Methylene Blue Research Articles

ZrO2 nanoparticles for effective dye degradation in wastewater: Synthesis, characterization, and photocatalytic performance under sunlight

The study addresses the critical issue of water contamination, focusing on the photodegradation of methylene blue (MB) dye as industrial waste. A novel method is presented to synthesize zirconium dioxide (ZrO2) nanoparticles (NPs) using zirconium hydrogen phosphate as a precursor. The results proved the formation of spherical nanoparticles with an average particle size of about 23.24 nm, confirmed by scanning electron microscopy (SEM). The structural analysis demonstrated the existence of both tetragonal and monoclinic phases, with the dominance of the tetragonal phase. The photocatalytic evaluation under sunlight irradiation showed an impressive MB degradation efficiency of about 80 % in a relatively short time of 80 min. Thus, the study highlights the potential of ZrO2 NPs sensitized by a novel approach as highly efficient photocatalysis for water treatment.

Investigation on novel chitin and chitosan from dung beetle Heteronitis castelnaui (Harold, 1865) and its potential application for organic dyes removal from aqueous solution

Chitosan, a natural polysaccharide, has attracted considerable attention as an environmentally friendly and highly efficient adsorbent for dye removal. It is usually produced by deacetylation or partial deacetylation of chitin. However, conventional sources of chitin and chitosan are limited, prompting the need for alternative sources with improved adsorption capabilities. Herein, this study focuses on exploring a novel chitin and chitosan source derived from the dung beetle and evaluates its potential for organic dye removal from aqueous solutions. The research involves the extraction and characterization of chitin and chitosan from dung beetle Heteronitis castelnaui (Harold, 1865) using various analytical techniques, including SEM, FT-IR, TGA, XRD, NMR, deacetylation degree and elemental analysis. The chitosan obtained was used for the formation of hydrogels with sodium alginate via cross-linking with calcium chloride. And then the prepared hydrogels were evaluated for its adsorption capacity through batch adsorption experiments using methylene blue as a model pollutant. The adsorption capacity for methylene blue was 1294.3 mg/g at room temperature with solution pH = 12, MB concentration of 1800 mg/L. Furthermore, the kinetics of the adsorption process were analyzed using pseudo-first-order and pseudo-second-order models to understand the rate of adsorption. The maximum adsorption capacities were determined using Langmuir and Freundlich isotherm models. This study provides valuable insights for the development of sustainable dye adsorption technologies, specifically investigating a novel chitosan source derived from the dung beetle.

Synthesis of targeted doxorubicin-loaded gold nanorod −mesoporous manganese dioxide core–shell nanostructure for ferroptosis, chemo-photothermal therapy in vitro and in vivo

In the current study, a core–shell inorganic nanostructure comprising a gold nanorod core and −mesoporous manganese dioxide shell was synthesized. Then, the mesoporous manganese dioxide shell was loaded with doxorubicin (DOX) and then coated with pluronic F127 and pluronic F127-folic acid conjugate (1.5:1 wt ratio of pluronic F127: pluronic F127-folic acid conjugate) to prepare targeted final platform. In this design, mesoporous manganese dioxide acted as a reservoir for DOX loading, anti-hypoxia, and MRI contrast agent, while the gold nanorod core acted as a photothermal and CT scan imaging agent. DOX was encapsulated in the mesoporous manganese dioxide shell with a loading capacity and loading efficiency of 19.8 % ± 0.2 and 99.0 % ± 0.9, respectively. The in vitro release experiment showed the impact of glutathione (GSH), mildly acidic pH, and laser irradiating toward accelerated stimuli-responsive DOX release. The ·OH production of the prepared platform was verified by methylene blue (MB) decomposition reaction. Furthermore, thermal imaging exhibited the ability of the prepared platform to convert the NIR irradiation to heat. In vitro cytotoxicity tests on the folate receptor-positive 4 T1 cell line revealed the remarkable cytotoxicity of the targeted formulation compared to the nontargeted formulation (statistically significant). The MTT experiment demonstrated that exposure to laser 808 irradiation enhanced cytotoxicity of the targeted formulation (p < 0.0001). The production of ROS in 4 T1 cells following treatment with the targeted formulation was demonstrated by the dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay. Furthermore, in vivo investigations by implementing subcutaneous 4 T1 tumorized female BABL/c mice indicated that the prepared platform was an effective system in suppressing tumor growth by combining chemotherapy with PTT (photothermal therapy). Additionally, simultanous PTT and anti-hypoxic activity of this system showed potent tumor growth suppression impact. The percent of tumor size reduction in mice treated with FA-F127-DOX@Au-MnO2 + 808 nm laser compared to the control group was 99.7 %. The results of the biodistribution investigation showed tumor accumulation and modified pharmacokinetics of the targeted system. Lastly, 6 and 24 h post-intravenous injection, CT-scan and MR imagings capability of the prepared platform was verified in preclinical stage. The prepared multipurpose system introduces great opportunity to provide multiple treatment strategy along with multimodal imaging capability in a single platform for breast cancer treatment.

Efficient degradation of methylene blue at near neutral pH based on heterogeneous Fenton-like system catalyzed by Fe2O3/MnO2

The contamination of aquatic environments by organic dye contaminants in industrial wastewater has attracted widespread global attention. The heterogeneous Fenton-like process presents an attractive method for degrading dye pollutants, especially when such reactions are conducted under neutral pH. In this study, Fe2O3/MnO2 composite was employed as a novel heterogeneous catalyst for activating hydrogen peroxide (H2O2) to oxidize and subsequently degrade methylene blue (MB) under neutral pH. Multiple characterization results have confirmed the presence of MnO2 and Fe2O3 as the primary phases of the synthesized compound catalyst. Degradation experiments have demonstrated that the degradation efficiency of MB approaches 100% under the conditions of H2O2 concentration of 0.30% and Fe2O3/MnO2 amount of 0.888 g/L. Furthermore, the Fe2O3/MnO2 catalyst exhibits consistent and outstanding catalytic activity within a broad pH range from 5 to 9 benefiting from the strong interface interaction in Fe2O3/MnO2. The investigation into the kinetics of the Fenton-like reaction indicates that the catalytic degradation of MB by Fe2O3/MnO2 in conjunction with H2O2 follows pseudo-first-order kinetics. Moreover, supplementary scavenging experiments have demonstrated the crucial role played by hydroxyl radicals (·OH) in the catalytic oxidation mechanism of MB. This study offers a promising catalyst for the treatment of dye-containing wastewater under neutral pH condition.

Preparation and Photocatalytic Properties of Al2O3-SiO2-TiO2 Porous Composite Semiconductor Ceramics.

Titanium dioxide (TiO2) is widely employed in the catalytic degradation of wastewater, owing to its robust stability, superior photocatalytic efficiency, and cost-effectiveness. Nonetheless, isolating the fine particulate photocatalysts from the solution post-reaction poses a significant challenge in practical photocatalytic processes. Furthermore, these particles have a tendency to agglomerate into larger clusters, which diminishes their stability. To address this issue, the present study has developed Al2O3-SiO2-TiO2 composite semiconductor porous ceramics and has systematically explored the influence of Al2O3 and SiO2 on the structure and properties of TiO2 porous ceramics. The findings reveal that the incorporation of Al2O3 augments the open porosity of the ceramics and inhibits the aggregation of TiO2, thereby increasing the catalytic site and improving the light absorption capacity. On the other hand, the addition of SiO2 enhances the bending strength of the ceramics and inhibits the conversion of anatase to rutile, thereby further enhancing its photocatalytic activity. Consequently, at an optimal composition of 55 wt.% Al2O3, 40 wt.% TiO2, and 5 wt.% SiO2, the resulting porous ceramics exhibit a methylene blue removal rate of 91.50%, and even after undergoing five cycles of testing, their catalytic efficiency remains approximately 83.82%. These outcomes underscore the exceptional photocatalytic degradation efficiency, recyclability, and reusability of the Al2O3-SiO2-TiO2 porous ceramics, suggesting their substantial potential for application in the treatment of dye wastewater, especially for the removal of methylene blue.

Enhanced photocatalytic performance of ternary g-C3N4/UiO-66/Ag3VO4 composite for methylene blue degradation under visible light irradiation

Anovel Ag3VO4/UiO-66/g-C3N4-based photocatalystwassynthesized using the solvothermal approach and characterized using XRD, SEM, FTIR, PL, and UV–Vis DRS. The photodegradation capacityof each componentwas tested using aqueous solutions of methylene blue (MB) and real sample solutions. It was found that the ternary composites (g-C3N4/UiO-66/Ag3VO4, 1 wt%, 5 wt%, 10 wt%, and 15 wt% g-C3N4) demonstrated higher degradation efficiency than the single and binary constituentsowing to beneficial interactions in the composite, which favor successful interfacial charge transfer and improve photogeneratede--h+pair separations. The influence of various experimental factors such as pH, initial dye amount, photocatalyst dose, and scavengers on MB degradation was examined. At optimal conditions of pH 6, catalyst load of 60 mg, and initialdye content of 10 ppm, the percent photodegradation of MB under irradiation with visible light (indoorsystem) was 99.35 %, while in the outdoor system,it was 99.5 % in 240 min. The selected photocatalyst was also applied for the degradation of real sewage sample solution, which was found to be 80.2 % under indoor and 89 % under outdoor experimental undertakings. After five cycles, the potential of the photocatalystremained substantial, indicating remarkable reusability. The scavenging experiment suggested that the principal active species were found to be superoxide (O2•) and hydroxide radicals (•OH). Thus, the composite g-C3N4/UiO-66/Ag3VO4 could be a promising option for industrial effluent removalapplications, particularly in the purification of organic dye-containing wastewater.

TWO IN ONE GRAM NEGATIVE ANTIBACTERIAL AGENT AND ORGANIC DYE PHOTOCATALYST FROM GREEN OCIMUM SANCTUM-BASED CO-DOPED CARBON DOT SILVER NANOCOMPOSITE.

This study reports, successful synthesis of Oxygen(O) and Nitrogen(N) co-doped Ocimum Sanctum plant-based or tulsi carbon dots-silver nanoparticle nanocomposites (TCD-AgNP) for the development of an efficient, highly active, low-cost fingerprint antibacterial agent against gram-negative organisms and a highly efficient photocatalyst for the degradation of methylene blue (MB). The novelty and advantage of this study is the development of highly stable, blue fluorescent, high quantum yield (40%) environmental -friendly TCD-AgNP nanocomposite through reduction method by using green TCDs. Spectrochemical characteristics of synthesized TCDs and TCD-AgNP nanocomposites were investigated through UV-Vis absorbance, Photoluminescence (PL) spectroscopy, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and Zeta potential measurements confirming excellent fluorescence, unique stability and effective O and N doping. High-resolution transmission electron microscopy (HR-TEM) images confirms that the synthesized TCDs and TCD-AgNP nanocomposites were spherical in shape with an average size of 6.3 nm and 11.5 nm respectively. The antibacterial studies proved that TCD-AgNP nanocomposites ware highly effective against Gram-negative (Serratia marcescens, E. coli,and Pseudomonas aeruginosa) microbial organisms. Besides, TCD-AgNP nanocomposite was used as a photocatalyst for the degradation of MB (10 ppm) under sunlight irradiation for regular intervals of time at room temperature with a photodegradation efficiency of 95.63%.

Lithium Chloride-Mediated enhancement of dye removal capacity in Borneo bamboo derived nanocellulose-based nanocomposite membranes (NCMs)

Demand for sustainable materials for membrane fabrication is rapidly increasing, particularly in Sarawak coastal areas. nanocellulose emerges as a promising alternative for membrane development due to its availability, intrinsic biodegradability, and high strength. However, the hydrophobicity of nanocellulose limits its applicability in water treatment operations. Hence necessitating the need for innovative solutions. Herein, we examine the potential of bamboo-derived nanocellulose to enhance nanocomposite membrane-based water treatment systems by incorporating lithium chloride as a pore-forming additive. Nanocomposite membranes (NCMs) were synthesised using a LiCl-doped solution of nanocellulose and polyvinylidene fluoride (PVDF) through phase inversion and controlled solidification methods. The results show that nanocellulose incorporation induces structural alterations in NCMs, with reduced size in cellulose microfibrils. The crystallinity of nanocellulose was enhanced through interactions between PVDF and nanocellulose. The integration of nanocellulose along with lithium chloride was observed to have a significant impact on water permeation flux, attaining 104 L/m2h due to improved hydrophobicity and reduced fouling. In addition, the developed NCMs recorded 93 % methylene blue (MB) removal within 10 min. Revealing high potential of NCMs as an alternative and sustainable material for the development of nanocomposite membranes to mitigate contemporary challenges of water scarcity.

Evaluation of antioxidant, catalytic and antidiabetic activity of Phaseolus vulgaris (French green bean) mediated nickel oxide and copper doped nickel oxide bimetallic nanoparticles

In this study, nickel oxide nanoparticles (NPs) and copper doped NiO bimetallic nanoparticles (Cu@NiO BMNPs) were synthesized using Phaseolus vulgaris extracts as reducing and stabilizing agents by sol gel methods. The chemical and physical properties of synthesized NiO NPs and Cu@NiO BMNPs were confirmed by various techniques, like UV Visible spectrophotometer (UV–Vis), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX), Transmission Electron Microscope (TEM) and X-ray diffraction (XRD) analysis. The optical properties of both NPs observed by UV–Vis analysis with well-defined peak and band gap value 3.2 eV & 2.62 eV. FTIR analysis confirmed the presence of functional group of NPs with fruits extract. The morphology of NPs was confirmed by SEM and TEM analysis as polygonal, rod and spherical shape. The elements present in NPs were confirmed by EDX analysis. The crystalline size calculated based on the XRD analysis was 49.78 nm and 53.66 nm for NiO and Cu@ NiO NPs respectively which were found to be slightly smaller than particle size determined from SEM and TEM micrograph. Antioxidant activity of NPs was examined using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging radicals, Catalytic activities were screened by the degradation of Methylene blue (MB) and by the inhibition of alpha-amylase enzyme, antidiabetic activity of NPs were evaluated using acarbose as standard drug. The Cu@NiO BMNPs showed 77.60 % antioxidant, 76.98 % photocatalytic and 88.86 % antidiabetic activity, which were found to be more as compared to NiO NPs. The NiO and Cu@NiO BMNPs were synthesized for the first-time using P. vulgaris extracts. This study clearly showed that P. vulgaris extracts mediated mono- and bimetallic NPs were more stable and biocompatible than their respective bulk particles.

Exploring the superior adsorption capacity of multi-layer graphene/alginate granules for the removal of methylene blue dye from water

Graphene-based materials are gaining increasing attention towards their use in manufacturing and environmental applications. In this context, multi-layer graphene (MG) has been recently applied for the adsorption of contaminants from water resulting in promising results. However, the extreme lightness of this material often makes it difficult to handle due to its potential dispersion in the surrounding environment as well as to its transport and loss with the effluent. In this study, a novel granular material was synthesized by embedding MG into an alginate matrix, resulting in the so-called granular MG (GMG). This material was tested for the adsorption of methylene blue (MB) from water, which is a typical dye used in textile industries and must be removed from the effluent. GMG materials with different MG contents (5 and 20 %) were compared with MG and a commercial adsorbent to assess their adsorption capacity and the most performing material was selected for in-depth physical and chemical characterization. The structural, surface, kinetic, isotherm, and thermodynamic properties, the pH and temperature dependence, as well as the regeneration and reuse of GMG 5% were investigated through batch adsorption tests under different operating conditions. The study reveals that GMG 5% has a superior adsorption capacity compared to the tested materials and can be considered as a promising alternative to commercial carbon-based materials according to techno-economic considerations.

Methylene blue sorption performance of lignocellulosic peach kernel shells modified with cellulose derivative chitosan as a new bioadsorbent

In this study, adsorption isotherms (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) and thermodynamic properties of cationic methylene blue (MB) dye adsorption onto chitosan-coated peach kernel shell waste (CTS-PKSh) from wastewater were investigated. CTS was cross-linked with citric acid (CA) and glutaraldehyde (GA). The adsorbents were characterized by FE-SEM/EDS, FTIR, and particle size distribution. MB adsorption behavior onto the biosorbents was investigated concerning parameters such as adsorbent dosage (0.8–8 g/L), time (0–540 min), pH (3−10), initial dye concentration (50–700 mg/L), and temperature (25–55 °C). The Langmiur qmax and experimentally qe MB adsorption capacities of the new adsorbents were found to be 227.27 and 201 mg/g for CA cross-linked CTS-PKSh (CA@CTS-PKSh) and 111.12 and 96.5 mg/g for GA cross-linked CTS-PKSh (GA@CTS-PKSh), respectively. The results of thermodynamic analysis showed that adsorption was feasible, exothermic, and spontaneous. According to adsorption and recyclability results, CA@CTS-PKSh was more effective for MB removal at a 2 g/L adsorbent dose for an initial dye concentration of 100 mg/L, 25 ± 1 °C, contact time 60 min, and pH 7.

Fabrication and evaluation of PVDF membranes modified with cellulose and cellulose esters from peanut (Arachis hypogea L.) shell for application in methylene blue filtration

Polyvinylidene fluoride (PVDF) membrane is frequently employed for filtration due to its excellent properties. The hydrophobicity of PVDF membrane causes easy fouling; therefore, hydrophilic polymer materials are required to increase hydrophilicity. This study applies cellulose and cellulose esters as fillers for PVDF membranes to solve the fouling problem. Cellulose esters, such as cellulose acetate (PSCA), cellulose benzoate (PSCB), and cellulose citrate (PSCC), were successfully synthesized from peanut shell cellulose (PSC) using Fischer and non-Fischer reactions. The phase inversion method was successfully used to fabricate PVDF membranes with cellulose or cellulose esters as fillers. The fabricated membranes have been applied for methylene blue (MB) filtration. Adding PSC fillers improved the hydrophilicity and performance of the PVDF membranes up to 23.49 ± 2.40 L m−2 h−1 for water flux and 95.75 ± 0.78 % for rejection of MB. Regarding cellulose esters, cellulose acetate gave the highest value of 77.63 L m−2 h−1 for water flux, and cellulose citrate gave the highest value of 86.88 ± 3.54 % for MB rejection. Hence, cellulose or cellulose esters from peanut shells are suitable fillers for MB filtration in PVDF membranes.

MoO3/HAp nanocomposites encapsulated in graphene oxide nanoparticle: Development of a novel ternary nanostructure and evaluation of its photocatalytic activity for the treatment of wastewater in environmental remediation

The growing problem of water contamination can be efficiently addressed using easily recoverable photocatalysts. Graphene Oxide (GO) is a well-studied photocatalyst for industrial effluent remediation, pharmaceutical degradation, and dye degradation. Its photophysical characteristics are morphology-dependent and show enhanced activity in MoO3/HAp nanocomposites. Hydrothermal synthesis of MoO3/HAp nanocomposites encapsulated in graphene formed a unique ternary nanostructure. XRD and XPS confirmed the crystalline phase and oxidation states, while FT-IR and EDAX validated atomic bonds and component dispersion. FE-SEM and HR-TEM showed a mesoporous surface and narrow size distribution. The visible-light-active MoO3/HAp/GO had a bandgap of 2.6 eV and low recombination rate. Photodegradation tests on antibiotics (Ciprofloxacin and Levofloxacin) and dyes (Congo Red and Methylene Blue) demonstrated high photocatalytic ability. Solar light achieved 98 % degradation for Ciprofloxacin, 88 % for Levofloxacin, 91 % for Congo Red, and 93 % for Methylene Blue. Post-photocatalytic analysis showed high catalyst reusability (13 % and 7 % reduction after 4 cycles for antibiotics; 13 % decrease after 5 cycles for dyes). Trapping experiments revealed that •OH and O2•- were key for antibiotic breakdown, while e− and h+ were crucial for dye degradation. This research highlights MoO3/HAp/GO's potential to eliminate persistent pollutants.

Synergistic adsorption-photocatalytic remediation of methylene blue dye from textile industry wastewater over NiFe LDH supported on tyre-ash derived activated carbon

The photocatalytic performance of the multilayered NiFe LDH/Activated Carbon was evaluated for the degradation of methylene blue (MB) in industrial textile wastewater, considering prior adsorption on the photocatalyst surface. The XRD, XPS, BET, TEM and FE-SEM results confirmed that the highly exposed mesoporous layers, carbon backbone, and interlayer anions serve as active sites responsible for the adsorption of MB dye due to the expected electrostatic interactions. Electrochemical methods such as CV, LSV and EIS revealed the improved conductivity and supported the interactions observed. Encouraged by these interactions, the irradiation of visible light enabled the degradation of methylene blue, and the degradation products were monitored using UPLC chromatograms and MS spectra. The removal efficiencies of the MB dye were found to be 17.5 %, 51.2 %, 67.1 %, 84.8 %, and 94.2 % due to photolysis, adsorption, and degradation on AC, NiFe LDH nanosheets, and NiFe LDH/AC nanocomposite, respectively. The results of the UPLC chromatograms and MS spectra suggested that MB was mineralized into simpler fragments after 30 min of visible light irradiation. Scavenging studies were examined using a series of scavenging agents. However, the maximum photodegradation was attained in the absence of the scavengers. The reusability studies showed that the MB photodegradation efficiency declined by 20.8 %, possibly due to the loss of the catalyst during the washing step. Nonetheless, the NiFe LDH/AC structure remained intact, suggesting the strong stability of the photocatalyst. The plausible degradation mechanism and probable degradation pathway of MB were outlined and supported by the chromatographs and MS results. The overall results suggest that photocatalysis of cationic dyes such as MB on NiFe LDH/AC should be encouraged to work towards sustainable solutions for textile water treatment.

Adsorption of methylene blue onto clay/carbon composite: kinetics and isotherms study

ABSTRACT Waste treatment for pollution control is a hot topic being studied and has received growing attention. In this study, spent bleaching earth (SBE), a waste material from the oil refineries, was pyrolyzed in a N2 atmosphere to produce an environmentally sustainable clay/carbon composite (SBE@C (500 °C)). SBE@C (500 °C) was tested for its ability to remove methylene blue (MB) from water. The Langmuir model best explained the adsorption isotherms, with maximum adsorption capacity of 29.54 mg/g (MB solution (10–60 mg/L)). The pseudo-second-order kinetic model effectively described the adsorption kinetics data. Thermodynamic parameters indicated spontaneous and endothermic processes. The impact of coexisting cations on MB adsorption by SBE@C (500 °C) decreased in the following order: Fe3+ &amp;gt; Al3+ &amp;gt; Mg2+ &amp;gt; K+ &amp;gt; Na+. The ionic strength results indicated that increasing the concentration of Na+ ions led to a decrease in adsorption capacity. MB removal was greatest at pH level of 8. The adsorption mechanisms involved π–π interactions, electrostatic interactions, and changes in physicochemical properties. After 3 cycles, SBE@C (500 °C) may be recycled up to 11 times before completely losing its adsorption capacity. Overall, SBE@C (500 °C) shows promise for removing MB from wastewater, while mitigating secondary pollution from SBE.

Extravasation with methylthioninium chloride

Introduction Methylthioninium chloride is used for multiple treatment purposes and is sometimes administered through peripheral intravenous lines. We highlight the potential adverse effects of methylthioninium chloride extravasation during continuous peripheral intravenous administration. Case summary A 38-year-old woman presented to the emergency department with multifactorial hypovolemic and septic shock. She was treated with a continuous peripheral infusion of intravenous methylthioninium chloride for shock refractory to multiple vasopressors. Images One day after administration commenced, the patient developed blue staining of the left upper arm due to extravasation of methylthioninium chloride proximal to the site of infusion. Further images show its later spread. Conclusion While reported cases of methylthioninium chloride extravasation are rare, it is our preference that methylthioninium chloride should be administered through a central line in cases of continuous infusion due to the risk of potential toxicity from extravasation.

The influence of operational factors on the photocatalytic degradation of methylene blue dye in aqueous Sr-Au-ZnO suspensions under UV-A light

Any of several processes that break down dyes, ideally into harmless chemicals, is referred to as industrial dye degradation. Water waste discharges various colors, particularly those used in the textile industry like methyl red and methylene blue, into ecosystems, leading to significant pollution of the water supply. Under UV-A irradiation, the photocatalytic degradation of a commercial heterocyclic aromatic chemical molecule called methylene blue (MB) has been investigated using an aqueous solution of Sr-Au-ZnO as a photocatalyst. Research has been done on how different process characteristics affect the degradation process. For the mineralization of MB dye under UV-A light, it was found that the optimized Sr-Au-ZnO was more effective than commercial catalysts (ZnO and benchmark photocatalyst Degussa P25), single metal dopants (Sr-ZnO, Au-ZnO), and prepared ZnO. The effects of operational parameters, such as the quantity of photocatalyst, dye concentration, and starting pH, on the photo-mineralization of MB are analyzed before optimal values are given. Chemical oxygen demand (COD) measurements have confirmed that MB is mineralized. Using GC–MS analysis, the intermediates produced during photodegradation were predicted, and an appropriate degradation pathway was suggested. This procedure can be used for treating wastewater from sewage since optimized Sr-Au-ZnO is reusable.

Synergistic effect of GN-Ag NPs enhancing the efficient catalytic degradation of MB and CR by PDA@MMT composite hydrogel

A novel composite hydrogel prepared from polyacrylamide (PAM), polydopamine-modified montmorillonite (PDA@MMT), graphene and hydroxypropyl cellulose (HPC), loaded with Ag NPs, was prepared for the catalytic degradation of methylene blue (MB) and Congo red (CR) using in situ reduction. HPC significantly enhanced the dispersion of PDA@MMT within the hydrogel, endowing the hydrogel with excellent mechanical properties, with stress and strain of 1773 kPa and 4005 %, and elastic modulus and toughness of 43.4 kPa and 29.54 MJ/m3, respectively. The introduction of graphene (GN) increased the rate of electron transfer during the catalytic process and significantly improved the catalytic efficiency, with catalytic rate constants of 1.360 and 0.803 min−1 for MB and CR at 20 °C, respectively. The hydrogels were endowed with excellent antimicrobial properties due to the introduction of Ag NPs. In the future, this hydrogel is expected to play an important role in environmental pollution control.

Development of a novel lightweight brick-activated carbon based BiVO4 photocatalyst and its adsorption-photocatalytic behavior for toxic dye removal in wastewater

The purpose of this research was to develop a novel photocatalyst by loading BiVO4 (BVO) particles on lightweight brick-activated carbon (LWB-AC). The characterizations of as-prepare samples were studied using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–VIS –NIR spectrophotometer (UV-VIS-NIR) techniques. The adsorption-photocatalytic methylene blue (MB) removal, methyl orange (MO) removal and rhodamine B (RhB) removal of the as-prepared LWB-AC based BVO photocatalyst were tested by irradiating visible light. The results showed that the LWB-AC based BVO photocatalyst exhibited the highest adsorption-photocatalytic efficiency for the removal of MB, MO and RhB dyes under visible light irradiation as compared to the other samples. This might be due to the synergistic effect between AC and BVO on the surface of LWB. Moreover, the presence of both AC and BVO on the surface of LWB helped in preventing the electron-hole recombination, resulting in the enhanced adsorption-photocatalytic activity. For reusability tests, the LWB-AC based BVO photocatalyst did not show the loss of adsorption-photodegradation ability of MB, MO and RhB dyes after five runs. A probable adsorption-photodegradation mechanism of LWB-AC based BVO photocatalyst was also proposed.

Tannic Acid-Based Self-Assembling Nanocarriers with Antiphotobleaching and Controlled Releasing Properties for Collaborative Near-Infrared Photothermal/Photodynamic Therapy.

Near-infrared (NIR) organic materials have been widely developed for tumor phototherapy due to their deep tumor penetration, good biodegradability, and high photothermal conversion (PCE). However, most of the NIR organic dyes are easily destroyed by photooxidation due to their big and long conjugated structures, such as cyanine dyes. Under light irradiation, the reactive oxygen species (ROS) produced by these NIR dyes can easily break their conjugated skeleton, resulting in a dramatic decrease in phototherapeutic efficiency. Herein, an NIR organic dye cyanine dye (CyS) and a photosensitizer methylene blue (MB) were chosen to prepare nanocarrier CMTNPs by facile self-assembling with a natural antioxidant, tannic acid (TA). TA can greatly enhance the stability of NIR cyanine dyes by scavenging ROS. Furthermore, CMTNPs have a character of pH/thermal dual response, allowing for controlled release of MB in the slightly acidic tumor environment during photothermal therapy. The released MB can turn on both fluorescence and photodynamic therapy effects. In vitro and in vivo experiments demonstrated the remarkable tumor ablation ability of CMTNPs. Thus, our study provided an antiphotobleaching and controlled release photosensitizer strategy through the introduction of antioxidant TA into the nanocarrier for efficient collaborative photothermal/photodynamic therapy.