greener reductant as well as stabilizing agent. The synthesized Co3O4 NSs were thoroughly analyzed using various techniques, including ultraviolet-visible (UV–vis) spectroscopy, fourier-transform infrared spectroscopy (FTIR), powder x-ray diffraction (PXRD), and field emission scanning electron microscopy (FE-SEM). A sharp absorption peak at 252 nm with a tail towards higher wavelength reveal the formation of Co3O4 NSs. The diffraction pattern reveals a face centered cubic structure of Co3O4 NSs. Morphological studies confirmed the substantial surface area of Co3O4 NSs which enable us to perform the catalytic degradation of azo dye, i.e., methyl orange. It provides that 10 mg of Co3O4 NSs is sufficient to degrade a 10 ppm aqueous methyl orange solution by 75.82 % in the dark and by 96.12 % under sunlight exposure. Thus, this study offers an excellent pathway for the synthesis of Co3O4 NSs and demonstrates their potential as a promising material for future catalytic applications.

CdS/g-C3N5 for heterogeneous catalytic degradation of hazardous pollutants

CdS, as an important photocatalytic degradation material, exhibits certain limitations. In our study, carbon nitride/cadmium sulfide (C3N5/CdS) nanocomposites were synthesized via an in-situ method, and the crystalline structure, composition, and morphology of the hybrid samples were evaluated using various techniques. The development of the Z-scheme heterojunction in the C3N5/CdS composite photocatalyst facilitated more effective separation of photogenerated charges, resulting in higher photocatalytic degradation efficiency. Under visible light irradiation at 425 nm, the composite with a 1:1 ratio exhibited the best degradation performance, achieving degradation rates of 93.8% for methyl orange solution and 96.8% for rhodamine B solution. Additionally, the introduction of C3N5 significantly reduced the photocorrosion of CdS. These experimental results were confirmed by fluorescence analysis, surface photovoltage (SPV) measurements, electrochemical tests, etc.

Surprising Effects of Al2O3 Coating on Tribocatalytic Degradation of Organic Dyes by CdS Nanoparticles

With a band gap of 2.4 eV, CdS has been extensively explored for photocatalytic applications under visible light irradiation. In this study, CdS nanoparticles have been investigated for the tribocatalytic degradation of concentrated Rhodamine B (RhB) and methyl orange (MO) solutions. For CdS nanoparticles in a glass beaker, 78.9% of 50 mg/L RhB and 69.8% of 20 mg/L MO solutions were degraded after 8 h and 24 h of magnetic stirring using Teflon magnetic rotary disks, respectively. While for CdS nanoparticles in a beaker with Al2O3 coated on its bottom, 99.8% of the RhB solution was degraded after 8 h of magnetic stirring and 95.6% of the MO solution was degraded after 12 h of magnetic stirring. Moreover, another contrast was observed between the two beaker bottoms—a new peak at 250 nm in UV–visible absorption spectra was only observed for the MO degradation by CdS in the as-received glass beaker, which indicates that MO molecules were only broken into smaller organic molecules in that case. These findings are meaningful for expanding the catalytic applications of CdS and for achieving a better understanding of tribocatalysis as well.

Quaternary Dielectric Triboelectric Nanogenerator for Self-Powered Electrochemical Systems.

The energy conversion efficiency of conventional binary dielectric triboelectric nanogenerators is not satisfactory due to the limitations of material selection and triboelectrification, which motivates the design of more efficient multicomponent structures to reveal the charge accumulation mechanism for improving the energy conversion efficiency. Herein, a rotating quaternary dielectric triboelectric nanogenerator (Q-TENG) is designed to construct a self-powered system integrating illumination, sensing, and electrochemical decolorization. Through the equivalent capacitance model, the mechanisms for charge generation, transfer, and accumulation in a Q-TENG are elucidated to achieve efficient matching of quaternary dielectric materials and high output performance. At a wind speed of 3.5 m s-1, the peak power density of the Q-TENG reaches 44.94 W m-2, setting a new record for a wind-driven TENG. A 5 ppm solution of methyl orange is completely degraded by the wind-driven Q-TENG in <6 h. This work not only guides the direction for constructing more efficient TENG systems but also promotes the practical development of self-powered electrochemical systems.

Synergistic Ag/g-C3N4 H2O2 System for Photocatalytic Degradation of Azo Dyes.

Graphitic carbon nitride (g-C3N4), known for being nontoxic, highly stable, and environmentally friendly, is extensively used in photocatalytic degradation technologies. Silver nanoparticles effectively capture the photogenerated electrons in g-C3N4, enhancing the photocatalytic efficiency. This study primarily focused on synthesizing graphitic carbon nitride via thermal polymerization and depositing noble metal silver onto g-C3N4 through photoreduction. Methyl orange (MO) and methylene blue (MB) were targeted as the pollutants in the photocatalytic experiments under visible light in conjunction with a H2O2 system. The characteristics peaks, structure, and morphology were analyzed using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). g-C3N4 loaded with 6% Ag exhibited superior photocatalytic performance; the photocatalytic fraction of the degraded materials of the MO and MB solutions reached 100% within 70 and 80 min, respectively, upon adding 1 mL and 2 mL of H2O2. ·OH and ·O2- were the primary active free radicals in the dye degradation process within the synergistic system. Stability tests also demonstrated that the photocatalyst maintained good reusability under the synergistic system.

Homogeneously assembled covalent organic framework membrane co-stitched by β-cyclodextrin and chitosan for dye separation

Covalent organic frameworks (COFs) based membranes have demonstrated great potential in molecular separation. However, COFs are usually synthesized as powders, and difficult to form large-area and highly crystalline membranes. There normally exists unfavorable crystal flaws and stacking defects in membranes, impairing their rejection performance. The severe reaction conditions of solvothermal synthesis also inhibit their fabrication. Here, a comprehensive strategy was developed to fabricate a homogeneously assembled COF membrane co-stitched by β-cyclodextrin (β-CD) and chitosan (CS). Specifically, the COF crystallites (named TATP) were homogeneously formed and assembled to be films at room temperature under the control of n-propylamine; The aminated CS chemically bonded the TATP crystallites on the substrate and helped assemble them to form dense films. β-CD molecules were subsequently embedded into the TATP layer and crosslinked to further stitch membrane defects. The prepared CD-TATP-NH2CS/nylon membrane demonstrated enhanced excellent rejection performance. It could reject 100 % of R250 (BB), Congo red, Direct blue15, and 99.4 % of Alcian blue. It also could selectively separate Methyl orange (MO) and BB mixed solutions with only MO passing through, owing to the co-stitching of the membrane defects by β-CD and CS. This study provides a significant concept and strategy for fabricating high-performance COF membranes.

Synthesis, characterization, and azo dye degradation performance of mechanically alloyed Mg65Cu20Y13La2 nanocrystalline powders

This research describes the synthesis of the multicomponent Mg65Cu20Y13La2 alloy by mechanical alloying (MA) to investigate the influence of milling times on the microstructure of alloy and degradation performance of methyl orange. The structural evolution of this alloy was investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDX) techniques. The thermal behavior of the alloys was investigated by differential scanning calorimetry (DSC). The crystallite size of the Mg65Cu20Y13La2 alloys was calculated using the Debye Scherrer equation with broadening of the XRD peaks. The methyl orange degradation efficiencies of the Mg65Cu20Y13La2 alloys were evaluated by using ultraviolet–visible (UV–Vis) spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), and gas chromatography–mass spectrometry (GC–MS) techniques. The XRD and SEM results showed that the microstructure of the powders changed during MA. After 10 h milling time, three intermetallic phases were obtained as Mg2Cu2La, Mg24Y5, and Mg2Cu. The results also showed that a solid solution phase, α-Mg(Cu, Y, La), with an average crystallite size 21 nm was formed after 100 h milling time. DSC trace of the Mg65Cu20Y13La2 powders showed two exothermic peaks for the 10 h milling time, while it did not show any peaks for the 100 h milling time. Photocatalytic decomposition of the methyl orange solution by the Mg65Cu20Y13La2 alloy was evaluated by UV–Vis spectra with a decrease in absorbance at a wavelength of 465 nm. After a 20 min exposure, UV–Vis, FT-IR, and GC–MS analysis showed that the methyl orange samples were almost completely degradation by using the Mg65Cu20Y13La2 powders. The Mg65Cu20Y13La2 alloy exhibits a good reusability of 92% by the four cycle and a high efficiency was achieved in all the pH values in the range of 5–9. The results prove that the Mg65Cu20Y13La2 alloy is an efficient and promising material for dyeing wastewater treatment.

Mussel-Inspired Multiwalled Carbon Nanotube Nanocomposite for Methyl Orange Removal: Adsorption and Regeneration Behaviors.

A mussel-inspired multiwalled carbon nanotube (MWCNT) nanocomposite (MWCNTs@CCh-PEI) was prepared by the co-deposition of catechol (CCh)/polyethyleneimine (PEI) and modification of MWCNTs for the efficient removal of methyl orange (MO). The effects of MO solution pH, contact time, initial MO concentration, and temperature on the adsorption capacity of MWCNTs@CCh-PEI were investigated. The results indicate that the adsorption capacity of MWCNTs@CCh-PEI was two times higher than that of pristine MWCNTs under the same conditions. The adsorption kinetics followed the pseudo-second-order model, suggesting that the adsorption process was chemisorption. The adsorption isotherm shows that the experimental data were fitted well with the Langmuir isotherm model, with a correlation coefficient of 0.9873, indicating that the adsorption process was monolayer adsorption. The theoretical maximum adsorption capacity was determined to be 400.00 mg·g-1. The adsorption thermodynamic data show that the adsorption process was exothermic and spontaneous. More importantly, the adsorption capacity of MWCNTs@CCh-PEI showed no significant decrease after eight reuse cycles. These results demonstrate that MWCNTs@CCh-PEI is expected to be an economical and efficient adsorbent for MO removal.

Characterization and Photocatalytic Activity of Er2Ti2O7 Prepared by Sol-Gel Method

In this article, the erbium nitrate pentahydrate (Er(NO3)3·5H2O), tetrabutyl titanate (C16H36O4Ti), glacial acetic acid (CH3COOH), and anhydrous ethanol (C2H5OH) were used as the main raw materials. The Er2Ti2O7 was successfully prepared by the sol-gel method. The structure and morphology of the samples were characterized by thermogravimetric-differential thermal analyzer (TG-DSC), X-ray diffractometer (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FT­IR). The 10 mg/L methyl orange solution was used as a simulated pollutant under UV light conditions. The effects of different temperatures and light times on the photocatalytic performance of the Er2Ti2O7 samples were investigated. The results showed that the pure Er2Ti2O7 samples could be successfully prepared by calcination in the temperature range of 750–1000 °C. The average grain size of Er2Ti2O7 was about 20–60 μm, and the photocatalytic performance of Er2Ti2O7 samples calcined at 900 °C was the best. When the illumination time is 90 min, the degradation rate of methyl orange reaches to about 100%. The preparation of Er2Ti2O7 by the sol-gel method is a kind of ultraviolet light photocatalyst with wide application prospects.

Surprising Effects of Ti and Al2O3 Coatings on Tribocatalytic Degradation of Organic Dyes by GaN Nanoparticles.

GaN is more stable than most metal oxide semiconductors for the photocatalytic degradation of organic pollutants in harsh conditions, while its catalytic efficiency has been difficult to be substantially improved. In this study, the tribocatalytic degradation of organic dyes by GaN nanoparticles has been investigated. Stimulated through magnetic stirring using homemade Teflon magnetic rotary disks in glass beakers, the GaN nanoparticles were found to induce negligible degradation in rhodamine B (RhB) and methyl orange (MO) solutions. Surprisingly, the degradation was greatly enhanced in beakers with Ti and Al2O3 coatings on their bottoms: 99.2% and 99.8% of the 20 mg/L RhB solutions were degraded in 3 h for the Ti and Al2O3 coatings, respectively, and 56% and 60.2% of the 20 mg/L MO solutions were degraded in 24 h for the Ti and Al2O3 coatings, respectively. Moreover, the MO molecules were only broken into smaller organic molecules for the Ti coating, while they were completely degraded for the Al2O3 coating. These findings are important for the catalytic degradation of organic pollutants by GaN in harsh environments and for achieving a better understanding of tribocatalysis as well.

Photoassisted Water Purification through an Electrochemically Artificially Adjusted p-Cu2O Light Absorption Layer.

The implementation of photoelectrochemical water purification technology can address prevailing environmental challenges that impede the advancement and prosperity of human society. In this study, Cu, which is abundant on Earth, was fabricated using an electrochemical deposition process, in which the preferential orientation direction and carrier concentration of the Cu-based oxide semiconductor were artificially adjusted by carefully controlling the OH- and applied voltage. In particular, Cu2O grown with a sufficient supply of OH- ions exhibited the (111) preferred orientation, and the (200) surface facet was exposed, independently achieving 90% decomposition efficiency in a methyl orange (MO) solution for 100 min. This specialized method minimizes the recombination loss of electron-hole pairs by increasing the charge separation and transport efficiency of the bulk and surface of the Cu2O multifunctional absorption layer. These discoveries and comprehension not only offer valuable perspectives on mitigating self-photocorrosion in Cu2O absorbing layers but also provide a convenient and expeditious method for the mass production of water purification systems that harness unlimited solar energy. These properties enable significant energy saving and promote high-speed independent removal of organic pollutants (i.e., MO reduction) during the water purification process.

Enhanced visible light photocatalytic activity of SDBS/C/Nd/TiO2 synthesized by using anionic surfactant SDBS as template agent

&lt;p&gt;The catalyst SDBS/C/Nd/TiO2 was synthesized by sol-gel method using TiO2 co-doped with C and Nd and anionic surfactant SDBS as template agent. The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron (SEM), X-ray photoelectron spectrometer (XPS) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and so on. Experimental results show that the crystal structure of the catalytic material is anatase type. Since doped elements change the energy band structure and electronic structure of TiO2, photogenerated electrons and holes can transition through the intermediate energy level, resulting in a decrease in the required excitation energy, thereby increasing the distance of its absorption edge moving toward the long wave direction, and meanwhile improving the utilization rate of visible light. The bandgap energy of the catalyst SDBS/C/Nd/TiO2 was 2.78 eV. Compared to pure TiO2 (3.1 eV), the band gap is reduced by 0.32eV. The photocatalytic experiments show that the degradation rate of the catalyst SDBS/C/Nd/TiO2 for methyl orange solution can reach 67%, and the catalytic performance is much improved than that of pure TiO2.&lt;/p&gt;

Preparation of Fe3O4@SiO2@N-TiO2 and Its Application for Photocatalytic Degradation of Methyl Orange in Na2SO4 Solution

In this paper, Fe3O4@SiO2@TiO2 and N-doped Fe3O4@SiO2@N-TiO2 photocatalysts with magnetic core-shell structures were prepared using a multi-step synthesis method. The materials were analyzed using various techniques, such as X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), selected-area electron diffraction patterns (SAED), and X-ray photoelectron spectroscopy (XPS). The results indicated that the prepared samples had an anatase structure, and N was successfully doped. Fe3O4@SiO2@TiO2 and Fe3O4@SiO2@N-TiO2 with different amounts of nitrogen doping were used for the study of photocatalytic degradation of methyl orange (MO) in pure MO solution, and in MO and Na2SO4 (MO-Na2SO4) mixed solution, respectively. The average photocatalytic degradation rate of MO in pure MO solution with three different batches each of Fe3O4@SiO2@TiO2 and Fe3O4@SiO2@N-TiO2 (3 mL of NH4OH used for doping) under high-pressure mercury lamp irradiation reached 85.25% ± 2.23% and 95.53% ± 0.53%, respectively. The average photocatalytic degradation rate of MO in the MO-Na2SO4 mixed solution with three different batches each of Fe3O4@SiO2@TiO2 and Fe3O4@SiO2@N-TiO2 (3 mL of NH4OH used for doping) under the same irradiation condition reached 90.46% ± 3.33% and 97.79% ± 2.09%, respectively. The results showed that Na2SO4 can promote photocatalytic degradation of MO. The experiment of recycling photocatalysts showed that there was still a good degradation effect after five cycles. Finally, the first-order kinetic model and the photocatalytic degradation mechanism were investigated.

Oxygen-deficient AgIO3 for efficiently photodegrading organic contaminants under natural sunlight

Defect engineering is regarded as an effective strategy to boost the photo-activity of photocatalysts for organic contaminants removal. In this work, abundant surface oxygen vacancies (Ov) are created on AgIO3 microsheets (AgIO3-OV) by a facile and controllable hydrogen chemical reduction approach. The introduction of surface Ov on AgIO3 broadens the photo-absorption region from ultraviolet to visible light, accelerates the photoinduced charges separation and migration, and also activates the formation of superoxide radicals (•O2−). The AgIO3-OV possesses an outstanding degradation rate constant of 0.035 min−1, for photocatalytic degrading methyl orange (MO) under illumination of natural sunlight with a light intensity is 50 mW/cm2, which is 7 and 3.5 times that of the pristine AgIO3 and C–AgIO3 (AgIO3 is calcined in air without generating Ov). In addition, the AgIO3-OV also exhibit considerable photoactivity for degrading other diverse organic contaminants, including azo dye (rhodamine B (RhB)), antibiotics (sulflsoxazole (SOX), norfloxacin (NOR), chlortetracycline hydrochloride (CTC), tetracycline hydrochloride (TC) and ofloxacin (OFX)), and even the mixture of organic contaminants (MO-RhB and CTC-OFX). After natural sunlight illumination for 50 min, 41.4% of total organic carbon (TOC) for MO-RhB mixed solution can be decreased over AgIO3-OV. In a broad range of solution pH from 3 to 11 or diverse water bodies of MO solution, AgIO3-OV exhibits attractive activity for decomposing MO. The MO photo-degradation process and mechanism over AgIO3-OV under natural sunlight irradiation has been systemically investigated and proposed. The toxicities of MO and its degradation intermediates over AgIO3-OV are compared using Toxicity Estimation Software (T.E.S.T.). Moreover, the non-toxicity of both AgIO3-OV catalyst and treated antibiotic solution (CTC-OFX mixture) are confirmed by E. coli DH5a cultivation test, supporting the feasibility of AgIO3-OV catalyst to treat organic contaminants in real water under natural sunlight illumination.