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Herein, we report the synthesis of an oxidized pine needle-thiosemicarbazone Schiff base (OPN-TSC) from whole pine needles (WPN) as a dual-purpose adsorbent to remove a cationic dye, methylene blue (MB), and Hg2+ ions in separate processes. The adsorbent was synthesized by periodate oxidation of WPN followed by a reaction with thiosemicarbazide. The syntheses of OPN and OPN-TSC were confirmed by FTIR, XRD, FESEM, EDS, BET, and surface charge analysis. The emergence of new peaks at 1729 cm−1 (–CHO stretching) and 1639 cm−1 (–COO− stretching) in the FTIR spectrum of OPN confirmed the oxidation of WPN to OPN. FTIR spectrum of OPN-TSC has a peak at 1604 cm−1 (C = N stretching), confirming the functionalization of OPN to OPN-TSC. XRD studies revealed an increase in the crystallinity of OPN and a decrease in the crystallinity of OPN-TSC because of the attachment of thiosemicarbazide to OPN. The values of %removal for MB and Hg2+ ions by OPN-TSC were found to be 87.36% and 98.2% with maximum adsorption capacity of 279.3 mg/g and 196 mg/g for MB and Hg2+ ions, respectively. The adsorption of MB followed pseudo-second-order kinetics with correlation coefficient (R2 of 0.99383) and Freundlich isotherm (R2 = 0.97239), whereas Hg2+ ion removal demonstrated the Elovich (R2 = 0.97076) and Langmuir isotherm (R2 = 0.95110). OPN-TSC is regenerable with significant recyclability up to 10 cycles for both the adsorbates. The studies established OPN-TSC as a low-cost, sustainable, biodegradable, environmentally benign, and promising adsorbent for the removal of hazardous cationic dyes and toxic metal ions from wastewater and industrial effluents, especially the textile effluents. [ABSTRACT FROM AUTHOR]

Methylene blue is a synthetic and cationic dye that finds utility in different fields including pharmaceutical, paper, textile, printing, carpet, and photography industries. Adsorption is a very effective technique to decolorize contaminated wastewater. This study aimed to determine the efficacy of Multiwalled Carbon Nanotubes (MWCNTs) as an adsorbent for decolorization of MB dye from aqueous solutions. The study examined various characteristics affecting adsorption, including concentration of dye, pH value, dosage of MWCNTs, and contact time. The results that growing the adsorbent dosage from (25 to 120) mg increased the dye efficiency rate from 62% to 98%, respectively, were shown. The study also evaluated pH, which is among the most critical factors influencing removal efficiency. The best pH for the removal efficiency was 6 at an initial concentration of MB dye 20 mgL-1, a contact time 60 min, and an MWCNT dosage 100 mg. Langmuir, Freundlich, and Temkin isotherms were used to describe the adsorption equilibrium. The Langmuir isotherm with an R² value of 0.9968 and a maximum capacity for adsorption of 19.6 mgg-1 provided a suitable fit for the data of the experiment. In comparison between the suitability of kinetic models pseudo-first-order, pseudo-second order, and Weber-Morris, the kinetics model's correlation value was shown to be greater than that of the pseudo-second order kinetic model with an R² value of 0.9982. [ABSTRACT FROM AUTHOR]

Phytoremediation developed as a green-clean, solar-driven and innovative technique for the eradication of contaminants from the environment from last two decades. In the present research work, phytoremediation potential of an ornamental plant Trachyspermumammi L. was examined for the removal of a triarylmethane–methylene blue and diazo-Congo red dye. The various parameters such as initial dye concentration, contact time, and pH were focused to explore the dye removal capability of T.ammi L. in wastewater. The increase in initial dye concentration affects the phytoremediation potential of the T.ammi L. and found to be reduced with enhancing the initial dye concentration of both the dyes. The plant achieved condition of equilibrium after 40 h of contact time with both Methylene blue and Congo red dyes. The kinetics of phytoremediation reaction with both Methylene blue and Congo red dyes were studied with the help of pseudo-first order, pseudo-second order, and Elovich models, and the results were well appropriated to pseudo-first order with the correlation value R2 ≥ 0.99 for methylene blue and R2 ≥ 0.97 for Congo red. The Langmuir and Freundlich isotherms studies of phytoremediation reaction found in favor of Freundlich equilibrium isotherm with correlation R2 ≥ 0.99 for both methylene blue and Congo red dyes. The finding of analytical studies disclosed that the phytoremediation mechanisms of Methylene blue and Congo red by T.ammi L. involves phytosorption through electrostatic interaction and hydrogen bonding and also degradation of dyes occur through desulfurization and denitrification. [ABSTRACT FROM AUTHOR]

In this study, kocho was prepared from pseudostem and corm of Ensete ventricosum (enset). The behaviors of kocho were examined by using FESEM, TGA, XRD and FTIR spectroscopy. The biosorption potential of kocho, a possible low-cost new biosorbent for the efficient removal of MB dye from wastewater was investigated. Biosorption experiments were carried out in batch mode to study the effects of biosorbent dosages (0.025-0.2 g), pH (2-10), initial concentrations of MB (10 to 100 mg/L) and contact time (10 to 120 min). The highest removal efficiency of methylene blue dye (94.2%) was recorded at optimum experimental conditions. Following the removal study, it was determined that the pseudo-second order kinetics (R² = 0.997) and Langmuir isothermal (R²= 0.996) models may well describe the MB dye biosorption process. Furthermore, this newly developed biosorbent was fairly recyclable up to five cycles without significant loss of re-adsorption efficiency (around 9.6% loss) between 1st and 5th cycle. Thus, the findings of this study revealed that a new kocho biosorbent derived from Ensete ventricosum can be used as a promising low-cost, environmentally friendly and efficient biosorbent for the rapid removal of MB from aqueous solutions. [ABSTRACT FROM AUTHOR]

BACKGROUND: Methyl orange (MO) and methylene blue (MB) from aqueous solutions were effectively removed using thermally treated pine (Pinus kesiya) leaves. The influences of solution pH (2–10), contact time (10–240 min) and initial dye concentration (100–500 mg L−1) were found to be significant in the process of dye removal. The experimental data were fitted with four isotherm models (Langmuir, Freundlich, Sips and Temkin) and four kinetic models (Elovich, pseudo‐first‐order, pseudo‐second‐order and intraparticle diffusion). Some mechanisms of the MO and MB adsorption onto the adsorbent material were proposed and discussed. Results: Among the four isotherm models examined, the experimental data gave the best fit with the Langmuir model. The maximum Langmuir adsorption capacities were 136.99 mg g−1 for MO and 140.85 mg g−1 for MB. Kinetic studies illustrated that the biosorption of both dyes onto pine leaves aligns with Elovich, pseudo‐first‐order, pseudo‐second‐order and intraparticle diffusion models. Thermodynamic studies showed that the uptake of the two dyes was regulated by physisorption, and it was spontaneous and endothermic in nature. Electrostatic interactions, as well as other noncovalent forces such as π–π interactions and hydrogen bonds, were mechanisms of dye adsorption on heat‐treated pine leaf biomass. Conclusion: The present study suggests that pine leaves could be a potential biosorbent for wastewater treatment due to their high availability and production, resulting in several environmental advantages. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis of magnetic fly ash composites and its application for the removal of methylene blue (MB) from wastewater. By-product of oil power plants, oil fly ash, was treated with magnetic nanoparticles after chemical surface modification and dubbed modified fly ash (MFA). MFA was characterized by X-ray fluorescence, diffractogram analysis, scanning electron microscopy, energy-dispersive X-ray (EDX), and Fourier transform infrared (FT-IR) and N2 physisorption. MB (methylene blue) was removed from an aqueous solution using the response surface modelling (RSM) technique, which was used for optimization reasons. All four independent factors were investigated to see how they affected the removal process: adsorbent dosage; contact time; pH; and beginning dye concentration. The rate of MB removal was strongly influenced by the pH of the solution. The Langmuir and Freundlich models were used to examine equilibrium data A for MB adsorption onto the MFA in linear and nonlinear forms. Langmuir gave a better fit. The adsorption kinetics shown by increased kinetic statistics were better characterized by a pseudo-second-order MFA model. As far as thermodynamic characteristics go, adsorption is endothermic and occurs spontaneously. It has been proven that MFA may be used as an adsorbent to remove MB dye with high efficiency, and the quadratic model has been proved to be statistically significant. [ABSTRACT FROM AUTHOR]

Water pollution emerges from different sources such as industry, domestic uses, use of pesticides and fertilisers and other daily uses of organic materials. Wastewater treatment has received great interest especially in the last few years and different techniques have been used for that object. The most recents are the advanced oxidation processes; where photocatalytic reactions represent a sounding technique. In the present work Methylene Blue dye (MB) is used as a model pollutant and the dye-polluted water is photocatalytically treated using TiO2 as nanoparticles and nanofiber in different dosages. The catalyst is supported on Agar-Agar before being used. Another set of experiments is run with silver-doped catalyst where the catalyst is doped with different concentrations of silver (Ag). Results showed that TiO2 nanoparticles have better performance as a photocatalyst than TiO2 nanofiber. It is clear that the highest performance is given by the catalyst doped with 2% silver (51.679% degradation). This is followed by doping with 3% silver (37.367% degradation) while doping with 1% silver gave results very close to the results of un-doped TiO2 (24.026% degradation for 1% silver-doped catalyst as compared to 24.393% degradation for the undoped catalyst). The Response Surface Methodology (RSM) is used for predicting the optimum values for the operating parameters which lead to the highest percentage dye degradation. The optimum values were found to be as follows: 40 ppm, 10 ppm and 5 for catalyst conc., dye conc. and pH, respectively. The maximum percent degradation achieved at these conditions was 49.45%. Validation of the model with experimental results showed that the model fits well this type of processes. [ABSTRACT FROM AUTHOR]

Herein, for the first time, a simple, green, direct immersion immobilisation method is reported for graphene oxide (GO) nanosheets using pomelo peel (PL) as a substrate. A GO/PL porous sponge was successfully prepared and used to remove methylene blue (MB) from dye wastewater. Considering the porosity, hydrophilicity and elasticity of the PL, the PL was placed in a GO aqueous suspension through direct immersion immobilisation. The carboxyl and hydroxyl groups in the peel could effectively capture and immobilise the GO nanosheets. GO was adsorbed into the PL pores and dispersed throughout the PL. Finally, the prepared super-hydrophilic and elastic GO/PL exhibited excellent adsorption performance towards MB in dye wastewater. The adsorption results revealed that the adsorption behaviour was consistent with the Langmuir isotherm and quasi-secondary kinetic models. The maximum equilibrium adsorption capacity of GO/PL towards MB was 124.2 mg/g, exceeding the values obtained for most of the previously reported adsorbents. Moreover, after five consecutive adsorption–desorption cycles, GO/PL retained 75% of its initial adsorption capacity. Mechanistic analysis revealed that pore filling, electrostatic attraction, ion exchange and hydrogen bonding interactions are the primary driving forces facilitating MB adsorption. [ABSTRACT FROM AUTHOR]

Methylene blue (MB) is one of the most widely studied organic molecules in the treatment of wastewater. Sorption, biodegradation, photodegradation, electrochemical oxidation, ozonation, and other advanced oxidative processes are frequently used to remove this dye from water solutions. The unexpected degradation of MB adsorbed on magnetic biochar from aqueous solution was observed. We found that the conditions of handling, such as drying temperature and storage period, substantially influenced the stability of the dye fixed on the (magnetic) carbon adsorbents. Twelve substances were identified by mass spectrometry as products of decomposition, mostly demethylated, oxidated, and hydroxylated substances. The decomposition of MB was further investigated using non-magnetic carbon biochars and aluminosilicate mineral zeolite. Our findings of the spontaneous decomposition of MB and the identification of the species of degradation offer a new approach to evaluate the mechanism of adsorption, the process of regeneration, and the toxicity of treated solutions. [ABSTRACT FROM AUTHOR]

Water pollution remains a global problem that urges researchers to develop new technologies aimed at environmental restoration. Here, this study aimed at obtaining an activated biochar from pequi almonds for dye removal. Before and after adsorption, the materials underwent characterization using techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Raman spectroscopy, and thermogravimetric analysis (TG). The biochar from the pequi almond was called BA, and the activated biochar from the pequi almond was called ABA. The influence of the pH, contact time, and adsorbate concentration on adsorption was investigated using the dye methylene blue. The morphological assessment revealed higher cracks and pores in the ABA than in the BA. The TG showed that the BA lost approximately 19% more mass than the ABA, indicating that activation occurred. The activation contributed to the decrease in the degree of disorder in the BA because of the increased number of graphitic carbon atoms (ordered) in the ABA, as observed via Raman. The adsorption kinetics followed a pseudo-second-order model, while the adsorption isotherms followed the Langmuir model. The BA adsorption capacity was 500.00 mg g−1, constituting a robust solution for dye removal from aqueous environments. Therefore, this implies the success of the process. [ABSTRACT FROM AUTHOR]

Incorporating TiO2 with CNTs and PAN nanofiber structures results in a photocatalytic membrane composite with an attractive response in the visible region. It offers an efficient process without post-treatment separation at the end of the photocatalytic treatment. The composite membranes were fabricated using electrospinning at 7 kV with 10 cm in the distance between needle tip and collector at a flow rate of 1 mL h−1. Polyacrylonitrile (PAN) was used as the polymer matrix. All the as-spun composites exhibited randomly oriented nanofibers. CNT increased the fiber diameters from 324 to 463 nm. The bandgap of TiO2 also shifted from 3.15 to 2.76 eV at the narrowest The color removal kinetics follow the Langmuir-Hinshelwood pseudo-first-order kinetics model with the highest rate constant of 0.0225 min−1 shown by PAN/TiO2/CNT 20%. More than 95% color removal of methylene blue after 100 min irradiation has been achieved using LED lamps of low energy visible light (43.5 W). Such a result is supposed to be the highest employing low energy lamps. [ABSTRACT FROM AUTHOR]

Neutral red (NR) and safranin-O (SO) dyes are used in industrial processes, which their inappropriate disposal in surface waters causes negative impacts. Alternative techniques have been investigated for the complete removal of dyes, in which the adsorption presents itself as a feasible option, especially when low-cost adsorbents obtained from industrial waste are used, such as soybean hulls (SBH). This study proposed the use of SBH for the adsorption of NR and SO dyes. The characterization showed heterogeneous and porous morphology with predominantly negative surface charges, which favored the fixation of the cationic dyes. The comparative study of SO and NR adsorption onto SBH and commercial granular activated carbon confirmed the good performance of the biosorbent material. The maximum adsorption capacities were 287.30 and 221.74 mg g−1 for NR and SO onto SBH, respectively. The equilibrium time was reached in 90 minutes for both dyes. The experimental data was adjusted to the Langmuir and pseudo-second-order models. Thermodynamics inferred endothermic, spontaneous and reversible characteristics to adsorptive processes. The main proposed adsorption mechanisms were hydrogen bonds, π-interactions and electrostatic interactions. The regeneration study showed the possibility of reusing SBH for 6 cycles, and the effect of ionic strength found that the adsorption efficiency was not reduced. Therefore, SBH demonstrated versatility and efficiency in the removal of cationic dyes from wastewater, evidencing its industrial applicability. [ABSTRACT FROM AUTHOR]

In the present study, the applicability of Mn-doped PbS nanoparticle synthesis for eliminating (methylene blue [MB]) dye rapidly from aqueous solutions was investigated. Identical techniques including Brunauer–Emmett–Teller theory, Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, differential thermal analysis and scanning electron microscopy have been utilised to characterise this novel material. The investigation showed the applicability of Mn-doped PbS nanoparticles as an available, suitable and low-cost adsorbent for proper deletion of (MB) dye from aqueous media. Also, the impacts of variables including initial (MB) dye (X1), pH (X2), adsorbent dosage (X3), sonication time (X4), central composite design and response surface methodology (RSM) were shown. In the current article, the values of 10 mgL−1, 0.025 g and 6.0 and 5.0 min were considered as the ideal values for (MB) dye removal, respectively. The adsorption data fitted well with the Langmuir isotherm model with correlation coefficient (R2 > 0.999), and the maximum adsorption capacities (qmax) were observed to be 200.0 mg g−1 for (MB) dye at desired conditions. The pseudo-second-order kinetics coincides quite well with the kinetic results. The thermodynamic parameters including enthalpy, entropy and Gibbs energy were calculated for the adsorption of these (MB) dyes using Mn-doped PbS nanoparticles that are suitable, spontaneous and exothermic. The use of artificial neural network model as a tool for determining mean square error (=0.607) for (MB) dye removal by Mn-doped PbS nanoparticles. Ultrasonic power had important role in shortening the adsorption time of (MB) dye by enhancing the dispersion of adsorbent in solution. Overall, Mn-doped PbS nanoparticles could be a promising adsorbent material for (MB) dye removal from aqueous solutions in a short time. [ABSTRACT FROM AUTHOR]

Methylene blue (MB) and basic red 9 (BR9) are cationic dyes that are commonly used in the dye industry and negatively affect humans and other living organisms. This study compares the performance of Indonesian rice husk (IRH) and Hungarian rice husk (HRH) as bio-adsorbents for removing MB and BR9 from aqueous solutions. Chemical content, zeta potential, and Fourier-transform infrared spectroscopy analyses were used to characterize the rice husks (RHs). Adsorption studies were performed through batch experiments involving several parameters, namely, pH, adsorbent dose, initial dye concentration, contact time, and temperature to observe the self-association (aggregation) of MB and BR9. Adsorption kinetic studies showed that maximum dye removal was achieved at a contact time of 120 min. MB and BR9 adsorption followed a pseudo-second order kinetic model, and the BET multilayer isotherm model provided a better fit to the experimental data of MB and BR9 adsorption. The IRH adsorption capacities were 15.0 mg/g for MB and 7.2 mg/g for BR9, whereas those of HRH were 24.4 mg/g for MB and 8.3 mg/g for BR9. Therefore, these RHs are potential bio-adsorbents for removing MB and BR9 from aqueous solutions. [ABSTRACT FROM AUTHOR]

This study was aimed to investigate the potential adsorptive behavior of mixed algae for decolorization of methylene blue dye from aqueous solution in the form of free and immobilized. Effects of initial pH value (3-9), biosorbent dosage (0.02-0.5)g/L, and initial concentration (10-50) mg/L for different contact time (0-180) min at 200 rpm shaking speed were investigated. In addition, experimental data were analyzed using adsorption (Langmuir and Freundlich) isotherms as well as kinetic models. The results demonstrated that the maximum decolorization percentage was 93% and 91% by free and immobilized algae, respectively for pH 6, 10 initial concentration, 0.3g/100mL algae dosage, and 90 min contact time. The results revealed that the Langmuir isotherm model was adequate for describing the dye removal process (R² = 0.99) for both forms. Results of pseudo-second order kinetic model revealed best fitting with the sorption data indicating that chemisorption process is the dominant mechanism controlling the dye removal. Furthermore, the characterization study performed using FT-IR and scanning electron micrograph techniques, revealed that the used algal biomass has good biosorption capabilities associated to active groups and surface structure and confirming that the immobilization was successful. [ABSTRACT FROM AUTHOR]

Using biomass materials for activated carbon preparation through a simple and expedient method is a highly appropriate approach for sustainable and green development. Here, for the first time the waste neem (Azadirachta Indica) leaf was used for the development of activated carbon in the microwave process assisted with K2CO3 as an activating agent, and its performance was checked for methylene blue dye (MB) removal. The neem leaves activated carbon (NLAC) was analyzed with sophisticated instrument, where the SEM, XRD and pHIEP results showed that NLAC surface has highly active pores, is crystalline in nature and has a pHIEP value of 6.9. The FTIR data indicated that a number of active functional groups (–OH, –COOH, etc.) were present on the NLAC surface. The BET data presented that material has a good surface area of 50.69 m2/g and a pore volume of 0.014 cm3/g. More than 96% of MB dye was removed in the obtained environments of 10 mg/L MB dye concentration, pH 7, contact time 100 min, adsorbent dose of 70 mg and temperature 80 °C, respectively. The removal data were suitably followed by Langmuir isotherm model (R2 = 0.96) having an uptake capacity of 132.52 mg/g. Kinetics data for MB removal were matched with the pseudo-second-order model with a R2 of 0.96. The adsorption process was spontaneous in nature, where Δ H and Δ S values were 0.029 kJ/mol and 0.095 kJ/Kmol. The adsorption mechanism was followed by three types of interaction, i.e., electrostatic attraction, hydrogen bonding and pi–pi interaction, respectively. [ABSTRACT FROM AUTHOR]

Glucose can be isomerized into fructose and dehydrated into key platform biochemicals, following the "bio-refinery concept". However, this process generates black and intractable substances called humin, which possess a polymeric furanic-type structure. In this study, glucose-derived humin (GDH) was obtained by reacting D-glucose with an allylamine catalyst in a deep eutectic solvent medium, followed by a carbonization step. GDH was used as a low-cost, green, and reusable adsorbent for removing cationic methylene blue (MB) dye from water. The morphology of carbonized GDH differs from pristine GDH. The removal efficiencies of MB dye using pristine GDH and carbonized GDH were 52% and 97%, respectively. Temperature measurements indicated an exothermic process following pseudo-first-order kinetics, with adsorption behavior described by the Langmuir isotherm. The optimum parameters were predicted using the response surface methodology and found to be a reaction time of 600 min, an initial dye concentration of 50 ppm, and a GDH weight of 0.11 g with 98.7% desirability. The MB dye removal rate optimized through this model was 96.85%, which was in good agreement with the experimentally obtained value (92.49%). After 10 cycles, the MB removal rate remained above 80%, showcasing the potential for GDH reuse and cost-effective wastewater treatment. [ABSTRACT FROM AUTHOR]

The effective results of the enzymatic decolorization of industrial azo dyes found in wastewater, which cause serious health and environmental problems, with peroxidases have recently increased the interest in these enzyme sources. Redox-mediated decolorization of Methylene Blue and Congo Red azo dyes with cauliflower (Brassica oleracea var. botrytis L.) peroxidase (CPOD) purified in one step using 4-amino 3-bromo 2-methyl benzohydrazide molecule was investigated for the first time. The inhibition effect of this molecule, which is used as a ligand in affinity chromatography, on the CPOD enzyme was investigated. The K i and IC 50 values for this enzyme were calculated as 0.113 ± 0.012 mM and 0.196 ± 0.011 mM, respectively. With the affinity gel obtained by binding to the Sepharose-4B- l -tyrosine matrix of this molecule, which shows a reversible inhibition effect, the purification values of CPOD enzyme were determined as 562-fold with a specific activity of 50,250 U mg−1. The purity of the enzyme was checked by the SDS-PAGE technique and its molecular weight was determined. A single band at 44 kDa was observed for the CPOD enzyme. In dye decolorization studies, the effects of dye, enzyme, and hydrogen peroxide concentrations as well as time, pH, and temperature were investigated. The profiles of the optimum conditions for both dyes were similar, and the percentages of decolorization of Methylene Blue and Congo Red under these conditions were 89% and 83%, respectively, at the end of the 40 min reaction time. Again, when examining the effect of metal ions on enzyme activity, it was found that there was no significant negative change in CPOD. [ABSTRACT FROM AUTHOR]

The progress of the textile industry has led to a severe increase in the discharge of colored effluents, polluted with dyes and metal ions (non-biodegradable, carcinogenic to humans and environmental hazards). The implementation of effective methodologies and materials for the treatment of wastewater has become an urgent requirement. The present work describes the application of two samples of mineral materials—Ghidirim diatomite and modified diatomite—as adsorbents for the removal of dyes—Acid Blue 350, Methylene Blue, Basic Red 2—and of metal ions—copper, zinc, and lead—from aqueous solutions. In order to determine the optimal working conditions by which to ensure maximum removal efficiency, the influence of the nature and amount of the sorbent, the initial concentration of pollutant, and the temperature were studied. Working under normal conditions (room temperature, solution pH) efficiencies greater than 80% were obtained for the removal of dyes and metal ions. The adsorption fitted well with the pseudo-second order kinetic model, and the maximum adsorption capacities were determined from the Langmuir isotherm model. The adsorption of investigated pollutants is an endothermic and spontaneous process. The results indicate that Ghidirim diatomite and modified diatomite have potential applications in water purification management, providing high removal efficiency of both dyes and metal ions. [ABSTRACT FROM AUTHOR]

This study is focused on a proposal of a smartphone imaging-based quantification for providing a simple and rapid method for the analysis of chemical oxygen demand (COD) and color throughout the use of the HSV and/or RGB model in digital devices. For COD, calibration curves were done based on the theoretical values of potassium biphthalate for a proper comparison between the spectrophotometer and the smartphone techniques. The smartphone camera and application attain an average accuracy higher than the analysis in the spectrophotometer (98.3 and 96.2%, respectively). In the color analysis, it was demonstrated that only the UV–vis bands measurement is not feasible to perform the real abatement of the dye in the water because the limiting concentration that allows obtaining a linear relationship in this equipment related to the dye concentration is about 10 mg L−1. Above this value, the spectrophotometer can not reach the real difference of color in the solution. Meanwhile, the smartphone method by using the camera reaches linearity until 50 mg L−1. From an environmental point of view, smartphones have been used for monitoring several organic and inorganic pollutants, however, no attempts have been published related to their use to evaluate the color and COD during wastewater treatment. Therefore, this investigation also aims to assess the utilization of these methods, for the first time, when high-colored water polluted by methylene blue (MB) was electrochemically treated by using a boron-dopped diamond (BDD) as the anode, with different current densities (j = 30, 45, 60, and 90 mA cm−2). COD and color abatement results clearly showed that different organic matter/color removal efficiencies were achieved, depending on the j used. All the results are aligned with the studies already available in the literature, with the total removal of color in 120 min of electrolysis with 60 and 90 mA cm−2, and almost 80% of COD abatement with the higher j. Moreover, samples of real effluent from beauty salons were compared, with standard deviation varying from only 3 to 40 mg O2 L−1, which is acceptable for COD values close to 2000. Finally, the methods here presented can be a great benefit for public water monitoring policies, since it is cheap and has a decentralized characteristic, given that smartphones are very common and portable devices. [ABSTRACT FROM AUTHOR]

To improve the adsorption capacity of SBP, an idea of adding the functional carboxylic groups using multivariant organic acids was raised and tried. Quaternary phosphonium bromide and maleic anhydride modified sugar beet pulp (PMSBP) was prepared by quaternary phosphonium modification on the basis of maleic anhydride-modified sugar beet pulp (MSBP). Characterization results showed that the thermal stability of PMSBP was improved compared to MSBP, and the surface of PMSBP showed uniform layered structure with large pores. The effects of temperature, reaction time, pH, and adsorbent dosage on the adsorption of two dyes by PMSBP were investigated. The adsorption of PMSBP on methyl orange (MO) fitted well with the Langmuir isotherm model and the pseudo-second-order kinetic model, and the Freundlich isotherm model could better describe the adsorption process of PMSBP on methylene blue (MB). The adsorption of MB and MO by PMSBP was exothermic and spontaneous. PMSBP was demonstrated to satisfy the essential requirement for application in wastewater treatment. Electrostatic attraction and ion exchange were speculated as the main adsorption mechanisms. So, the broom modification theory of bio-sorbents was practical and offered a way to improve bio-sorbents adsorption capacity. [Display omitted] • We managed reusage of sugar beet pulp and improved its added value. • We improved adsorption performance of sugar beet pulp by multifunctional modification. • Modified sugar beet pulp could remove about 85 % of dyes in 2.5 h. • Modified sugar beet pulp had a decent regeneration performance. [ABSTRACT FROM AUTHOR]

Polysulfone (PSF) nanofibers with porous structures were fabricated by solution-blowing technique in one step which of a ternary blends of PSF/N, N-dimethylacetamide (DMAc)/tetrahydrofuran (THF) at ambient environment. The pore structure on PSF nanofibers could be controlled exactly by tuning the proportion of THF in the spinning solvents. The porous hierarchical structures forming in- and outside of the nanofibers were mainly due to the rapid volatilization of THF during the high-speed N2 purging spinning process, and the optimal content of THF was determined about 30 wt% in the mixed solvents. Then the PSF porous nanofibers were modified by in-situ polymerization of polyaniline (PANI) and polydopamine (PDA), respectively, via a simple one-step deposition process. The performance and characteristics of the nanofibers were characterized by ATR-FTIR spectroscopy, field-emission scanning electron microscopy, water contact angle, and N2 adsorption/desorption measurement, etc. The results demonstrated that the porous structure on nanofibers was gradually prominent while the specific surface area (SSA) and the average pores size of nanofibers also rose continuously along with the increasing content of THF in the mixed solvent. The BET surface area and the average pore diameter were 30.91 m2/g and 17.63 nm, respectively, at 3/7 THF/DMAc mix weight ratio. After immobilizing the PANI or PDA on nanofibers, the surface wettability of the composite nanofibers was improved obviously due to the existence of hydrophilic units. Furthermore, the nanofibers were utilized as a stable and reliable adsorbent for methylene blue (MB) and methyl orange (MO) dye removal from wastewater. The different pH values of dye adsorption as well as adsorption kinetics and isotherms were comprehensively investigated to analyze the adsorption capacity and mechanism. The adsorption performance of the dyes onto porous nanofibers especially for PDA or PANI-modified mats was strongly depended on the pH values and various physical or chemical synergistic effects. The dye adsorption mechanism of membranes was verified by the equation analysis and well described with the pseudo-second-order kinetics and Freundlich isotherm model. Finally, the dye-adsorbed nanofibers exhibited excellent reusability after four cycles of adsorption. [ABSTRACT FROM AUTHOR]

In the present work, an effort was made for the first time to develop novel catalysts by recycling broken borosilicate glass (BSG) loaded with iron and cobalt for the abatement of methylene blue (MB) and COD from real textile wastewater. In the study, the comparison of adsorption, single ozonation (SO), and catalytic ozonation with both catalysts (Fe-BSG) and (Co-BSG) for the removal of MB was evaluated on various operational parameters such as ozone flow (0.552–1.08 mg/min), reaction time (2–23 min), catalyst dose (1.25–5 g/L), and pH (4–10). Moreover, the prepared catalysts Fe-BSG and Co-BSG were characterized by SEM, FTIR, EDS, and BET. Furthermore, results revealed that the Co-BSG/O3 was more efficient than others and decolorization of MB was found to be 6.2%, 72%, 79%, and 92% at 6.8 pH in 8 min, and removal of COD was 3.5%, 69%, 81%, and 93% at pH 6.8 in 40 min for BSG, SO, Fe-BSG/O3, and Co-BSG/O3, respectively. In the current investigation, the tert-butyl alcohol effect exposed the leading role of hydroxyl radicals during Co-BSG/O3 as the MB efficiency was reduced by 28% in addition of hydroxyl radical scavengers as compared to the SO process. It was found that the catalyst remained stable and efficient after 3 cycles due to the minute quantity of metal leached. Therefore, the studied novel advanced method may significantly be applied on the industrial scale for the abatement of dyes and COD from real textile wastewater. [ABSTRACT FROM AUTHOR]

Organic azo dyes such as Methylene Blue (MB) pollute water and are considered a global threat to the health and environment. Accordingly, the present study aims to fabricate cost-effective, eco-friendly, and highly performing hybrid beads of Poly (Acrylonitrile-co-Styrene/Pyrrole)@Poly Vinyl Pyrrolidone (Poly (AN-co-ST/Py)@PVP) for Methylene Blue dye adsorption via the phase inversion technique. The fabricated hybrid beads were physico-chemically characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and atomic force microscopy (AFM). The required experimental adsorption conditions were optimized: contact time, dye solution pH, beads dosage, and MB initial concentration. Langmuir isotherm and pseudo-second order kinetic models described the MB adsorption equilibrium and kinetics well. Only 0.8 g of the fabricated hybrid beads were needed to achieve a maximum of 90% dye removal after 180 min of equilibrium time. For screening, twenty-five runs were applied, and thirteen runs were optimized using the Plackett–Burman Design (PBD) model. Time is the most effective factor in PBD, with an efficiency rate of 88.42%, according to the optimization stage of the process after initial screening revealed that time, dosage, and dye concentration were the most important variables. The fabricated hybrid beads reveal a great ability to adsorb MB molecules effectively from wastewater samples. [ABSTRACT FROM AUTHOR]

TiO2 photoanodes have gained significant attention for the removal of organic pollutants through photoelectrocatalytic processes, with the aim of developing a cost-effective and efficient method for improving the degradation of pollutants in surface water. This study investigated the effects of adding titanium nanooxide (Degussa P25) containing 70% anatase and 30% rutile phases on the properties of nanostructured TiO2 photoanodes prepared on glass substrates (indium tin oxide (ITO)) using sol–gel/dip coating techniques The results obtained from ultraviolet–visible transmittance spectroscopy, electrochemical (EC) impedance spectroscopy, photocurrent, and atomic force microscopy analyses revealed that the addition of Degussa P25 improved the electrical conductivity of the TiO2/ITO anode and reduced the optical bandgap from 3.50 to 3.35 eV, while the size of the titanium oxide particles decreased to about 75 nm. The EC impedance spectra measurement confirms that the addition of titanium nanooxide Degussa P25 improved the electrical conductivity for TiO2/ITO anode. The photoelectrocatalysis (PEC) performance of the TiO2 photoanodes was investigated via the degradation of methylene blue (MB) under UVA light irradiation. The AB photoanode (with the addition of Degussa P25) exhibited excellent PEC performance, with 95.9% color removal efficiency and 63% total organic carbon (TOC) removal efficiency, compared to 92% color removal efficiency and 56% TOC removal efficiency for the A photoanode (without the addition of Degussa P25). The kinetic constants (k) were 134 × 10−4, 110 × 10−4 (min−1) for A and AB anodes, respectively, and the degradation of MB followed first-order kinetics for all anodes. The A and AB anodes were compared as electrodes for the degradation of MB using PEC, photocatalysis (PC), and EC technologies. Subsequently, The A and AB anodes were utilized as electrodes to compare the performance of PEC, PC, and EC technologies for the degradation of MB. The results showed that the AB anode exhibited higher efficiency in all PC technologies, with color removal (%) efficiencies of 95.9% (PEC), 33% (PC), and 21% (EC) compared to 92% (PEC), 28% (PC), and 19% (EC) for the A anode. Additionally, the photooxidation process had a 2.1% effect on the degradation of the initial MB concentration. [ABSTRACT FROM AUTHOR]

In this paper, we present the first attempt to evaluate the role of carboxymethyl cellulose (CMC) as a chelating agent in the sol–gel auto-combustion method of producing barium hexaferrite (BaFe12O19). We also report the application of the system as a photocatalyst for dye degradation. The formation, morphology, and crystalline structure of the synthesized nanoparticles are determined using XRD, SEM, EDS, VSM, FTIR, and TEM techniques. High efficiency under visible light, with a band gap of 1.62 eV and a BET surface of 17.93 m2/g, has been observed for the BaFe12O19 catalyst. The operating parameters, such as reaction time, initial dye concentration, light intensity, reusability, and dye type, are studied. Degradation rates as high as 98.26% (Kapp = 0.082 min–1) and 89.07% (Kapp = 0.0743 min–1) were obtained for cases of methylene blue and malachite green under conditions of visible light irradiations when BaFe12O19 was used. The BaFe12O19 catalyst has been shown to exhibit a high degradation performance for cationic dyes. Furthermore, BaFe12O19 magnetic nanoparticles show excellent reusability for dye degradation because the photocatalyst did not exhibit a significant decrease in its activity even after five runs (81.56%). As a result, the current study confirmed that photocatalytic degradation was a promising technology for saving water and treating wastewater formed from textile dye industries. The technique can be used to study the efficiency of photocatalytic degradation and understand the process of recycling waste effluents under conditions of minimized water use. [ABSTRACT FROM AUTHOR]

The kinetics and mechanism of the oxidative decolorization of methylene blue (MB+) as a cationic dye by persulfate using silver(I) catalyst in aqueous acidic medium were studied. The effects of different parameters like [H+], [Ag+], reactant concentration, micelles, and temperatures were investigated. The kinetic data showed that the oxidative decolorization of [MB]+ by persulfate obeyed pseudo‐first‐order kinetics by taking a large excess of [S2O82−] over [MB+]. The observed rate constant increases with increasing of [H+]. A plausible mechanism for the silver(I) enhanced decolorization of [MB]+ by persulfate is suggested which is consistent with the experimental rate law. The effect of micelles such as SDS and Triton X‐100 on the reaction rate is investigated. The rate of reaction decreases with increasing [SDS] but is not affected by Triton X‐100. The mechanism of the electron transfer process between [MB]+ and S2O82– proceeds through an outer‐sphere mechanism. Thermodynamic activation parameters ΔH* and ΔS* were calculated. The experimental data may be useful for the layout of wastewater treatment containing various types of dyes. [ABSTRACT FROM AUTHOR]

Electrolytic active water was prepared by electrolytic treatment of sodium chloride aqueous solution using a self-made device. In order to investigate the properties of electrolytic active water, the pH value, available chlorine contents and decolorization ability on methylene blue solution were tested and compared with that of sodium hypochlorite aqueous solution. Experimental results showed that the electrolytic active water has higher oxidation capacity and decolorization efficiency for methylene blue compared with sodium hypochlorite solution, implying maybe other reactive oxygen species components besides hypochlorite existed in the electrolytic active water. The electrolytic active water was stable under long-term storage, and mechanical force with oxidation activity did not decrease. In addition, the decolorization kinetics of methylene blue in the electrolytic active water was explored, and it was found that, in general, the decolorization reaction of methylene blue in electrolytic active water was consistent with the first-order reaction kinetics model, but when the pH value of electrolytic active water solution was weakly alkaline or neutral, the decolorization reaction of methylene blue was closer to the second-order reaction kinetics model. [ABSTRACT FROM AUTHOR]

Dyes are hazardous to public health and the environment. Herein, we synthesized Ti-doped porous SiO2 microspheres utilizing a one-step sol-gel method as an effective adsorbent for the removal of cationic dyes from wastewater. The study of the varying individual parameters such as titanium-silica ratio, pH, adsorbent dose, and dye concentration indicated that the adsorption of methylene blue (MB) by Si3TiO10 microspheres exhibited excellent performance, including a wide range of applications (pH = 4–11), fast adsorption rate (15 min removed 90.8% of MB), high adsorption capacity (215.29 mg/g), excellent selectivity (adsorption capacity toward cationic dyes (98%) and < 5% toward anionic dyes), easy desorption steps, steady performance and multiple cycles (10 times). In addition, the adsorption process of MB by microspheres is consistent with the proposed second-order kinetic model (R2 = 0.999) and Langmuir isothermal model (RL2 = 0.997). With the assistance of FT-IR, XRD, XPS, BET, SEM, and TG-DTG techniques, it was demonstrated that the great pore size (8.15 nm) and large specific surface area (267.97 m2/g) of the microspheres could promote the contact between the active site and MB, thus achieving efficient removal of MB by using hydrogen bonding and electrostatic attraction. Furthermore, the unique spherical mesoporous structure, and the Si-O-Ti bond formed by the Ti doping rather than via simple wrapping and adhesion modification, which also ensured the stability of the microspheres during multiple cycles and the desorption process. [ABSTRACT FROM AUTHOR]

Herein, fabrication of a novel eco-friendly and effective biosorbent (SCB-GO-PAA) nanocomposite were investigated by modification of sugarcane bagasse (SCB) as lignocellulosic biomass with graphene oxide (GO) and polyacrylic acid (PAA) using homogenizer as a new technique to prepare (SCB-GO-PAA) nanocomposite. The fabricated materials were characterized using SEM, FTIR, TGA, and XRD, and were tested to adsorb methylene blue (MB) dye from aqueous solution. Adsorption parameters were studied to investigate the optimum conditions that achieve the higher adsorption capacity. The adsorption processes were carried out according to Langmuir isothermal model and pseudo-second-order kinetic model with maximum sorption capacity of MB-dye by SCB, SCB-GO, and SCB-GO-PAA nanocomposite of 143.56, 265.85, and 543.28 mgg−1, respectively. The results revealed that the fabricated biosorbents are promising materials with considerable adsorption capacity comparing to other novel adsorbents. Also, this eco-friendly and effective bioadsorbent can be utilized on large scale to remove MB-dye from various types of wastewater. [ABSTRACT FROM AUTHOR]

This work aimed to use Algerian Zean oak (AZO) sawdust in its raw state, without undergoing any physico-chemical treatment, to estimate its efficiency for removing methylene blue (MB), a cationic dye widely used in the textile industry. The physico-chemical properties of the biomaterial were characterized by scanning electron microscopy, Fourier-transform infrared, X-ray diffraction, and Brunauer–Emmet–Teller for measuring its specific surface area. The chemical characteristics of the AZO sawdust surface were further examined by the zero-charge point (pHPZC), iodine, MB numbers, and Boehm titration tests. The batch study was performed by varying parameters such as contact time, particle size, pH, temperature, adsorbent dose, and initial dye concentration. By optimizing these parameters, an adsorption capacity of 52.376 mg/g was attained, at pH = 7 and room temperature, using a dose of 1 g/L AZO at C0 = 20 mg/L for an equilibrium time of 45 min. The adsorption capacity of the MB is enhanced by increasing the initial dye concentration and the biosorbent dose. The kinetic data were modeled using the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The results reveal that the pseudo-second-order model better describes the experimental data. Furthermore, the adsorption isotherms well follow the Sips and Langmuir models. The thermodynamic study revealed that the adsorption process of MB on AZO sawdust is a spontaneous, exothermic, and favorable phenomenon. Therefore, AZO sawdust could be considered an efficient biosorbent and a preferred alternative to activated carbon to remove MB. [ABSTRACT FROM AUTHOR]

In this study, Zr‐Ag co‐doped TiO2 (ZAT) photocatalyst films having varied numbers of layers (1, 2, 3, and 4) have been developed to coat on ceramic tile substrates by sol‐gel spin coating technique. The specimens were tested to determine antibacterial activity against Escherichia coli and the capability to degrade gaseous formaldehyde under visible light. X‐ray diffraction, ultraviolet and visible absorption spectroscopy, water contact angle, and scanning electron microscopy were applied to characterize the structural and morphological properties of the samples. The photocatalytic reactivity of the nanocomposite films was investigated by the decolorization of methylene blue (MB) dye under visible light irradiation. The results showed that the two‐layer ZAT photocatalyst film on ceramic tile exhibited the highest photocatalytic decolorization of MB, with 60.36% efficiency. The ZAT tile had formaldehyde degradation efficiency up to 32.74% within only 6 h under visible light irradiation, higher than that of the bare ceramic tile (4.90%). Additionally, the ZAT thin films could enhance anti‐E. coli activity and could be capable of degrading air pollution. [ABSTRACT FROM AUTHOR]

This paper documents the synthesis of magnetic carbon gels by encapsulating iron nanoparticles in porous carbon gel matrix and studying its application in dye adsorption and catalytic reduction reaction. The effects of magnetic nanoparticles under the purview of this study were investigated using X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunauer, Emmett and Teller (BET) surface area, Barrett–Joyner–Halenda (BJH) pore size distribution analysis, Raman spectroscopy and vibrating sample magnetometer. The adsorption capability of the magnetic gels in removing methylene blue dye pollutant from water was examined using different initial dye concentration (10–30 mg/L). The effect of pH, adsorbent dosage on adsorption and the kinetics, equilibrium and thermodynamics of the adsorption were investigated in detail. Spontaneous and favourable nature of the adsorption was confirmed with a maximum adsorption capacity of 67.75 mg/g. In addition, the catalytic properties of the gels were also probed using the model catalytic conversion of p-nitrophenol to p-aminophenol with NaBH4. The magnetic gels showed excellent activity towards the catalytic reduction of 60 ppm p-nitrophenol with a rate constant of 0.299 min−1, that is comparable with several previously reported catalysts. The response of the gel to external magnetic field made the catalyst easily recoverable. The immobilization of Fe nanoparticles in the graphitic carbon matrix prevented the aggregation as well as oxidation problem making it reusable without any significant loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

To effectively remove methylene blue (MB) from dye wastewater, a novel activated carbon (BAC) was manufactured through co-pyrolysis of bamboo shoot shell and K2FeO4. The activation process was optimized to a temperature of 750 °C and an activation time of 90 min based on its excellent adsorption capacity of 560.94 mg/g with a yield of 10.03%. The physicochemical and adsorption properties of BACs were investigated. The BAC had an ultrahigh specific surface area of 2327.7 cm2/g and abundant active functional groups. The adsorption mechanisms included chemisorption and physisorption. The Freundlich model could be used to describe the isothermal adsorption of MB. The kinetics confirmed that the adsorption of MB belonged to the pseudo-second-order model. Intra-particle diffusion was the main rate-limiting step. The thermodynamic study showed that the adsorption process was endothermic and temperature was beneficial for the improvement of adsorption property. Furthermore, the removal rate of MB was 63.5% after three cycles. The BAC will have great potential for commercial development for purifying dye wastewater. [ABSTRACT FROM AUTHOR]

The removal of pollutants such as dyes and bacteria has become a tedious process hence there is a need for multifunctional materials that can be used for the removal or degradation of various pollutants from wastewater. In this study, a flowerlike NiO nanoparticle was synthesised and used for the removal of dyes and bacterial from water. Sutherlendia frutescene plant extract was used as a reducing agent. SEM and XRD confirmed the formation of this material through morphological analysis and phase identification, respectively. EDX further corroborated the formation with the present dominant phases of Ni and O. TGA showed the material was stable, furthermore, UV-Vis was able to demonstrate the optical properties of the material with excitation at the absorption wavelength of 302 nm and with a bandgap of 3.5 eV. This material was further tested for the degradation of two dye pollutants, methylene blue and malachite green. A percentage degradation of 89% and 98%, respectively, was achieved. The materials could be reused at least three times before losing their stability. Upon testing the model bacterial strains, E. faecalis and P. aurugenosa,the SfNiO activity was more active towards gram-positive bacteria. This study has shown that it is possible to produce environmentally safe materials that can be used for the degradation of various dyes and removal of both gram-negative and gram-positive bacterial strains in our water streams. [ABSTRACT FROM AUTHOR]

Electrodeposited bismuth ferrite (BiFeO3) thin films on fluorine-doped tin oxide (FTO) substrate were employed as photoanodes in the photoelectrocatalytic degradation of methylene blue. The BiFeO3 thin films electrodeposited for 300 s, 600 s, 1200 s, 1800 s and 3600 s were characterised with XRD, field emission scanning electron microscopy (FESEM) and UV–vis diffuse reflectance spectroscopy. SEM images displayed different morphology at different electrodeposition times which affects the photoelectrocatalytic (PEC) performances. The FESEM cross-sectional area was used to measure the thickness of the film. The optical properties showed that the band gaps of the photoanodes were increasing as the electrodeposition time increased. The photocurrent response obtained showed that all thin film photoanodes responded to visible light and lower charge transfer resistance (from electrochemical impedance spectroscopy studies) was observed with photoanodes electrodeposited at a shorter time compared to those at a longer time. The PEC application of the photoanode for the removal of methylene blue (MB) dye in water showed that the percentage degradation decreased with an increase in electrodeposition time with removal rates of 97.6% and 70% observed in 300 s and 3600 s electrodeposition time, respectively. The extent of mineralisation was measured by total organic carbon and reusability studies were carried out. Control experiments such as adsorption, photolysis, photocatalysis and electrocatalysis processes were also investigated in comparison with PEC. The electrodeposition approach with citric acid exhibited improved electrode stability while mitigating the problem of catalyst leaching or peeling off during the PEC process. [ABSTRACT FROM AUTHOR]

The extensive use of synthetic materials in modern society presents a great challenge to environmental and water quality. As such, numerous studies were dedicated to the removal of emerging contaminants from water using novel materials as sorbents or catalysts. With large reserves and low material costs, Earth material has also attracted great attention for contaminant removal. Halloysite is a 1:1 layered clay mineral with moderate cation exchange capacity that can be used for the removal of cationic contaminants. On the other hand, as it may bear positive charges on the aluminum hydroxyl sheets, it could be used to remove anionic contaminants. In this study, the removal of a cationic dye, methylene blue (MB), and an anionic dye, alizarin red S (ARS), from the water was evaluated from single and mixed solutions. The results suggested that from single solutions, MB removal was via cation exchange while ARS removal could have originated from anion exchange. From mixed solutions, their removal was mutually increased, which may be due to a synergistic effect in the presence of a type of charged dyes serving as counterions to enhance the sorption of dyes of opposite charges. This finding suggests that halloysite may serve as a sorbent for the removal of organic contaminants of different charges at the same time, which is a new perspective that needs further evaluation and expansion. [ABSTRACT FROM AUTHOR]

The present research work was carried out on isolating lignocellulolytic enzyme-producing natural bacterial isolates of the Sundarban Mangrove ecosystem in West Bengal, India. Multiple bacterial isolations and qualitative as well as quantitative screening of the isolates was conducted by selective media plates and dye decolorization assay. Growth characterization of the top three isolates, namely GD1, GD2, and GD3, was determined in both nutrient broth and selective media. GD1 showed laccase activity in ABTS plate and decolorized congo red, malachite green, and methylene blue by 64.82%, 47.69%, and 33.33%, respectively, which is the inherent property of laccase. Along with the maximum laccase activity (9.72U/L), it also showed a little amount of cellulase (5.8U/ml) and pectinase (0.55U/ ml) activity in the enzyme assay. GD2 showed maximum cellulase activity (6.56U/ml) with only 3.3% degradation of congo red and 39.43% degradation of malachite green. Like GD1, GD2 also bears 5.6U/L laccase and 0.12U/ml pectinase enzyme activity. The last isolate, GD3 specialized in pectinase production and having 4.4U/ml enzyme activity, degraded congo red by 66.75% and malachite green by 54.26%. All isolates showed activity between 30° and 37°C, and pH ranges from 4.5 to 7. The outcomes of this research will be useful in the fiber industry like jute or banana, dye industry, pulp-paper industry, and textile industry for waste remediation, recycling, and fiber modification. [ABSTRACT FROM AUTHOR]

Existing methods for dye removal have their limitations and can be expensive and not very effective. Therefore, the search for efficient, effective, less expensive, and environmentally-friendly ways to remove industrial dyes from water remains open. Methylene blue (MB) removal from aqueous solutions is studied using raw laterite soil as a low-cost adsorbent. The physico-chemical properties and surface area were determined. Effects of parameters such as contact time, laterite dosage, pH, and ionic salts on MB adsorption by raw laterite were examined. The results showed that the maximum removal efficiency of MB adsorption was observed at pH values above 10, after 60 min of contact time, and with an adsorbent (raw Laterite) dose of 1.00 g in 100mL of dye solution. Increasing the salt concentration decreased the absorption of dye from solution. Ionic salt media containing, CaCl2 and KCl have shown maximum and minimum influence, respectively, on the adsorption of MB by raw laterite soil. At the optimum conditions, the experimental adsorption capacity of raw laterite was 2.930 mg/g. The experimental data fitted the pseudo-second order kinetic model (R² = 0.99). The Freundlich adsorption isotherm model (R² = 0.99) showed the best fit to the experimental adsorption data. According to the Freundlich isotherm model, the calculated adsorption capacity of raw laterite was 2.949 mg/g. Desorption studies with several solvents revealed that the adsorbent could successfully retain MB, up to 33.89%. Therefore, it can be considered that raw laterite soil is effective in removing MB from aqueous solutions. [ABSTRACT FROM AUTHOR]

The present study focused on the decolorization of methylene blue (MB) and the production of polyhydroxyalkanoate (PHA) by Enterobacter strain TS1L using PHA medium containing 50 mg/l of MB. The highest PHA production at 56.02 ± 6.26% of dry cell weight (% DCW) was observed after 24 h of cultivation, while the most effective dye decolorization at 92.57 ± 0.03% was observed after 72 h of cultivation at 150 rpm and 35 °C. The characterization of the extracted biopolymer proves the presence of medium-chain-length-co-long-chain-length PHA (mcl-co-lcl PHA) by gas chromatography-mass spectrometry (GC-MS). TS1L accumulated mcl-co-lcl-PHA, consisting of 3-hydroxytetradecanoate (3HTD), 3-hydroxyhexadecanoate (3HHD) and 3-hydroxyoctadecanoate (3HOD). 3(HTD-co-HHD-co-HOD) was also observed at 39.49 ± 0.10, 50.36 ± 0.20 and 9.88 ± 0.20 mol%, respectively. This is the first report of mcl-co-lcl PHA production by Enterobacter strain TS1L using PHA-MB medium as a substrate. [ABSTRACT FROM AUTHOR]

Carbon porous materials obtained through KOH activation of a furfural + hydroquinone + urotropine mixture were applied as adsorbent for the remediation of methylene blue (MB). The impact of porous structure with special attention to pore size distribution along with well-known pore volume and specific surface area on the remediation of MB was well investigated and elucidated. Findings obtained revealed that pore size distribution plays a crucial role in the liquid-phase adsorption of organic dyes like MB. By varying the synthesis mode parameters, in particular, the activating agent/precursor mass ratio, with the composition and initial components ratios remaining unchanged, samples with different pore size distribution were obtained. It was found that the material predominantly containing pores with an average equivalent diameter of ~ 3.5 nm appears to be the efficient MB adsorbent. The resulting highly porous carbon materials demonstrated high MB adsorption capacity (up to 2555 mg/g). Furthermore, to fully elucidate the adsorption mechanisms occurring on the obtained materials, a comprehensive mathematical processing of experimental data was performed out using the known kinetic and diffusion models (pseudo-first- and pseudo-second order, and intraparticle diffusion), as well as adsorption equilibrium isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich). It can be concluded that the porous carbon materials obtained and described in the present work are effective adsorbents for the removal of MB and may possess great potential for the treatment of dye-containing wastewater. [ABSTRACT FROM AUTHOR]

This study presents the preparation of oil palm empty fruit bunch (OPEFB) activated char from gasification plant residues via phosphoric acid chemical treatment for adsorption of methylene blue (MB) in aqueous solution. The Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis were conducted to identify the characteristic of OPEFB. Adsorption experiments were carried out to determine the effects of initial dye concentration 100-300 mg/L, contact time, pH 2-10 and temperature 30°C-60°C. The optimum conditions were achieved at adsorbent dosage, pH, initial dye concentration and temperature of 0.2 g/200 mL, 6, 100 mg/L and 60°C, respectively with 91.44% of MB removal. From isotherm study, the Freundlich isotherm model fitted the adsorption data very well owing to its higher value of correlation factor (R2 = 0.9352), compared to Langmuir model (R2 = 0.8682). The Langmuir maximum monolayer capacity, qm was estimated at 167.2 mg/g. The results from the kinetic study showed that the MB adsorption followed a pseudo-second-order kinetic model (R2 = 0.9216-0.9581). The adsorption of the MB dye onto OPEFB activated char was an endothermic and spontaneous process with H°, G° and S° values of 58.379 kJ/mol, -0.70505 kJ/mol and 194.955 J/molK, respectively. The obtained results suggest that the OPEFB char could be a promising candidate as an adsorbent for MB removal. [ABSTRACT FROM AUTHOR]

A γ‐Mo8O26‐based organic–inorganic hybrid [Cu2(L)2(γ‐Mo8O26)0.5(H2O)]•H2O (CuLMo8) [L = 5‐(pyrimidyl)tetrazolate] was hydrothermally synthesized and fully characterized by various spectral techniques. In the crystal structure of CuLMo8, the μ2‐bridging γ‐Mo8 anion coordinates with Cu ions to extend into a 2D network. CuLMo8 displayed excellent photo‐Fenton‐like catalyst properties for MB degradation under UV light irradiation. Complete decolorization of MB solution was finished in 5 min, and the degradation rate reached 97.9% in 7 min. The degradation rate of the present system was much higher than that of similar systems in the literature. The synergistic effect of CuLMo8 and H2O2 was the fundamental reason for the high degradation rate. Initial pH value and concentration of MB solution, catalyst dosage, and concentration of H2O2 were the main factors to affect the degradation rate. Hydroxyl (•OH) and superoxide (•O2H/O2•‐) radicals were the major reactive species to degrade MB molecules. Moreover, the total organic carbon (TOC) removal was about 37.5% in 3 h, indicating mineralization and decolorization did not take place at the same time. The possible MB degradation pathway was deduced depending on the data gained. In view of the high catalytic efficiency, repeated use, and no need to adjust the pH value of MB solution, this heterogeneous catalyst might have potential to deal with practical wastewater. [ABSTRACT FROM AUTHOR]

Biosorption was carried out using Fraxinus excelsior L. (Oleaceae) (FEO) as a natural waste to remove methylene blue from aqueous solutions. Based on the results of the study carried out under optimum conditions (pH: 6, initial dye concentration: 5 mg/L, biosorbent dose: 1 g, contact time: 30 min, stirring speed: 150 rpm, and temperature: 298 K), the FEO biosorbent removed 89% of methylene blue from aqueous solutions. In addition, parameters affecting biosorption (pH, initial dye concentration, biosorbent dose, temperature, and stirring speed) were examined, and isotherm, kinetic, and thermodynamic studies were performed. Freundlich, Langmuir, Elovich, Temkin, and Dubinin–Radushkevich isotherms were calculated in the isotherm studies, and the Freundlich isotherm was higher than the others. The correlation coefficient of pseudo-second-order kinetic model was higher than for the pseudo-first-order kinetic model. The ΔG values from the thermodynamic studies showed that the process occurred spontaneously. Consequently, the FEO biosorbent is suitable in removing synthetic dyes from aqueous solutions due to its effectiveness, low cost, and eco-friendly characteristics. [ABSTRACT FROM AUTHOR]

In this work, graphitic carbon nitride (g-C3N4)/titanium dioxide (TiO2) nanoparticles with heterostructures were synthesized in situ from a mixture of melamine and peroxo-titanium complexes in a calcination process. The TiO2 nanoparticles are well-dispersed on the g-C3N4 nanosheets. The prepared TiO2/g-C3N4 composites have a heterostructure and excellent photocatalytic activity for decomposing methylene blue (MB) under visible light irradiation. The as-obtained g-C3N4 embroiled with TiO2 has a much larger surface area than its components (66.7 and 6.6 m2·g−1 for TiO2 and g-C3N4 against 95.5–143.8 m2·g−1 for the composite, respectively). It enhances the separation of photo-generated charge carriers. The TiO2/g-C3N4 photocatalytic degradation of MB was investigated in aqueous heterogeneous suspensions. The experimental kinetic data for the photocatalytic process follow the pseudo-first-order kinetic model. Furthermore, TiO2/g-C3N4 retains high photocatalytic activity after four reaction cycles. In addition to prompt removal of the color, the TiO2/g-C3N4 photocatalyst can oxidize MB almost completely to final oxidation products. The pathway of MB decomposition was also addressed. Additionally, the TiO2/g-C3N4 photocatalytic system was employed to eliminate other typical organic pigments, such as malachite green, methyl blue, and methyl red. The TiO2/g-C3N4 material, with remarkable dye degradability, is a promising catalyst in industrial textile treatment and can find applications in light-harvesting systems. [ABSTRACT FROM AUTHOR]

Wastewater contains organic compounds, including dyes, which have potential risks to the environment. Hence, these compound needs to be eliminated from the aqueous solution. In the present study, chitosan-pectin composite (Cs-Pc) was used as an adsorbent to remove methylene blue dye (MB) from synthetic wastewater. To evaluate the parameters affecting adsorption, including the initial MB concentration, solution pH, contact time, and Cs-Pc dose, batch experiments were carried out. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), and pH point of zero charges (pH pzc) were applied for characterizations of Cs-Pc. The optimum conditions were obtained with an initial MB concentration of 50 mg L−1: solution pH ~ 11, Cs-Pc dose: 1.5 g L−1 and 180 min contact time, which caused 97.77% of MB removal. In addition, the removal efficiency of MB was more influenced by pH than by sorbate dose. Also, Cs-Pc had a higher ability to remove MB than chitosan and pectin, probably due to its highly porous structure and rough surfaces that provides active sites and facilitate MB adsorption. The maximum removal efficiency and the adsorption capacity of MB onto Cs-Pc at 500 mg L−1 concentration under optimum conditions were 98.67% and 328.02 mg g−1, respectively. The adsorption kinetics and isotherms were best described by pseudo-second-order and Freundlich equation, respectively. After four times of recycling, the removal efficiency of MB was above 96%. Electrostatic and pi-pi interactions are the main mechanisms for the removal of MB onto the adsorbent. So the application of Cs-Pc is promising for MB removal from polluted solutions not only due to its strong adsorbing capability but also due to its excellent ability to reuse. [ABSTRACT FROM AUTHOR]

The study analyzed the potential of leaf powder prepared from the residual leaves of the species Sansevieria trifasciata, as a potential adsorbent for methylene blue (MB) removal. The equilibrium was reached fast for almost all concentrations after 60 min, obtaining the maximum capacity of 139.98 mg g−1 for 200 mg L−1. The increase in temperature disfavored the dye adsorption, with the maximum adsorption capacity of 225.8 mg g−1, observed for 298 K. The thermodynamic parameters confirmed that the adsorption process is spontaneous and exothermic. A direct sloping curve was established for the fixed bed, with breakthrough time (tb), column stoichiometric capacities (qeq), and the mass transfer zone lengths (Zm) were 1430, 1130, and 525 min; 60.48, 187.01, and 322.65 mg g−1; and 8.81, 11.28, and 10.71 cm, for 100, 200, and 500 mg L−1, respectively. Furthermore, in a mixture of several dyes, the adsorbent obtained the removal of 51% of the color. [ABSTRACT FROM AUTHOR]

Porous TiO2/activated carbon (AC) material was synthesized by grafting peroxo-hydro titanium complexes to rice husk-derived activated carbon. It was found that the morphology of TiO2/AC consists of TiO2 fine particles highly dispersed on the AC matrix. The obtained TiO2/AC composites with high surface area and a red shift exhibit an excellent adsorption performance in both single and trinary system toward methylene blue (MB), methyl orange (MO), and methyl red (MR). The isotherm models including extended Langmuir, P-factor, ideal adsorbed solution theory (IAST) for Langmuir, Freundlich, and Sips models were applied to study the adsorption equilibrium data of trinary solutions. It was found that IAST for Freundlich and Langmuir models were the most suitable one to describe the adsorption of the three dyes on TiO2/AC material. The high maximum adsorption capacities (mmol g-1) in single/trinary mixture were found as 0.452/0.340 for MB; 0.329/0.321 for MO; and 0.806/2.04 for MR. Moreover, the recyclability experiments showed that the adsorbent could be reused through photocatalytic self-cleaning for at least three cycles with stable capacity. Thus, the TiO2/AC can be effectively employed for the removal of dyes from industrial textile wastewater. [ABSTRACT FROM AUTHOR]

In this study, sweet-potato-vine-based porous carbon (SPVPC) was prepared using zinc chloride as an activating and pore-forming agent. The optimised SPVPC exhibited abundant porous structures with a high specific surface area of 1397.8 m2 g−1. Moreover, SPVPC exhibited excellent adsorption characteristics for removing methylene blue (MB) from aqueous solutions. The maximum adsorption capacity for MB reached 653.6 mg g−1, and the reusability was satisfactory. The adsorption kinetics and isotherm were in good agreement with the pseudo-second-order kinetics and Langmuir models, respectively. The adsorption mechanism was summarised as the synergistic effects of the hierarchically porous structures in SPVPC and various interactions between SPVPC and MB. Considering its low cost and excellent adsorption performance, the prepared porous carbon is a promising adsorbent candidate for dye wastewater treatment. [ABSTRACT FROM AUTHOR]