Dye Concentration Research Articles

Natural dyes (Tithonia diversifolia, Tagetes minuta and Bidens pilosa) sensitized solar cells with reduced graphene based electrodes

The search for suitable alternatives to non-renewable polluting energy sources is a continuous and an active undertaking. There is particular focus towards production of low cost, eco-friendly and more efficient dye sensitized solar cells (DSSCs). Natural dyes DSSCs have the capability of generating green energy at low production cost and hence become a promising class of photovoltaic cells. However, there are inherent problems encountered by the conventional DSSCs including photoanode and cathode related problems such as high cost and electron-hole recombination resulting in a low rate of photoelectric conversion efficiency. In this work, organic dyes from Tithonia diversifolia, Tagetes minuta and Bidens pilosa were used as sensitizers as replacement of synthetic dyes of the conventional DSSCs. The study in addition sought to replace conventional photoanode and cathodes with rGO-TiO2 photo anode and rGO counter electrode. The Tithonia diversifolia has one absorption peak at 665 nm indicating the presence of chlorophyll dye while Tagetes minuta has absorbption peaks at 534 nm suggestive of anthocyanin dye (a flavonoid), 607 nm and 660 nm confirming the presence of chlorophyll a dyes while Bidens pilosa has an absorption peak at 665 nm which again suggests the presence of chlorophyll dye. The tendency of the three natural dyes to absorb in the regions above 650 nm indicates their usefulness for use as dyes for DSSC. The I-V curves of the fabricated natural DSSCs show that when TiO2 is used as the photo anode, Tithonia diversifolia registered a higher efficiency of 0.18 % while Tagetes minuta had the lowest efficiency of 0.08 %. When rGO is incorporated in the TiO2 photo anode, there is an improvement in the solar cell efficiency for all the fabricated DSSCs with Tithonia diversifolia having the highest at 1.56 %. Thus incorporating rGO in the TiO2 photo anode greatly improved the power conversion efficiency of the DSSC. Tithonia diversifolia dye had the highest efficiency which may be attributed to the concentration of the chlorophyll dye.

Compost as Green Adsorbent for the Azo Dyes: Structural Characterization and Dye Removal Mechanism

The study aimed to determine the feasibility of using compost as a ‘green adsorbent’ for the removal of five anionic azo dyes belonging to the monoazo, disazo and trisazo classes: Direct Red 81 (DR-81), Direct Blue 74 (DB-74), Reactive Blue 81 (RB-81), Reactive Red 198 (RR-198) and Acid Black 194 (ABk-194) from aqueous solutions. The adsorption capacity of the compost was determined using a batch method with initial dye concentrations ranging from 1 to 1000 mg/L. The kinetics of dye removal followed a pseudo-second-order model, indicating chemisorption as the rate-limiting step. The monoazo dyes RB-81, RR-198 and ABk-194 with the smaller molecule size were adsorbed the fastest. The Langmuir and Sips models best fit the adsorption system with maximum adsorption capacities in the range of 12.64 mg/g (RR-198)—20.92 mg/g (ABk-194) and 12.57 mg/g (RR-198)—25.43 mg/g (ABk-194), respectively. The adsorption depended on the dye structure, especially on the ratio of the numbers of proton donors to proton acceptor locations in functional groups. The differences in the adsorption mechanism could be explained by thermodynamic properties such as dipole moments, HOMO–LUMO energy gap, polarizability, electron affinity, ionization potential, electronegativity and chemical hardness obtained by Density Functional Theory.Graphical

Preparation of magnetite nanoparticles and their application in the removal of methylene blue dye from wastewater

Wastewater is discharged in large amounts from different industries; thus, wastewater treatment is currently one of the main concerns, advanced oxidation is a promising technique for wastewater treatment. This research aims to synthesize magnetite nanoparticles and study their application in wastewater treatment via adsorption and advanced oxidation processes. Magnetite nanoparticles were synthesized via coprecipitation technique between ferric and ferrous sulfate at a molar ratio of 2:1. The prepared sample was characterized using FTIR, XRD, TEM, BET surface area, zeta potential, VSM, and UV‒visible spectroscopy. XRD confirmed the formation of a single face-centered cubic (FCC) spinel structure of Fe3O4. TEM revealed an average particle size of 29.2 nm and a BET surface area of 70.1 m2 g−1. UV‒visible spectroscopy revealed that the UV–visible peak of the sample was obtained at 410 nm. VSM confirmed the attraction of the sample to a magnet with a magnetization of 60 (emu/g). The removal efficiency of methylene blue was studied using adsorption and advanced oxidation methods. For adsorption, the studied parameters were dye concentration 2–10 ppm, 3–10 pH, and 50:300 mg Fe3O4/L. For advanced oxidation, peroxide was used with nanomagnetite as a catalyst, and the studied parameters were pH 2–11, magnetite dose 20–200 PPM, and peroxide dose 500–2000 PPM. The removal efficiency by adsorption reached 95.11% by adding 50 mg of Fe3O4/L and 10 ppm dye conc at 6.5 pH; on the other hand, in advanced oxidation, it reached 98.5% by adding 110 PPM magnetite and 2000 ppm H2O2 at pH 11. The magnetite nanoparticles were reused for ten cycles of advanced oxidation, for a 10% reduction in removal efficiency at the tenth cycle.

Bovine bone-derived hydroxyapatite/carbon quantum dot nanocomposite: synthesis, characterisation, and Acid Black 210 dye removal

ABSTRACT This study explores the synthesis and characterisation of a hydroxyapatite/carbon quantum dot (HAp/CQD) nanocomposite for the removal of Acid Black 210 dye (AB210) from aqueous solutions. HAp was synthesised from bovine bone through deproteinization, demineralisation, and carbonisation processes. Structural analysis confirmed the formation of hexagonal hydroxyapatite with enhanced crystallinity post-activation. Scanning electron microscopy revealed well-defined porous structures with uniform distribution, corroborated by EDAX. FTIR spectroscopy was employed to identify chemical functional groups. Additionally, BET surface area analysis demonstrated a significant surface area of 290.67 m2/g and a pore diameter of 10.784 nm. Adsorption studies examined the effects of various parameters on AB210 removal, including initial dye concentration, adsorbent dosage, temperature, and pH. The optimal values were found to be 50 mg/L for dye concentration, 1 g for adsorbent dosage, and 50°C for temperature, while removal efficiency increased with rising pH. The adsorption was characterised using both Langmuir and Freundlich isotherm models, with the Langmuir model providing a better fit, particularly at 50°C. The monolayer saturated adsorption capacity was 66.22 mg/g, with a corresponding Langmuir constant of 0.3039 L/mg. Kinetic analysis using pseudo-first-order and pseudo-second-order models indicated that the process was controlled by chemisorption, with the pseudo-second-order model showing an excellent fit. The calculated rate constant (k2) and equilibrium adsorption capacity (qe) were determined to be 0.00694 min− 1 and 12.3609 mg/g, respectively, with an R2 value of 0.9683. Overall, the study underscores the efficacy of the HAp/CQD nanocomposite in AB210 dye removal, particularly under optimised conditions, offering valuable insights into its potential applications in environmental remediation.

High removal of methylene blue and methyl violet dyes from aqueous solutions using efficient biomaterial byproduct

Dyes are among the toxic contaminants that significantly impact water ecosystems. A biomaterial prepared from Zizyphus Spina-Christi seed (ZSCS) to remove methylene blue (MB) and methyl violet (MV) from an aqueous solution was investigated. Several techniques have been used, including FTIR, SEM, EDX, XPS, and TGA, to characterize the physical and chemical properties of ZSCS. The effect of various parameters such as pH, adsorbent dosage, contact time, temperature, and initial dye concentration on the adsorption process were studied. The ZSCS adsorbent showed efficient MB and MV dye adsorption with Langmuir adsorption capacity of 666.66 and 476.19 mg/g, respectively, at experimental condition [(pH = 6; time = 30 min; T = 45 °C, dye concentration: 500 mg/L, and adsorbent dose = 0.6 g/L for MB and 1 g/L for MV dye)]. Kinetic and isotherm models were applied to fit the experimental outcomes. The result showed that ZSCS showed an ultrafast absorption process with a high removal efficiency of MB and MV within 5 min indicating its effective adsorption properties. The Langmuir isotherm model was the most suitable model for describing the adsorption of MB and MV dyes on ZSCS. The pseudo-second-order model kinetic fits better to MB and MV adsorption onto ZSCS than other models, suggesting that the adsorption mechanism followed chemisorption. Our results could offer an efficient cost-effective approach for dye removal from wastewater.

Removal of Acid Orange 7 dye using Makgeolli lees with ultrasonic assistance

AbstractThis study investigated the efficient removal of Acid Orange 7 (AO7) dye in water by using Makgeolli lees, a popular by‐product obtained during the production of traditional Makgeolli beverages in Korea. By incorporating ultrasound, the effects of contact time, Makgeolli lees dosage, initial AO7 dye concentration, and initial pH of the dye solution were investigated and comprehensively compared with the same experiment using the stirring method. The results consistently showed ultrasound not only enhances the excellent adsorption ability of Makgeolli lees but also accelerates the process compared to the stirring method. The Langmuir isotherm model best described the adsorption process for both methods, suggesting monolayer adsorption on the surface of Makgeolli lees, with maximum capacities of 25.13 mg/g for ultrasound at 40 kHz and 20.41 mg/g for stirring methods. Furthermore, the study showed that optimal dye removal efficiency can be achieved with ultrasound conditions at 28 kHz frequency, 125 W/L power density, and 100% ultrasound intensity. This research promises that the integration of low‐cost biomass coupled with ultrasound could provide a potential solution for dye wastewater treatment.

Engineered hybrid iron‐cobalt metal oxide nanoparticles for effective adsorption of malachite green dye

AbstractBACKGROUNDHybrid iron and cobalt metal oxide nanoparticles are well known; however, are not optimized in terms of size and stability. We engineered these hybrid nanoparticles using the co‐precipitation method and characterized them by various techniques, which are then used for the effective adsorption and removal of malachite green (MG) dye.RESULTSThe ideal conditions for synthesis are determined to be 50:50 ratio of Fe2O3 and CoO, pH of 11, temperature range of 40 °C–60 °C, and reactant addition time of 20 min. These hybrid nanoadsorbents effectively eliminated MG dye from aqueous solutions. Factors such as initial MG dye concentration, pH of the medium, contact time, temperature, and nanoadsorbent dose were optimized for the MG removal to achieve a maximum removal efficiency of 96.9%. Non‐linear fitting of data indicates that both Langmuir and Freundlich models provided the best fit, suggesting the presence of both monolayer and multilayer adsorption of MG on hybrid nanoparticles. The kinetics of MG dye removal are better controlled by the intraparticle diffusion (IPD) phenomenon. The adsorption of MG onto the hybrid nanoparticles was confirmed to be endothermic, with negative ΔG and positive ΔH values. The optimized synthetic conditions also positively impacted the hybrid nanoparticles which enhanced the adsorption and exhibited ferromagnetic behavior as compared to the superparamagnetic behavior reported in the literature, making them significantly important for dye removal applications.CONCLUSIONThese findings demonstrate the potential of optimized hybrid nanoparticles as effective nanoadsorbents for dye removal applications, with implications for further applications in photocatalysis and sensing. © 2024 Society of Chemical Industry (SCI).

Effective removal of textile dye via synergy of adsorption and photocatalysis over ZnS nanoparticles: Synthesis, modeling, and mechanism

In this work, we prepared sulfur-zinc nanoparticles (ZnS-TGA) functionalized with thioglycolic acid by a hydrothermal method and tested their photodegradation ability by solar irradiation. ZnS-TGA were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM), UV–Vis spectrophotometer and photoluminescence spectroscopy. In the characterization of these nanoparticles, thioglycolic acid proved to be a strong capping ligand, with a specific surface area of 36.82 m2/g and an average size of 7.15 nm. To test the photocatalytic degradability of the product, methylene blue (MB) was used as a model pollutant. Various operational variables were investigated, including pH, amount of nanoparticles, dye concentration, contact time and temperature. The equilibrium adsorption tests, and the statistical physical calculations allowed the analysis of the energetic and steric variables of the adsorption of MB dye molecules on the surface of these nanoparticles. The equilibrium data were well fitted with Langmuir-Freundlich (L-F) and the adsorption kinetics with pseudo-first order. The maximum adsorption capacity of the MB dye removal process was 30.92 mg g−1 at pH 7 and 298 K, and this process was spontaneous and exothermic. The dye molecules and the surface of the nanoparticles exhibited physical interactions with adsorption energies of 23.31–25.92 kJ/mol. The photocatalytic activity of these nanoparticles resulted in a dye degradation efficiency of 91.1 % in 180 min. The photocatalytic efficiency remained almost unchanged after five consecutive degradation cycles, resulting in a methylene blue degradation of 85 %. According to these results, these environmentally friendly nanoparticles have the potential to purify industrial and urban liquids contaminated with harmful organic compounds such as dye molecules.

Modeling sustainable photocatalytic degradation of acidic dyes using Jordanian nano-Kaolin–TiO2 and solar energy: Synergetic mechanistic insights

The abstract highlights the global issue of environmental contamination caused by organic compounds and the exploration of various methods for its resolution. One such approach involves the utilization of titanium dioxide (TiO2) as a photocatalyst in conjunction with natural adsorption materials like kaolin. The study employed a modeling-based approach to investigate the sustainable photocatalytic degradation of acidic dyes using a Jordanian nano-kaolin–TiO2 composite material and solar energy. Mechanistic insights were gained through the identification of the dominant reactive oxygen species (ROS) involved in the degradation process, as well as the synergetic effect between adsorption and photocatalysis. The Jordanian nano-kaolin–TiO2 composite was synthesized using the sol-gel method and characterized. The nanocomposite photocatalyst exhibited particle sizes ranging from 27 to 41 nm, with the TiO2 nanoparticles well-dispersed within the kaolin matrix. The efficacy of this nanocomposite in removing Congo-red dye was investigated under various conditions, including pH, initial dye concentration, and photocatalyst amount. The optimal conditions for dye removal were found to be at pH 5, with an initial dye concentration of 20 ppm, and using 0.1 g of photocatalyst, resulting in a 95 % removal efficiency. The mechanistic insights gained from this study indicate that the hydroxyl radicals (•OH) generated during the photocatalytic process play a dominant role in the degradation of the acidic dye. Furthermore, the synergetic effect between the adsorption of the dye molecules onto the photocatalyst surface and the subsequent photocatalytic degradation by the ROS was found to enhance the overall removal efficiency. These findings contribute to the fundamental understanding of the photodegradation mechanisms and guide the development of more efficient photocatalytic systems for the treatment of acidic dye-containing wastewater. The use of solar power during the purification procedure also leads to cost reduction and strengthens sustainability efforts.

Corn Husk‐Derived Carbon Fused with Iron Oxide as Adsorbent for Cationic Dyes

AbstractThe development of nanomaterials for dye degradation has garnered significant interest due to their efficiency, environmental benefits, and cost‐effectiveness. In this study, a nanocomposite adsorbent composed of α‐Fe2O3 coupled with carbon derived from eco‐friendly corn husk has been developed. This material effectively captured cationic dyes, Methylene Blue (MB) and Malachite Green (MG), from aqueous solutions, including industrial dye effluent from local industry. The synthesized nanocomposite demonstrated rapid removal of MB and MG from the solution without the need for additional oxidizing or reducing agents. The adsorption conditions by varying parameters such as adsorbent dose, contact time, solution pH, initial dye concentration, and temperature have been optimized. Adsorption isothermal studies indicated that the Langmuir isotherm model best explained the adsorption process. Kinetic studies revealed that the adsorption process follows a pseudo‐first‐order model for MB, while the intraparticle diffusion model is more appropriate for MG. Moreover, the nanocomposite exhibited excellent reusability and regenerability for dye adsorption. Our study showcases the effectiveness of the synthesized nanocomposite adsorbent, comprising α‐Fe2O3 integrated with carbon derived from eco‐friendly corn husk using a simple and sustainable methodology, in efficiently removing cationic dyes from textile wastewater. This approach offers a promising solution for environmental remediation.

Bioremediation of Brilliant Green cationic dye from water using Nutraceutical Industrial Coriander Seed Spent as an adsorbent: adsorption isotherms, kinetic models, and thermodynamic studies.

The article details a feasibility study of removing Brilliant Green (BG), a mutagenic dye from an aqueous solution by adsorption using low-cost coriander seed spent as a by-product in the nutraceutical industry. The study includes an analysis of the parameters that affect the adsorption process. The variables that have been identified include pH, dye concentration, process temperature, adsorbent amount, and particle size of the adsorbent. To obtain information on the adsorption process and to design the mechanism of the adsorption system on experimental equilibrium, 10 isotherm models, namely, Langmuir, Freundlich, Jovanovic, Dubinin-Radushkevich, Sips, Redlich-Peterson, Toth, Vieth-Sladek, Brouers-Sotolongo, and Radke-Prausnitz were applied. It was discovered that the experimental adsorption capacity, qe, was roughly 110mgg-1. The result has a maximum adsorption of 136.17 mgg-1 as predicted by Dubinin-Radushkevich isotherm. Diffusion film models, Dumwald-Wagner and Weber-Morris models, and pseudo-first- and second-order models, were used to determine the adsorption kinetics. It was realized that the adsorption kinetics data fit into a pseudo-second-order model. Thermodynamic analysis with a reduced enthalpy change suggests a physical process. The values of the thermodynamic parameters ΔG0, ΔH0, and ΔS0 demonstrated an endothermic and nearly spontaneous process of adsorption. The small valuation of ΔH0 specifies that the process is physical. FTIR spectroscopy and SEM imaging were used to confirm that the BG dye had been adsorbing on the adsorbent surface. The study concludes that NICSS is an effective adsorbent to extract BG dye from wastewater solutions, offers insights into numerous dye and adsorbent interaction possibilities and indicates that the process can be scaled to fit into the concept of circular economy.

Methylene Blue and Rhodamine B Dyes' Efficient Removal Using Biocarbons Developed from Waste.

The preparation of biocarbons from cellulose fibres utilised in the production of baby nappy mats (sourced from Feniks Recycling company, Poland) for the removal of methylene blue and rhodamine B dyes has been documented. A Brunauer, Emmett and Teller analysis revealed a surface area within the range of 384 to 450 m2/g. The objective of this study was to investigate the removal efficiency of dyes from aqueous solutions by biocarbons, with a particular focus on the influence of various parameters, including pH, dye concentration, adsorbent dosage, shaking speed, contact time, and temperature. The maximum adsorption capacity of the dyes onto the biocarbons was found to be 85 mg/g for methylene blue and 48 mg/g for rhodamine B, respectively. The Langmuir equation proved to be the most suitable for interpreting the sorption of organic dyes. The adsorption process was found to exhibit a chemisorption mechanism, effectively mirroring the pseudo-second-order kinetics. Furthermore, the adsorption of dyes was observed to be endothermic (the enthalpy change was positive, 9.1-62.6 kJ/mol) and spontaneous under the tested operating conditions. The findings of this study indicate that biocarbons represent a cost-effective option for the removal of methylene blue and rhodamine B. The adsorption method was observed to be an effective and straightforward approach for the removal of these dyes. The results of the Boehm titration analysis and zero charge point value indicated that the synthesised biomaterials exhibited a slightly basic surface character.

Facile synthesis of SrO/CeO2/alginate nanocomposite for the photocatalytic degradation of reactive red 195 dye and CO2 capturing

The SrO/CeO2/ALG nanocomposite was successfully constructed by using the co-precipitation method and was analyzed with zeta potential, FTIR, SEM, XRD and BET techniques. A common Azo dye, namely Reactive Red 195, widely utilized in the dyeing industry and causing environmental pollution, was chosen to examine the photodegradation of SrO/CeO2/ALG nanocomposite, and it was shown that this dye could be successfully degraded by prepared nanocomposite. Impacts of factors such as pH, contact time and effect of different concentrations of dye and catalyst, the effect of scavengers and the effect of hydrogen peroxide were investigated to find out degradation efficiency. This SrO/CeO2/ALG nanocomposite was used for the photodegradation of reactive red 195 dye and 93 % degradation efficiency was obtained at pH 3, 6 mg of catalyst concentration, dye concentration of 10 ppm, and contact time of 90 min. Degradation kinetic studies were determined by applying first-order and Langmuir-Hinshelwood reactions. The results exhibit a novel method for the synthesis of nanocomposite to effectively cause photodegradation of organic pollutants from wastewater and can be applied to industrial manufacture. The mesoporous SrO/CeO2/ALG nanocomposite also captured 4.31 and 2.98 mmol/g CO2 at 25 and 40 °C temperatures, respectively.

Long-term and high-efficiency capture of Escherichia coli using cellulose acetate nanofiber membrane functionalized with reactive 19 dye and polyhexamethylene biguanide

Cellulose acetate (CA) nanofibers have been popularly applied in various biomedical and textile products. In this work, a textile azo-dye Reactive Green 19 (RG19) was selected to be chemically coupled to the CA nanofiber membrane to form dyed CA nanofiber membrane (namely CA-RG19) and then poly(hexamethylene biguanide) (PHMB) as an antibacterial reagent was physically attached to the dyed CA nanofiber membrane, forming CA-RG19-PHMB nanofiber membrane. The nanofiber membranes were evaluated for their physical and mechanical properties, including functional group analysis, morphological characterization, and thermal stability assessment. To investigate the antibacterial properties of the nanofiber membrane, various concentrations of RG19 dye and PHMB were tested to evaluate the antibacterial efficiency (AE) against Escherichia coli of the membranes. It was found that the CA-RG19-PHMB nanofiber membrane exhibited an AE value of approximately 100 %, with the immobilization concentrations of RG19 dye and PHMB being 373.46 mg/g and 0.333 mg/g, respectively. The CA-RG19-PHMB nanofiber membrane showed 100 % antibacterial efficacy after 10 min against E. coli cells. Furthermore, the storage stability of the CA-RG19-PHMB nanofiber membrane remained at approximately 100 % of its initial antibacterial efficacy after 60 days, and it exhibited excellent antibacterial efficacy after five cycles.

Low-cost ceramic membrane production for dye removal

Low-cost ceramic membrane was evaluated on a bench scale, in the separation process of blue methylene dye. Raw materials were characterized by XRD and XRF. The ceramic membrane was produced by dry uniaxial compaction and characterized by XRD, porosity and permeability with pure water. The membrane contains a composition of 65.00 % chocobofe clay, 5.00 % corn starch kaolin, 20.00 % magnesite concentrate and 5.00 % corn starch and sintering temperature of 650 °C. The initial blue methylene dye concentration was 50 mg/L, pressure 2 bar, 25 °C. The low-cost ceramic membrane was effective in separating blue methylene dye, with porosity of 53 % and average pore size of 0.48 µm, as well as pure water flow of 520 L/m2.h. The blue methylene dye rejection was 100.00 %. The membrane reuse demonstrated good performance after 15 cycles. A preliminary costs analysis of the production for low-cost membrane was carried out and the value found was 233.55 $/m2.

Decolorization of anthraquinone dye (Reactive Blue 4) in the microbial fuel cell by Baker’s yeast: process optimization

The release of anthraquinone dyes in aquatic sources has a huge impact on the environment because of their turbidity, toxicity, mutagenicity, and carcinogenicity effects. Microbial Fuel Cell (MFC) is a hopeful technology for the decolorization of dyes. The goal of the present study is the decolorization of Reactive Blue 4 (RB4) as an anthraquinone dye from an aqueous solution by Baker’s yeast in MFC. The selection of three parameters (dye concentration, glucose concentration, and airflow rate) and optimization of dye decolorization and chemical oxygen demand (COD) removal are performed using response surface methodology (RSM). The results demonstrated that the interaction between parameters does not affect the dye decolorization efficiency, whereas the interaction between dye concentration and glucose concentration was found to be significant for COD removal. Accordingly, the optimum conditions for maximum dye decolorization and COD removal were obtained at a dye concentration of 50 mgL−1, a glucose concentration of 1 gL−1, and an airflow rate of 10 mLmin−1.

Optimization of the dosage of ZnO photocatalyst for the degradation of sunlight driven multi dose organic dye brilliant green

In this study, we prepared ZnO nanocrystals using a chemical precipitation approach with different precursor concentrations for optimization. The structural, optical, and morphological properties of the synthesized nanocrystals were analyzed. Sunlight-driven photocatalysis was investigated for its ability to degrade a low concentration (70 ppm) of brilliant green (BG) dye using the optimized ZnO at different dosages (0.05, 0.1, and 0.15 g). Among the different dosages of ZnO, it was noted that at a low catalyst concentration of 0.05 g, the degradation efficiency was only 58.47 % even after 120 min of light exposure. When the concentration increased to 0.1 g, the rate of degradation reached 95.33 % within 90 min. At a higher dosage of 0.15 g, only 86.26 % degradation was recorded within 90 min, indicating that the optimal catalyst dosage was 0.1 g. To investigate how the dye dosage affected the degradation efficiency of the catalyst, experiments were performed using higher dye concentrations of 100 and 120 ppm with 0.1 g of catalyst. As the dye concentration was increased, the degradation rate decreased. Tests were conducted using different scavengers, including EDTA (a hole scavenger), benzoquinone (a superoxide radical scavenger), and isopropyl alcohol (a hydroxyl radical scavenger), to determine which free radical was mainly breaking down BG. In the presence of EDTA, the degradation ability of the catalyst decreased to 35 %. When the superoxide radical scavenger benzoquinone was used, the degradation efficiency decreased to approximately 22 %. On the other hand, the hydroxyl radical scavenger IPA reduced the degradation efficiency to 13 %. Based on the above discussion, the synergistic effect of holes and superoxide radicals is mainly responsible for the degradation of brilliant green. To test the practical use of the ZnO catalyst, we conducted an experiment to assess its reusability. Even after the third cycle, the ZnO exhibits 94 % degradation, confirming its reusability.

Exploring of new Poly(Thiourea-Amide) as a prospective bismarck Brown Y dye adsorbent: Synthesis via ultrasound irradiation, isotherms, kinetic, thermodynamic, and DFT studies

In this work, a facial ultrasound technique was employed to synthesize poly (N1-((6-aminopyridin-2-yl)carbamothioyl)-N3-carbamothioylisophthalamide) (PTUA) as a new polymer from a condensation reaction of isophthaloyl diisothiocyanate and 2, 6-diaminopyridine. Different techniques were utilized to identify the chemical structure of the synthesized polymer including FTIR spectra, 1HNMR spectra, thermal gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and field emission scanning electron microscopy (FESEM). The capability of the synthesized polymer to adsorb Bismarck brown Y (BBY) dye from an aqueous solution was analytically evaluated. Several effective parameters on the adsorption process including contact time, pH, dye concentration, adsorbent dose, and temperature were extensively investigated. The adsorption process was found to be completed with a contact time of 45 min. The results indicated that the optimal adsorption pH was 8 with removal efficiency of 85.331 % and the adsorbed amount of BBY dye increased when the temperature was increased. The adsorption isotherms analysis revealed that the Langmuir model with a correlation coefficient (R2 = 0.9982) was the most relevant to describe the adsorption process compared with the Freundlich model (R2 = 0.9863). By applying the Langmuir isotherm, the maximum adsorption capacity was obtained with a value of 132.39 mg/g. The study of adsorption kinetics showed that the adsorption model of BBY dye onto the polymer surface significantly correlated with a pseudo-second-order model. Based on the thermodynamic studies, the calculated ΔG was negative, ΔH was endothermic, and ΔS was positive, verifying the adsorption process is spontaneous. The desorption percentage of BBY dye was calculated with a value of 81.574 % utilizing methanol as an optimal solvent. The density functional theory (DFT) approach was applied to acquire good understanding for the adsorption process.

Enhanced piezocatalytic degradation of cationic dyes using graphene oxide and magnetic beads Nanomaterials: Synthesis, Characterization, and mechanistic insights

Sequestration of organic pollutants by the method of degradation is one of the safest ways to completely remove them from water bodies, without generating harmful by-products. Piezocatalytic degradation for this approach has been gaining much research attention, in recent times, due to its high efficiency. The present work reports synthesis of four types of Graphene Oxide-Chitin-Magnetic Iron Oxide Beads Nanomaterials, each with a different ratio of Graphene oxide (GO) and Chitin (CH). Among these, GO-CH-MIOBs NM-4 showed a superior Piezocatalytic degradation capacity towards methylene blue (MB), crystal violet (CV) and Rhodamine 6G (R6G) dyes. Various parameters influencing the piezocatalytic performance of the material such as kinetic factors, initial dye concentration, strength of ultrasonic vibration etc., have been analyzed thoroughly. Degradation rate constant (K) values of 63.4, 59.34 and 48.36 /min were obtained for MB, CV and R6G Dyes respectively. Moreover, cycling tests for all three dyes reflected significant stability of these materials as evident from the high degradation efficiencies of 99.80, 99.24 and 99.12 % within 60 min being retained for MB, CV and Rh6G dyes even after the 5th cycle. These nanomaterials can be a good addition in the list of high efficiency piezocatalyts for water purification with no secondary wastes being produced. Comparison of the XPS spectra before and after sonication gave insight into the mechanism of piezocatalytic degradation which highlighted hydroxyl and superoxide radicals as the main attacking species which are responsible for the degradation process.

FACILE SYNTHESIS OF ACTIVATED CARBON/ALGINATE/CHITOSAN COMPOSITE BEADS AS RHEMAZOLE BRILLIANT BLUE R ADSORBENT

Developing composite beads composed of chitosan, alginate, and activated carbon for dye removal is essential due to their improved adsorption capabilities and environmental benefits. By utilizing natural resources efficiently for an effective dye removal process, this study developed an activated carbon/alginate/chitosan composite bead as Rhemazole Brilliant Blue R (RBBR) adsorbent. The surface shape of composites exhibits more protrusions, grooves, and asymmetric pores than activated carbon, which could improve dye adsorption capability. FTIR analysis verified that functional groups such as OH, NH, protonated amine, and carboxylate from the constituent polymers were enriched in the activated carbon/alginate/chitosan composite. These groups also function as active sites for adsorbents. It was aligned with the composite beads' Freundlich isotherm model, which shows that heterogeneous or many active sites contribute to adsorption and provide multilayer adsorption. The kinetic model of pseudo-second order fits well with the adsorption process, indicating that chemisorption is the rate-limiting step in RBBR adsorption. The optimum adsorption conditions were at pH 1, with an adsorbent dose of 0.08 g, RBBR dye concentration of 125 mg/L, and a contact time of 60 min. The composite beads also exhibit stability in acidic and basic solutions, with the effectiveness of being reused up to four times, providing a reusable adsorbent with versatility in various water treatment conditions. Hence, synthesizing activated carbon/alginate/chitosan composite beads presents a promising solution for sustainable wastewater treatment based on biodegradable and eco-friendly composite.