Dye Concentration Research Articles

Synergistic adsorption of methylene blue using ternary composite of phosphoric acid geopolymer, calcium alginate, and sodium lauryl sulfate.

The removal of dyes from the aquatic ecosystem is necessary being a major threat to life. For enhanced remediation of methylene blue (MB) dye, a new ternary biopolymer-geopolymer-surfactant composite adsorbent is synthesized by combining phosphoric acid geopolymer (PAGP), calcium alginate (Alg), and sodium lauryl sulfate (SLS). During the synthesis of the composites, PAGP and SLS were mixed with the alginate matrix, producing porous hybrid beads. The PAGP-SLS-alginate (PSA) beads prepared were characterized using different analytical tools, i.e., scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FTIR), X-ray diffractometry (XRD), surface area and porosimetery (SAP), and thermogravimetric analysis (TGA). To ascertain the ideal conditions for the adsorption process, a batch reactor procedure was used to investigate the effects of several parameters on MB adsorption, including pH (2, 4, 6, 8, 10), PSA adsorbent dosage (0.06-0.12 g), MB concentration (50-500 mg/L), contact time (15 to 300 min), and temperature (25, 35, and 45 °C). The SEM investigation indicated that ~ 1860 μm-sized PSA beads with 6-8 μm voids are generated. Based on XRD, FTIR, and SAP examinations, the material is amorphous, having numerous functional groups and an average pore size of 6.42 nm. Variation of pH has a little effect on the adsorption process, and the pH of 7.44 was found to be the pHpzc of the PSA beads. According to the findings of the batch study, equilibrium adsorption was obtained in 270-300 min, showing that the adsorption process was moderately slow-moving and effective. The dye adsorption linearly increased with initial dye concentration over concentration range of 50-500 mg/L and reciprocally decreased with rise in temperature. 0.06 g adsorbent dose, 25 °C, pH10, and 270 min were found to be the better conditions for adsorption experiments. Langmuir isotherm fitted well compared to Freundlich, Temkin, and Dubinin-Radushkevich (DR) isotherm models on the experimental data, and the maximum adsorption capacity(qmax) calculated was 1666.6 mg. g-1. Pseudo-second-order (PSO) kinetics model and multi steps (two) intra particle diffusion (IPD) model fitted well on the adsorption kinetics data. The system's entropy, Gibbs free energy, and change in enthalpy were measured and found to be -109.171 J. mol-1. K-1, - 8.198 to - 6.014 kJ. mol-1, and - 40.747 kJ. mol-1. Thermodynamics study revealed that adsorption process is exothermic, energetically favorable and resulting in the decrease in randomness. Chemisorption is found to be the dominant mechanism as confirmed by pH effect, Langmuir isotherm, PSO kinetics, IPD model, and thermodynamics parameters. PSA beads were successfully regenerated using ethanol in a course of 120 min and re-used for five times. To sum up, the PSA adsorbent's impressive adsorption capability of 1666.66 mg/g highlights its potential as a successful solution for methylene blue removal. The results of this study add to the expanding corpus of information on sophisticated adsorption materials and demonstrate PSA's potential for real-world uses in wastewater treatment and environmental clean-up.

Modeling and optimization of dyeing process of polyamide 6 and woolen fabrics with plum-tree leaves using artificial intelligence

The dyeing process of textile materials is inherently intricate, influenced by a myriad of factors, including dye concentration, dyeing time, pH level, temperature, type of dye, fiber composition, mechanical agitation, salt concentration, mordants, fixatives, water quality, dyeing method, and pre-treatment processes. The intricacy of achieving optimal settings during dyeing poses a significant challenge. In response, this study introduces a novel algorithmic approach that integrates response surface methodology (RSM), artificial neural network (ANN), and genetic algorithm (GA) techniques for the precise fine-tuning of concentration, time, pH, and temperature. The primary focus is on quantifying color strength, represented as K/S, as the response variable in the dyeing process of polyamide 6 and woolen fabric, utilizing plum-tree leaves as a sustainable dye source. Results indicate that ANN (R2 ~ 1) performs much better than RSM (R2 > 0.92). The optimization results, employing ANN-GA integration, indicate that a concentration of 100 wt.%, time of 86.06 min, pH level of 8.28, and a temperature of 100 °C yield a K/S value of 10.21 for polyamide 6 fabric. Similarly, a concentration of 55.85 wt.%, time of 120 min, pH level of 5, and temperature of 100 °C yield a K/S value of 7.65 for woolen fabric. This proposed methodology not only paves the way for sustainable textile dyeing but also facilitates the optimization of diverse dyeing processes for textile materials.

Ultrasound-assisted enhanced adsorption of textile dyes with metal organic frameworks

In this study, ZIF-67 based metal–organic framework (MOF) is used for the adsorption of several synthetic dye effluents (Malachite green (MG), Rhodamine-B (Rh-B), Methylene Blue (MB) and Congo Red (CR)) with intensified adsorption in the presence of ultrasound. The adsorption capacity of ZIF-67 is evaluated for multiple single dye systems and binary dye mixtures. The effect of different operational parameters such as contact time, adsorbent dosage, dye concentration, temperature, pH, binary dye systems, real effluents, and the presence of ultrasound is explored in detail. The adsorption for single dye systems shows the removal efficiencies in the order of MG > CR > Rh-B > MB. The adsorption of CR and MG on ZIF-67 followed Langmuir isotherm which estimated the maximum adsorption capacity of 701 and 3623 mg. g−1 respectively. An optimum adsorbent loading of 1 g.L−1 is effective for the efficient removal of MG and CR. Further, thermodynamic studies indicate that the adsorption process is spontaneous and endothermic. The kinetic models for both dyes suggested a prevailing chemisorption mechanism, in line with the pseudo second-order model (PSOM). For binary dye systems of MG and CR, the selectivity towards maximum adsorption capacity is favored with MG compared to CR. Ultrasound-assisted adsorption intensified the removal efficiency up to ∼ 67 % and ∼ 93 % within 5 min for CR and MG respectively. ZIF-67 is stable over multiple consecutive cycles affirming its reliability for reuse. Maximum removal of dyes was also obtained with real textile dye effluents.

Bi-doped g-C3N4/Bi2WO6 ternary composites for superior photocatalytic degradation of reactive orange 16 under visible light irradiation

Because of unrestricted disposal, the concentration of reactive dyes in wastewater is gradually increasing. Owing to their eco-toxicity their removal becomes so crucial. In this regard, Bi(0)-doped g-C3N4/Bi2WO6 (g-C3N4/Bi@Bi2WO6) nanocomposites were prepared by wet impregnation followed by calcination. Remarkably, the Bi(0) doping occurs concertedly during the preparation of Bi2WO6 without the addition of any extra reducing agent. The efficacy of the photocatalyst for eliminating reactive orange 16 was evaluated under visible light irradiation. XRD, FESEM, HRTEM, DRS, XPS, BET, etc., were employed to characterize these hybrids. The presence of Bi(0) was confirmed by HRTEM and XPS. Increasing the g-C3N4 content enhances the specific surface and reduces the charge transfer resistance. Among the various photocatalysts, the 20 wt% g-C3N4/Bi@Bi2WO6 hybrid owned the highest degradation efficiency of 89 % after 300 min of reaction time. The controlled experiments confirm the participation of holes and superoxide anions during the reactions. The various reaction intermediates were detected by HRMS providing the necessary evidence about the mechanism. The heterostructure possesses excellent reusability and stability. Due to enhanced catalytic activity, high stability, and ease of synthesis, the reported composite can be considered as a promising catalyst for the degradation of pollutants.

Bi-doped g-C3N4/Bi2WO6 ternary composites for superior photocatalytic degradation of reactive orange 16 under visible light irradiation

Because of unrestricted disposal, the concentration of reactive dyes in wastewater is gradually increasing. Owing to their eco-toxicity their removal becomes so crucial. In this regard, Bi(0)-doped g-C3N4/Bi2WO6 (g-C3N4/Bi@Bi2WO6) nanocomposites were prepared by wet impregnation followed by calcination. Remarkably, the Bi(0) doping occurs concertedly during the preparation of Bi2WO6 without the addition of any extra reducing agent. The efficacy of the photocatalyst for eliminating reactive orange 16 was evaluated under visible light irradiation. XRD, FESEM, HRTEM, DRS, XPS, BET, etc., were employed to characterize these hybrids. The presence of Bi(0) was confirmed by HRTEM and XPS. Increasing the g-C3N4 content enhances the specific surface and reduces the charge transfer resistance. Among the various photocatalysts, the 20 wt% g-C3N4/Bi@Bi2WO6 hybrid owned the highest degradation efficiency of 89 % after 300 min of reaction time. The controlled experiments confirm the participation of hydroxyl radicals and superoxide anions during the reactions. The Various reaction intermediates were detected by HRMS providing the necessary evidence about the mechanism. The heterostructure possesses excellent reusability and stability. Due to enhanced catalytic activity, high stability, and ease of synthesis, the reported composite can be considered as a promising catalyst for the degradation of pollutants.

Effective sunlight photodegradation of methylene blue dye using zinc oxide doped with mono- and bi-metals of Ag and Ce

Nanosized spherical particles of pure ZnO and their doped ZnO photocatalysts with mono- or bi- Ag and Ce-metal oxides at different weight portions (i.e., 2 and 4 wt%) through the sol-gel route followed by a calcination at 500 °C for 2 h were employed for exploring the photodegradation of methylene blue (MB) dye under direct sunlight. The produced photocatalysts were characterized by X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) surface area, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), fourier transform infrared (FTIR), and UV-Vis diffuse reflectance spectroscopy (DRS). XRD patterns confirmed the formation of hexagonal wurtzite polycrystalline structure of ZnO with good crystallinity. Bi-doped ZnO photocatalysts with smaller particle sizes showed efficient improving in the photocatalytic activity of ZnO under direct sunlight irradiation. The enhanced photodegradation performance of doped samples could be attributed to the reduction in the crystallite size and band gap, as well as the presence of excess oxygen vacancies and Zn interstitial sites in the nanoparticles obtained. The calculated band gap of pure ZnO decreased from 3.07 to 2.79 eV for 2 %Ag-4 %Ce/ZnO. This doped sample degraded the MB dye completely at 60 min, whereas pure ZnO exhibited 100 % degradation of MB at 180 min. Moreover, 2 % Ag-4 %Ce/ZnO photocatalyst has the highest kinetic rate of photodegradation as compared to other samples over two initial concentrations of MB dye (0.09667 min−1 at Co= 10 mg/L and 0.04433 min−1 at Co= 20 mg/L). Hence, Hence, the obtained 2 % Ag-4 % Ce doped ZnO showcased the superb breakdown of MB dye under sunlight irradiation for positioning it as a promising material for water remediation.

Assessment of Natural Bentonite Efficacy for Dye Removal in Textile Wastewater Treatment : Implication for Mitigating River Citarum Pollution

Textile industries contribute significantly to the economy but release harmful pollutants into the environment, especially rivers. The effluent from the textile industry contained toxic dyes that can harm the river ecosystem. Several studies have been conducted to reduce toxic dyes in a river system using bentonite as an adsorbent to reduce river pollution effectively. However, the effectiveness of bentonite still needs to be tested again using textile liquid waste that has not gone through any waste processing at all. Citarum is one of the main rivers on Java Island, which suffers from textile effluent, especially azo dyes which are toxic, mutagenic and carcinogenic which can harm the aquatic ecosystem. Therefore, this study aims to implement natural bentonite as an adsorbent to remove dyes from textile wastewater. We performed a laboratory test to adsorption on bentonite and textile wastewater considering the variation of adsorbent weight of 10 g and 20 g in 100 mL of textile wastewater stirred in an Erlenmeyer flask at room temperature for 0-300 minutes. The initial concentration of textile wastewater used was 10%, 30%, and 50%. We found that the maximum dye removal efficiency was 91.25% with 10% initial concentration treatment, 20 g adsorbent weight, and 60 minutes contact time. Longer contact time will increase the removal efficiency and adsorption capacity, while higher adsorbent dosage will decrease the concentration of dyes in wastewater. Efficient textile wastewater treatment has improved water quality, effectively meeting river water quality standards and environmental regulations.

Surface methodology for optimized adsorption of hazardous organic pollutant from aqueous solutions via novel magnetic metal organic framework: Kinetics, isotherm study, and DFT calculations

An efficient way to remove Janus Green B (JGB) dye from contaminated water sources is using of magnetic cerium (III) metal–organic framework (MCe-MOF). Analytical methods such as PXRD, TEM, FESEM, FT-IR, PZC, and XPS were used in the characterization of the MCe-MOF microspheres in order to assess the phase, crystallinity, shape, surface characteristics, and chemical composition of the MCe-MOF material. Impressive physical characteristics of the synthesized MCe-MOF material included a high surface area of 1340.05 m2/g. Conversely, MCe-MOF’s magnetic saturation (MS) was measured at 36.47 emu.g−1. The purpose of the study was to determine if MCe-MOF could effectively remove JGB dye from wastewater by adsorption. Adsorption settings that were studied included pH, adsorbent dose, beginning dye concentration, contact time, and temperature. The JGB electrical characteristics, reactivity, and shape were ascertained through the application of density functional theory (DFT). The placement of electrophilic and nucleophilic attack sites is in good agreement with the molecular orbitals (HOMO and LUMO) and MEP results, according to DFT. Based on the findings, MCe-MOF had a high capacity for adsorbing JGB dye, with an adsorption data fit by pseudo-second-order kinetic models and the Langmuir isotherm. It was evident from the adsorption energy of 27.8 kJ.mol−1 that chemisorption was the mode of adsorption. The optimal conditions for attaining a high adsorption capacity were found to be pH 8 and 0.02 g of MCe-MOF dose. The adsorption process of JGB dye onto MCe-MOF was seen to be spontaneous, endothermic, and random, as indicated by the temperature-dependent increases in the thermodynamic parameters ΔGo, ΔHo, and ΔSo. The adsorption process was optimized through the application of Response Surface Methodology and Box-Behnken design (RSM, BBD). The successful removal of dyes from the MCe-MOF material was made possible by these methods. While π-π bonding happens through the interaction of aromatic rings, chemisorption entails the formation of chemical interactions between the adsorbate and adsorbent. Electrostatic interactions arise from the attraction or repulsion of charges between the adsorbate and adsorbent, and pore-filling happens when the adsorbate fills the adsorbent’s pores. For the removal of JGB dye from wastewater, MCe-MOF exhibits great potential as an adsorbent because of its numerous adsorption processes and high adsorption capacity.

Treatment of Reactive Orange 16 Dye-Bearing Wastewater by Electro-Fenton Process with Stainless-Steel Electrodes: Statistical Optimization and Operational Analysis

Abstract: In the current work, the Electro-Fenton (EF) based Reactive Orange 16 (RO16) dye treatment was studied and compared with central composite (CC) and Taguchi design (TD) statistical optimization tools. Color removal (RC) and COD decay (RCOD) were chosen responses for the effect of pH (A), electrolysis time (B), initial dye concentration (C), and current density (D). The facecentred CC design and L16 orthogonal array were used in the experimental procedures. At optimal conditions, the coefficient of determination (R2) values of 0.99 for CC and 0.97 for TD suggest statistical significance and good model agreement. The results of the ANOVA and Prob. > F values supported the model’s successful experimental data fitting. Taguchi method was found as an appropriate methodology for parameter percentage contributions with fewer experimental runs. Moreover, the S/N ratio charts proved to be a successful CC design replacement. The current density and pH were found to be the most important factors for the EF process. A higher biodegradability (BOD5/COD) and minimum iron concentration (0.45 mg/L) in the effluent sludge demonstrated good environmental disposal suitability. In the last, the effect of various inhibitors/scavengers (SO4 −2, PO4 −3, EDTA, etc.) on the EF process performance was also carried out.

Insights of the adsorption mechanism of Bemacid Red using coagulation-flocculation sludge: Optimisation using BBD-RSM and DFT calculations

This study optimized the adsorption parameters for removing Bemacid Red dye using biochar derived from coagulation-flocculation sludge. The biochar was comprehensively characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, thermogravimetric analysis, X-ray fluorescence, and point of zero charge determination. Adsorption experiments were conducted by varying the adsorbent dose, temperature, contact time, and initial dye concentration. A Box-Behnken design with response surface methodology was used to optimize the conditions. The experimental results closely matched the model predictions. The analysis of variance validated the model. The optimum conditions were 1.2 g. L−1, 45 °C, 40 min, and 80 mg. L−1 initial concentration, achieving 97.27 % removal efficiency. B3LYP/6-31G(d) quantum calculations supported the results. Global reactivity descriptors and local Fukui indices were calculated to elucidate adsorption mechanisms. This study highlights the effectiveness of low-cost coagulation sludge biochar for removing dyes from textile wastewater and provides a comprehensive understanding of the adsorption process through experimental and theoretical approaches.

RSM-CCD directed modeling and optimization of a low-cost adsorbent based on sodium dodecyl sulfate for the selective removal of malachite green and methylene blue dyes: Kinetics, isotherm, and thermodynamics analysis

Sodium dodecyl sulfate (SDS) is widely used as a surface modifier to improve the sorption capacity of sorbents due to its high surface area, non-toxicity, biodegradability, and strong affinity for various impurities. The present works aims at investigating the efficiency of hydrogel adsorbent prepared from sodium dodecyl sulfate for treating malachite green (MG) and methylene blue (MB) dyes. An RSM-based central composite design was utilized to optimize the percentage swelling of the four key synthesis parameters: initiator concentration, monomer concentration, crosslinker concentration, and solvent. The optimal process conditions are as follows: 12.5 mM L−1 initiator, 306 mM L−1 monomer, 23 mM L−1 crosslinker, and 14 mM L−1. Additionally, the mechanism of their formation was investigated by various physical methods, viz., FTIR, XRD, Raman, H1-NMR, SEM-EDS, TGA, and BET. The applicability of the adsorbent was examined in detail as a function of time, pH, adsorbent dose, initial dye concentration, and temperature. The optimum conditions are as follows: pH=7, adsorbent amount = 0.1 g/L, and initial dye concentration = 100 mg/L, contact time = 120 min at ambient temperature. The hydrogel exhibits maximum sorption capacities of 137.74 mg g−1 for MG and 373.13 mg g−1 for MB, respectively. The mechanism of dye adsorption has been established, and the kinetic study suggests that the adsorption follows a pseudo-second-order reaction. Furthermore, the adsorption isotherms at different equilibrium conditions fit well with the Langmuir adsorption model, indicating a chemisorption process. Thermodynamic analyses justified the spontaneous and exothermic nature of dye adsorption, primarily through electrostatic interactions. The adsorption–desorption study of the resulting hydrogel exhibited excellent adsorption efficiency of 42.07 % for MG, and 63.35 % for MB, and desorption efficiency of MG was lowered from 55.3 % to 22.63 % and MB from 35.57 % to 18.8 % even after 5 consecutive cycles. Consequently, this sorbent provides a versatile and sustainable solution for treating dyes waste water.

A novel approach for modification of montmorillonite using banana peel ash extract for enhanced adsorption efficiency of methylene blue dye

Water contamination from dyes is a major issue that needs to be solved effectively. Addressing this issue, the study aims to improve the adsorption capacity of montmorillonite (MMT) by its modification for removing methylene blue (MB) dye. Powder XRD, FTIR, FESEM, HRTEM, BET, and XPS were employed to analyze the modified materials. Various parameters were studied to optimize the adsorption efficiency of modified MMT. To enhance the removal efficiency of MMT (70.05 ± 0.16 %), this study has modified MMT with banana peel ash extract (BPAE) which achieved maximum MB removal of 98.54 ± 0.31 % under neutral pH, with an equilibrium time of 150 min, initial dye concentration of 120 mg/L, and adsorbent dosage of 1.4 g/L at ambient temperature (32 °C). Among the isotherm models, the Langmuir model showed a maximum adsorption capacity of 100 mg/g. Experimental data fitted well with the Elovich kinetic model. Reusability was efficient up to the third cycle, retaining 56.96 ± 0.39 % efficiency.

Revolutionizing dye removal from wastewater using low-cost natural material

The contamination of wastewater by textile dyes has emerged as a significant and pressing environmental concern that requires immediate attention and the development of inventive solutions. One highly effective technique for addressing this issue involves using adsorption processes with nanoparticles for dye removal. To address this challenge, white stone powder (WSP) and calcined white stone powder (CWSP) were prepared for their potential in adsorbing and removing dyes from wastewater. The effect of pH, dosage, contact time, initial dye concentrations, and temperature were optimized during the present study. Furthermore, the equilibrium data for the WSP were subjected to rigorous analysis using multiple isothermal models, including the Freundlich, Langmuir, Dubinin Radushkevich, Harkin Jura, and Temkin models. A comparison of calculated and experimental uptake capacities and higher values of the correlation coefficient indicated that the Freundlich model fited better than the other models. In addition to the isothermal modeling, the morphology of the adsorbent materials was examined. The dye uptake capacity (mg/g) of white stone powder was 72.24 which increased up to 92.56 after calcination. This research work highlighted the potential of the calcined WSP as a cost-effective and efficient alternative for removing dyes from wastewater, presenting a promising solution to this pressing environmental issue.

Simultaneous deep eutectic solvent based microextraction of Allura Red and Brilliant Blue in violet-purple foodstuffs

A vortex-assisted simultaneous deep eutectic solvent based microextraction and spectrophotometric determination method was established for the first time to simultaneously monitor Allura Red and Brilliant Blue in violet-purple foodstuffs. A ternary deep eutectic solvent was created using benzoic acid, tetra butyl ammonium bromide and benzyl alcohol at 1:1:3mol ratio. The method variables including pH, volume of deep eutectic solvent and vortex time were optimized by Box-Behnken design of response surface methodology. The limits of detection were determined to be 25 and 9µg/L for Allura Red and Brilliant Blue, respectively. The linear dynamic ranges of the method were obtained between 82-12000 and 29-4200µg/L for Allura Red and Brilliant Blue, respectively. Preconcentration factor of the method was obtained as 15. Greenness evaluation was performed using Analytical GREEnness tools. Extraction mechanisms affecting quantitative simultaneous microextraction of the target dyes were explained. The developed method was validated with high-performance liquid chromatography analysis. Analyte addition-recovery tests were also applied to confectionery samples to validate the proposed method and determine the dye contents of foodstuffs. Allura Red and Brilliant Blue contents of violet-purple confectioneries were determined between 3.85-74.59 and 4.02-26.11µg/g concentrations with 94.5-98.6% and 93.0-101.0% recoveries, respectively.

Factorial experimental design for removal of Indigo Carmine and Brilliant Yellow dyes from solutions by coagulation

Textile and food industries produce huge amounts of wastewaters containing dye residues. When these wastewaters are discharged to receiving surface waters like as lakes and rivers, aesthetically unpleasant situations form. Therefore, these wastewaters should be treated. Wastewater treatment is sometimes an expensive operation and cheap methods should be developed. The removal of Indigo Carmine (I.C., Acid dye) and Brilliant Yellow (B.Y., Azo dye) from synthetically prepared solutions was studied by coagulation using iron chloride salt in a batch reactor at room temperature. As an experimental approach, two leveled factorial design with three factors was applied as a function of pH (4-12), iron chloride amount (0.1-0.4 g/500 mL) and dye concentration (100-200 mg/L). Low pHs supported to removal of these two dyes. The results showed that 100% I.C. dye removal and 90.5% B.Y. dye removal were achieved. The all parameters were statistically insignificant for both the dyes. Indigo Carmine and Brilliant Yellow dyes were removed from solutions successfully. The applied treatment method was evaluated as promising due to low sludge production, low cost, low coagulation duration and high performance. A time span of 5 minutes was found as enough for removals of both of the dyes. After treatment of I.C. and B.Y. dyes by coagulation, the coagulated dyes were determined as unreusable due to iron complex by these dyes. Flocculation was found to be ineffective. A continuous flow reactor was successfully adopted for these dyes.

Novel eco-friendly spectrophotometric determination of lercanidipine hydrochloride in tablets using methyl red

The aim of the work was to develop a simple, eco-friendly, quick, affordable and alternative spectrophotometric procedure that uses the azodye methyl red (MR) for the determination of lercanidipine in its dosage form considering the “green” chemistry principles. Materials and methods. Analytical equipment: Shimadzu UV-1800 double beam UV-visible spectrophotometer (Japan) with included UV-Probe 2.70 software, RAD WAG AS 200/C precise analytical balance (Poland), Elmasonic EASY 40H ultrasonic bath. Lercanidipine hydrochloride (purity 99 %) was purchased from Jiyan Chemicals (India). Lercanidipine tablets 10 mg and 20 mg were used in our experiments. Results and discussion. To determine the amount of lercanidipine in tablets, a spectrophotometric method has been developed. To select the best dye for the method development, we tested a variety of dyes, including MR, bromocresol purple, bromophenol blue, cresol red, bromocresol green and bromothymol blue. We selected MR as the reagent based on the experimental studies' outcomes, and the solvent was an acetonitrile and ethanol mixture with a ratio of 95 to 5. The optimal parameters were determined for the quantitation of lercanidipine in tablets utilizing MR with 5×10-5 mol/L of dye concentration, 0.5 ml of MR solution, at a temperature of 25 °C without heating; detection wavelength was 498 nm and reaction time of 5 min. By using the molar ratios (saturation) method and Job's (continuous variations) approach, the stoichiometric coefficients of reacting components involving lercanidipine and dye were established to be 1:1. The proposed spectrophotometric procedure was linear within the concentration ranging from 6.48 – 32.41 μg/mL. Using the least squares method, a regression equation was generated: y = 0.0208x – 0.0318. The correlation coefficient was higher than 0.999, indicating that the analytical procedures' linearity is acceptable; the limit of detection and limit of quantitation were 1.19 μg/mL and 3.62 μg/mL, respectively. The robustness, accuracy and precision of the study results fell within acceptable limits. The proposed method was successfully applied to determine the content of lercanidipine in its tablet dosage forms. The analysis of the method's "greenness" using AGREE and GAPI tools yielded excellent results. Conclusions. The method that has been developed can serve as an alternative approach for the routine control of lercanidipine content in its tablets

Synthesis and application of gadolinium-doped ZnO/silica mesoporous nanocomposite for methylene blue removal

In this study, a silica mesoporous nanomaterial was synthesized using a hydrothermal method and then surface-modified with Gadolinium-doped ZnO nanoparticles. The synthesized samples were characterized using FTIR, XRD, BET, XPS, FESEM, and EDS techniques for surface and structural morphology analysis. Structural analysis revealed that the synthesized SBA-15 mesoporous silica possessed a crystalline structure. Conversely, the mesoporous material modified with zinc oxide and gadolinium oxide nanoparticles became amorphous. The activity of this nanocomposite for the removal of methylene blue, a colored pollutant, was evaluated. Five factors affecting methylene blue removal efficiency, including initial dye concentration, adsorbent amount, contact time, pH, and temperature, were investigated. The optimal values identified for efficient methylene blue removal were: initial concentration 10 mg/L (ppm), adsorbent amount 0.015 g, time 15 min, pH 7, and temperature 25 °C. The reusability of the adsorbent was also investigated, and it was found to exhibit good reusability for up to 8 cycles without a significant decrease in its methylene blue removal efficiency.

Heterogeneous Fenton process using GO@Fe3O4/Cu catalyst for the degradation of reactive dyes from aqueous solutions: modeling and optimisation

ABSTRACT Various industries such as textile, paper, rubber, plastic, and cosmetics use dyes to produce their products. Some dyes used in textile industries are teratogenic, carcinogenic, mutagenic, and dangerous for humans and other organisms. This study aimed to determine the amount of removal of reactive dyes from aqueous solutions during the heterogeneous Fenton process. In this study, iron oxide nanoparticles and copper nanoparticles were loaded on graphene oxide (GO). GO@Fe3O4/Cu catalyst was synthesised and applied to remove reactive dyes from aqueous solutions in a heterogeneous Fenton process. Contact time, pH, catalyst dose, dye concentration, and H2O2 dose were considered effective parameters. Experiments were designed according to the Box-Behnken design in the Design Expert software. Catalyst properties were determined using SEM, VSM, XRD, and FTIR analysis. The ANOVA showed that the selected statistical model with R2 0.965, p < 0.0001, and F-value 27.79 was significant. In the optimal conditions of pH 3, H2O2 dose 0.48 mL, catalyst dose 0.34 g/L, dye concentration 22 mg/L, and contact time 9 min, the degradation efficiency of Reactive Blue 21 (RB21), Reactive Red 195 (RR195) and Reactive Red 19 (RR19) were 92, 97, and 80%, respectively. The results showed that after 5 cycles of recycling, the catalyst had a high efficiency in pollutant removal and could be utilised many times for dye decomposition. GO@Fe3O4/Cu catalyst was successfully synthesised using a simple method. The heterogeneous Fenton process with a magnetic catalyst in the presence of H2O2 has a high potential to remove reactive dyes from the aqueous solution.

Artificial neural network modelling and experimental investigations of malachite green adsorption on novel carboxymethyl cellulose/β-cyclodextrin/nickel cobaltite composite

This study presents a novel polymer nanocomposite based on carboxymethyl cellulose and β-cyclodextrin crosslinked with succinic acid (CMC-SA-β-CD) containing nickel cobaltite (NCO) nano-reinforcement. Various analytical techniques have been employed to investigate the structural, thermal, and morphological features of the resulting nanocomposite. The CMC-SA-β-CD/NCO nanocomposite has been utilized as an adsorbent for the removal of bisphenol-A (BPA, R% <40 %), malachite green (MG, R% > 75 %)), and Congo red (CR, no adsorption) from the synthetic wastewater. The study systematically explored the impact of various parameters on the adsorption process, and the interactions between MG and CMC-SA-β-CD/NCO were discussed. The adsorption data were fitted to different models to elucidate the kinetics and thermodynamics of the adsorption process. An artificial neural network (ANN) analysis was employed to train the experimental dataset for predicting adsorption outcomes. Despite a low BET surface area (0.798 m2 g−1), CMC-SA-β-CD/NCO was found to exhibit high MG adsorption capacity. CMC-SA-β-CD/NCO exhibited better MG adsorption performance at pH 5.5, 40 mg L−1 MG dye concentration, 170 min equilibrium time, 20 mg CMC-SA-β-CD/NCO dose with more than 90 % removal efficiency. Moreover, the thermodynamic studies suggest that the adsorption of MG was exothermic with ΔH° value −9.93 ± 0.76 kJ mol−1. The isotherm studies revealed that the Langmuir model was the best model to describe the adsorption of MG on CMC-SA-β-CD/NCO indicating monolayer surface coverage with Langmuir adsorption capacity of 182 ± 4 mg g−1. The energy of adsorption (11.4 ± 0.8 kJ mol−1) indicated chemisorption of MG on the composite surface. The kinetics studies revealed that the pseudo-first-order model best described the adsorption kinetics with qe = 86.7 ± 2.9 mg g−1. A good removal efficiency (>70 %) was retained after five regeneration reuse cycles. The ANN-trained data showed good linearity between predicted and actual data for the adsorption capacity (R-value>0.99), indicating the reliability of the prediction model. The developed nanocomposite, composed predominantly of biodegradable material, is facile to synthesize and exhibited excellent monolayer adsorption of MG providing a new sustainable adsorbent for selective MG removal.

Oxalic Acid-Assisted Photo-Fenton Catalysis Using Magnetic Fe3O4 Nanoparticles for Complete Removal of Textile Dye

Textile industry effluents contain several hazardous substances, such as dye-containing effluents, which pose environmental and aesthetic challenges. Presently, the microbial-based remediation process is in use. This study investigated the application of ferrous–ferric oxide (Fe3O4) nanoparticles, a readily formulated nanoadsorbent, to remove scattered dye molecules from industrial effluents. The ferrous–ferric oxide nanoparticles were prepared using a chemical co-precipitation method. The nanoparticles had 26.93 emu g−1 magnetization, with sizes smaller than 20 nm, and possessed a highly purified cubic spinel crystallite structure. The catalytic activity of the iron oxide depended on the dose, photocatalytic enhancer, i.e., H2O2 level, pH of the reaction medium, and dye concentration. We optimized the Fenton-like reaction to work best using 1.0 g/L of ferrous–ferric oxide nanoparticles, 60 mM oxalic acid at pH 7.0, and 60 ppm of dye. Iron oxides act as photocatalysts, and oxalic acid generates electron–hole pairs. Consequently, higher amounts of super-radicals cause the rapid degradation of dye and pseudo-first-order reactions. Liquid chromatography–mass spectrometry (LC-MS) analysis revealed the ferrous–ferric oxide nanoparticles decolorized and destroyed Disperse Red 277 in 180 min under visible light. Hence, complete demineralization is observed using a photo-Fenton-like reaction within 3 h under visible light. These high-capacity, easy-to-separate next-generation adsorption systems are suggested to be suitable for industrial-scale use. Ferrous–ferric oxide nanoparticles with increased adsorption and magnetic properties could be utilized to clean environmental pollution.