Initial Dye Concentration Research Articles

Synthesis and characterization of zinc ferrite nanoparticles@GO for the photocatalytic degradation of Methylene Blue dye under visible light

Due to rising environmental pollution, there has been a growing focus on photo degradation catalysts for pollution removal. Under visible light irradiation, methylene blue dye (MB) photocatalytic degradation has been studied using Zinc ferrite nanoparticles (ZnFe2O4 NPs) and Zinc ferrite nanoparticles/graphene oxide (ZnFe2O4/GO). Methylene blue dye is a carcinogenic pollutant that poses risks to both humans and marine life. The synthesis of ZnFe2O4/GO was achieved by the biotemplating method. Synthesized nanoparticles were loaded on graphene oxide (GO) in different ratios (Zn1:GO1, Zn1:GO3, and Zn1:GO5). Nanocomposite characterization was done utilizing Raman Spectroscopy analysis, FT–IR, XRD, BET, FE-SEM–EDX, XPS, and TEM. The confirmation of the cubic spinel structure of ZnFe2O4 NPs has been validated uniformly distributed on the surface of the GO sheets. The vigorous interaction between ZnFe2O4 NPs and graphene sheets facilitates rapid electron mobility, enhancing electron separation and holes in photocatalytic applications. The aforementioned parameters are crucial in MB’s photocatalytic degradation performance. Photocatalytic degradation processes depend on pH solution, initial dye concentration, and catalyst dosage. The outcomes demonstrated that augmenting the proportion of graphene oxide amplified MB photo degradation. Under the optimum conditions of 1 g/L dose, pH 8, 10 mg/L initial dye concentration, and 180-min irradiation time, the degradation ratio increased to 51.17 %, 59.70 %, 89.49 %, and 97.38 % using ZnFe2O4, Zn1:GO1, Zn1:GO3, and Zn1:GO5, respectively. Based on the photo degradation process, GO exhibited superior photocatalytic performance at the highest concentration. The kinetics data showed that the photo degradation reaction adheres to the pseudo-second-order. The study indicated that the eco-friendly, non-toxic photocatalyst ZnFe2O4/GO can be used as an effective potential substance for water treatment as well as the elimination of hazardous organic dyes from aqueous solutions.

Efficient removal of Rhodamine-B dye using sulfonated/un-sulfonated three-dimensional mesoporous carbon nitride prepared from KIT-6 template: kinetics, modelling, thermodynamic analysis

Mesoporous carbon nitride (MCN-K) was prepared using mesoporous KIT-6 material as a template and ethylenediamine and carbon tetrachloride as N and C sources, respectively. The synthesized MCN-K was treated with sulfuric acid under different experimental conditions, thus obtaining sulfonated MCN-KS adsorbents. The effects of initial solution pH, initial dye concentration, adsorbent amount, and temperature on Rhodamine-B (Rh-B) dye removal were investigated. The XRD, FT-IR, and N2 adsorption–desorption analyses confirmed that the mesoporous carbon nitride structure was successfully synthesized. The high nitrogen content (C/N molar ratio: 4.0) of the MCN-K sample was confirmed by (carbon, hydrogen, nitrogen and sulfur) CHNS elemental analysis. The XPS analysis was used to characterize the chemical states of the C, N and S atoms in the MCN-K and MCN-KS sorbents. It was found that there was not much difference between the removal percentages (93.13–89.92%) obtained in the pH range (4–12) studied. This result was attributed to the zwitter-ion form of Rh-B. The exothermic nature of the adsorption process of Rh-B on the MCN-K sorbent was determined by adsorption experiments performed at different temperatures. Adsorption capacities obtained from the Langmuir model were 185.2–104.2 mg/g in the studied temperature range. The kinetic behavior of the adsorption process was explained by the pseudo-second-order kinetic model in terms of both correlation coefficients (R2 > 0.91) and qe (35.59–190.26 mg/g) values. When the percentages of dye removal of the un-sulfonated and sulfonated samples were compared, it was found that sulfonation increased the adsorption rate considerably but did not contribute positively to the dye removal percentage.

Electrochemically deposited zinc oxide films on stainless steel for photo degradation of Basic Red 18 dye

<p style="margin-top:8px; margin-bottom:8px; text-align:justify"><span style="font-size:11pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman",serif">In this</span></span></span><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman",serif"> study, zinc oxide (ZnO) films have been electrochemically deposited on stainless steel and its photocatalytic activity on the degradation of BR 18 dyes was tested. The effects of different electrodeposition conditions such as deposition potential and deposition time on the nanostructures of ZnO films were investigated in detail and the best electrodeposition conditions were optimized. The electrochemical, structural and morphological, were characterized by cyclic voltammetry (CV), chronoamperometry, X-ray diffraction (XRD), scanning electron microscope (SEM), respectively. The best removal efficiency was 37% at -1.2 V, and increased up to 53% after 300 sec coating. The number of electrodes (1, 2, 3 and 4 coatings) and dye concentration (5, 10, 15 mg/L) covered with -1.2 V potential and the coating synthesized in 300 seconds were studied. A complete removal was obtained when the number of electrodes covered was 4 and at 5 mg/L initial dye concentration. The number of reuses was tested up to 5 cycles. ZnO coatings on stainless steel that were electrochemically charged showed good photocatalytic stability. </span></span></span><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman",serif">Because ZnO films have both economic and environmental advantages, it is imperative that they can be synthesized using environmentally benign processes and used in photocatalysis. This novel strategy provides a chance to utilize ZnO film photocatalytic characteristics for a range of environmental remediation applications in addition to providing a sustainable wastewater management solution.</span></span></span></span></span></span></p>

Fabrication of a reusable carbon quantum dots (CQDs) modified nanocomposite with enhanced visible light photocatalytic activity

In awareness of industrial dye wastewater, carbon quantum dots (CQDs) and cobalt zinc ferrite (CZF) nanocomposites were synthesised for the making of carbon quantum dots coated cobalt zinc ferrite (CZF@CQDs) nanophotocatalyst using oxidative polymerization reaction. The results of TEM, zeta potential value, and FTIR confirm highly dispersed 1–4 nm particles with the − 45.7 mV carboxylic functionalized surface of CQDs. The results of the synthesised CZF@CQDs photocatalyst showed an average particle size of ~ 15 nm according to TEM, SEM, and XRD. The photocatalyst showed a 1.20 eV band gap, which followed the perfect visible light irradiation. TGA and DTA revealed the good thermal stability of the nanophotocatalyst. VSM was carried out, and the saturation magnetisations for CZF and CZF@CQDs were 42.44 and 36.14 emu/g, respectively. A multipoint study determined the BET-specific surface area of the CZF@CQDs photocatalyst to be 149.87 m2/g. Under visible light irradiation, the final CZF@CQDs nanophotocatalyst demonstrated remarkable efficiency (~ 95% within 25 min) in the photocatalytic destruction of Reactive Blue 222 (RB 222) and Reactive Yellow 145 (RY 145) dyes, as well as mechanical stability and recyclability. Even after the recycling of the degradation study, the nanophotocatalyst efficiency (~ 82%, 7th cycles) was predominantly maintained. The effects of several parameters were also investigated, including initial dye concentration, nanophotocatalyst concentration, CQD content, initial pH of the dye solution, and reaction kinetics. Degradation study data follow the first-order reaction rate (R2 > 0.93). Finally, a simple and low-cost synthesis approach, rapid degradation, and outstanding stability of the CQD-coated CZF nanophotocatalyst should make it a potential photocatalyst for dye wastewater treatment.

Enhanced Dye Adsorption on Cold Plasma-Oxidized Multi-Walled Carbon Nanotubes: A Comparative Study.

The oxidation of multi-walled carbon nanotubes (MWCNTs) using cold plasma was investigated for their subsequent use as adsorbents for the removal of dyes from aqueous solutions. The properties of MWCNTs after plasma modification and their adsorption capacities were compared with pristine and chemically oxidized nanotubes. The modification process employed a reactor where plasma was generated through dielectric barrier discharges (DBD) powered by high-voltage nanosecond pulses. Various modification conditions were examined, such as processing time and pulse voltage amplitude. The degree of oxidation and the impact on the chemistry and structure of the nanotubes was investigated through various physicochemical and morphological characterization techniques (XPS, BET, TEM, etc.). Maximum oxidation (O/C = 0.09 from O/C = 0.02 for pristine MWCNTs) was achieved after 60 min of nanopulsed-DBD plasma treatment. Subsequently, the modified nanotubes were used as adsorbents for the removal of the dye methylene blue (MB) from water. The adsorption experiments examined the effects of contact time between the adsorbent and MB, as well as the initial dye concentration in water. The plasma-modified nanotubes exhibited high MB removal efficiency, with adsorption capacity proportional to the degree of oxidation. Notably, their adsorption capacity significantly increased compared to both pristine and chemically oxidized MWCNTs (~54% and ~9%, respectively). Finally, the kinetics and mechanism of the adsorption process were studied, with experimental data fitting well to the pseudo-second-order kinetic model and the Langmuir isotherm model. This study underscores the potential of plasma technology as a low-cost and environmentally friendly approach for material modification and water purification.

Modified starch as a component of environmentally friendly polymer adsorbents − from synthesis and characterization to potential application in the removal of toxic C.I. Basic Yellow 2 dye

Increasing global degradation of the aquatic environment is forcing the search for new and low-cost adsorbents of reduced toxicity, derived from natural and renewable sources. To meet these expectations, a new approach to adsorbent fabrication was developed.The study aimed to synthesize, characterize, and apply environmentally friendly adsorbents based on poly(ethylene glycol dimethacrylate-co-vinyl acetate) (EGDMA-VA) with unmodified/modified starch (St). The first step proposed a new mechanochemical method of starch modification using thiourea (T) and potassium dihydrogen phosphate (P). Then, the functionalized starch was used to obtain polymeric microspheres. The final step involves their application for the removal of toxic C.I. Basic Yellow 2 (BY2) dye. The pristine materials and adsorbents were characterized by ATR/FT-IR and XPS, DSC, SEM/EDX, porous structure, particle size distribution, tendency to swell, and pHpzc.Adsorption batch studies of BY2 as a function of time (1–60 min), initial dye concentration (1–25 mg/L, pH=8.3), temperature (298–328 K), and competing electrolyte (5–15 g/L Na2SO4) and surfactant (0.1–0.5 g/L CTAB) presence were carried out. The kinetic studies were analyzed using pseudo-first order, pseudo-second order, and intraparticle diffusion models. The equilibrium studies revealed that the Freundlich isotherm model (kF=5.62–6.56 mg1-1/n L1/n) described BY2-adsorbents systems rather than Langmuir, Temkin or Dubinin-Radushkevich. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) pointed to the exothermic nature of adsorption and its spontaneousness. Importantly, the starch-modified microspheres were regenerated, too.

Potential Conversion of Coconut Husk-Waste to Magnetic Cellulose Designed for Synthetic Dye Removal

Increasing concern about sustainability and environmental issues caused by the massive amount of solid biomass waste in Indonesia has driven efforts to develop new products for various endues applications in energy, environment, and health sectors. This study uses coconut husk as the cellulose source to fabricate magnetic cellulose (MC) via coprecipitation with iron chloride salts. Combining cellulose with magnetite nanoparticles aims to improve the removal rate of synthetic dye as the latter provides high catalytic activity in the Fenton degradation process to eliminate persistent pollutants. The paramagnetic characteristics that MC possesses also make them quickly recovered after use. The adsorption capacity is found at 252.2 mg/g (pH 7, temperature of 30°C, the dye initial concentration of 100 ppm, and the precursor mass ratio of 1:4.8:25) for Rhodamine-B. The dye mineralization in this condition also reaches 50%, indicating that this adsorbent can be used as an efficient material to adsorb and degrade dye from an aqueous solution. This magnetic adsorbent will be of immense potential application for removing organic contaminants, particularly synthetic dyes, due to its good performance, simple separation, and ability to perform both adsorption and degradation processes simultaneously.

Synthesis of iron loaded jackfruit peel biochar through microwave heating as a stable and active heterogenous Fenton catalyst for dye degradation

Iron-loaded biochar derived from jackfruit peels (Fe-JP) was synthesised by pyrolysis in a microwave furnace and iron was loaded onto the peels prior to pyrolysis, facilitated by sonication. The primary objective of the investigation was to examine the degradation process of methylene blue (MB) dye and Acid Red 1 (AR1) dye by the using Fe-JP biochar as a heterogeneous Fenton catalyst. The investigation encompassed an examination of the impact of different operating parameters, such as pH, catalyst dosage, and H2O2 concentration. The synthesised Fenton catalyst underwent characterization using Field Emission scanning electron microscopy (FESEM), Energy Dispersive X-ray (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques, Fourier transform infrared (FTIR) spectra analysis, Raman spectroscopy, Brunauer-Emmet-Teller (BET) analysis. At a pH of 3, using an initial MB dye concentration of 20 mg/L and initial AR1 dye concentration of 50 mg/L, an 8 mM H2O2 concentration, and a catalyst dose of 2 g/L, the maximum dye removal efficiency reached 96.5 % and 98 % respectively, while the total organic carbon (TOC) removal efficiency reached 68.5 % and 75 % respectively. The observed reaction time under the given experimental conditions was 120 min. The thermal stability of the biochar catalyst was found to be excellent based on the Thermogravimetric analysis (TGA) and Differential Scanning Calorimeter (DSC) studies. The catalysts that were developed demonstrated remarkable durability and negligible leaching of iron, hence enabling their repeated usage in subsequent cycles. The findings of the investigation suggest that the primary mechanism responsible for the degradation of the dye was the surface-based heterogeneous Fenton activity. Additionally, the effect of adsorption on the elimination of colour under varying pH conditions was examined, which had a very low influence in dye degradation (<30 %). The conducted scavenging investigations in the research have indicated the major involvement of hydroxyl radicals (OH) in the degradation process, followed by surface-bound hydroxyl radicals (OHsurface), superoxide radicals (O2−) and ultimately by singlet oxygen radicals (1O2). The study's economic analysis demonstrated that using microwave mode of heating for catalyst synthesis is both green and cost-effective. This observation suggests the possibility of practical implications in the domain of dye degradation.

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

Effect of KOH- and NaOH-modified fly ash on the adsorption of methylene blue and crystal violet dyes: a Box-Behnken design study

ABSTRACT Coal Fly Ash (FA) and modified fly ash (mFA), treated with either KOH or NaOH, were used to remove methylene blue (MB) and crystal violet (CV) dyes from aqueous solution. Several techniques, including Thermogravimetric analysis, X-Ray diffraction analysis, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller, and Scanning Electron Microscopy, were used to characterise both FA and mFA. To optimise the adsorption process, the Response Surface Methodology (RSM) with the Box – Behnken design (BBD) was applied. Key parameters such as solution pH (4–10), initial dye concentration (200–300 mg/L), contact time (15–180 minutes), and temperature (30–50°C) were varied to assess their impact on adsorption efficiency. The adsorption followed the Langmuir model and pseudo-second-order (PSO) kinetic model. The adsorption capacity of mFA for MB dye was 49.5 mg/g at 50°C, while for CV dye, it was 495.5 mg/g at the same temperature. The adsorption mechanism involved electrostatic attraction, n-π interaction, Yoshida hydrogen bonding, and hydrogen bonding. These results highlight the effectiveness of mFA as a high-capacity adsorbent for treating MB and CV dyes in water solutions.

Hibiscus leaf petiole derived activated carbon as a potential sorbent for basic green 4 and reactive yellow 15 dye exclusion from aqueous solution

In this study, hibiscus leaf petiole powder is used as a source of carbon to prepare bio-adsorbent. This bio-adsorbent is carbonized by heating and activated thereafter by means of KOH and employed as an alternative adsorbent for Basic Green 4 (BG4) and Reactive Yellow 15 (RY15) dyes. Microstructural features observed from scanning electron microscope (SEM) shows the presence of openings/voids before adsorption and their disappearance after dye adsorption. Fourier transform infrared (FTIR) spectrum shows the shift in peak positions of prominent functional moieties post adsorption endorsing the contact between bio-adsorbent and the dye molecules. The dye adsorption performance of as prepared bio-adsorbent on both the dyes were evaluated by varying the solution pH value between 3 and 9, initial dye concentration, Co between 30–90 mg/L, interaction time, t between 10 and 60 min and adsorbent dose, m between 0.1 and 0.6 g/50 ml. The optimal condition investigated for dye exclusion is computed to be Co = 30 mg/L, t = 40 min, m = 0.3 g for both the dyes. However, the pH values of 9 and 3 respectively were found to be optimum for the removal of BG4 and RY15. Maximum adsorption capacity (qm) for RY15 and BG4 were found to be 41.23 and 61.38 mg/g respectively revealing hibiscus leaf derived activated carbon as an excellent bio-adsorbent. The adsorption kinetics of both dyes followed pseudo-second-order model and the adsorption isotherms is best suited to Langmuir model. These findings confirm that the as prepared bio-adsorbent can be successfully employed as an unconventional adsorbent to remove the toxic dyes from aqueous solutions.

Adsorption kinetics and thermodynamics of metal complex acid dyes on silk fabric

This study reports the adsorption phenomena of metal complex acid dyes onto silk fabric. Two commercial metal complex acid dyes namely Bestalan Yellow SF and Bestalan Navy SF were adsorbed onto degummed silk fabric. The functional properties and surface morphology of silk fabric were investigated with FT-IR spectroscopy and FE-SEM respectively. The typical absorption band of C = O stretching was found at 1620 cm−1 indicating amide I structure and C-N stretching as well as N-H bending vibrations were observed at 1510 cm−1 suggesting the β-sheet crystallites of amide I and amide II silk proteins. The effectiveness of degumming performance was confirmed by SEM images. The adsorption of dyes by silk fabric was investigated with respect to pH, initial dye bath concentration, and contact time. It was found that the adsorption of dye onto silk fabric was highly influenced by the dye bath pH, initial dye concentration, and contact time. The higher dye adsorption was observed at acidic dye bath condition (pH = 3.5). The adsorption of dye was also increased with the increase of the initial dye bath concentration. The dyes adsorption reached at equilibrium condition after 80 min. The adsorption isotherm and kinetics were also evaluated based on the experimental results. The adsorption pattern fitted well to the Langmuir adsorption isotherm with high correlation coefficient (R 2>0.97) for both dyes. The kinetic parameters suggested that the pseudo-second-order model is more suitable compare to the pseudo-first-order model considering the higher regression coefficients ( R 2 = ∼ 0.99 ) . The maximum adsorption of Bestalan Yellow SF and Bestalan Navy SF was found to be 232.5 and 222.2 mg/g respectively. The thermodynamic data were studied at 25, 40 and 60 °C. The change of Gibbs free energy of the system was positive indicating the spontaneous nature of the adsorption. The values of ΔH (-4.68 kJ/mole −3.65 kJ/mole) suggested the exothermic environment and the negative values of ΔS (-0.035 and −0.034 kJ/mole/k) advocated the good interaction between the metal complex acid dyes and silk fabric. The Langmuir adsorption model and pseudo-second-order kinetic suggested that the dyeing of metal complex acid dyes on silk fabric was controlled by ion-exchange chemical reaction.

Efficient removal of Methylene blue dye from aqueous medium utilizing eco-friendly chitosan adsorbents

ABSTARCT Dyes released through various industrial operations are a major threat to the environment. The recent study introduced an eco-friendly adsorbent based on the grafting of phenolic acids (caffeic and/or gallic acids) on chitosan to reduce the hazardous impact of color effluent pollution. The morphology and structure of synthesized adsorbents were confirmed by physical and chemical tools such as TGA, FTIR, SEM, EDX, point of zero charge, water regain, and resistance of adsorbents to dissociation in acidic media. The synthesized adsorbents’ removal efficiency toward MB dye, a model cationic organic pollutant, from aqueous medium was evaluated. The factors impacting dye adsorption were investigated, including pH, dye initial concentration, and temperature. The response surface methodology (RSM) was used to confirm the interaction effects of the process variables and optimize the ideal conditions of adsorption. The maximum adsorption capacity was 257.0 and 391.8 mg/g for AI and AII, respectively, at initial MB concentration of 550 ± 1 mg/L, pH 8, and 21 ± 1 °C. MB adsorption is an exothermic chemosorption process that takes place via electrostatic attraction in an alkaline medium. Both AI and AII demonstrated significant reuse ability when eluted with a 0.5 M HCl solution.

Continuous Remediation of Congo Red Dye Using Polyurethane-Polyaniline Nano-Composite Foam: Experiment and Optimization Study

This study employed an innovative approach, utilizing prepared dried polyurethane-polyaniline nano-composite, through in-situ polymerization, for continuous remediation of Congo red dye. Response Surface Methodology (RSM) based on the Box-Behnken design (BBD) model was utilized to optimize the processing parameters, including initial dye concentration, flow rate, and pH. The two-factor interaction (2FI) model emerged as the most significant, highlighting the influence of individual and interaction effects of the factors. Optimization of the dye remediation process yielded the optimal conditions of a flow rate of 10 mL/min, acidic pH of 5.00, and dye concentration of 20 mg/L, resulting in an impressive, predicted removal efficiency of 99.09% agreeing with the experimental value. Moreover, the maximum adsorption capacity was determined to be 329.68 mg/g. Characterization of the adsorbent material involved techniques such as Scanning electron microscopy (SEM), Fourier transforms infrared spectra (FTIR), X-ray spectroscopy (XRD), and Zeta potential analysis. This material offers a sustainable alternative in industries to treat Congo red dye before being disposed of into the environment.

Green Synthesis of MgO Nano Particle Loaded Onto Carbon for Effective Rhodamine B Dye Removal

ABSTRACTIn this study, Rhodamine B dye (RhB) is effectively removed from aqueous solutions by using nano‐MgO and nano‐MgO activated carbon as an adsorbent. First, potassium hydroxide was used in a chemical activation process to create activated carbon from the Anacardium occidentale shell, often known as the cashew nutshell. Rosa cymose extract was used in a quick precipitation process to create nano‐magnesium oxide in a sustainable way. Activated carbon composite impregnated with nano‐magnesium oxide was made using a dropwise process. The study examined the nanocomposite that removed the dye Rhodamine B from the aqueous solution. Using SEM, XRD, FTIR, and EDX, the nano‐Mgo and nano‐MgO‐AC were analyzed. Using a scanning electron microscope, an analysis was conducted on the evenly distributed accumulation of MgO nanoparticles added to the activated carbon. The capability of nano‐MgO‐activated carbon to decolorize RhB was investigated. The effects of beginning pH ranges of 2.0–9.0, initial dye concentrations of 10–40 ppm, biosorbent dosages of 0.2–1.2 g, and contact times ranging from 10 to 60 min were investigated. At pH 5, most dye was eliminated. The work has shown that RhB may be effectively removed from aqueous medium using nano‐MgO‐AC, it could potentially be used as an affordable adsorbent material. Equilibrium estimations were acknowledged strongly through Langmuir approximations with a correlation determination of 0.985.

SOFT MODIFICATION AND FUNCTIONALIZATION OF LIGNOCELLULOSIC BIOMASS USED AS A LOW-COST EFFICIENT BIOSORBENT TO REMOVE BASIC FUCHSINE FROM AQUEOUS SOLUTION

This study proposes a new modification of lignocellulosic biomass based on apricot kernel shells with composite activation KI/KOH and functionalized with a tolerant material (MgO) powder. Apricot kernel shells (NAK), modified apricot kernel shells (MAK) and doped apricot kernel shells (DAK) obtained were characterized using various methods, such as infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and point of zero charge (pHpzc). The adsorbents were also evaluated in batch adsorption, using basic fuchsine dye (BF) to determine the performance and specific capacity of the adsorption process. The results showed that only 90 min and 0.1 g of DAK or MAK are sufficient to remove 93% and 91%, respectively, of basic fuchsine from aqueous solutions with a concentration of 20 mg/L in a volume of 100 mL. The MAK and DAK adsorbents can be reused for 5 cycles before their yield decreases below 50%, without requiring complex regeneration procedures, only drying for 4 h at 105°C. The evolution of adsorption was analyzed under different parameters, such as contact time, initial dose of adsorbent, initial dye concentration, initial pH, and temperature. The kinetic adsorption models indicate that the pseudo-second-order model was more suitable than the pseudo-first-order and intraparticle diffusion models for describing the adsorption process. The equilibrium adsorption data of BF were better fitted by the Langmuir isotherm, compared to the Freundlich and Temkin isotherms.

Investigation of Eucalyptus camaldulensis and Tamarix aphylla species' capacities for methylene blue removal in wastewater and heavy metal remediation in soil.

In the contemporary landscape, the reuse of wastewater holds paramount significance. Concurrently, wastewater carries an array of pollutants encompassing chemical dyes and heavy metals. This study delves into the potential of Tamarix aphylla (TA) and Eucalyptus camaldulensis (EC) species for mitigating heavy metals in soil and eliminating methylene blue dye (MB) from wastewater. The research begins with assessing the dye adsorption process, considering pivotal factors such as initial pH, adsorbent dosage, initial dye concentration, and contact time. Outcomes reveal EC's superiority in dye removal compared to TA. As a bioremediation agent, EC exhibits a 90.46% removal efficacy for MB within 15 min, with pH 7.0 as the operative condition. Equilibrium analysis employs Temkin (T), Freundlich (F), and Langmuir (L) isotherms, revealing an excellent fit with the L isotherm model. The study delves further by probing surface adsorption kinetics through pseudo-first-order (PFO) and pseudo-second-order (PSO) models. Furthermore, to discern the divergent impacts of EC and TA on soil heavy metal reduction, soil samples were collected from three distinct zones: an untouched control area, alongside areas where EC and TA were cultivated at the Yazd wastewater site in Iran. Heavy metal levels in the soil were meticulously assessed through rigorous measurement and statistical scrutiny. The findings spotlight TA-cultivated soil as having the highest levels across all examined factors. Ultimately, EC emerges as the superior contender, proficiently excelling in both MB eliminations from wastewater and heavy metal amelioration in the soil, positioning it as the preferred phytoremediation agent.

Study of the adsorption mechanism of certain dyes from wastewater on commercial activated carbon using the Langmuir and Freundlich methods

In today's society, there is significant emphasis on environmental protection, with research focused on reducing pollution and developing effective depollution techniques. A growing concern is the presence of colored discharges in wastewater, which contain high levels of toxic substances that pose substantial risks to ecosystems. To mitigate these risks, various methods are employed to remove pollutants from industrial effluents, with adsorption being one of the most effective. Among the adsorbents used, activated carbon is the most commonly utilized due to its high surface area and adsorption capacity. This study aims to enhance the understanding of how two organic dyes, Methyl Red and Methylene Blue, can be removed from aqueous media through adsorption onto commercial activated carbon. The adsorption kinetics and isotherms were employed to elucidate the mechanisms involved in the elimination of these dyes from water. The kinetics were investigated using a stirred reactor, with experiments designed to vary parameters such as the initial dye concentration, the mass of the adsorbent, and the contact time. The experimental data were modeled using kinetic equations of first and second order. The results indicated that the adsorption of both Methyl Red and Methylene Blue onto activated carbon followed a pseudo-second-order kinetic model, as evidenced by large regression coefficients, signifying a good fit. This suggests that the adsorption process is likely controlled by chemisorption, involving valency forces through sharing or exchange of electrons between adsorbent and adsorbate. Additionally, the adsorption isotherms were analyzed to further understand the adsorption mechanisms and capacity. The results showed that the adsorption of both dyes onto commercial activated carbon conformed well to the Freundlich isotherm model. This model implies that adsorption occurs on a heterogeneous surface with a non-uniform distribution of adsorption heat over the surface. Overall, this study provides valuable insights into the adsorption behavior of Methyl Red and Methylene Blue on activated carbon, highlighting the effectiveness of this adsorbent in removing organic dyes from wastewater. The findings underscore the potential of using commercial activated carbon in the treatment of industrial effluents, contributing to the development of more efficient and sustainable water purification methods.

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.

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.