Study of the adsorption capacity of kaolin clay and its composite for removing methyl green dye from an aqueous medium

Cadmium sulphide (CdS) nanoparticles (NPs) were synthesized through hydrothermal route and characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Energy dispersive X-ray analysis, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and Thermo gravimetric analysis (TGA).The band gap of CdS nanoparticles was found to be 2.38 eV. CdS NPs are crystalline aggregates with hexagonal structure as shown by SEM and XRD analysis. TGA study revealed that the synthesized nanomaterials were very stable to temperature and only 6.54% total loss occurred during heating range (25 °C-600 °C).The CdS NPs were used for the first time against the degradation of Eosin B (EB) and Methyl green (MG) dyes in aqueous solution.The degradation of EB and MG over CdS nanocatalysts followed second order kinetics. The predicted activation energies for both the dyes' reactions were 61.1 kJ/mol and 32.11 kJ/mol, respectively. About 95% and 90% dye degradation was observed at the time interval of 160 minutes for EB and MG, respectively. High percent degradation of EB was observed at high pH (pH 0) while at low pH (pH 4) high percent degradation was found for MG dye. Maximum dye degradation was found at the optimal dose (0.03 g/L) of the catalyst and at low dye concentration. The rate of EB and MG dye degradation was found to increase with increase in temperature up to 45 °C. The recyclability study showed that CdS nanoparticles could be reused for the degradation of the given dyes. Good antibacterial activity against Staphylococcus aureus was shown by CdS NPs. From the biocompatibility it was confirmed that CdS NPS are bioincompatible compatible.

Promising catalyst of cooper impregnated on natural material (CT) synthesized via wet impregnation method, in order to enhance the catalytic wet peroxide oxidation during the degradation of organic matter in a batch reactor under mild conditions. Three different percentages of copper metal (2.5, 5 and 7.5 %) incorporated into CT material which are referred as follows 2.5% Cu-CT, 5% Cu-CT and 7.5% Cu-CT were investigated in the oxidation catalytic of methyl green (MG) dye. The chemical composition, the morphology and the structure of raw CT and all prepared samples, were investigated by X-ray fluorescence, Fourier transform infrared spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) to get a better understand concerning the catalytic activity behavior of Cu-CT catalyst. Different variable examined the catalytic activity of the samples obtained such as initial concentrations of dye, copper (Cu) loading, temperature and H 2 O 2 effect was investigated to enhance the MG conversion. CWPO experiments showed that 2.5% Cu-CT catalysts have the maximum catalytic activity during the degradation of MG dye. The presence of copper on CT support ameliorates the hydroxyl radicals in the reaction medium after the contact with H 2 O 2 thus enhanced the catalytic conversion of the CT pristine. The optimum conditions showing an important catalytic conversion of MG dye (95 %) at 2.5% of copper loading, 139.10 -3 mol.L -1 H 2 O 2, temperature of 40 °C and at pH 6.0 during 30 min as a reaction time.

Graphene oxide (GO) nanocomposite with Gd and Fe doped LaNiO3 and their photocatalyst efficacy for methyl green oxidation under visible light exposure

A novel catalyst of ceria-nanorods loaded on carbon xerogel for catalytic wet oxidation of methyl green dye

TiO2nanoparticles were immobilized on two porous materials used as catalyst supports, namely, activated carbon (AC) and natural clay (NC), through an impregnation process using TiO2(P25) as precursor. The so-prepared composite materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), and nitrogen physisorption, that is, Brunauer-Emmett-Teller (BET) surface area determination. SEM and TEM observation evidenced that TiO2was deposited on AC and NC surface. XRD results confirmed that TiO2existed in a mixture of anatase and rutile phases. The specific surface area of photocatalysts decreased drastically in comparison with the original materials. The photocatalytic activity of these materials was assayed in the oxidation of Methyl Green (MG) dye in aqueous medium under UV irradiation. TiO2/AC exhibited higher photocatalytic oxidation activity than TiO2at neutral pH. Total mineralization of MG was confirmed by means of COD analysis, pointing to these materials as an efficient, cost-effective, and environment friendly alternative for water treatment.

Graphene oxide nanocomposite with CuSe and photocatalytic removal of methyl green dye under visible light irradiation

Use of Cyclea peltata mediated gold nanospheres for adsorptive degradation of methyl green dye

Ultra-rapid catalytic reduction of methyl green dye using tetra methyl ammonium bromide derived cobalt nanoparticles

Adsorption of cationic methyl green (MG) on nontreated (AB) and purified (AP) natural Sejnane clay type was studied in an equilibrium batch process. This work reported the application of kaolinite-rich heterogeneous clay for the removal of a cationic dye. Effects of contact time, initial dye concentration, mass adsorbent, pH, and temperature on the MG removal were checked. The adsorbent before and after adsorption processes was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and atomic adsorption spectrophotometer. Equilibrium data were mathematically modeled using the Freundlich, Langmuir, and intraparticle diffusion models. Kinetic of adsorption was determined by pseudo-first-order and pseudo-second-order models. The free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were calculated. A fast increase in the equilibrium removal of the cationic dye was obtained at a pH ranging between 3 and 11 and moderate temperature. This rapid MG adsorption proved the efficiency of kaolinite clay in cationic dye removal. Decolorizing yields were 73.3% for AB and 99.8% for AP. Thus, the adsorption capacity of purified clay was clearly higher than of H2SO4 and thermic activated clays. The data more closely resembled a pseudo-second-order model process, and the clay had reasonable Freundlich adsorption capacity. Adsorption process was endothermic and spontaneous chemisorption. SEM analysis showed that the adsorbed MG had remarkably changed the morphology of raw and purified clay surface. The low desorption rates confirmed effectiveness of this type of material for the retention of methyl green molecules. Thus, tested clays have no environmental impact.

Preparation of new bio-based chitosan/Fe2O3/NiFe2O4 as an efficient removal of methyl green from aqueous solution.

Halloysite nanotubes (HNTs) were used to successfully remove methyl green dye from water. The HNTs were also characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), 29Si and 27Al magic angle spinning nuclear magnetic resonance with magic angle spinning (MAS-NMR) and nitrogen adsorption at 77 K. SEM and TEM micrographs showed that HNTs have lengths of 0.2 to 1.5 μm, an outer diameter of 100 nm and lumen of 20 nm wide. X-ray diffraction patterns showed that the HNTs were totally dehydrated. HNTs may be regarded as a mesoporous material with a pore size distribution in the range of 1.5-150 A and specific surface area of 34.49 m2g-1. The adsorption kinetics and equilibrium data of the dye, initial dye concentration, temperature, pH and contact time effect on removal efficiency were also investigated. Pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elrich models were evaluated in order to determine the rate parameters. The adsorption rate followed pseudo-second-order kinetic model. Adsorption revealed that methyl green was adsorbed as the Langmuir isotherm model describes and the maximum adsorption capacity of the HNTs was achieved (185 mgg−1), being an efficient adsorbent for methyl green adsorption.

Background: In recent years, azo dyes have become the dominant choice in the textile industry, accounting for about 60-70% of all dyes used, which has led to growing environmental concerns. Aim: This research focused on the photocatalytic degradation of methyl orange (MO) and methyl green (MG) dyes using a novel g-C₃N₄ (GCN)/polyaniline (PANI)/Ag composite under visible light. Methods: This composite was synthesized through a straightforward preparation process and characterized by using various techniques, including UV-visible spectroscopy (UV-Vis), Fourier- transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and cyclic voltammetry (CV). Results: Characterization results confirmed the incorporation of PANI and Ag nanoparticles into the GCN matrix. This composite enhanced the visible light absorption and improved charge separation, leading to increased photocatalytic efficiency. Photocatalytic experiments were conducted under visible light irradiation with a catalyst dosage of 10 mg in a 10-ppm solution of the MO and MG dyes mixture. Conclusion: The GCN/PANI/Ag composite achieved significant degradation efficiencies of 70% for MO and 69% for MG within 120 minutes. The degradation process followed first-order kinetics, with rate constants of 0.0087 min⁻¹ for MO and 0.0086 min⁻¹ for MG, respectively. Reusability tests showed that the composite retained over 60% of its initial efficiency after five cycles. These findings highlight the potential of the GCN/PANI/Ag composite as a sustainable and effective photocatalyst for visible-light-driven dye degradation, offering an eco-friendly approach to wastewater treatment.

The aim of this research study was to apply experimental design in the optimization of influencing parameters on the corrosion inhibition efficiency of Methyl Green (MG) dye using the weight loss (WL) technique. Corrosion inhibition of carbon steel (CS) in the presence of different concentrations of MG dye in 1 M HClO4 solution has been studied. Results showed that inhibition efficiency (IE) increased with increasing concentration of MG dye up to 1.0 × 10−3 mol/L, and decreased with raising temperature. The free energy values calculated from the Langmuir adsorption isotherm for MG dye (-36.24 to -38.04 kJ/mol) suggested that MG dye molecules adsorbed onto CS surface via a physicochemical mechanism.

In the current investigation, the solar photocatalytic degradation of two cationic model dyes (methyl green (MG) and crystal violet (CV)) was studied using α-Fe2O3/ZnFe2O4 nanocomposite. The fine powder of nanoparticles was obtained by co-precipitation method at pH = 10 and characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and UV-vis spectroscopy. The surface properties were further examined through temperature-programmed desorption (TPD) and point of zero charge (PZC) measurements to assess the acid–base characteristics and surface charge behavior of the material. Adsorption and photocatalytic performance were systematically evaluated in both single and binary systems. Dark adsorption experiments showed a better affinity of the α-Fe2O3/ZnFe2O4 heterosystem towards MG dye in both cases. Under natural sunlight irradiation in the individual system, the photocatalytic activity of the nanoparticles was significantly higher for MG (81.67% removal) compared to CV (41.70%). Kinetics analysis revealed that the photodegradation of both dyes followed a pseudo-first-order model. In binary systems, competitive adsorption effects strongly influenced the degradation behavior, with MG showing preferential adsorption and higher degradation rates. Moreover, the MG discoloration kinetics followed a second-order model, while CV kinetics transitioned from second- to zero-order with increased initial concentration.

This research investigated the utilization of graphene quantum dot/montmorillonite (GQD/MMT) as an effective nanofiller in a hydrogel composed of salep biopolymer. The semi-IPN hydrogel was synthesized using salep as the substrate, acrylamide (AAm) as the monomer, ammonium persulfate (APS) as an initiator in free radical polymerization, and N,N'-methylenebisacrylamide (MBA) as a cross-linking agent. The hydrogels were applied to remove safranin (SA), methylene blue (MB), crystal violet (CV), methyl green (MG), congo red (CR), and malachite green (MG) dyes from the water. The diverse properties were analyzed using a scanning electron microscope, fourier infrared spectroscopy, mapping, energy dispersive spectroscopy, weighing analysis, X-ray diffraction, and thermal stability analyses. The optimism of the prepared adsorbent in dye absorption was evaluated by measuring the swelling amount, pH impact, adsorbent dosage, and contact time. The adsorption calculations were described using kinetics and isotherm models. The results indicated that the Langmuir isotherm model (R2 = 99.6) and the pseudo-second-order kinetic model (R2 = 99.9) provided the best fit for the absorption process of MB. The presence of additional amounts of GQD/MMT had a reciprocal effect on the adsorption efficiency due to the accumulation of GQD/MMT in the semi-interpenetrating polymer network (semi-IPN (structure. The findings revealed that the samples exhibited high thermal stability, and the absorption process was primarily chemical. Furthermore, the nanocomposite hydrogels demonstrated distinct mechanisms for absorbing anionic dye (CR) and cationic dye (MB). Under optimal conditions, using 7 wt% GQD/MMT at a concentration of 5 ppm, pH = 7, an adsorbent dosage of 50 mg, at room temperature, and a contact time of 90 min, the maximum removal efficiencies were achieved: MB (96.2%), SA (98.2%), MG (86%), CV (99.8%), MG (95.8%), and CR (63.4%). These results highlight the adsorbent's high absorption capacity, rapid removal rate, and reusability, demonstrating its potential as an eco-friendly and cost-effective solution for removing dyes from water.