Photocatalytic Activation of Peroxymonosulfate by CuO/ γ ‐Al 2 O 3 for Degradation of Crystal Violet in Aqueous Media

Rhodamine B (RhB) is a highly toxic dye that poses significant health risks. In this study, CuZn-ZIFs was synthesized and analyzed by various techniques such as Powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDS) and Brunauer–Emmett–Teller (BET). In clearly defined technical parameters, CuZn-ZIFs exhibited a notable heat resistance up to 600°C and featured a distinct polygonal structure. Furthermore, an assessment revealed a Specific Surface Area of 1242.7 m2·g-1, accompanied by a pore volume of 0.47 cm3·g-1, a pore size measuring 11.53 Å, and an average particle size of 28.67 nm. Not only that, it was found to be effective in promoting the oxidation of peroxymonosulfate (PMS) for RhB treatment. The results showed that over 90% of RhB concentration 40 mg·L-1 was degraded within 50 minutes in the presence of PMS and 0.15 g·L-1 of CuZn-ZIFs catalyst at room temperature. Additionally, the catalyst demonstrated remarkable reusability, maintaining high removal efficiency after five cycles. It indicated that this material has great potential as an effective heterogeneous catalyst for removing toxic dyes from aqueous solutions.

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.

A bimetallic nanocatalyst from carbonaceous waste for crystal violet degradation

In this study, a valuable adsorbent was functionalized using commercial ZnO and a mango seed extract (MS-Ext) as a green approach for synthesis. Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy-dispersive X-ray analysis spectraconfirmed the presence of bioactive phenolic compounds and ions on the surface of ZnO. Functionalized Cu-doped ZnO/MS-Ext exhibits high efficacy in acidic, neutral, and alkaline medium, as indicated by 98.3% and 93.7% removal of methylene blue (MB) and crystal violet (CV) dyes, respectively. Cu-doped ZnO/MS-Ext has a zeta potential significantly lower than pristine zinc oxide (p-ZnO), which results in enhanced adsorption of cationic MB and CV dyes. In binary systems, both MB and CV were significantly removed in acidic and alkaline media, with 92% and 87% being removed for CV in acidic and alkaline media, respectively. In contrast, the removal efficiency of methyl orange dye (MO) was 16.4%, 6.6% and 11.2% for p-ZnO, ZnO/Ext and Cu-doped ZnO/Ext, respectively. In general, the adsorption kinetics of MB on Cu-doped ZnO/MS-Ext follow this order: linear pseudo-second-order (PSO) > nonlinear pseudo-second-order (PSO) > nonlinear Elovich model > linear Elovich model. The Langmuir isotherm represents the adsorption process and indicates that MB, CV, and MO are chemisorbed onto the surface of the adsorbent at localized active centers of the MS-extract functional groups. In a binary system consisting of MB and CV, the maximum adsorption capacity (qm) was 72.49 mg/g and 46.61 mg/g, respectively. The adsorption mechanism is governed by electrostatic attraction and repulsion, coordination bonds, and π–π interactions between cationic and anionic dyes upon Cu-doped ZnO/Ext surfaces.

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.

Citric acid-functionalized Acacia pods as a robust biosorbent for decontamination of wastewater containing crystal violet dye: Experimental study combined with statistical optimization

Background: Crystal violet dye is stable and difficult to be biodegraded owing to the existence of the multiple aromatic rings of the crystal violet molecules. Removing crystal violet dye from the wastewater is a major challenge. Objective: The aim of the research is to synthesize barium carbonate/tin dioxide nanoparticles and investigate the photocatalytic performance for the degradation of crystal violet. Methods: Barium carbonate/tin dioxide nanoparticles were synthesized via a facile hydrothermal route without any surfactants. The crystal structure, micro-morphology, size and optical performance of the barium carbonate/tin dioxide nanoparticles were investigated by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and solid ultraviolet-visible diffuse reflectance spectrum. Results : The size of the barium carbonate/tin dioxide nanoparticles is 20 nm to 200 nm with the band gap of 3.71 eV. The photocatalytic activity of the barium carbonate/tin dioxide nanoparticles was measured by the photocatalytic degradation of crystal violet. The crystal violet degradation efficiency reaches 92.1% with the ultraviolet-visible irradiation time of 8 h using 10 mg barium carbonate/tin dioxide nanoparticles. The crystal violet degradation ratio increases to 96.1% when the dosage of the barium carbonate/tin dioxide nanoparticles increases to 20 mg/10 mL crystal violet dye solution. Active species capture photocatalytic experiments showed that the holes, hydroxyl radicals and superoxide ion radicals are the main active species. Reusability experiments displayed that the barium carbonate/tin dioxide nanoparticles are stable for the crystal violet dye degradation. Conclusion: The barium carbonate/tin dioxide nanoparticles show good photocatalytic performance toward crystal violet under ultraviolet light irradiation.

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.

Cobalt phthalocyanine-supported reduced graphene oxide: A highly efficient catalyst for heterogeneous activation of peroxymonosulfate for rhodamine B and pentachlorophenol degradation

Organic dyes are pollutants that threaten aquatic life and human health. These dyes are used in various industries; therefore, recent research focuses on the problem of their removal from wastewater. This aim of this study is to examine the clay/Gum Arabic nanocomposite (CG/NC) as an adsorbent to adsorb methylene blue (MB) and crystal violet (CV) dyes from synthetic wastewater. The CG/NC was characterized using Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Brunaure-Emmett-Teller (BET). The effect of parameters that may influence the efficiency of removing MB and CV dyes was studied: (dosage of CG/NC, contact time, pH values, initial concentration, and temperature), and the optimal conditions for removal were determined. Furthermore, an Artificial Neural Network (ANN) model was adopted in this study. The results designated that the adsorption behavior adhered to the Langmuir model and conformed to pseudo-second-order kinetics. The results also indicated that the removal efficiency reached 99%, and qmax reached 66.7 mg/g and 52.9 mg/g for MB and CV, respectively. Results also proved that CG/NC can be reused up to four times with high efficiency. The ANN models have proven effective in predicting the process of the removal, with the low Mean Square Error (MSE = 1.824 and 1.001) and high Correlation Coefficient (R2 = 0.945 and 0.952) for the MB and CV dyes, respectively.

Organic dyes are pollutants that threaten aquatic life and human health. These dyes are used in various industries; therefore, recent research focuses on the problem of their removal from wastewater. The aim of this study is to examine the clay/gum arabic nanocomposite (CG/NC) as an adsorbent to adsorb methylene blue (MB) and crystal violet (CV) dyes from synthetic wastewater. The CG/NC was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunaure–Emmett–Teller (BET). The effect of parameters that may influence the efficiency of removing MB and CV dyes was studied (dosage of CG/NC, contact time, pH values, initial concentration, and temperature), and the optimal conditions for removal were determined. Furthermore, an artificial neural network (ANN) model was adopted in this study. The results indicated that the adsorption behavior adhered to the Langmuir model and conformed to pseudo-second-order kinetics. The results also indicated that the removal efficiency reached 99%, and qmax reached 66.7 mg/g and 52.9 mg/g for MB and CV, respectively. Results also proved that CG/NC can be reused up to four times with high efficiency. The ANN models proved effective in predicting the process of the removal, with low mean squared errors (MSE = 1.824 and 1.001) and high correlation coefficients (R2 = 0.945 and 0.952) for the MB and CV dyes, respectively.

Efficient plant biomass utilization is a key component in advancing a sustainable and circular bioeconomy. ZnO nanoparticle synthesis using plant extracts is actively studied as a part of this effort. Here, green ZnO nanoparticles were prepared using Licania tomentosa Benth (also known as Oiti) leaf extract. Characterization of the produced green ZnO nanoparticles (NPs) involved X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and UV–Visible spectroscopy (UV-Vis) techniques. Furthermore, we investigated photocatalytic degradation of the crystal violet (CV) dye catalyzed by the obtained ZnO NPs and evaluated the efficiency of the photodegradation process. The synthesized nanoparticles have an average crystallite size of 12.4 nm, as measured by XRD and have a spherical shape as revealed by SEM. UV–Vis studies show that ZnO nanoparticles have a relatively small band gap of 2.75 eV, as estimated by Tauc plot. The photodegradation activity tests using synthesized green ZnO NPs showed that approximately 79% of CV dye is decomposed in 2 h after being exposed to UV irradiation under experimentally studied conditions. The photodecomposition of CV is impacted by different factors, such as the catalyst bandgap and loading, the pH and the intensity of light. Moreover, an optimum photocatalyst loading was determined. Our studies reveal that Oiti leaf extract can be efficiently used for ZnO NPs synthesis, which has significant potential for photodegradation applications.

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.

The employment of green synthesized nanomaterials for water pollution prevention is increasing nowadays. Herein, Mn-doped ZnO nanoparticles were synthesized using Peganum Harmala seed extract and subsequently used for crystal violet (CV) dye removal from aqueous solutions. The first part of the study describes the preparation of the adsorbent (Mn-ZnO NPs) using a simple coprecipitation method. The surface properties of the material were characterized by Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The second part investigates the adsorption of CV dye onto the surface of the prepared Mn-ZnO NPs. Additionally, the isotherm,kinetics, and thermodynamics of the adsorption process were studied in detail. Batch adsorption analysis was carried out by evaluating different parameters, such as the amount of the adsorbent (0.01g to 0.04 g), CV concentration (20 to 80 mg/L), adsorption time (30 to 120 min), and temperature (35 to 65 ⁰C). The maximum CV dye adsorption capacity of the Mn-ZnO NPs was 45.60 mg/g. The thermodynamic study revealed the spontaneous, exothermic, and feasible nature of the adsorption process, primarily driven by physical forces. Kinetic and isotherm analyses indicated that the adsorption of the dye best fit the Freundlich isotherm and pseudo-second-order models, respectively. Mn-doped ZnO is considered an effective adsorbent for CV, benefiting from its rapid and easy preparation, non-toxic nature, and 94 % adsorption efficiency. The material holds potential for future applications in the removal of organic dyes from wastewater.

Peroxymonosulfate activation by Mn3O4/metal-organic framework for degradation of refractory aqueous organic pollutant rhodamine B