Facile synthesis of Fe2O3 nanoparticles from Egyptian insecticide cans for efficient photocatalytic degradation of methylene blue and crystal violet dyes.

In this work, novel mixtures based on silicon and tin materials were synthesised via reaction of 2.407, 5.247, 7.195, or 9.59 g of tin chloride dihydrate with 6 g of sodium metasilicate pentahydrate. The samples, which were synthesised using 2.407, 5.247, 7.195, and 9.59 g, are abbreviated as T1, T2, T3, and T4, respectively. XRD confirmed that these mixtures consist of amorphous Sn/Si, sodium tin silicate, tin oxide, and sodium silicate. The average crystallite size of T1, T2, T3, and T4 samples is 5.23, 8.13, 12.26, 15.72 nm, respectively. The synthesised mixtures were used as adsorbents for the removal of methylene blue and crystal violet dyes from aqueous media. 15 min, pH 6, and 298 Kelvin are regarded as the optimum conditions for the removal of studied dyes using T1, T2, T3, and T4 samples. The adsorption process of crystal violet or methylene blue dyes was fitted well with the Langmuir equilibrium isotherm and pseudo-second-order kinetic model. The thermodynamic parameters confirmed that the removal of crystal violet and methylene blue dyes is chemical, spontaneous, and exothermic. The maximum adsorption capacity of T1, T2, T3, and T4 samples towards crystal violet dye is 34.81, 36.83, 29.46, and 11.98 mg/g, respectively. Also, the maximum adsorption capacity of T1, T2, T3, and T4 samples towards methylene blue dye is 30.13, 29.33, 17.09, and 13.43 mg/g, respectively. HCl: butanol (1:3) can efficiently desorb the dyes for three cycles of adsorption/desorption. Hence, the adsorbents can be used successfully several times for the removal of crystal violet and methylene blue dyes.

In this study, the adsorbent of Crystal Violet (CV) and Methylene Blue (MB) dyes was synthesized from the hybridization of Spirulina sp. algae biomass with silica as a matrix (ASS). Hybridization of Spirulina sp. algae biomass was carried out through a sol-gel process using tetraethyl orthosilicate precursors. The ASS adsorbent was characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller surface area method and scanning electron microscopy-energy-dispersive-X ray. The CV and MB dyes adsorption onto ASS adsorbent was studied through adsorption experiments using the batch method. The optimum adsorption of CV and MB dyes is at pH of 8 and contact time of 60 min. The CV and MB dye kinetics on the ASS adsorbent tend to follow the pseudo-second-order kinetics model with rate constant (k2) of 0.3 and 0.2 (g mg− 1 min− 1) respectively. The isotherm adsorption pattern of CV and MB dyes follows the Freundlich adsorption isotherm with KF values of 1.07 and 1.05 (mg g− 1) (L mg− 1)1/n, respectively. In the simultaneous adsorption process, CV dyes were more adsorbed than MB in solution to the ASS adsorbent.

In this research, activated carbon was obtained from rubber fruit shells (ACRPs). The obtained activated carbon (ACRPs) was modified by magnetite particle coating and silanization with triethoxyiphenylsilane (TEPS) to produce a new magnetic adsorbent (ACRPs-MS). The affinity of as-prepared adsorbent (ACRPs-MS) toward methylene blue (MB) and crystal violet (CV) dyes was tested in mono-component and bi-component solutions. Structural characterization proves the success of the magnetite coating process and the silanization of ACRPs. In the infrared (IR) spectroscopy spectrum of ACRPs-MS, Si-O-Fe and Si-O-Si bonds were identified, which indicated the presence of magnetite and silane. This is also supported by the elemental composition contained in the energy-dispersive X-ray (EDX) diffractogram. In addition, the presence of the porous structure of the surface of the material and the increase in the specific surface area increase the accessibility of contaminants such as MB and CV dyes to be adsorbed to the ACRPs-MS adsorption site effectively. The experimental results showed that the adsorption of mono-component MB and CV dyes by ACRPs-MS was optimum at pH8 and an interaction time of 60min. The adsorption kinetics of mono-component MB and CV dyes by ACRPs-MS tended to follow pseudo-second-order kinetics (PSO) models with PSO rate constant (k2) values of 0.198 and 0.993gmg-1min-1, respectively. The adsorption of MB and CV dyes by ACRPs-MS in a bi-component mixture tends to follow the Langmuir isotherm model with adsorption capacity (qm) values of 85.060 and 90.504mgg-1, respectively. Analysis of adsorption data on the bi-component mixture between MB and CV by ACRPs-MS with the Langmuir isotherm equation for a binary mixture resulted in qm of 22.645 × 10-3mmol equiv g-1. ACRPs-MS material can be used repeatedly five times with adsorption ability > 80%. Desorption of MB and CV dyes was carried out using 0.05M HCl solution. ACRPs-MS material was able to adsorb MB and CV dyes with a large adsorption capacity and could be used in repeated adsorption. Thus, it can be stated that ACRPs-MS can be used as an effective adsorbent for MB and CV dyes, either singly or in a bi-component mixture.

In this study, it was aimed to use Prunus spinosa L. fruit pulp as an adsorbent zero-waste and low-cost for the removal of toxic methylene blue (MB) and crystal violet (CV) dyes from aqueous solutions. The adsorbent was characterized utilizing FTIR-ATR, SEM, and pHpzc tests. The pHpzc value of the adsorbent is 4.96. According to optimization experiments, the optimum adsorbent dosage was determined as 0.05 g/50 mL for MB and CV dyes, the optimum pH values were determined as approximately 7 for MB and CV dyes, and the optimum contact time was determined as 45 min for MB and 30 min for CV dyes. The Langmuir model has been used to calculate the maximum adsorption capacities of MB and CV dyes at a temperature of 298 K. The obtained values are 59.59 mg/g for MB and 53.19 mg/g for CV. The experimental data for Prunus spinosa L. for both dyes exhibited a pseudo-second-order kinetic model. According to error analyses, the reproducibility and applicability of isotherm and kinetic models were investigated. From thermodynamic results, the enthalpy values were calculated as − 42.04 kJ/mol for MB and − 24.08 kJ/mol for CV dyes, which indicates that the process is exothermic. Also, the Gibbs free energies of MB and CV dyes were determined as − 34.20 kJ/mol and − 32.33 kJ/mol at 298 K, which indicates the process is spontaneous. Research and comparisons with other adsorbents have demonstrated that Prunus spinosa L. is a cost-effective and appealing choice for removing MB and CV dyes from water solutions. Graphical Abstract

Fly ash-based geopolymer as a novel photocatalyst for degradation of dye from wastewater

In the present study, we report the synthesis of Fe3O4 and Zn-doped Fe3O4 (Zn/Fe3O4) nanoparticles by a simple co-precipitation method. The morphology, structure and optical properties of the samples are characterized by transmission electron microscopy, X-ray diffraction, UV–visible spectroscopy, Fourier transform infrared spectroscopy, energy dispersive spectroscopy and UV–visible spectroscopy. The antibacterial, electrochemical energy storage and photocatalytic properties of the nanoparticles are studied in detail, and the results are discussed. Antibacterial activity of Fe3O4 and Zn/Fe3O4 nanoparticles are analyzed by disc diffusion method on Gram-negative pathogen Salmonella typhi and Gram-positive pathogen Staphylococcus aureus. Zn/Fe3O4 nanoparticles show a higher zone of inhibition because of having a larger specific surface area than the pure Fe3O4 nanoparticles. The electrochemical energy storage performances of the nanoparticles are tested in a symmetric two-electrode configuration, and the measurement demonstrated that Zn doping nearly doubles the energy storage properties of the Fe3O4 nanoparticles. The study of the photocatalytic degradation of methyl blue (MB) dye under UV irradiation in the presence of pure and doped Fe3O4 nanoparticles reveal that both nanoparticles act as ideal catalysts for degradation of MB dye.

In the present work, Schiff base ligand has been synthesized from synthesized dialdehyde and primary amine. The synthesized ligand and its copper metal complex were characterized by melting point & spectral analysis such as IR, 1HNMR, 13C and GC-MS. In the presence of H2O2 as an oxidising agent the photocatalytic performance of the complex was assessed by the photodegradation of dyes. By carrying spectrophotometrically on irradiation of visible light using Cu(II) metal complex of Schiff base ligand the photocatalytic degradation of Naphthol Blue Black dye (NBB), Rhodamine B (RB) and Methylene Blue (MB) dyes was carried out. The photocatalytic degradation of NBB, RB and MB dyes was carried out with reference to effect of time. The results revealed that Cu-complex of Schiff base ligand is consistent for photocatalysis of these dyes for treatment of authentic effluents. The results show that the optimal dose for maximal degradation of these dyes was found to be 5 mgL-1 of the Cu(II) metal complex. The % degradation of NBB, RB and MB were found to be 55%, 50% and 80% in the visible light irradiation. The % degradation of MB dye was greater as compare to other two dyes. The order of % degradation of three dyes by copper metal complex was found as MB > NBB >RB

Insight into adsorption mechanism, modeling, and desirability function of crystal violet and methylene blue dyes by microalgae: Box-Behnken design application

Tin sulfide (SnS) nanoparticles were prepared from tin(II) dithiocarbamate single source precursors. Powder X-ray diffraction patterns of the SnS nanoparticles confirmed orthorhombic herzenbergite phase of tin sulfide. High-resolution transmission electron microscope images show spherically shaped tin sulfide with particles size in the range 1.0–2.8 nm. The bandgap energy obtained from Tauc plots is in the range 2.95–3.32 eV. The as-prepared SnS nanoparticles were used as nano photocatalysts for the degradation of brilliant green (BG), crystal violet (CV), methylene blue (MB) and methyl red (MR) under visible light irradiation. The degradation efficiency of BG by the SnS nanoparticles after 180 min irradiation are 76%, 81% and 70% by SnS-1, SnS-2 and SnS-3. Degradation efficiency of 66%, 90% and 75% were obtained for SnS-1, SnS-2 and SnS-3, respectively, against CV dye. While the efficiency of 79%, 97% and 93% were obtained for SnS-1, SnS-2 and SnS-3, respectively, against MB dye. The results showed that the as-prepared SnS nanoparticles are efficient photocatalyst for the degradation of BG, CV, MB and MR dyes. Liquid chromatography-mass spectrometry was used to investigate the degradation pathway of the organic dyes. The effects of irradiation time, scavengers and photostability on the photocatalysis process were also evaluated.

Novel Beta-Cyclodextrin-based Fe3O4 nanocomposite has been synthesised through copolymerisation by incorporating Fe3O4 nanoparticles into the polymer matrix. Ultraviolet-Visible (UV-Visible) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric (TGA) analysis, Point of Zero Charge, X-ray diffraction (XRD), and Scanning electron microscopy (SEM) analysis have been used to characterise the Fe3O4 Nanoparticles and β-CDHs@Fe3O4 nanocomposite. The synthesised β-CDHs@Fe3O4 nanocomposite has been utilised for the adsorption of methylene blue (MB) dye from aqueous solutions. The maximum percentage removal of MB dye at optimum pH 7 and was found to be 98.51%. The adsorption capacity (qe) of β-CDHs@Fe3O4 nanocomposite has been found to be 268.09 mg/g at optimum dosages 1.2 g/L, pH 7, temperature 25°C, concentration 100 mg/L and an agitation speed of 200 rpm. Adsorption data have been fitted with three isotherm models namely Langmuir, Freundlich, and Temkin, and it was found to be the best fit with the Langmuir isotherm model. Kinetic studies like the pseudo-first order, pseudo-second order, and intra-particle diffusion model were also performed to study the adsorption mechanism. Further, thermodynamic studies demonstrate that the reaction was exothermic and spontaneous. Photocatalytic degradation of MB dye under visible light has also been studied, and 79.01% degradation of the dye was observed. Also, desorption of the nanocomposite was performed, and it was found to be reusable up to 5 times with 90% dye-desorption in the fifth cycle.

Industrial chemical pollutants such as methylene blue (MB) dye are released into the water body and potentially cause harm to the human and aquatic biosphere. Therefore, this study aims to synthesize eco-friendly nanocatalysts, i.e., reduced graphene oxide (rGO), zinc oxide (ZnO), and reduced graphene oxide-zinc oxide (rGO@ZnO) nanocomposites, for efficient photocatalytic degradation of MB dye. A graphite rod was obtained from waste dry cell batteries for the electrochemical exfoliation synthesis of graphene oxide (GO) and rGO. For the eco-friendly synthesis of ZnO and rGO@ZnO nanocatalysts, Croton macrostachyus leaf extract was used as a reducing and capping agent. The synthesized nanocatalysts were characterized using a UV–Vis spectrophotometer, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy with energy-dispersive X-ray. The eco-friendly synthesized rGO, ZnO, and rGO@ZnO nanocatalysts were applied for the photocatalytic degradation of MB dye using direct sunlight irradiation. At optimum parameters, photocatalytic degradation of MB dye efficiency reached up to 66%, 96.5%, and 99.0%, respectively. Furthermore, kinetics of the photodegradation reaction based on rGO, ZnO, and rGO@ZnO nanocatalysts follow pseudo-first-order with a rate constant of 2.16 × 10–3 min−1, 4.97 × 10−3 min−1, and 5.03 × 10−3 min−1, respectively. Lastly, this study promotes a low catalyst load (20 mg) for the efficient photodegradation of MB dye.

Controllable synthesis of semiconducting anatase TiO2 nanostructures for visible light driven photocatalytic degradation of crystal violet and methylene blue dye.

Improved sono-assisted adsorption of a binary dye mixture using bis(2-ethylhexyl) phosphate modified Amberlite XAD-2 resin and response optimization

ZnO is a semiconductor material that has important physical and chemical properties, which are frequently and significantly enhanced by the addition of impurities, such as doping. A study of the structural properties of pristine and functionalized (i.e., doped with Antimony and Tungsten) ZnO nanoparticles has been conducted for the photocatalyst-based degradation of methylene blue (MB) dye under both Ultraviolet (UV) and solar light. Authors have used a 1% concentration of dopant for doping purposes. The synthesized materials were characterized for structural analysis, functional group identification, spectroscopic measurements, and morphological examination using X-ray diffraction (XRD), Fourier transform-infrared (FTIR), UV-Vis spectroscopy (UV-Vis), and Field emission scanning electron microscope (FESEM) techniques. XRD analysis confirmed that the synthesized-doped materials retained the wurtzite hexagonal structure with a purity of 99%. Transmission electron microscope (TEM) analysis data reveals the average size of pure ZnO-NPs was found to be 7 nm; after doping the size was found to be increased to 18 nm and 9.55 nm, respectively, for ZnO-W and ZnO-Sb. As per FESEM analysis results, minor morphological changes were observed after doping. The Ultraviolet Differential reflectance spectroscopy UV-DRS study revealed the confirmation of ZnO doping with antimony and tungsten, which exhibited a blue shift. The decrease in the band-gap on doping makes the ZnO-NPs more efficient for photocatalytic applications. The photocatalytic efficiency of pristine and doped ZnO-NPs catalysts for methylene blue photocatalytic degradation (PCD) was analyzed under both UV and solar irradiation. This study analyzed the effect of pH, nano-photocatalyst dose, and initial dye concentration (ICD) on the PCD of MB. The obtained analytical results showed that the ideal conditions for the PCD of MB dye are as follows: pH = 9, the quantity of the nano-photocatalyst used was 300 mg/L, and an initial MB dye dose of 10 ppm. These conditions lead to a PCD of about 91% of the MB dye by using ZnO-Sb nano-photocatalyst on exposure to solar radiation. The reusability study also revealed the stability of nano-photocatalysts. The current research may pave the way for the removal of hazardous dyes from wastewater discharged by many industries.

Coal Fly Ash (FA) and modified fly ash (mFA), treated with either KOH or NaOH, were used to remove methylene blue (MB) and crystal violet (CV) dyes from aqueous solution. Several techniques, including Thermogravimetric analysis, X-Ray diffraction analysis, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller, and Scanning Electron Microscopy, were used to characterise both FA and mFA. To optimise the adsorption process, the Response Surface Methodology (RSM) with the Box – Behnken design (BBD) was applied. Key parameters such as solution pH (4–10), initial dye concentration (200–300 mg/L), contact time (15–180 minutes), and temperature (30–50°C) were varied to assess their impact on adsorption efficiency. The adsorption followed the Langmuir model and pseudo-second-order (PSO) kinetic model. The adsorption capacity of mFA for MB dye was 49.5 mg/g at 50°C, while for CV dye, it was 495.5 mg/g at the same temperature. The adsorption mechanism involved electrostatic attraction, n-π interaction, Yoshida hydrogen bonding, and hydrogen bonding. These results highlight the effectiveness of mFA as a high-capacity adsorbent for treating MB and CV dyes in water solutions.