Initial Dye Concentration Research Articles

Construction of heterojunction superparamagnetic Cd0.5Ag0.5Fe2O4 nanocomposite photocatalyst for simulated textile effluent oxidation

Abstract Significant attempts have been recently made regarding nanomaterials due to their several environmental applications especially in wastewater treatment technologies. Among the available nanoparticles, ferrite based substances are gaining a special interest since their superior characteristics such as their magnetic nature, high adsorption capacity and large specific surface area. In this regard, Cd0.5Ag0.5Fe2O4 was prepared using the green simple co-precipitation route. Then, the sample is characterized via Scanning Electron Microscopy (SEM) that proved the produced material’s surface morphology. The substance is then employed as a catalyst source for Fenton reaction to oxidize textile effluent solution containing Rhodamine B (Rh-B 6G) dye. The oxidation experiment conducted under ultraviolet (UV) light with the ferrite-based Fenton catalyst supplemented with hydrogen peroxide showed an exceptional removal rate of up to 94% removals. Notably, the oxidation system is significantly impacted by the operational variables. The oxidation efficiency of the dye was maximized at pH 3.0 and 50 mg/L and 1600 mg/L for ferrite-based Fenton catalyst and H2O2, respectively. The impacts of the operational factors, i.e. initial pH value, initial dye concentration, catalyst, and H2O2 concentrations were also investigated. This perspective introduces the role of a superparamagnetic material to be a recyclable sustained catalyst.

Adsorption and kinetic studies of dyes onto BaFe12O19 Ferrite Nanoparticles

Abstract In this work, Barium hexaferrite (BaFe12O19) nanoparticles were used for industrial waste water treatment from methylene blue (MB) and congored (CR) dyes. Batch adsorber with mechanical stirring column was used to test various experimental parameters like contact time, initial dye concentration and adsorbent dosage for the removal of these dyes. For the removal of MB and CR dyes using magnetic nanoparticles, the maximum adsorption capacities were 200 and 124.5 mg/g respectively. The maximum removal efficiencies were 90 % for MB removal onto the nanoparticles and 80% for CR removal. In order to analyze the kinetic data, pseudo first and second order kinetic models have been used. For all studied variables and based on correlation coefficient (R) values and graphical presentation, the results confirm that pseudo second order model fits well the experimental data.

Reuse and Recovery of Water from Industrial Textile Dyeing Effluent Using High-Performance Electrodes Continuous Flow Electrocoagulation Reactor

The dye effluents released from the textile and printing industries contain strong colorants, inorganic salts, and other toxic compounds. The conventional coagulation technique of dye effluent treatment is plagued with issues of low removal rate of color, generation of large quantities of sludge, and toxic end-products. Recently electrocoagulation technique gained immense attention due to its high efficiency. This technique involves the dissolution of the sacrificial anodes to provide an active metal hydroxide as a strong coagulant that destabilizes the pollutants and removes them by precipitation or flocculation. This study is about the efficiency of the electrocoagulation process using titanium coated - aluminum and mild steel electrodes to treat industrial dye wastewater. Effects of parameters such as current density & initial dye concentration were investigated. It was observed that, for the same current density, electrode consumption was higher with TiO2/Al electrode than with mild steel electrode, resulting in more color removal efficiency (CRE) using TiO2/Al electrode. The settling rate of the flocs was higher in the rector having TiO2/Al electrode at the 100 mL with current density (2.5 mL.min-1 to 5.3 mL.min-1), while in the reactor with mild steel electrode, the settling rate was very less. The results showed that dye removal was 95.11% and 92.1% for mild steel and titanium-coated electrodes, respectively. It was observed that 50 % of Aluminum was removed from the treated effluent after the final stage of filtration. Based on the multicriteria analysis to identify the optimum operational parameters to be applied at the field level, it was observed that maximum CRE may be obtained with TiO2/Al electrode and the applied current of 1 Amps with a flow rate of 100 mL.min-1. It can be concluded that electrocoagulation is a highly efficient and the fastest method to treat dye effluents from industries.

Alginate functionalized sugarcane cellulose-based beads to improve methylene blue adsorption from aqueous solution

The study was carried out with the goal of synthesizing composite bead of cellulose, chitosan functionalized by sodium alginate using as an efficient and applicable adsorbent for methylene blue removal. Fabricating parameters of the material synthesis process like cellulose mass, sodium hydroxide concentration, immersing time and sodium alginate concentration were assessed in detail. The dye adsorption performance in water under the influence of pH, contact time, dye initial concentration, the material mass, shaking speed, temperature was also thoroughly evaluated. The results of advanced analyses showed that the beads were successfully synthesized with a rough surface and mesoporous structure. The adsorption isotherm and adsorption kinetics of dye adsorption process exhibited that the process was consistent with the Freundlich adsorption isotherm and the pseudo-second-order kinetic model, indicating a favorable physical adsorption process with multilayer of the dye on the adsorbent surface. The intra-particle diffusion model showed the strong dye adsorption by the beads occurred during the first two and half hours. The adsorbent could maintain its adsorption performance of 86 % for three times of regeneration. Finally, this study provided a recyclable and effective adsorbent for dyes separation from water.

Utilization of macadamia nutshell-derived activated carbon for enhanced congo red adsorption

This study addresses the challenge of removing Congo red (CR) from aqueous solutions using activated carbon (AC) derived from macadamia nutshells (MNS). A unique two-step carbonization and pyrolysis process was employed to produce MNS-AC with high surface area and porosity. Key experimental variables, including initial CR concentration, contact time, and pH, were systematically varied in batch mode. Results indicated that the modified AC achieved significantly higher removal percentages compared to unmodified charcoal. At pH 2.0 and an initial dye concentration of 50 mg L−1, CR removal reached 97.48 % for MNS-AC3. The maximum adsorption capacity (qmax) of 58.29 mg g−1 was observed at an initial dye concentration of 200 mg L−1. The pseudo-second-order kinetic model closely matched the experimental data, and equilibrium data analysis using Langmuir and Dubinin-Radushkevich (D-R) isotherm models provided excellent fits. This research demonstrates the potential of using industrial biomass waste to develop sustainable solutions for dye removal in wastewater treatment.

Efficient three-dimensional electrochemical degradation of alizarin red by CeO2−MnO2/NF particle electrode synergized with ozone

In this study, nickel foam-loaded Mn and Ce bimetallic oxide composites were successfully synthesized as particle electrodes by a hydrothermal method and synergized with ozone for the efficient degradation of alizarin red (AR), a typical anthraquinone dye. The effects of common factors on the degradation rate of alizarin red were investigated. The optimal experimental conditions were derived as applied voltage = 3.5 V, initial pH = 5.5, NaCl concentration of 4.5 g/L, and initial dye concentration of 20 mg/L. The particle electrode had a high cyclic stability after five cycles. The active sites of the dye molecular structure were analyzed in combination with the Fukui function, and the degradation pathway of alizarin red was proposed on this basis. By comparing the degradation effect of alizarin red under three different systems of O3, 3DER and 3DER-O3, it was confirmed that the three-dimensional electrode has a good synergistic effect in conjunction with ozone. Finally, the degradation mechanism of alizarin red under the CeO2−MnO2/NF synergistic ozone system was derived, in which the single linear oxygen (1O2) played a major role in the degradation process.

Adsorption Properties and Mechanisms of Methylene Blue by Modified Sphagnum Moss Bio-Based Adsorbents.

The abundant pore structure and carbon composition of sphagnum peat moss render it a bio-based adsorbent for efficient methylene blue removal from wastewater. By utilizing sphagnum moss sourced from Guizhou, China, as raw material, a cost-effective and highly efficient bio-based adsorbent material was prepared through chemical modification. The structure and performance of the modified sphagnum moss were characterized using SEM, EDS, FTIR, and TGA techniques. Batch adsorption experiments explored the effects of contact time, adsorbent dosage, pH, initial dye concentration, and temperature on adsorption performance. Kinetics, isotherm models, and thermodynamics elucidated the adsorption behavior and mechanism. The modified sphagnum moss exhibited increased surface roughness and uniform surface modification, enhancing active site availability for improved adsorption. Experimental data aligned well with the Freundlich isotherm model and pseudo-second-order kinetic model, indicating efficient adsorption. The study elucidated the adsorption mechanism, laying a foundation for effective methylene blue removal. The utilization of modified sphagnum moss demonstrates significant potential in effectively removing MB from contaminated solutions due to its robust adsorption capability and efficient reusability.

Activation of Peroxymonosulfate using a novel heterogeneous catalyst SO-gCN@ZIF-67 for excellent degradation of Brilliant Green dye

This work presents a design of a novel heterogeneous catalyst, SO-gCN@ZIF-67, comprising Co-based MOF, ZIF-67, over a two-dimensional S and O co-doped graphitic carbon nitride nanosheet is reported. This novel heterogeneous SO-gCN@ZIF-67 catalyst is used to degrade organic polluting dyes by activating Peroxymonosulfate (PMS) at room temperature. Various analytical and spectroscopic techniques, such as PXRD, FT-IR, FE-SEM, EDS, HR-TEM, XPS, and UV-DRS, were employed to characterize the as-synthesized nano-catalyst. The as-prepared catalyst can activate PMS effectively to rapidly decolorize the Brilliant Green dye (BG dye) solution at room temperature. The catalyst SO-gCN@ZIF-67 showed high efficiency for PMS activation and decolorization of approximately 96.7 % BG dye with a catalyst concentration of 80.0 mg/L, which was achieved in 15 min. The degradation of the dye obeyed pseudo-first-order kinetics with a reaction rate constant of 0.2262 min−1. Further, the parameters that could influence the activation of PMS, such as the role of different catalysts, catalyst dosage, PMS dosage, and initial dye concentration, were also investigated. Radical trapping experiments revealed that O2− radicals and non-radical singlet oxygen, 1O2, were involved in the degradation of BG dye. A plausible mechanism for the degradation has been proposed using SO-gCN@ZIF-67 and the PMS system.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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

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

KINETIC, ISOTHERM AND THERMODYNAMIC STUDIES OF THE ADSORPTION OF CRESOL RED DYE USING AGRICULTURAL WASTES

Agricultural wastes and plant biomass are alternative low-cost adsorbents because they can be used without or with a minimum processing. In the present study, batch experiments were carried out to study the adsorption of cresol red (CR) unto mango leaf (ML) and orange peel (OP). Several parameters that affect adsorption process such as pH, adsorbent dosage, contact time, initial dye concentration and temperature were investigated. FTIR and SEM were used to determine the functional group responsible for adsorption. The results revealed that the highest adsorption efficiency was at pH 5 for the two adsorbents. It was also discovered that CR removal efficiency increased with the increase in contact time and adsorbent dosage while adsorption capacity was higher with increase in initial dye concentration but removal efficiency was lowered. The kinetics conform with the pseudofirst-order kinetic model for mango leaf but conform with the pseudo-second-order kinetic for orange mesocarp due to the value of the correlation coefficient (R2). Based on the value of correlation coefficient, the experimental results for the removal by mango leaf best fitted the Langmuir isotherm model with monolayer adsorption capacity of 70.64 mg. g-1, while Freundlich isotherm model was best fitted to the experimental results for the adsorption of CR by Orange peel. The thermodynamic results revealed that the process is spontaneous and endothermic.

Removal of congo red and malachite green from aqueous solution using ternary GO/Bi2O3/MgO materials by co-precipitation method

The present work describes the preparation of Bismuth oxide and magnesium oxide modified with graphene oxide (GO/Bi2O3/MgO) using the co-precipitation method for the elimination of malachite green (MG) and congo red (CR) dyes from aqueous solution. The synthesized GO/Bi2O3/MgO materials were analyzed by using FTIR, SEM, XRD, EDX and EDS. The batch experiment was aimed to investigate the adsorption process by varying various parameters of optimum value for CR and MG dye adsorption such as adsorbent dosage was 100 mg, contact time was 30 min, stirring speed was 250 rpm, initial dye concentration was 30 mg L−1 and pH was 6.5. From experimental data, we concluded that for elimination of MG and CR dye with higher coefficient value (R2) was best fitted with the Langmuir isotherm model. The maximum adsorption capacity was observed to be 45.454 mg/g for MG and 58.823 mg/g for CR, respectively. The mechanism of the adsorbent and both the dyes were explained by electrostatic interaction, π-π interaction, and hydrogen bonding. To check the stability of the GO/Bi2O3/MgO materials, we performed the reusability study using various solvents like methanol, ethanol, water, sodium hydroxide and acetone. Among various solvents, NaOH has shown maximum desorption of both dyes.

Enhancing hydrochar production and proprieties from biogenic waste: Merging response surface methodology and machine learning for organic pollutant remediation

The valorization of biogenic waste by hydrothermal carbonization is widely discussed in research. However, to our knowledge, no study has combined almond shells and olive pomace to synthesize a solid carbon material. The purpose of this study is to enhance the hydrochar process from AS and OP using RSM methodology and machine learning models: ANN, SVM and XG-Boost. Subsequently, a study was carried out on the removal of organic pollutants by the synthesized material. The optimum Co-HTC operating conditions obtained at 180 C, 90 min with acid catalyst corresponding to 71.51 % and 87.13 % for mass yield and carbon retention rate respectively according to RSM-CCD. The comparison between RSM-CCD and ML in terms of prediction concludes that RSM remains more efficient in terms of planning and optimization. However, ANN is more suitable for modeling and predicting mass yields and carbon retention rates. Hydrochar’s physicochemical properties were evaluated by the use of spectroscopic methods like FTIR, SEM, XRD, and CHNO. To conclude, we studied the performance of HCop in methylene blue adsorption, varying the following parameters: pH, contact time, initial dye concentration, adsorbent dose and temperature. In addition, kinetic and isothermal models were studied to describe the dominant mechanisms in the MB adsorption process. The MB maximal adsorption using HCop obtained at pH 9, with an initial dye concentration of 100 mg. L−1, 40-min contact time, 0.1 g/L adsorbent dose, and a temperature between 25 and 30 °C. In conclusion, these results provide important information on the use of Co-HTC to convert biogenic wastes into high-performance carbon materials for the appropriate removal of organic pollutants. More studies are needed to use the material in other fields of application.