Blue Concentration Research Articles

Low-Cost Adsorbent Development: Sulfuric Acid-Activated Teak Sawdust for Effective Methylene Blue Removal

The expansion of the global textile industry has resulted in a decline in environmental quality. Environmental pollution resulting from textile dye waste may include heavy metals and dyes, which exhibit carcinogenic and mutagenic effects. Many studies have been done to reduce the harm of dyes. Extensive research has been undertaken to mitigate the detrimental effects of dyes. One cost-effective approach for managing dye pollution is the adsorption of methylene blue using sulfuric acid-activated teak sawdust. Teak wood sawdust, a byproduct of the furniture industry that is abundant and underutilized, contains active sites within its constituent compounds, including cellulose, hemicellulose, and lignin. This study was designed to determine the ability of teak sawdust to adsorb methylene blue. In this investigation, the biosorbent will be characterized using fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) to analyze its active sites and surface morphology. Additionally, the study aimed to elucidate the impact of variation contact time, pH solution, and alteration in methylene blue concentration on the adsorption capacity for methylene blue, employing a UV-Vis spectrophotometer for measurement. The research results demonstrated that optimal adsorption occurred at a contact time of 30 minutes and a pH of 6, with the adsorption efficiency reaching 99.67% as a function of contact time. The kinetic study was modeled using a pseudo-second-order approach, with a kinetic constant of 79.71 g mg⁻¹ min⁻¹. The maximum adsorption capacity was 1.351 mg g⁻¹, the n value was 1, and the percentage of methylene blue adsorbed reached 99.88%.

Fe-modified Eriobotrya japonica seed biochar for removal of methylene blue: Isotherms, thermodynamic, kinetic studies

In this study, biochar and magnetic biochar were used to remove methylene blue from the aqueous solution. This study also presents the preparation of biochar and magnetic biochar. Biochar and magnetic biochar used as adsorbent substances were obtained from loquat seeds (Eriobotrya japonica). The prepared adsorbent materials were characterized using SEM-EDS, BET, XRD and FT-IR. The effects of pH, time, amount of biochar and magnetic biochar, initial methylene blue (MnB) concentration and temperature were investigated. The sorption of MnB on biochar of Eriobotrya japonica seeds (b-ER) and iron-modified (mb-ER) is an endothermic process. R2 values, calculated and experimental adsorption capacity values were compared (R2 = 0.992 b-ER-MnB and R2=0.983 mb-ER-MnB) b-ER and for mb-ER the MnB adsorption process was found to fit the pseudo-second order-kinetic model. It was found to be more suitable for Langmuir adsorption isotherms when the adsorption isotherms were investigated. The maximum adsorption capacity was 40.650 ± 2.036 mg/g for b-ER-MnB and 81.697 ± 4.085 mg/g for mb-ER-MnB. According to the results obtained, mb-ER can be used effectively in the removal of methylene blue from aqueous solutions.

Optimized Photocatalytic Degradation of Methylene Blue Using Titaniferous Sand/ZnO Composite: A Sustainable Approach to Wastewater Treatment

This study explores a novel approach to enhancing photocatalytic efficiency by utilizing an industrial residue, titaniferous sand, in combination with ZnO. The purifying efficiency of this semiconductor mixture was studied for the removal of methylene blue in a fixed-bed reactor. The main objective was to find out with what percentage the titaniferous sand could be incorporated into the ZnO for maximum photocatalytic performance. Box-Behnken Design (BBD) in the Response Surface Methodology (RSM) was used to optimize the operative parameters. The influence of titaniferous sand/ZnO ratio (A:1-2.8), pH (B:4-10) and irradiation time (C:120-480 minutes) on the degradation efficiency of the dye was studied. Initial concentrations of methyl blue and total semiconductor mixture were set at 25 mg/L and 10 g/L, respectively. The ANOVA analysis showed that the photocatalytic process was significantly affected by a positive individual effect of the titaniferous sand/ZnO ratio and the irradiation time. A quadratic polynomial of the second order accurately represented the experimental values with a correlation coefficient R2 of 0.9921. In addition, this model had a p-value of less than 0.0001 and an F-value of 84.09. Thus, the model used was quite appropriate. Optimal conditions were obtained for a ratio (titaniferous sand/ZnO) of 1.51057, i.e. a titaniferous sand percentage of 66%, a pH of 9.97487 and an irradiation time of 479.765 minutes. Under these conditions, a degradation of 99.4915% was obtained. In addition, the photocatalytic degradation kinetics of methylene blue on the titaniferous sand and ZnO mixture followed the Langmuir-Hinshelwood model and was of the first order with an apparent kinetic constant of 0.402 h-1.

Acryloyl starch/carboxymethyl cellulose grafting copolymerization composite hydrogel for efficient adsorption of methylene blue

Abstract An efficient composite adsorbent was prepared based on acryloyl starch/carboxymethyl cellulose grafting copolymerization for the adsorptive removal of methylene blue. The developed composite hydrogels were characterized by means of FTIR, SEM (EDS-SEM), and XRD. Various parameters affecting the removal of methylene blue such as the type of adsorbents, pHs, the amount of adsorbents dosage, initial methylene blue concentration, and contact time were optimized using a series of batch adsorption experiments. The experimental data of the adsorption process were more fitted to Langmuir isotherm (R 2 = 0.9898) with a maximum adsorption capacity of 483.5 mg/g and batch kinetic experiments revealed that the adsorption process followed quasi-second-order kinetic model. The adsorption process was rapid and equilibrium was reached within 30 min. When the adsorption dosage is 0.2 g L−1, the adsorption yield for 100 mg L−1 methylene blue solution can reach 96.7 %. Therefore, acryloyl starch/carboxymethyl cellulose grafting copolymerization composite hydrogel present excellent adsorption efficiency, shows the potential application in future treatment of dyes wastewater.

Assessment of the adsorption capacity of biochar samples obtained from agricultural biomasses

The study consists of adsorption tests on two samples of biochar, obtained from rice husk and coconut fiber biochar biomass, as well as a sample of charcarbon, both prepared under different conditions: macerated and non-macerated; impregnation with and without HCl and H3PO4; and washing or not with deionized water after impregnation. The test was performed in duplicate, for 30 min, with masses of 0.5 g; 0.3 g; 0.1 g; and 0.05 g, and an initial methylene blue concentration of 0.01 g∙L-1. The study was carried out with the objective of identifying, in the analyzed samples, the material with the greatest adsorption capacity of methylene blue dye, comparing the data with commercial activated carbon. The results identified removal above 70 % in both types of biochars, suggesting the feasibility of application as an adsorbent material to remove organic contaminants. The sample that most closely resembled the removal percentage of commercial activated carbon (98.84 %) was that of biochar obtained from coconut fibers, with 91.71 %. Thus, the research showed promise in studying the application and valorization of biochars, produced from agro-industrial waste, in adsorption processes.

Predicting trends in atmospheric CO2 across the Mid-Pleistocene Transition using existing climate archives

Abstract. During the Mid-Pleistocene Transition (MPT), ca. 1200–800 000 years ago (ka), the Earth's glacial cycles changed from 41 to 100 kyr periodicity. The emergence of this longer ice age periodicity was accompanied by higher global ice volume in glacial periods and lower global ice volume in interglacial periods. Since there is no known change in external orbital forcing across the MPT, it is generally agreed that the cause of this transition is internal to the Earth system. Resolving the climate, carbon cycle, and cryosphere processes responsible for the MPT remains a major challenge in Earth and palaeoclimate science. To address this challenge, the international ice core community has prioritised recovery of an ice core record spanning the MPT interval. Here we present results from a simple generalised least-squares (GLS) model that predicts atmospheric CO2 out to 1.8 Myr. Our prediction utilises existing records of atmospheric carbon dioxide (CO2) from Antarctic ice cores spanning the past 800 kyr along with the existing LR04 benthic δ18Ocalcite stack (Lisiecki and Raymo, 2005; hereafter “benthic δ18O stack”) from marine sediment cores. Our predictions assume that the relationship between CO2 and benthic δ18O over the past 800 000 years can be extended over the last 1.5 million years. The implicit null hypothesis is that there has been no fundamental change in feedbacks between atmospheric CO2 and the climate parameters represented by benthic δ18O, global ice volume, and ocean temperature. We test the GLS-model-predicted CO2 concentrations against observed blue ice CO2 concentrations, δ11B-based CO2 reconstructions from marine sediment cores, and δ13C of leaf-wax-based CO2 reconstructions (Higgins et al., 2015; Yan et al., 2019; Yamamoto et al., 2022). We show that there is no clear evidence from the existing blue ice or proxy CO2 data to reject our predictions or our associated null hypothesis. A definitive test and/or rejection of the null hypothesis may be provided following recovery and analysis of continuous oldest ice core records from Antarctica, which are still several years away. The record presented here should provide a useful comparison for the oldest ice core records and an opportunity for further constraints on the processes involved in the MPT.

Bio-sorption of methylene blue using Datura stramonium leaves as adsorbent

Present study was accomplished to prospect the viability of using the Datura stramonium leaves powder (DS) as an adsorbent to remove the methylene blue from aqueous solution. The physico-chemical characteristics of the studied adsorbent were examined. The optimum parameters such as contact time, particle size, absorbent dose, initial methylene blue concentration, and pH were investigated by performing batch experiments models. The kinetics and the isotherms adsorption were evaluated by varying the initial concentration and using the optimum parameters. The optimum of contact time is 30min, with a removal capacity of 89.60 %. The optimal adsorbent concentration to reach the maximum removal of methylene blue (89.54 %) is 18 g/L. An initial methylene blue concentration of 50 ppm is ideal to reach the maximum capacity of removal (92.72 %). The optimum particle size is 80 mm. The kinetics of the adsorption process are in accordance with the pseudo-second order model. Experimental values of the adsorption capacity are close proximity to the optimum values predicted by the pseudo-second order model. Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Harkin-Jura and Hasley isotherms were applied to represent the data obtained from the adsorption studies. The highest R2 values were related to Freundlich, Dubinin-Radushkevich and Hasley isotherm models.

Simulation and modeling of methylene blue dye removal by an agri-food waste (Peanut shells)

Our study explores the potential of utilizing peanut shells, an abundant and low-cost food waste, as a natural adsorbent for the removal of industrial dyes, specifically methylene blue. We conducted a detailed investigation of the adsorption process, which revealed that it conforms to both Langmuir and Freundlich isotherms, indicating the ability of peanut shells to adsorb methylene blue effectively. To optimize the adsorption yield, we employed a Box-Behnken experimental design. This approach allowed us to assess the impact of several key factors, including the mass of the adsorbent, dye concentration, pH, temperature, stirring rate, and the ionic strength of salts in the solution. The mathematical model and simulation of the adsorption process helped us identify the best conditions for maximizing the dye removal. Our experiments resulted in a maximum adsorption efficiency of 97%, achieved under optimal conditions: 1.5 g of adsorbent, a methylene blue concentration of 40 mg/L, pH 11, temperature of 65°C, 0 mg/L ionic strength, and a stirring rate of 165 rpm. These findings suggest that peanut shells are a viable, eco-friendly alternative for dye removal, offering a sustainable solution for wastewater treatment and contributing to waste reduction.

Chaos-driven detection of methylene blue in wastewater using fractional calculus and laser systems

Abstract Methylene blue (MB) concentrations in residual water were detected using fractional calculus, the Rössler chaotic attractor and laser systems. A Nd:YVO4 nanosecond pulsed laser at 532 nm, with pulse energies ranging from 2 µJ to 7 µJ, was applied to irradiate different water samples containing MB concentrations from 20 µl to 100 µl. Fractional calculus was employed with the purpose of modeling the temperature distribution in the samples, with the Caputo fractional derivative describing photothermal effects induced by laser irradiation. Different MB concentrations were detected by using the Rössler chaotic attractor, it monitored variation on concentrations, associating attractor shapes with MB concentrations. Lower concentrations showed a weaker attractor response, whereas higher concentrations manifest stronger attractor shapes in magnitude. Raman spectroscopy confirmed the detection of MB in residual water from the Requena dam, located in Tepeji del Río de Ocampo, Hidalgo, Mexico. The application of fractional calculus improved the prediction of heat distribution in the samples, by incorporating numerical simulation. The results suggest that this approach is suitable for real-time monitoring, as it associates MB concentrations with distinct chaotic attractor shapes. This technique shows promise for the detection of other contaminants as well. Future research should focus on refining this method and expanding its application to develop innovative monitoring solutions.

Use of Active Carbon Produced by Hydrothermal Method from Agricultural Waste in Methylene Blue Removal

In this study, the use of activated carbon produced from agricultural waste via the hydrothermal method for the removal of methylene blue from solution was examined. Pistachio roasting facility waste was selected as the agricultural waste. For activated carbon production, carbonized products were treated in a hydrothermal device in the presence of an activator for various durations. During processes conducted at a constant temperature, high pressure was achieved, allowing the activated carbon to attain a high adsorption capacity. The results showed that the sample with a KOH impregnation ratio of 1:1, treated in a hydrothermal device for 480 minutes at 160 °C, was able to remove methylene blue with a 99.85% extraction yield in a solution with a 350 ppm methylene blue concentration.

Scale-bridging and modelling study of graphene shell composite adsorption for dye removal in water treatment

Continuous fixed-bed adsorption is a cost-effective water-treatment method for dye removal. This research examined parameters such as bed heights (5, 7, and 9 cm), initial methylene blue (MB) concentrations (10, 15, and 20 mg/L), and feed flow rates (8, 10, 12 and mL/min) on fixed-bed adsorption performance. Our findings showed that the performance was improved under longer exhaustion times not only with increasing column bed heights, but also with decreasing initial MB concentrations and feed flow rates. Of note, the Thomas and Yoon-Nelson models accurately described MB adsorption in a fixed-bed column, with R2 values from 0.7525 to 0.9833. Response surface methodology via central composite design optimized column bed heights and feed flow rates on the duration required to achieve 50 % of column breakthrough. The coefficient of determination (R2) and analysis of variance demonstrated the significance of the Two Factor Interaction (2FI) model in fitting the actual values. The optimum conditions were determined to be as follows: a bed height of 5 cm; a feed flow rate of 8 mL/min; and a duration of 54.74 min to achieve 50 % of column breakthrough. Lastly, a confirmatory test further verified the precision of the proposed optimum conditions with an error of only 0.02 %.

Methylene Blue Degradation Using Non-Thermal Plasma

Methylene blue (C16H18ClN3) dye can be decomposed using non-thermal plasma. However, there is a problem in that the maintenance of electrodes and dielectrics is necessary due to the durability and heat generation problems due to the high temperatures. Therefore, in this study, a comparative experiment was performed between the flat DBD plasma module and the diffuser DBD module under the same conditions. For methylene blue decomposition, the characteristic changes in the air flow rate, ozone production rate, energy consumption rate, and decomposition rate were compared. In the experiment, 7 L water was placed in a 15 L reactor, and measurements were performed for approximately 1 h. We performed the same process by setting the initial methylene blue concentration to 143 mg/L. According to the results, the flat DBD module achieved a decomposition rate of 100% in 40 min, an energy yield of 46.7 g/kWh, and an ozone generation amount of 6.5 g/h. The diffuser DBD module achieved a decomposition rate of 90%, an energy production of 24.6 g/kWh, and an ozone generation of 1.97 g/h in 60 min.

Optimization of methylene blue photodegradation by Cr-PTC[sbnd]HIna/TiO2 composite using box-behnken design application

The Cr-PTCHIna/TiO2 composite synthesized using an isonicotinic acid modulated chromium and perylene-based metal-organic framework (Cr-PTCHIna MOF) and titanium oxide (TiO2) showed promising results for the photodegradation of methylene blue. The composite was synthesized through the solvothermal method with a molar ratio of Cr and Ti of 1:1 mmol. The XRD diffraction patterns of Cr-PTCHIna/TiO2 composite showed sharp peaks at 2θ = 12°, 25°, 27°, 37°, 48°, 54°, 55°, and 62° with crystal sizes of 14.144 nm. The Cr-PTCHIna/TiO2 composite has a band gap energy of 2.02 eV and a rod-shaped morphology with a particle size of 239.16 nm. The Box-Behnken Design (BBD) demonstrated that the composite can achieve an optimum degradation efficiency of methylene blue of 88.55 % under methylene blue initial concentration of 35.7 ppm, pH 6.6, and photocatalyst mass of 0.13 % under 250-watt Mercury lamp irradiation for 2 h.

Silica Gel From Bagasse Ash for Methylene Blue Adsorption

Most silica sources are from non-renewable natural sand or rock materials, which affect the element's diminishing availability in the environment. Because bagasse ash has a relatively high silica concentration, it can be used as a silica source to manufacture silica gel. HCl is added during the sol-gel process of silica gel synthesis. The silica gel's characterization employs FTIR, XRD, and SEM instruments. Characterization results showed that silica gel contains silanol groups identified by the appearance of vibrations at the wavenumber of 3383,93 cm-1 and 1635,17 cm-1. Vibrations of the siloxane group appear at the wavenumber of 1020,83 cm-1 and 579,88 cm-1. Silica gel diffractogram showing dilated diffraction peaks at 2q = 22,90ᵒ. Silica gel has potential as an adsorbent in adsorbing methylene blue dye. The ideal parameters for the methylene blue adsorption process are pH 10 and 45 minutes of contact time., silica gel weight of 0.1 g, and methylene blue concentration of 100 mg/L. Using the Langmuir isotherm rule, the silica gel of bagasse ash has a high adsorption capacity of 56.818 mg/g.

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.

PSf Membrane-Impregnated Jute-Copper Nanocomposite as Highly Efficient Dye Removal Material.

Water pollution, driven by the discharge of dyes from industrial processes, poses a significant environmental and health hazard worldwide. Methylene blue, a common dye, constitutes particular concern due to its persistence and toxicity. Conventional wastewater treatment methods often struggle to effectively remove such contaminants. In this study, we introduce a novel approach utilizing a polysulfone-based composite membrane incorporating pretreated jute fibers and copper nanoparticles for the removal of methylene blue from aqueous solutions. The pretreated jute fibers undergo alkali and hydrogen peroxide treatments to enhance their adsorption capabilities, while copper nanoparticles are incorporated into the membrane to bolster its antimicrobial properties. Through comprehensive characterization techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), and scanning electron microscopy (SEM), we confirm the structural and chemical properties of the composite membranes. Batch adsorption studies reveal the superior performance of the composite membrane compared with individual components. Specifically, at lower methylene blue concentrations (∼20 ppm), the composite membrane demonstrates a remarkable percent removal value of about 97%, while at higher concentrations (∼100 ppm), the percent removal remains substantial at 85%. Additionally, desorption studies elucidate the retention capacity of the adsorbed dye, indicating the feasibility of the composite membrane for practical applications in wastewater treatment. These findings underscore the potential of nanocomposite-fiber membranes as sustainable and cost-effective solutions for mitigating water pollution. By harnessing advancements in nanotechnology and materials science, the presented innovative composite membranes could offer promising avenues for addressing water pollution challenges and promoting environmental sustainability.

Agricultural low-cost waste adsorption of methylene blue and modelling linear isotherm method versus nonlinear prediction

AbstractThis study shows that geographically marked wheat hull, named Siyez, rice hull Sarı Kılçık, and Taşköprü Garlic stalk were used as agricultural waste to potential adsorbent materials for removing methylene blue from aqueous solution. Experimental data were evaluated in both equilibrium batch process and kinetic studies. In addition, the factors that affect the adsorption capacities, such as pH solutions, methylene blue concentration, contact time, and temperatures, were also investigated. Obtained data were subject to two constant adsorption models of Langmuir, Freundlich, Temkin, and Dubinin−Radushkevich. The kinetic models (pseudo-first-order, pseudo-second-order, intra-particle diffusion and film diffusion) and thermodynamic parameters were evaluated. The adsorption isotherms, characterized by an excellent fit with the Langmuir model (R2 = 0.99) across all adsorbents, underscore the prevalence of monolayer adsorption of methylene blue, in contrast to the Freundlich equation. Adsorption kinetics of the methylene blue onto the adsorbents followed pseudo-second-order kinetic model. According to high regression coefficient (R2) and minimal values of nonlinear error functions like RMSE; the maximum monolayer adsorption capacities of wheat hull, rice hull and garlic stalk were found to be 62.50 (mg/g), 54.94 (mg/g), and 370.37 (mg/g), respectively. The results indicated that these proposed adsorbents could be low-cost and effective adsorbents for water purification and have adsorption capacity as much as comparable with the literature. In batch equilibrium studies, the adsorption of methylene blue dye onto the wheat hull, rice hull, and garlic stalk exhibited a significant correlation with temperature, contact time, and initial concentration of methylene blue dye and Adaptive Neuro-Fuzzy Inference System algorithm for forecasting overall the system parameter well fitted with these findings with the accuracy of outputs (R2 about 0.99 for each). Consequently, the thermodynamic analysis revealed that the adsorption process takes place in bulk diffusion by liquid phase mass transfer and occurred spontaneously with endothermically except garlic stalk. Adsorption thermodynamic studies show that the adsorption of methylene blue onto the garlic stalk was spontaneous and exothermic. Graphical Abstract

An Experimental and Theoretical Investigation on Highly Reusable Visible Light Active CoTe Nanosheets for Improved Photocatalytic Degradation of Toxic Aniline Blue Dye

AbstractSemiconductor‐assisted photocatalytic treatment is among the most effective methods for eliminating persistent contaminants from industrial wastewater. This study presents a hydrothermal approach for the preparation of Cobalt Telluride (CoTe) nanosheets for the degradation of aniline blue dye under visible light irradiation. The synthesized catalyst was characterized using various techniques, including X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X‐ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, RAMAN spectroscopy, high‐Resolution transmission electron microscopy (HRTEM), and X‐ray photoelectron spectroscopy (XPS). Tauc's model was used to determine the optical band gap. The key operating parameters, such as the amount of CoTe, initial aniline blue (AB) concentration, and contact time, have been optimized to achieve the highest AB degradation percentage. Under visible light, 98 % of dye degradation occurred within 60 minutes. The degradation process was further assessed using total organic carbon (TOC) measurements. Free‐radical capture experiments were conducted to identify the role of radical species in the photocatalytic process. The photocatalytic process revealed that the equilibrium data aligns well with the Langmuir‐Hinshelwood kinetic model. A rate constant of 0.03486 min−1 was obtained. The photocatalyst demonstrated excellent recyclability, maintaining efficiency and structural integrity over five cycles. The photocatalytic experiment results also have been confirmed by a density functional theory (DFT) calculation.

Sustainable removal of methylene blue dye from textile effluents by magnetized Tea waste and Peanut shells

Methylene blue finds numerous applications across various industries but its prolonged exposure to living organisms can result in significant health risks. In this study, the adsorption of magnetized Peanut shells and Tea waste for methylene blue dye removal has been reported. The biosorbents were synthesized by co-precipitation method and their suitability for methylene blue adsorption was confirmed through characterization techniques including Scanning Electron Microscope, Fourier Transfer Infrared Spectroscopy and X-Ray Diffraction analysis. After optimizing for pH (8.0), temperature (312 k), biosorbents dosage 25 mg/L with contact periods (35 min for Tea waste@Fe3O4 and 40 min for Peanut shells@Fe3O4), and initial methylene blue concentrations (5 ppm), the removal percentages of 95.88 % for Tea waste@Fe3O4 and 84.11 % for Peanut shells@Fe3O4 were achieved effectively. The equilibrium data for MB dye adsorption fitted well with the Langmuir model (R2 = 0.99) for Tea waste@Fe3O4 which indicated the formation of monolayer formation of adsorbate at the surface of adsorbent and the Freundlich model (R2 = 0.98) for Peanut shells@Fe3O4 confirmed the multilayers formation of MB dye at the material surface. Kinetic studies specified that both Tea waste@Fe3O4 (R2 = 0.99) and Peanut shells@Fe3O4 (R2 = 0.99) followed the pseudo-second order. Thermodynamic analysis showed that the adsorption process on Tea waste@Fe3O4 and Peanut shells@Fe3O4 was spontaneous (−ΔG) and endothermic. Tea waste@Fe3O4 exhibited ΔH (27.97 kJ/mol) and entropy ΔS (93.69 kJ/mol) while ΔH = 208.9 kJ/mol and ΔS 62 kJ/mol were found for Peanut shells@Fe3O4. The performance of the proposed biosorbent in industrial effluent demonstrated their effectiveness, highlighting their potential as a cost effective and sustainable solution for wastewater treatment.

Photodegradation, kinetics and non-linear error functions of methylene blue dye using SrZrO3 perovskite photocatalyst

The degradation of methylene blue dye-contaminated wastewater via photocatalysis is an efficient approach towards environmental remediation. The SrZrO3 perovskite photocatalyst was synthesized using the modified Pechini sol-gel method, and characterized using XRD, FESEM, FTIR, and UV–visible spectrophotometer. Crystallite size obtained by the Scherrer and Williamson-Hall methods were 45.56 and 44.50 nm, respectively. The sample exhibited an orthorhombic crystal structure. The optical bandgap was estimated to be 5.31 eV. Kinetic study for the degradation of methylene blue dye using SrZrO3 in the presence of H2O2 showed complete decontamination of the methylene blue dye in the time interval of 90–120 min under visible light irradiation. The degradation efficiency was above 80.1 % under illumination and less than 40.1 % in dark. Kinetic studies were performed by varying the dose of photocatalyst and initial concentration of methylene blue. It was observed that higher dose of the photocatalyst and lower concentration of the contaminant produced higher rate of degradation. The solution pH 3 and catalysts dosage of 200 mg yielded the highest rate of degradation. The experimental data fitted best into the Psuedosecond order kinetic model with the highest R2 value, indicating a strong linear relationship. The experimental data was subjected into nonlinear error functions, where the Psuedo-second order kinetic model demonstrated lower values of error functions. The results suggest that the prepared SrZrO3 photocatalyst coupled H2O2 is a promising photocatalyst for the decontamination of methylene blue dye under visible light irradiation.