Cationic Methylene Blue Research Articles

Self-assembly behavior of layered titanium niobate and methylene blue cation and electrochemical detection of dopamine

A novel nanocomposite MB/Ti5NbO14 was successfully synthesized by exfoliation/restacking method. The structure and morphology were characterized by X-ray powder diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis), and Fourier transform infrared (FTIR). It is indicated that materials were successfully synthesized, and MB was successfully intercalated between the layers of [Ti5NbO14]3− forming a layer with its molecular plane inclined to [Ti5NbO14]3− layer at about 39.88°. Meanwhile, electrochemical measurement demonstrated that MB/Ti5NbO14 nanocomposite exhibited enhanced electrochemical activities towards the oxidation of dopamine due to increased electro-transport properties. And the MB/Ti5NbO14 modified electrode has a detection limit of 2.01 µM (R/N 3.0) with the concentration range from 0.0249 to 0.4988 mM. This study indicated that this electrochemical sensor has satisfactory stability, and detects dopamine with strong anti-interference performance, repeatability, and reproducibility.

Facile production of three-dimensional chitosan fiber embedded with zinc oxide as recoverable photocatalyst for organic dye degradation

Herein we report on a facile and green strategy for continuous production of chitosan-zinc oxide fibers and then compare their photodegradation performance against three organic dyes (i.e., methylene blue (MB), methyl orange (MO) and Rhodamine B, respectively) under different lights. Chitosan-zinc hydrogel fibers (CS/Zn) with different zinc loadings are obtained by direct mixing of chitosan and zinc acetate solutions using a double-syringe injection device. The as-prepared CS/Zn fibers are then immersed into glutaraldehyde (GA) and sodium hydroxide solutions, respectively, and dried at T = 50 °C. The resultant CS/ZnO/GA fibers of ca. 617 μm in diameter are characterized using X-ray diffraction (XRD), thermogravimetric analysis and field emission scanning electron microscope (FE-SEM). XRD and FE-SEM data confirm that the CS/ZnO/GA fibers consist of a large amount of hexagonal wurtzite ZnO nanorods up to 550 nm in length, and exhibit three-dimensional interconnected macroporous architecture. Photodegradation results clearly show that the CS/ZnO/GA fibers are effective for the removal of organic dyes upon UV irradiation and can be easily recovered and reused for at least 6 consecutive cycles. Unlike most reported CS/ZnO nanocomposites, the current CS/ZnO/GA fiber shows a higher adsorption of cationic MB rather than anionic MO, the mechanism of which is proposed.

Investigation of Dye Removal Capability of Blast Furnace Slag in Wastewater Treatment

Blast Furnace Slag (BFS) is a by-product of the iron ore processing industry with potential to be used in different industrial applications. In this research, BFS was used to examine its ability for dye removal from wastewater. The efficiency of two types of BFS samples for removal of cationic methylene blue (MB) and acidic methyl orange (MO) dyes was investigated and results found that the optimal conditions for treatment of wastewater were 80 g/L of adsorbent dose and 1 h of treatment time for both dyes. BFS was found to be more effective for removal of the acidic MO dye than the cationic MB dye. Under shorter residence times, the results showed reverse trends with BFS samples removing higher concentrations of MB than MO. The BFS chemistry had additional impacts on the efficiency of dye removal. Higher basicity of BFS had lower dye removal ability for adsorption of acidic dye when applied at smaller concentrations, while for cationic dye when applied at higher concentrations. The results showed that BFS has potential role for pre-treatment of industrial wastewater contaminated with dyes and may contribute to reduced use of more expensive adsorbents, such as activated carbons.

Porous Organic Polymer Synthesized by Green Diazo-Coupling Reaction for Adsorptive Removal of Methylene Blue.

A porous organic polymer (marked as DT-POP), which contains abundant free phenolic hydroxyl groups, is synthesized by the well-known green azo-coupling reaction in water, characterized, and utilized as an effective adsorbent for the elimination of methylene blue (MB) from water solutions. The presence of permanent mesopores, abundant active functional groups, and π-electron enrichment ascribed to phenyl rings make DT-POP an efficient adsorbent for MB due to strong hydrogen bonding, π–π, and electrostatic interactions with the cationic dye MB. DT-POP with high stability and high adsorption capacity can be reused many times and thus shows high applicability in pollutant disposal.

A porous amide-functionalized pto-type MOF exhibiting selective capture and separation of cationic MB dye

A porous amide-functionalized two-fold interpenetrated MOF with pto-type topology, HNUST-10, has been solvothermally synthesized and characterized. HNUST-10 possesses large open channels and exhibits efficient selective capture and separation of cationic methylene blue (MB) dye from low concentration DMF solution at 298 K as compared with other organic dyes such as methyl orange, Sudan II, Congo red, etc.

Simultaneous Dyeing and Finishing of Cotton Fabric in Presence of Starch Nanoparticles as Reinforcement Agent Using Citric Acid Based Finishing Formulation

ABSTRACT To augment high performance, coloration and functional finishing onto cotton fabrics; novel approach for simultaneous dyeing and finishing in addition to reinforcement effect were applied by conventional pad-dry-cure method in one step. This was done to explore the potential of reduction in energy consumption and production time as well as dyes and chemicals. For this purpose, our previously prepared starch nanoparticles (SNPs) as a reinforcement biopolymer were incorporated in cross-linking formulation of cotton fabrics embracing different concentrations of citric acid and cationic dyes, i.e., Methylene Blue and Crystal Violet in presence of sodium hypophosphite as a proficient catalyst at 1500C for 2 minutes. Evaluation of the treated fabric performance with respect to color strength (K/S), fastness properties to light, rubbing and perspiration, add on %, dry wrinkle recovery angles, tensile strength, fabric stiffness, antibacterial effect and ultraviolet protection factor were appraised. It is seen from the obtained results that; the simultaneously dyed and finished fabric in presence of SNPs showed higher color strength, dry wrinkle recovery angle, tensile strength, fabric stiffness, antibacterial and UPF functionalities in addition to considerable light, rubbing and perspiration fastness in comparison with untreated fabric. Besides, FTIR spectra exhibited the chemical structure of treated fabrics with respect to the presence of the ester crosslinking and functional groups of cationic dyes in questions in comparison with untreated fabric. The durability of the imparted functional properties was confirmed also by washing test.

Photocatalytic Degradation of the Light Sensitive Organic Dyes: Methylene Blue and Rose Bengal by Using Urea Derived g-C3N4/ZnO Nanocomposites

In this study, we report the fabrication of graphitic carbon nitride doped zinc oxide nanocomposites, g-C3N4/ZnO, (Zn-Us) by using different amount of urea. They were further characterized by X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman, UV-vis, Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) techniques. The prepared nanocomposites were used as photocatalysts for the mineralization of the light sensitive dyes Methylene Blue (MB) and Rose Bengal (RB) under UV light irradiation, and corresponding photo-mechanism was proposed. Benefiting from these photocatalytic characteristics, urea derived g-C3N4/ZnO photocatalysts have been found to have excellent photodegradation activity against the MB and RB for 6 h and 4 h, respectively. Under the given experimental conditions, the degradation percentage of fabricated Zn-Us were shown ~90% for both model dyes. Compared to cationic MB dye, anionic RB dye is more actively degraded on the surface of prepared photocatalysts. The results obtained can be effectively used for future practical applications in wastewater treatment

Induced Circular Dichroism of Methylene Blue in Self-Assembled Pullulan Nanoparticles

This study reports self-assembled pullulan nanoparticles (PUNPs) obtained by the diafiltration method after dissolving phthalic pullulan in dimethylformamide, which was prepared by esterification between the primary hydroxyl groups of the pullulan and carboxylic acids of phthalic anhydride. The morphologies of the PUNPs observed by transmission electron microscopy (TEM) were spherical shapes. The particle sizes of the PUNPs measured by dynamic light scattering (DLS) were around 75.3 nm with −49.32 mV zeta potential. The ordered structure of pullulan measured by circular dichroism (CD) spectroscopy and X-ray diffraction (XRD) was enhanced by the formation of self-assembled polymeric NPs. Methylene blue (MB) used in tissue imaging agent was loaded into PUNPs via ionic bonding of cationic MB and anionic PUNPs, the CD of MB was induced in the PUNPs in the range of 500–700 nm whose crossing point matched κmax in the UV region of MB.

Fabrication of semi-interpenetrated PVA/PAMPS hydrogel as a reusable adsorbent for cationic methylene blue dye: isotherms, kinetics and thermodynamics studies

A reusable adsorbent was developed based on semi-interpenetrated hydrogel made of poly(vinyl alcohol) (PVA) and poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) for the adsorptive removal of cationic methylene blue (MB) dye. The developed PVA/PAMPS adsorbent hydrogel was characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA) and scanning electron microscope (SEM) analysis tools. Consequence of the variation of AMPS concentration on water uptake profile and polymer add-on (%) was explored. In addition, batch adsorption studies were performed to evaluate the aptitude of the developed adsorbent for MB dye removal under several adsorption conditions. The results showed an increase in the add-on (%) value up to 70% with increasing AMPS content up to 5%. Moreover, the MB dye removal was occurred quickly at the initial stage and recorded 60% after only 5 min from the initial contact time, while it recorded a maximum value of 86% at 25 oC. The experimental adsorption data were well-fitted to the Langmuir isotherm model and followed the pseudo-second-order kinetic model. Moreover, the adsorption of MB dye by the adsorbent hydrogel was an endothermic process. Besides, the PVA/PAMPS adsorbent exhibited better reusability with a maximum removal (%) exceeded 70% after five consecutive cycles. The results obtained from this study infer that the PVA/PAMPS adsorbent hydrogel could be effectually used as an appropriate and reusable adsorbent for removing cationic MB dye molecules from wastewater bodies.

Robust and lightweight biofoam based on cellulose nanofibrils for high-efficient methylene blue adsorption

Robust and ultralight biofoams had been successfully prepared using readily available and biocompatible cellulose nanofibrils (CNFs) as the matrix. The γ-glycidoxypropyltrimethoxysilane (GPTMS) was first added into the CNFs suspension to act as a crosslinker to form covalent linkages between cellulose chains. Then the gelatin was incorporated into the networks via reacting with the epoxy groups on GPTMS and forming hydrogen bonding with CNFs. The content of gelatin had a significant influence on the properties of the obtained foams. With the introduction of a small amount of gelatin, the foams exhibited significantly enhanced mechanical properties and stability in water in comparison with the CNF foams without GPTMS and/or gelatin. The foams containing the appropriate ratio of gelatin to CNFs possessed the high porosity (99.16%), ultralow density (0.0077 g/cm3), good mechanical properties, and abundant functional groups (hydroxyl and carboxylate groups). These features made it an ideal adsorbent toward methylene blue (MB) and the maximum adsorption capacity could reach up to 430.33 mg/g. Additionally, the cationic MB could be removed from the mixed cationic/anionic dye solutions with high selectivity, possibly due to the strong electrostatic interactions between MB and the adsorbent. Furthermore, the recycling test demonstrated the good reusability of this biofoam. Therefore, this work provides an environmentally benign method to fabricate robust CNF-based foams, which can be considered as green adsorbents for the treatment of water pollutants.

TiO2 modified orthocortical and paracortical cells having enhanced photocatalytic degradation and photoreduction properties

In this study, cortical cells resultant from wool fibers were loaded with TiO2 nanoparticles in a hydrothermal process and were then engineered as organic-nonorganic hybrid composite photocatalysts for both photodegradation of organic dyes and photoreduction of heavy metal ions. The microstructure and photocatalytic properties of TiO2 modified cortical cells (i.e. both orthocortical and paracortical cells) were systematically characterized using a series of analytical techniques including FESEM, TEM, element analysis, Mott–Schottky curve, BET specific surface area, Zeta potentials, as well as XRD, FTIR, XPS, DRS, PL, UPS, EDS and ESR spectra. Their photocatalytic performance and trapping experiments of the TiO2 modified cortical cells were measured in the photodegradation of methylene blue (MB) dye and Congo Red (CR) dye as well as the photoreduction of Cr(VI) ions under visible light irradiation. It was found that anatase TiO2 nanoparticles were chemically grafted on the surface of the two cortical cells via O–Ti4+/O–Ti3+ bonds, and that TiO2 nanoparticles were formed inside the orthocortical cells in the hydrothermal process. The TiO2 modified orthocortical and paracortical cells possessed much higher photocatalytic efficiency than the commercially available TiO2 nanoparticle powder, Degussa P25, in the photodegradation of cationic MB dye and photoreduction of Cr(VI) ions, while their photocatalytic efficiency in the photodegradation of anionic CR dye is smaller because of their greater negative Zeta potentials and photogenerated holes as the main reactive radical species. In comparison with the TiO2 modified paracortical cells, the higher photocatalytic efficiency of the TiO2 modified orthocortical cells was demonstrated in the photodegradation of MB dye solution and this might be due to both the S-doped TiO2 nanoparticles infiltrated into the naturally hydrophilic orthocortical cells and the primary reactive radical species of photogenerated holes being trapped in the cells.

Hydroxyapatite nanocomposite as a potential agent in osteosarcoma PDT.

Using Nanoplatforms as a hauler for photosensitizers is a bespoke paradigm to improve its bioavailability and to boost the PDT efficacy. Herein, the photodynamic cytotoxicity of methylene blue (MB) loaded on hydroxyapatite nanoparticles (HA-NPs) was tested against human osteosarcoma-derived cells (Saos-2 cell line). HA-NPs and HA-NPs loaded with MB (HA-NPs-MB) were prepared by a chemical precipitation method and characterized by TEM, Zeta potential, FTIR, and XRD. TEM images revealed that HA-NPs have a rod shape with a diameter of 14-17 nm and length around 46-64 nm. FTIR and Zeta potential confirmed the adsorption of cationic MB on HA-NPs. XRD pattern was identical to the standard XRD pattern of HA-NPs. Incubation of Saos-2 cells (24 h) with HA-NPs-MB then irradiation of cells (5 min) with a diode laser (808 nm), causes a higher decrement of cell viability (determined by MTT assay) than that caused by free MB. The LC50 was 57.53 µg/mL and 86.99 µg/mL for HA-NPs-MB and free MB, respectively. Thus, the nanoformulation of MB greatly reduced the dose of MB required for effective PDT. This study also investigated the mode of cell death after incubation of cells with free MB or HA-NPs-MB composite then exposure to laser radiation. The results revealed that the majority of cells died by apoptosis while a minor fraction of cells died by necrosis, especially in the case of HA-NPs-MB. Levels of caspase-3 and death receptor-4 (DR-4) were more elevated in the case of HA-NPs-MB than free MB. The effect of the prepared nanocomposite and free MB on Raw murine macrophage (RAW 264.7) viability was also examined using the MTT assay. The results indicated that HA-NPs-MB in the presence of laser has a great cytotoxic effect on macrophage cells compared to other treatments. This may present an advantage through decreasing macrophage that promotes tumor growth. In conclusion, HA-NPs-MB nanocomposite surmounts free MB and HA-NPs in destroying macrophage cells and Saos-2 cells through apoptosis in the presence of laser irradiation. This study introduces a thorough and new insight on osteosarcoma (cancer cell line Saos-2) PDT using HA-NPs-MB exploiting the biosafety of HA-NPs.

Adsorption performance of UiO-66 towards organic dyes: Effect of activation conditions

The Zr-based metal-organic framework (MOF, UiO-66) was synthesized solvothermally. The synthesized UiO-66 was activated using different solvents (acetone, chloroform, and ethanol) via two activation methods of centrifugation and Soxhlet extraction over different periods (1–10 days). The crystalline structure and morphology of the synthesized UiO-66s were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and field-emission scanning electron microscopy (FESEM) techniques. The adsorption behaviors of the synthesized UiO-66s were then investigated by selecting anionic methyl red (MR) and cationic methylene blue (MB) as the model dyes. It was found that a change in activation solvent and activation method would alter the physical properties of UiO-66, such as surface area, pore-volume, pore diameter, and surface charge. Experimental adsorption tests demonstrated that UiO-66 activated by ethanol via the Soxhlet extraction method for five days (abbreviated as ES-5) presented higher MR uptake capacity (243 mg/g) than the other synthesized UiO-66s, ascribed to its large surface area and total pore volume. Furthermore, it was found that the uptake capacity of ES-5 for cationic MB and anionic MR dyes increased and decreased, respectively, with raising the solution pH. This resulted in superior adsorption selectivity of MB over MR at pH 9.1. All in all, the findings of this work showed that the Soxhlet extraction method holds great promise for the activation of different MOFs.

Adsorption and heterogeneous Fenton catalytic performance for magnetic Fe3O4/reduced graphene oxide aerogel

Heterogeneous Fenton system has been widely used in water treatment because of its effective degradability in a wide range of pH. A two-step hydrothermal method for the synthesis of Fe3O4/reduced graphene oxide (RGO) aerogel was designed as an efficient and recyclable heterogeneous Fenton catalyst for degradation of methylene blue (MB). Firstly, the Fe3O4 colloidal solution was synthesized by hydrothermal progress. Secondly, graphene oxide hydrogels were formed by the self-assembling and reduced to graphene during the hydrothermal reaction. Meanwhile, zero-dimensional Fe3O4 nanoparticles were anchored onto the graphene oxide through the colloidal coagulation effect. The obtained samples were characterized by XRD, SEM, TEM, BET, Zeta, XPS, Raman, TG, and VSM. Adsorption isotherm and kinetics of MB onto Fe3O4/RGO composites revealed that the maximum adsorption capacity was 163.83 mg/g, and the adsorption process confirmed to the pseudo-second-order model. The determinants of heterogeneous Fenton system including oxidant concentration, initial pH, and reaction mechanism were investigated. The studies indicated that MB degradation efficiencies increased with the initial pH increasing (pH 3–10), showing a complete degradation in alkaline condition within 60 min. It is due to that catalytic reaction mainly occurs on the solid–liquid interface, as pH values increase, the electrostatic attraction between the cationic MB molecules and the surface of Fe3O4/RGO increases, the enhancement of adsorptivity is helpful to improve catalytic activity. The catalyst can be easily recovered by an applied magnetic field and exhibited excellent stability after five degradation cycles.

Synthesis of cellulose carbon aerogel via combined technology of wet ball-milling and TEMPO-mediated oxidation and its supersorption performance to ionic dyes

In this study, modified cellulose aerogels (CAs) were obtained via wet ball-milling and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation and were further applied to prepare cellulose-derived carbon aerogels (CCAs) by pyrolyzing. The results showed that the successive treatments by ball-milling and oxidation completely opened the CA fibers and converted them into plane or wrinkle structures. CCAs contained porous and graphite-like structures and its specific surface area reached up to 2825 m2/g. The maximum adsorption capacities of CCAs were 1078 mg/g for methylene blue (MB) and 644 mg/g for alizarin reds (ARS). The sorption of dyes occurred via hydrophobic partition, pore-filling, H-bonding, p/π-π electron donor–acceptor interactions. For the cationic MB, electrostatic attraction reinforced the sorption, while the electrostatic repulsion between the anionic ARS and CCAs was weakened by high salty. Besides, CCAs showed excellent salt tolerance. The present study provides an excellent CCA adsorbent by successive modification of ball-milling and oxidation of CAs.

Biosynthesized gold nanoparticles as photocatalysts for selective degradation of cationic dye and their antimicrobial activity

Herein, polyphenol stabilized gold nanoparticles (AuNPs) have been synthesized for selective removal of cationic dyes from aqueous solution. Gold nanoparticles have been synthesized using Cassytha filiformis plant extract and characterized by UV–vis spectroscopy (UV–vis), High-Resolution Transmission Electron Microscopy (HR-TEM) and X-ray diffraction (XRD). The size of AuNPs was found to be in the range of 8–20 nm with an average size of 12 nm. The newly generated AuNPs demonstrate excellent potential in removing cationic dye such as methylene blue (MB) via photocatalytic degradation under sunlight. The adsorption/degradation behaviour of cationic MB on AuNPs adsorbent from the aqueous solution was studied by varying parameters such as pH and different light sources. Alkaline pH and sunlight were found to be crucial in dye degradation. The adoption of the ultrasonic waves (UW) leads to reduce sorption time significantly with an increase in the sorption ability and at the optimum condition. The AuNPs appear to be promising with a maximum dye loading capacity of 595.23 mg/g and dye degradation efficiency was found to be 87 % after 20 min. Additionally, the antimicrobial studies confirm the significant inhibition (zone of inhibition: 20 mm) of growth of Mycobacterium smegmatis, a model organism for Mycobacterium tuberculosis, suggesting the advancement of a novel new generation eco-friendly and cost-effective ‘green’ AuNPs.

Optimization and Adsorption Behavior of Nanostructured NiFe2O4/Poly AMPS Grafted Biopolymer

By grafting polysaccharides backbone of biopolymer (alginate) on synthetic polymer nanocomposite chains (PAMPS/NiFe2O4) to remove methylene blue and toxic heavy metal (Cu2+) from aqueous solutions, a superadsorbent was prepared. Using FTIR, TGA, X-ray diffraction, TEM, and SEM studied the structures of native and grafted alginate hydrogels. Adsorption experiments have been optimized using RSM/CCD response surface methodology and analyzed as a pH solution and adsorbent dose function. The initial concentrations of metal and dye, temperature, and contact time were also discussed and isothermal, thermodynamic adsorption, and kinetic theoretical constants were calculated as well. Results revealed that alginate grafted nanocomposite PAMPS/NiFe2O4 enhanced the proportion of methylene blue (MB) color removal up to (98.32%) and metal ion discharge (83%). The optimum cationic dye MB and Cu2+ ions adsorption capability were acquired at pH (5.75 and 4) and temperature (318.15 K) respectively. For both MB dye and Cu2+ ions, the pseudo-2nd-order model has effectively defined the adsorption kinetics and the Freundlich model could precisely explain adsorption isotherms than the Cu2+ Langmuir adsorption model, while the adsorption of MB dye showed a greater presence for both Freundlich and Langmuir designs. MB dye and Cu2+ ions have recorded the highest adsorption capacity of 275.6 and 22.81 mg/g respectively; indicating an efficient separation of adsorbent from aqueous solutions for both cationic dyes and toxic heavy metals.

Kinetics and equilibrium adsorption of methylene blue onto cotton gin trash bioadsorbents

Cotton gin trash (CGT), a residual lignocellulosic biomass generated during the ginning process of cotton fibres, is proposed for valorization and application in environmental remediation. Taking advantage of its availability and composition, rich in hydroxyl, carboxyl, and carbonyl groups, CGT is studied for its suitability for dye removal. Cotton gin trash films are synthesized using a single-step process with formic acid and tested for methylene blue (MB) adsorption. The morphology, chemical structure, surface area, zeta potential and crystallinity of the films are also reported. The hydroxyl groups in CGT increased by the film preparation and further enhanced the zeta potential of CGT towards the negative direction. Overall, the adsorption process is governed by the physisorption characteristic, where a greater potential difference between CGT and cationic MB improved the dye uptake. The adsorption system is described as favourable, fitting better with Langmuir isotherm model. The maximum adsorption capacity of the CGT films is 209 mg/g, which compares favourably against other reported lignocellulosic materials. Overall, the results indicate the CGT has an enormous potential as an adsorbent material for dye separation from wastewaters.

The effects of chitin/chitosan nanowhiskers on the thermal, mechanical and dye adsorption properties of electrospun PVA nanofibrous membranes

Poly(vinyl alcohol) (PVA) nanofibrous membranes (NFMs) containing various contents of α-chitin nanowhiskers (CtNWs) or chitosan nanowhiskers (CsNWs) were fabricated via electrospinning. The CtNWs were extracted by acid hydrolysis of chitin obtained from shrimp shells. The CsNWs were prepared by surface deacetylation of CtNWs by alkaline treatment. The CtNWs and CsNWs were characterized using transmission electron microscopy and X-ray diffractometry. The morphological and structural analyses of the PVA NFMs containing CtNWS or CsNWs were conducted by field emission scanning electron microscopy and attenuated total reflectance infrared spectroscopy. Also, the physical properties of the NFMs were investigated using thermogravimetric analysis and texture analyzer. The adsorption capacity toward cationic methylene blue of the PVA NFMs with CtNWs or CsNWs was evaluated using UV–Vis spectrophotometry, and it was found that the electrostatic repulsive force due to the surface positive charges of CtNWs and CsNWs reduced the adsorption performance.

Efficient Selective Sorption of Cationic Organic Pollutant from Water and Its Photocatalytic Degradation by AlVO₄/g-C₃N₄ Nanocomposite.

This study reports the synthesis, characterization and water remediation application of novel AlVO₄/g-C₃N₄ nanocomposites. The nanocomposite has been synthesized by a low temperature solid-state reaction using graphitic carbon nitride (g-C₃N₄) obtained via calcination of melamine and AlVO₄ prepared via assisted sonochemical technique. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared spectroscopy (FTIR), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), and the N₂ gas adsorption Brunauer-Emmett-Teller (BET) method has been used to characterize the pristine and composite samples. AlVO₄ and g-C₃N₄ interact with each other forming a hybrid composite, which shows excellent ability for selective sorption of cationic MB (methylene blue) dye from wastewater. The initial dye concentration, pH and amount of sorbent has been varied and their effect on the adsorption process has been analysed. The photocatalytic efficiency of the MB dye adsorbed pristine g-C₃N₄, AlVO₄:g-C₃N₄ (1:3) and AlVO₄:g-C₃N₄ (1:1) composite has been tested under visible light. With increased proportion of AlVO₄ in the samples, the photocatalytic efficiency improved and the best photodegradation has been observed for the AlVO₄:g-C₃N₄ (1:1) sample. Photoluminescence (PL) studies, photocurrent response measurements and electrochemical impedance spectroscopy (EIS) indicates enhanced separation of the photogenerated electron/hole pairs leading to effective degradation of the MB dye solution in case of the AlVO₄:g-C₃N₄ (1:1) composite sample. The photocatalytic mechanism has been elucidated and it could be inferred that photogenerated holes and superoxide anion radicals play a major role in the photocatalysis process.