Explore the vast range of titles available.

In this research work, we reported the synthesis of a spherical-shaped bismuth vanadate (BiVO4) photocatalyst using a cost-effective, simple, chemical hydrothermal method and studied the effect of deposition temperatures on the structural, morphological, optical properties, etc. The XRD result confirmed the monoclinic scheelite phase of BiVO4. An XPS study confirmed the occurrence of Bi, V, and O elements and also found that Bi and V exist in +3 and +5 oxidation states, respectively. SEM micrographs revealed the spherical-shaped morphology of the BiVO4 photocatalyst. Optical investigation showed that the bandgap of the BiVO4 photocatalyst varied between 2.25 and 2.32 eV. The as-synthesized BiVO4 photocatalyst was used to study the photocatalytic degradation of crystal violet (CV) dye under visible light illumination. The photocatalytic degradation experiment showed that the degradation percentage of crystal violet dye using BiVO4 reached 98.21% after 120 min. Mineralization of crystal violet dye was studied using a chemical oxygen demand analysis.

Polyporaceae are known as wood decaying fungi with enzymatic production that plays an important role in environmental processes. Laccase (Lac) and lignin peroxidase (LiP) are two of the most explored enzymes and show significant industrial importance in degrading textile dyes, including Remazol Brilliant Blue R (RBBR), Crystal Violet (CV) and Congo Red (CR) that are some of the most commonly tested. Six strains representing six species of Hexagonia and Trametes (Polyporaceae) from South America were selected to evaluate Lac and LiP production and degradation of these dyes. The dataset of rDNA ITS confirmed the identity of the species, the amplification using LccF–LccR and Lip1–Lip2 primers detected Lac and LiP gene fragments in four and five strains, respectively, and the biostimulation essays of Lac and LiP showed the production of enzymes by all strains, being T. versicolor (VRTO 1064) and H. hydnoides (URM 9027) the best producers of Lac (117.839 U L-1) and LiP (109.370 U L-1), respectively. For RBBR, T. villosa (URM 8022) presented the best results (84.18 %). CR decolorization ranged from 61.37% to 68.74% by five strains, with lower results for T. lactinea (URM 8350) (19.9 %). Finally, T. sanguinea (URM 8774) had the best results for CV (85.06 %). Trametes lactinea (URM 8350), T. versicolor (VRTO 1064), and T. villosa (URM 8022) did not decolorize CV. Our results highlight the underexplored enzymatic potential of strains from South America and show that the strains here studied are promising alternatives to decolorize industrial textile dyes.

The current study explores the effectiveness of coconut husk for crystal violet dye sequestration employing a batch experimental setup. Characterization of adsorbent was carried out via FTIR, and SEM techniques and results confirmed the involvement of OMe, COC and hydroxyl functional groups in dye uptake, and the rough, porous nature of adsorbent and after adsorption dye molecules colonized these holes resulting in dye exclusion. Effects of various adsorption parameters such as pH, adsorbent dose, contact time, initial dye concentration, and temperature of solution were studied. Crystal violet adsorption on coconut husk was highly pH-dependent, with maximum removal occurring at basic pH. Maximum removal of dye, i.e., 81%, takes place at optimized conditions. Kinetic data was analyzed by pseudo-first, pseudo-second order and an intra-particle diffusion model. Results showed that the pseudo-second order kinetic model best described adsorption of crystal violet onto coconut husk. Langmuir, Freundlich, and D-R adsorption isotherms were also used to test their appropriateness to experimental data and the Freundlich isotherm fits best to data. Thermodynamic parameters showed that the current process was spontaneous, endothermic in nature with continuous decrease in entropy. Established practice is 79% applicable to tap water and in acidic medium nearly 80% of adsorbent was recovered, confirming the effectiveness and appropriateness of coconut husk for crystal violet dye exclusion from wastewater.

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 pH 8 and an interaction time of 60 min. 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 ( k 2 ) values of 0.198 and 0.993 g mg −1  min −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 ( q m ) values of 85.060 and 90.504 mg g −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 q m of 22.645 × 10 –3  mmol 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 0.05 M 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. Graphical Abstract

The current study is focused on fabrication of a ternary metal oxide nanocomposite (ZnO/CuO/Ag2O) as an efficient and superior photocatalyst by step-wise implanting of p-type CuO and Ag2O semiconductors onto an n-type semiconductor (ZnO) via a chemical method. The structural and textural characteristics of the manufactured samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy combined with electron dispersive spectroscopy (FESEM-EDS) and UV–visible spectroscopy. The photocatalytic performance of the fabricated ternary nanocomposite was tested against the photocatalytic degradation of crystal violet (CV) and rhodamine B (RhB) organic dyes under solar light irradiation. The ternary nanocomposite demonstrated about 99.05% and 97.38% degradation efficiency toward CV and RhB dyes under solar light irradiation in a time period of 105 min. The calculated rate constants (k, min−1) for degradation under solar light over the ZnO/CuO/Ag2O nanocomposite were 4.26 and 3.61 times higher than the k value obtained over ZnO nanoparticles for CV and RhB dyes, respectively. The main reactive species taking part in the photodegradation processes were •OH and •O2− over ZnO/CuO/Ag2O photocatalysts under solar light illumination. Furthermore, the recycle experiments confirmed good reusability and photo-stability of the ZnO/CuO/Ag2O ternary nanocomposite.

Dye-based industries, particularly small and medium scale, discharge their effluents into waterways without treatment due to cost considerations. We investigated the use of biochars produced from the woody tree Gliricidia sepium at 300 °C (GBC300) and 500 °C (GBC500) in the laboratory and at 700 °C from a dendro bioenergy industry (GBC700), to evaluate their potential for sorption of crystal violet (CV) dye. Experiments were conducted to assess the effect of pH reaction time and CV loading on the adsorption process. The equilibrium adsorption capacity was higher with GBC700 (7.9 mg g−1) than GBC500 (4.9 mg g−1) and GBC300 (4.4 mg g−1), at pH 8. The CV sorption process was dependent on the pH, surface area and pore volume of biochar (GBC). Both Freundlich and Hill isotherm models fitted best to the equilibrium isotherm data suggesting cooperative interactions via physisorption and chemisorption mechanisms for CV sorption. The highest Hill sorption capacity of 125.5 mg g−1 was given by GBC700 at pH 8. Kinetic data followed the pseudo-second-order model, suggesting that the sorption process is more inclined toward the chemisorption mechanism. Pore diffusion, π–π electron donor–acceptor interaction and H-bonding were postulated to be involved in physisorption, whereas electrostatic interactions of protonated amine group of CV and negatively charged GBC surface led to a chemisorption type of adsorption. Overall, GBC produced as a by-product of the dendro industry could be a promising remedy for CV removal from an aqueous environment.

Organic dyes that are extensively released in wastewater from various industries remain the priority concern in the modern world. Therefore, a novel catalyst, bismuth–iron selenide, was prepared through the solvothermal process for photocatalytic degradation of a carcinogenic crystal violet dye. The catalyst was supported with chitosan to form iron–bismuth selenide–chitosan microspheres (BISe-CM). The synthesized catalyst was composed of iron, bismuth, and selenium in a definite proportion based on EDX analysis. FTIR analysis confirmed the synthesis of BISe-CM from characteristic bands of metal selenium bond as well as the typical bands of chitosan. SEM analysis illustrated the average diameter of the barren catalyst to be 54.8 nm, while the average size of the microspheres was 982.5 um. The BISe-CM has the surface of a pore with an average size of 0.5 um. XRD analysis revealed that the synthesized catalyst was composed of Fe 3 Se 4 and Bi 2 Se 3 . The prepared catalyst showed better degradation efficiency for crystal violet dye at optimized conditions under solar irradiation. Employing 0.2 g of BISe-CM resulted in complete degradation for 30 ppm of crystal violet dye in 150 min at pH 8.0. The reusability of the catalyst up to four consecutive times makes it a more attractive and practical candidate. Moreover, the catalyst followed pseudo-first-order kinetics in the decontamination of crystal violet. Conclusively, the novel photocatalyst showed the best decolorizing property of crystal violet under sunlight irradiation and could be a suitable alternative for dye decontamination from wastewater.

Releasing wastewater containing organic dyes into water bodies generates a variety of hazards for humans and marine life. Thus, developing effective adsorbents to remove organic dyes from wastewater is critical. Herein, a mixture of the orange peel (OP) and watermelon rind (WR) wastes was converted into a mesoporous activated carbon (OPWRAC) via microwave-induced ZnCl 2 . Several analytical techniques such as XRD, N 2 adsorption–desorption isotherms, FTIR, pH pzc , and SEM–EDX were applied to characterize the physicochemical properties of OPWRAC. Subsequently, the adsorptive efficiency of OPWRAC was comprehensively explored towards the removal of two structurally different organic dyes, namely, crystal violet (CV) and methylene blue (MB). The operational adsorption conditions such as OPWRAC dose (0.04–0.1 g) coded as (A), solution pH (4–10) coded as (B), and contact time (10–60 min) coded as (C) were statistically optimized using the response surface methodology-Box-Behnken design (RSM-BBD). The adsorption isotherm data for CV and MB dyes agree with the Freundlich model, and the kinetic data can be explained by the pseudo-second-order model. Thus, OPWRAC displays remarkable adsorption capacity for capturing CV (137.8 mg/g) and MB (200.7 mg/g). The tailored adsorption mechanism of CV and MB by the OPWRAC indicates the involvement of several types of electrostatic forces, π-π stacking, pore filling, and H-bonding. The output of this research shows the feasibility of converting the mixture of OP and WR into promising activated carbon with potential application for capturing two structurally cationic dyes from an aqueous environment.

Today, nanoscience explores the potential of nanoparticles due to their extraordinary properties compared to bulk materials. The synthesis of metal nanoparticles using plant extracts is a very promising method for environmental remediation, which gets global attention due to pollution-led global warming. In the present study, iron nanoparticles (FeNPs) were successfully synthesized by the green method using Vernonia amygdalina plant leaf extract as a natural reducing and capping agent. Biosynthesized FeNPs were characterized with different analytical techniques such as UV–visible, FT-IR, XRD, and SEM. The analysis revealed the formation of amorphous FeNPs with an irregular morphology and non-uniform distribution in size and shape. The average particle size was approximately 2.31 µm. According to the catalytic degradation investigation, the FeNPs produced via the green approach are highly effective in breaking down both CV and MB into non-toxic products, with a maximum degradation efficiency of 97.47% and 94.22%, respectively, when the right conditions are met. The kinetics study exhibited a high correlation coefficient close to unity (0.999) and (0.995) for the degradation of MB and CV, respectively, for the zero-order pseudo-kinetics model, which describes the model as highly suitable for the degradation of both dyes by FeNPs compared to other models. The reusability and stability of biosynthesized nano-catalysts were studied and successfully used as efficient catalysts with a slight decrease in the degradation rate more than four times. The results from this study illustrate that green synthesized FeNPs offer a cost-effective, environmentally friendly, and efficient means for the catalytic degradation of organic dyes.

Adsorption is a simple and effective method to remove heavy metal ions and anionic or cationic dyes from aqueous or waste solutions. Herein, we report on the adsorption of a cationic dye crystal violet on a low-cost natural material. The diatomite was obtained from Sig deposit (west of Algeria) and then treated with 1 M HCl solution. Natural clay (diatomite) was characterized using different physical-chemical methods, including, X-ray powder diffraction, X-ray fluorescence, thermogravimetric analysis, scanning electron microscopy, and Fourier transform infrared and pH of zero charge. The effect of various experimental parameters, such as initial dye concentration, adsorbent dose, initial pH, and shaking time on adsorption was investigated. The maximum adsorption capacity was found to be 82.0 mg.g − 1 for treated Diatomite and 75.0 mg.g − 1 for raw diatomite, with equilibrium reached within 120 min. Adsorption kinetics followed the pseudo-second-order model, with high correlation coefficients (R² = 0.998 for treated diatomite and R² = 0.999 for raw diatomite). The isotherm data showed the best fit with the Langmuir model. Optimal adsorption occurred at pH 8 for treated diatomite and pH 10 for raw diatomite.