Optimizing adsorptive removal of malachite green and methyl orange dyes from simulated wastewater by Mn‐doped CuO‐Nanoparticles loaded on activated carbon using CCD‐RSM: Mechanism,regeneration, isotherm,kinetic, and thermodynamic studies

In the present work, Mn‐doped CuO‐NPs‐AC was prepared by a simple method, characterized using various techniques such as FESEM, EDX, XRD, PSD, and pH_pzc and finally used for the adsorption of malachite green (MG) and methyl orange (MO) in a number of single and binary solutions. A series of adsorption experiments were conducted to investigate and optimize the influence of various factors (such as different pH, concentration of MG and MO, adsorbent mass, and sonication time) on the simultaneous adsorption of MG and MO using response surface methodology. Under optimal conditions of pH 10, adsorbent dose of 0.02 g, MG concentration of 30 mg L^?1, MO concentration of 30 mg L^?1, and sonication time of 4.5 min at room temperature, the maximum predicted adsorption was observed to be 100.0%, for both MG and MO, showing that there is a favorable harmony between the experimental data and model predictions. The adsorption isotherm of MO and MG by Mn‐doped CuO‐NPs‐AC could be well clarified by the Langmuir model with maximum adsorption capacity of 320.69 mg g^?1 and 290.11 mg g^?1 in the single solution and 233.02 mg g^?1 and 205.53 mg g^?1 in the binary solution by 0.005 g of adsorbent mass for MG and MO, respectively. Kinetic studies also revealed that both MG and MO adsorption were better defined by the pseudo‐second order model for both solutions. In addition, the thermodynamic constant studies disclosed that the adsorption of MG and MO was likely to be influenced by a physisorption mechanism. Eventually, the reusability of the Mn‐doped CuO‐NPs‐AC after six times showed a reduction in the adsorption percentage of MG and MO.     

Synthesis of CuS nanoparticles loaded on activated carbon composite for ultrasound‐assisted adsorption removal of dye pollutants: Process optimization using CCD‐RSM,equilibrium and kinetic studies

In this study, the CuS nanoparticles loaded on activated carbon (CuS‐NPs‐AC) composite was synthesized and then, characterized by XRD and FE‐SEM analyses. The prepared composite was used as a potential adsorbent for the simultaneous ultrasound‐assisted removal of Indigo Carmine (IC) and Safranin‐O (SO). The CuS‐NPs‐AC dose (0.01‐0.03 g), sonication time (1‐5 min), initial SO concentration (5‐15 mg L^‐1) and initial IC concentration (5‐15 mg L^‐1) as expectable effective parameters were studied by central composite design (CCD) under response surface methodology (RSM) to obtain an useful knowledge about the effect of simultaneous interaction between IC and SO on their removal percentage. The optimum SO and IC removal percentages were determined to be 98.24 and 97.15% at pH = 6, 0.03 g of the CuS‐NPs‐AC, 3 min sonication time, 12 and 10 mg L^‐1 of IC and SO. The values of coefficient of determination (R²) for SO and IC were 0.9608 and 0.9796, respectively, indicating the favorable fitness of the experimental data to the second order polynomial regression model. The isotherm data were well correlated with Freundlich model. The maximum monolayer adsorption capacities of 87.5 and 69.90 mg g^‐1 at room temperature for IC and SO in the investigated binary system expressed the high efficiency of the novel adsorbent for water cleanup within a short time. The investigation of correlation between time and rate of adsorption revealed that IC and SO adsorption onto the CuS‐NPs‐AC followed pseudo‐second‐order and intra‐particle diffusion simultaneously.     

Simultaneous removal of Cu2+ and Cr3+ ions from aqueous solution based on Complexation with Eriochrome cyanine‐R and derivative spectrophotometric method

TiO₂ nanoparticles deposited on activated carbon (TiO₂–NP–AC) was prepared and characterized by XRD and SEM analysis. Subsequently, simultaneous ultrasound‐assisted adsorption of Cu²⁺ and Cr³⁺ ions onto TiO₂‐NPs‐AC after complexation via eriochrome cyanine R (ECR) has been investigated with UV–Vis and FAA spectrophotometer. Spectra overlapping of the ECR‐Cu and ECR‐Cr complex was resolve by derivative spectrophotometric technique. The effects of various parameters such as initial Cu²⁺ (A) and Cr³⁺ (B) ions concentrations, TiO₂‐NPs‐AC mass (C), sonication time (D) and pH (E) on the removal percentage were investigated and optimized by central composite design (CCD). The optimize conditions were set as: 4.21 min, 0.019 mg, 20.02 and 13.22 mg L^?1 and 6.63 for sonication time, TiO₂–NP–AC mass, initial Cr³⁺ and Cu²⁺ ions concentration and pH, respectively. The experimental equilibrium data fitting to Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models show that the Langmuir model is a good and suitable model for evaluation and the actual behavior of adsorption process and maximum adsorption capacity of 105.26 and 93.46 mg g^?1 were obtained for Cu²⁺ and Cr³⁺ ions, respectively. Kinetic evaluation of experimental data showed that the adsorption processes followed well pseudo second order and intraparticle diffusion models.     

Comparative study of acid yellow 119 adsorption onto activated carbon prepared from lemon wood and ZnO nanoparticles loaded on activated carbon

Activated carbon from lemon wood (AC) and ZnO nanoparticles loaded on activated carbon (ZnO‐NP‐AC) were prepared and their efficiency for effective acid yellow 199 (AY 199) removal under various operational conditions was investigated. The dependence of removal efficiency on variables such as AY 199 concentration, amount of adsorbent and contact time was optimized using response surface methodology and Design‐Expert. ZnO nanoparticles and ZnO‐NP‐AC were studied using various techniques such as scanning electron microscopy, X‐ray diffraction and energy‐dispersive X‐ray analysis. The optimum pH was studied using one‐at‐a‐time method to achieve maximum dye removal percentage. Small amounts of the proposed adsorbents (0.025 and 0.025 g) were sufficient for successful removal of AY 199 in short times (4.0 and 4.0 min) with high adsorption capacity (85.51 and 116.29 mg g^?1 for AC and ZnO‐NPs‐AC, respectively). Fitting the empirical equilibrium data to several conventional isotherm models at optimum conditions indicated the appropriateness of the Langmuir model with high correlation coefficient (0.999 and 0.978 for AC and ZnO‐NPs‐AC, respectively) for representation and explanation of experimental data. Kinetics evaluation of experiments at various time intervals revealed that adsorption processes can be well predicted and fitted by pseudo‐second‐order and Elovich models. This study revealed that the combination of ZnO nanoparticles and AC following simple loading led to significant improvement in the removal process in short adsorption time which was enhanced by mixing the media via sonication.     

Synthesis and characterization of antibacterial chromium iron oxide nanoparticle‐loaded activated carbon for ultrasound‐assisted wastewater treatment

The aim of this study was to evaluate the surface adsorption capacity of CrFeO₃ nanoparticle‐loaded activated carbon (CrFeO₃‐NPs–AC) for the removal of a cationic dye (methyl violet, MV). CrFeO₃‐NPs were hydrothermally synthesized and loaded on AC followed by characterization using X‐ray diffraction, field‐emission scanning electron microscopy and energy‐dispersive and Fourier transform infrared spectroscopies. The CrFeO₃‐NPs were tested for in vitro antibacterial activities against Gram‐positive (Staphylococcus aureus) and Gram‐negative (Pseudomonas aeruginosa) bacteria. Minimum inhibitory and minimum bactericidal concentrations of CrFeO₃‐NPs–AC were obtained to be 50 and 100 μg ml^?1, respectively, against S. aureus and 25 and 50 μg ml^?1 against P. aeruginosa. These results indicated the antibacterial properties of CrFeO₃‐NPs–AC. To investigate the adsorption process, several systematic experiments were designed by varying parameters such as adsorbent mass, pH, initial MV concentration and sonication time. The adsorption process was modelled and the optimal conditions were determined to be 0.013 g, 7.4, 15 mg l^?1 and 8 min for adsorbent mass, pH, MV concentration and sonication time, respectively. The real experimental data were found to be efficiently explained by response surface methodology and genetic algorithm model. Kinetic studies for MV adsorption showed rapid sorption dynamics described by a second‐order kinetic model, suggesting a chemisorption mechanism. Then, the experimental equilibrium data obtained at various concentrations of MV and adsorbent masses were fitted to conventional Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. Dye adsorption equilibrium data were fitted well to the Langmuir isotherm. From the Langmuir model, the maximum monolayer capacity was calculated to be 65.67 mg g^?1 at optimum adsorbent mass.     

Multi‐responses optimization of simultaneous adsorption of methylene blue and malachite green dyes in binary aqueous system onto Ni:FeO(OH)‐NWs‐AC using experimental design: derivative spectrophotometry method

In this research, response surface methodology (RSM) approach using Central Composite Design (CCD) coupled by derivative spectrophotometry method was applied to develop mathematical model and optimize process parameters for simultaneous adsorption of methylene blue (MB) and malachite green (MG) from aqueous solution using Ni:FeO(OH) ‐ NWs‐AC. The optimal conditions to adsorption of MB and MG in binary mixture solution from aqueous solution were found at pH 8.0, MB concentration 20 mg L^‐1, MG concentration 20 mg L^‐1, adsorbent dosage 0.033 g and contact time 40 min. At these conditions, high adsorption efficiency (99.39% and 100.0% for MB and MG, respectively) was achieved. Among experimental equilibrium, Langmuir isotherm model fitted well with maximum monolayer adsorption capacity of 28.6 and 29.8 mg g^‐1 for MB and MG, respectively. The adsorption kinetic data followed pseudo second‐order kinetics for MB and MG dyes.     

An easily organic–inorganic hybrid optical sensor based on dithizone impregnation on mesoporous SBA‐15 for simultaneous detection and removal of Pb(II) ions from water samples: Response‐surface methodology

In this study, a novel organic–inorganic hybrid adsorbent for single‐step detection and removal of Pb(II) ions based on dithizone (DZ) anchored on mesoporous SBA‐15 was fabricated. The designed solid optical sensor revealed rapid colorimetric responses and high selectivity. Central composite design (CCD) combined with desirability function (DF) was applied to evaluate the interactive effects and optimization of important variables such as pH value, mesoporous SBA‐15 dosage, contact time and initial concentration of Pb(II) ions and optimum conditions for each of the factors were obtained 6.0, 25 mg, 30 min and 20 μg ml^{− 1}, respectively. This adsorbent or solid optical chemo sensor exhibited a linear range of 1.0 to 100.0 μg ml⁻¹ of Pb(II) ion concentration with a detection limit of 0.07 μg ml⁻¹. This adsorbent was applied to determine and remove the Pb(II) in spiked samples. Various isotherm models such as Langmuir, Freundlich, Temkin and Dubinin–Radushkevich were studied for fitting the experimental equilibrium data. Langmuir model was chosen as an efficient model. Various kinetic models such as pseudo‐first, second order intraparticle, diffusion models were studied for analysis of experimental adsorption data and the pseudo second order model was chosen as an efficient model.     

Selective and sensitive determination of silver ions at trace levels based on ultrasonic‐assisted dispersive solid‐phase extraction using ion‐imprinted polymer nanoparticles

We describe ultrasonic‐assisted dispersive solid‐phase extraction based on ion‐imprinted polymer (UA‐DSPE‐IIP) nanoparticles for the selective extraction of silver ions. Ultrasound is a good and robust method to facilitate the extraction of target ions in the sorption step and elution of the target ions in the desorption step. The IIP nanoparticles used in the UA‐DSPE‐IIP were prepared by precipitation polymerization. To prepare the IIP nanoparticles, 2‐vinylpyridine, ethylene glycol dimethacrylate, 2,2′‐azobisisobutyronitrile, 2‐picolinic acid, silver and chloroform–methanol (50:50) solution were used as functional monomer, cross‐linker, initiator, silver‐binding ligand, template ion and porogen, respectively. The IIP nanoparticles were characterized using Fourier transformed infrared spectroscopy, thermogravimetric and differential thermal analysis, X‐ray diffraction and scanning electron microscopy. A Box–Behnken design was used for optimization of sorption and desorption steps in UA‐DSPE‐IIP. In the sorption step: pH of solution, IIP amount (mg), sonication time for sorption (min); in the desorption step: concentration of eluent (mol l⁻¹), volume of eluent (ml), sonication time (min) for desorption were investigated and optimized by Box–Behnken design. The optimum conditions for the method were: pH of solution, 7; sonication time for sorption, 7 min; IIP amount, 17 mg; type and concentration of eluent, HCl 1.5 mol l⁻¹; volume of eluent, 2 ml; sonication time for desorption, 140 s. Under the optimized conditions the limit of detection and relative standard deviation for the detection of silver ions using UA‐DSPE‐IIP were found to be 0.09 μg l⁻¹ and <3%, respectively.     

Optimization of solid phase dispersive field‐assisted ultrasonication for the extraction of auramine O and crystal violet dyes using central composite design

Simultaneous preconcentration and determination of auramine o (AO) and crystal violet (CV) dyes from aqueous solution was conducted by ultrasound assisted (dispersive) solid phase microextraction (UASPME) based on SnO₂/SnS composite loaded activated carbon (SnO₂/SnS‐NCs‐AC). The prepared of SnO₂/SnS‐NCs‐AC was characterized by FESEM and XRD analysis. Main and interaction influences of operational parameters such as pH, sonication time, amounts of sorbent, and type of eluent on extraction efficiency were investigated by central composite design and optimized with desirability function approach (DFA). ANOVA was conducted and shows that optimized values were found at 15.33 min sonication time, 0.019 g SnO₂/SnS‐NCs‐AC mass, pH 5.46 and among different solvents, dimethyl formamide was selected as an efficient eluent. Under this conditions recoverees percentage were obtained 82.85% and 86.70% for AO and CV, respectively. Based on F‐test under ANOVA all main effect and interaction effect of understudy parameters has the significant effect on the responses. At optimum conditions, limit of detection (0.0015 and 0.001 mg/l), limit of quantitation (0.4 and 0.4 mg/l), limit of linearity (9.0 and 9.0 mg/l), enrichment factor (33.48 and 83.71) and percent relative standard deviation (3.44 and 4.20) were found to be for auramine o and crystal violet dyes, respectively. Finally, the method was successfully applied for the preconcentration and determination of AO and CV in water samples and ER% of 89.0‐97.0 and 96.2–98.0% as acceptable range were found to be for AO and CV samples, respectively.     

Synthesis of nano‐sized magnetite mesoporous carbon for removal of Reactive Yellow dye from aqueous solutions

In this study, core‐shell structures of magnetite nanoparticles coated with CMK‐8 ordered mesoporous carbon (Fe₃O₄@SiO₂‐CMK‐8 NPs) have been successfully synthesized for the first time by carbonizing sucrose inside the pores of the Kit‐6 mesoporous silica. The nano‐sized mesoporous particles were characterized by X‐ray diffraction, Fourier transform‐infrared spectroscopy, scanning electron microscope, dynamic light scattering, vibrating‐sample magnetometer, Brunauer–Emmett–Teller (BET) and transmission electron microscopy instruments. The obtained nanocomposite was used for removal of Reactive Yellow 160 (RY 160) dye from aqueous samples. The N₂ adsorption–desorption method (at 77 K) confirmed the mesoporous structure of synthesized Fe₃O₄@SiO₂‐CMK‐8 NPs. Also, the surface area was calculated by the BET method and Langmuir plot as 276.84 m²/g and 352.32 m²/g, respectively. The surface area, volume and pore diameter of synthesized nanoparticles (NPs) were calculated from the pore size distribution curves using the Barrett–Joyner–Halenda formula (BJH). To obtain the optimum experimental variables, the effect of various experimental parameters on the dye removal efficiency was studied using Taguchi orthogonal array experimental design method. According to the experimental results, about 90.0% of RY 160 was removed from aqueous solutions at the adsorbent amount of 0.06 g, pH 3 and ionic strength = 0.05 m during 10 min. The pseudo‐second order kinetic model provided a very good fit for the RY 160 dye removal (R² = 0.999). The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were applied to describe the equilibrium isotherms, and the Langmuir isotherm showed the best fit to data with the maximum adsorption capacity of 62.893 mg/g. Furthermore, the Fe₃O₄@SiO₂‐CMK‐8 NPs could be simply recovered by external magnet, and exhibited recyclability and reusability for a subsequent six runs.     

Atenolol sequestration using activated carbon derived from gasified Glyricidia sepium

Activated carbon (AC) derived from gasified Glyricidia sepium woodchip (GGSWAC) was prepared using KOH and CO₂ activation via microwave radiation technique to remove atenolol (ATN) from aqueous solution. The surface area (S_BET) and total pore volume (TPV) of GGSWAC were 483.07 m²/g and 0.255 cm³, respectively. The n-BET model fits well with the isothermal data indicating a multilayer adsorption with the saturation capacity of 121, 143 and 163 mg/g at 30, 45 and 60 °C, respectively. The kinetic study showed that ATN adsorption followed Avrami model equation (R² ≅ 0.99). Based on the thermodynamic parameters, the adsorption of ATN onto GGSWAC was endothermic (ΔH_S = 234.17 kJ/mol) in the first layer of adsorption and exothermic in the subsequent layer (ΔH_L = −165.62 kJ/mol). The ATN adsorption was controlled by both diffusion and chemisorption. In continuous operation, the Thomas (R² = 0.9822) and Yoon–Nelson (R² = 0.9817) models successfully predicted the ATN adsorption.     

Lanthanum ion–impregnated granular activated carbon for the removal of phenol from aqueous solution: Equilibrium and kinetic study

The current study discusses application of the lanthanum ions (La³⁺) as an activating agent incorporated /immobilized into coconut shell–based granular activated carbon (GAC) for porosity development; subsequently, the carbon material is used for the adsorption of phenol from aqueous solutions. The new carbons were characterized using FTIR, XRD, CHNO, burn off, and carbon yield. The surface functional groups were determined by Boehm titration. The Brunauer–Emmett–Teller (BET) surface area of the carbons is 953 m² g⁻¹ (GACLa1073), 997 m² g⁻¹ (GAC383), and 973 m² g⁻¹ (GACO383). Langmuir, Freundlich, Dubinin–Radushkevich, and John–Sivanandan Achari (J-SA) isotherm models on the equilibrium isotherm data were examined for the new carbon-phenol system. It is found that the Langmuir isotherm fits better with a monolayer adsorption capacity, highest for GACLa1073 (387.59 mg g⁻¹) followed by GAC383 (303.03 mg g⁻¹) and GACO383 (197.62 mg g⁻¹). Kinetic studies reveal that the adsorption system follows the pseudo–second-order kinetic model. Isotherm analysis by the phase change method of John-Sivanandan Achari (J-SA) isotherm gives a better insight into adsorption phenomena, which is accompanied by regeneration studies of carbon with >75% for GACLa1073 after three cycles.     

Structural,thermal, optical and conductivity studies of Co/ZnO nanoparticles doped CMC polymer for solid state battery applications

In this study, a simple chemical precipitation method was used to synthesize ZnO: Co²⁺ as nanoparticles. The solution casting technique was used for the preparation of polymer films of Carboxymethyl cellulose (CMC) doped with different contents (0.5, 1.5, 3, and 5 wt%) of ZnO/Co NPs. As shown by the X-ray diffraction, the average size of ZnO/Co crystallite of the NPs is 25.6 nm. Meanwhile, the addition of ZnO/Co reduced the semi-crystallinity of CMC. The Fourier transform infrared (FTIR) confirmed the interaction between the ZnO/Co NPs and the polymer CMC. The direct and indirect band gap (Eg) was reduced from (5.32–5.01 eV and 5.20 to 4.99 eV respectively) with the increase in ZnO/Co NPs content up to 3 wt% after this content the Eg is increased as shown by the UV–Vis spectra. In addition, the results of TGA displayed the decomposition of the nanocomposite to be little compared to that of the pure CMC indicating the success of fabrication of products. The improvement of the ionic conductivity was noticed upon the addition of ZnO/Co NPs into the polymer CMC system which can be explained in terms of an increase in amorphicity as shown by the impedance spectroscopic study. It was found that the optimum ionic conductivity (3.209 × 10⁻⁶ Scm⁻¹) at ambient temperature was higher for the sample containing 1.5 wt% ZnO/Co NPs with highest of amorphicity and the lowest total loss of weight. Therefore, the improvements in optical properties, thermal stability, and AC conductivity which were observed represent a strong support for the use of the nanocomposite films in the solid state battery applications.     

Application of response surface methodology to optimize pipette tip micro-solid phase extraction of dyes from seawater by molecularly imprinted polymer and their determination by HPLC

In this paper, a novel pipette tip micro-solid phase extraction based on molecularly imprinted polymer as a selective sorbent was developed and applied for extraction, pre-concentration and high-performance liquid chromatographic determination of trace amounts of malachite green (MG), rhodamine B (RB), methyl orange (MO) and acid red 18 (AR) dyes in seawater samples. Different parameters affecting the extraction efficiency such as type and volume of eluent solvent, sample volume, number of cycles of extraction and desorption, amount of sorbent and pH of the sample solution were evaluated using one-variable-at-a-time and response surface methodology. In order to optimize dyes extraction, seven factors in three levels were used for Box–Behnken experimental design. Under optimum extraction condition, pH of sample solution was 3.1 for MG, 3.0 for RB, 7.1 for MO and 6.1 for AR; volume of eluent solvent (HCl, 0.5 mol L⁻¹) was 200 µL; volume of the sample solution was 10 mL (for MG) and 4 mL (for RB, MO and AR); the concentration of triton X-114 was 0.085 (MG), 0.10 (RB), 0.08 (MO) and 0.075 (AR) % v/v; the number of extraction cycles was 10 (MG), 6 (RB), 5 (MO) and 7 (AR); the number of elution cycles was 10, 6, 5 and 9, respectively, for MG, RB, MO and AR; NaCl concentration was 0.4 mol L⁻¹; and amount of MIP was 2.0 mg for all dyes. The linear range of calibration curves was 0.5–250.0 µg L⁻¹ for malachite green and methyl orange and 0.5–150.0 µg L⁻¹ for both rhodamine B and acid red 18. The detection limits calculated to be 0.083, 0.10, 0.12 and 0.17 µg L⁻¹ for MG, RB, MO and AR, respectively. The developed protocol was successfully used for determination of dyes in seawater of Chabahar Bay. The mean recoveries were ranged between 76.1 and 97.3% by mean relative standard deviations of 1.2–7.1%.

     

Preparation and characterization of novel bi-functionalized xerogel for removal of methylene blue and lead ions from aqueous solution in batch and fixed-bed modes: RSM optimization,kinetic and equilibrium studies

A new bi-functionalized xerogel is fabricated and then was identified by ²⁹Si CP MAS NMR, SEM, FTIR, and nitrogen adsorption–desorption approaches. As-prepared xerogel efficiency for simultaneous uptake of methylene blue (MB) and Pb²⁺ ions from aqueous solution is investigated. Individual and combination effects of operating variables (xerogel mass, contact time and initial MB and Pb²⁺ ion concentration) on the retention performance is achieved with central composite design (CCD) and upgraded through response surface method (RSM). Batch equilibrium outcomes uncovered that MB and Pb²⁺ ions adsorption onto hybrid composite could be all around depicted by Langmuir isotherm model contrasted with Freundlich equation. Howbeit, the column trials reported that the breakthrough capacities of MB and Pb(II) are observed to be 512 mg.g⁻¹ and 400 mg.g⁻¹ respectively. XPS and FTIR investigations uncovered that the main mechanism of lead uptake ought to be credited to the chelation with –NH₂ and ion exchange with –SH groups in the xerogel frameworks. While the MB adsorption system is proposed to be electrostatic attractions, π-π stacking interactions and hydrogen bonds. The work undertaken in this research highlights the major role of the as-synthesized xerogel for treatment of industrial wastewater.     

Thermodynamics’ study of the adsorption process of methylene blue on activated carbon at different ionic strengths

The adsorption constant of aqueous solution of methylene blue (MB), (800 · 10⁻⁶ mol · dm³) on activated carbon (AC) has been investigated by means of UV–Visible spectroscopy. The adsorption process is very fast and is physical in nature; however, it is complicated by the factors inherent in the structures of both the MB solution and AC, such as tendency of MB to form molecular aggregates in solution. In this work, the effects of various experimental parameters such as temperature and ionic strength have been investigated, using a batch adsorption technique to obtain information on treating effluents from the dye industry. Utilizing the van’t Hoff relation, which describes the dependence of equilibrium constant on temperature, as a constraint, we determine the spectral responses of the free and adsorbed amounts, as well as the enthalpy of the adsorption equilibrium.     

Application of artificial neural network for comparison and modeling of the ultrasonic and stirrer assisted removal of anionic dye using activated carbon supported with nanostructure material

In this study, a green approach has been described for the synthesis of copper sulfide nanoparticles loaded on activated carbon (CuS‐NP‐AC) and usability of it for the removal of sunset yellow (SY) dye by ultrasound‐assisted and stirrer has been compared. In addition, the artificial neural network (ANN) model has been employed for a forecasting removal percentage of SY dye using the results obtained. This material was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The impact of variables, including initial dye concentration (mg/L), pH, adsorbent dosage (g), sonication time (min) and temperature (°C) on SY removal was studied. Fitting the experimental equilibrium data of different isotherm models such as Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models display the suitability and applicability of the Langmuir model. Analysis of experimental adsorption data of different kinetic models including pseudo‐first and second order, Elovich and intraparticle diffusion models indicate the applicability of the second‐order equation model. The adsorbent (0.005 g) is applicable for successful removal of SY dye (> 98%) in short time (9 min) under ultrasound condition. A three layer ANN models with 8 and 6 neurons at hidden layer was selected as optimal models using stirrer and ultrasonic, respectively. These models displayed a good agreement between forecasted data and experimental data with the determination coefficient (R²) of 0.9948 and 0.9907 and mean squared error (MSE) of 0.0001 and 0.0002 for training set using stirrer and ultrasonic, respectively.     

Surface‐initiated atom transfer radical polymerization of a new rhodanine‐based monomer for rapid magnetic removal of Co(II) ions from aqueous solutions

The present study reports synthesis and characterization of a new acrylamide‐based monomer containing rhodanine moiety, N‐3‐amino‐thiazolidine‐4‐one‐acrylamide (ATA). Poly(ATA)‐grafted magnetite nanoparticles (poly(ATA)‐g‐MNPs) were prepared using surface‐initiated atom transfer radical polymerization of the monomer on Fe₃O₄ nanoparticles. The grafted nanoparticles were characterized by Fourier transform infrared analysis, scanning electron microscopy, X‐ray diffraction, and vibrating sample magnetometry. The amount of the grafted polymer was 209 mg g⁻¹, as calculated from thermogravimetric analysis experiment. The capability of poly(ATA)‐g‐MNPs to remove Co(II) cations was shown under optimal conditions of contact time, pH, adsorbent dosage, and initial Co(II) concentration. About 86% of the Co(II) cations were removed over 7 minutes. The adsorption kinetics obeyed the pseudo–second‐order kinetic equation, and the Langmuir isotherm model best described the adsorption isotherm with a maximum adsorption capacity of 3.62 mg g⁻¹. The thermodynamic investigation showed spontaneous nature of the adsorption process (ΔG = −2.90 kJ mol⁻¹ at 25°C ± 1°C). In addition, the poly(ATA)‐g‐MNPs were regenerated by simply washing with an aqueous 0.1M HCl solution. The study of the reusability of the prepared magnetic sorbent revealed that the sorbent can be reused without a significant decrease in the extraction efficiency and be recovered by 95.4% after 7 cycles. These findings suggest that the grafted nanoparticles are stable and reusable adsorbent and can be potentially applied to water treatment in efficient removal of Co(II) cations.     

Quartzite an efficient adsorbent for the removal of anionic and cationic dyes from aqueous solutions

Quartzite obtained from local source was investigated for the removal of anionic dye congo red (CR) and cationic dye malachite green (MG) as an adsorbent from aqueous solution in batch experiment. The adsorption process was studied as a function of dye concentration, contact time, pH and temperature. Adsorption process was described well by Langmuir and Freundlich isotherms. The adsorption capacity remained 666.7 mg/g for CR dye and 348.125 mg/g for MG dye. Data was analyzed thermodynamically, ΔH⁰ and ΔG⁰ values proved that adsorption of CR and MG is an endothermic and spontaneous process. Adsorption data fitted best in the pseudo-first order kinetic model. The adsorption data proved that quartzite exhibits the best adsorption capacity and can be utilized for the removal of anionic and cationic dyes.