Adsorption Of Malachite Green Dye Research Articles

Volcanic ashe and its NaOH modified adsorbent for superb cationic dye uptake from water: Statistical evaluation, optimization, and mechanistic studies

The adsorptive performance of the natural Saudi Arabian volcanic ash (VA) and its NaOH-modified form (VA-NaOH) for Malachite green (MG) uptake from water were evaluated using response surface methodology (RSM) modeling technique and mechanistic aspects studies. The characterization analyses showed that both materials possess abundant functional groups (O–H, Si–OH, Si-O and Al-O), mineral salts (SiO2, Al2O3, CaO, Fe2O3, MgO), better surface characteristics leading to favorable adsorption of MG dye from water. The MG removals and the uptake capacities data were well described by cubic polynomial models with optimal condition at 25 °C, initial MG concentration of 120 mg/L, and pH 10 for VA and VA-NaOH. The kinetics of MG adsorption was best explained by pseudo-second order, while the Redlich–Peterson model fitted the equilibrium isotherms. The maximum Langmuir uptake capacity of 152 mg/g (VA) and 158 mg/g (VA-NaOH). The adsorption mechanism was speculated to be endothermic and involving both mono and multi-layer surface adsorption comprising chemisorption process (ΔG° = −27.6 to −33.9 kJ/mol), with increasing randomness scale at the liquid/solid interface without considerable entropy changes. The excellent regeneration ability, after successive cycles of desorption-adsorption, further indicates the high potential of the natural Saudi volcanic ash as excellent adsorbent for dyes removal from aqueous systems.

Integrated experimental and theoretical insights for Malachite Green Dye adsorption from wastewater using low cost adsorbent.

Water pollution is one of the problems that threaten humanity, and to confront it with only experimental procedures is not enough. It is necessary to integrate both practical methods and theoretical calculations to achieve decontamination with the most accurate interpretation. Hence, discussing the experimental mechanism study of Malachite Green (MG) dye adsorption with the help of the application of density functional theory (DFT) calculations is the main goal of this article. The experimental results affirmed that the preparation of γ-Al2O3 by precipitation method using (NH4)2CO3 improved the porosity, the surface capability, and the adsorbent capacities (qmax = 210 mg/g) at optimum condition compared with the previous studies. Kinetic and equilibrium studies showed that the adsorption follows the pseudo-second-order model and Freundlich isotherm model, respectively. Also, the calculated and observed thermodynamic parameters exerted positive values of ΔH° and ΔS°, which translates into an endothermic process with increasing disorder of the system. Theoretical calculations at DFT- B3LYP/6-31G (d,P) level of theory were calculated to show the selectivity of using the cationic form of MG in the experimental measurements to find the interaction mechanism. The electronic structure and intramolecular charge transfer of MG, its cationic form and the complex of MG-Al were investigated theoretically at the B3LYP/6-31 G (d,p) level of theory. The equilibrium geometries of MG, its cationic form and the complex of MG-Al were determined, and it was found that these geometries are non-planar. The EHOMO and ELUMO energies can be used to calculate the global properties; chemical hardness (η), softness (S) and electronegativity (χ). The calculated non-linear optical parameters (NLO) of the studied compounds, the electronic dipole moment (μ), first-order hyperpolarizability (β), the hyper-Rayleigh scattering (βHRS) and the depolarization ratio (DR), showed promising optical properties. Finally, the computational and the experimental results indicated that the adsorption efficiency of MG from wastewater was directly associated with the dye electrophilicity power.

Adsorption capacity of the biochar obtained from Pinus patula wood micro-gasification for the treatment of polluted water containing malachite green dye

In this work, the adsorption capacity of the biochar obtained from Pinus patula biomass micro-gasification was studied using malachite green (MG) as the probe pollutant. For this purpose, the biomass type (wood pellets and chips) was selected to produce two kinds of biochar (BC). Afterwards, the effects of the adsorbent dose (6, 9 and 12 g/L), the solution pH (4, 7 and 10) and the BC particle size distribution (150–300, 300–450 and 450–600 μm) for the maximization of the MG retention by the selected BC were evaluated using a faced-centered central composite design, as response surface methodology. The results indicated that the BC derived from wood chips (BWC) exhibited a higher MG dye adsorption capacity than the BC obtained from the wood pellets (BWP) gasification under the same operating conditions after having reached the equilibrium. A second-order regression model was built for describing the MG adsorption behaviour by BWC under the considered experimental domain. The model, which was validated, resulted to be statistically significant and suitable to represent the MG adsorption by the studied BC with a p-value of 0.00 and a correlation coefficient (R2) of 95.59%. Additionally, a three-dimensional response surface graph and a contour plot were utilized to analyze the interaction effects between the factors influencing the adsorption system and to discern the optimal operating conditions for the use of BWC. The maximal MG dye retention (99.70%) was found to be at an adsorbent dose, pH solution and a particle size distribution of 9.80 g/L, 10 and from 150 to 300 μm, respectively. Therefore, the BWC tested can be utilized for the treatment of water polluted with dyes, contributing to the establishment of a circular economy.

Enhanced sono-assisted adsorptive uptake of malachite green dye onto magnesium ferrite nanoparticles: Kinetic, isotherm and cost analysis

In this study, the performance of magnesium ferrite nanoparticles (MgF-NPs) as adsorbent was assessed for removal of toxic malachite green (MG) dye from aqueous solution under ultrasonic irradiation. The MgF-NPs exhibited specific surface area of 70.266 m2/g and pore volume of 0.311 cc/g with an average pore diameter of 7.354 nm. Optimum solution pH was found to be 8.0 for sono-assisted MG dye adsorption, which is favourable for large scale field application of the proposed method. The adsorption reaction aided by ultrasonication could yield more than 90% MG dye removal within 15 min of reaction due to enhancement of mass transfer. However, instead of ultrasonication when overhead stirring and shaking was used as mixing methods then the MG dye removal efficacy was dropped to 70% and 65%, respectively. The adsorption kinetic strictly followed the pseudo-second-order model and equilibrium isotherm analysis followed the Langmuir isotherm model with maximum monolayer adsorption capacity of 487.60 mg/g. The presence of chloride ion hindered the MG dye removal efficiency from 91% to 67%, whereas the presence of nitrate, sulfate and phosphate ions in the dye solution could not affect the dye removal efficacy significantly. The cost analysis for synthesis of MgF-NPs revealed that the cost involvement of 50.88 USD/Kg of adsorbent which may be considered as economical for large scale industrial application.

Adsorption of Malachite Green Dye onto Mesoporous Natural Inorganic Clays: Their Equilibrium Isotherm and Kinetics Studies

Contamination of water with organic dyes is a major environmental concern as it causes serious life-threatening environmental problems. The present research was designed to evaluate the potential of three different natural inorganic clays (NICs) i.e., Pakistani bentonite clay (PB), bentonite purchased from Alfa Aesar (BT), and Turkish red mud (RM) for malachite green (MG) dye removal from an aqueous solution. Various analytical techniques, namely X-ray fluorescence spectrometry (XRF), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller surface area measurement (BET), and thermogravimetric analysis (TGA), were used to investigate the physicochemical properties of the NICs samples. The effect of adsorption operational parameters such as contact time, aqueous phase pH, dye concentration, and amount of NICs on the adsorption behavior of MG onto NICs samples were investigated under the batch adsorption system. The equilibrium and kinetic inspection reflected the best description of MG adsorption behavior by the Langmuir isotherm model and pseudo-first-order kinetic model, respectively. The results indicated that the adsorption was favorable at higher pH. The maximum adsorption capacities calculated by Langmuir isotherm for PB, BT, and RM were found to be 243.90 mg/g, 188.68 mg/g, and 172.41 mg/g, respectively. It can be concluded that natural inorganic clays with a higher surface area can be used as an effective adsorbent material to remove the MG dye from an aqueous solution.

Utilization of prepared activated biochar from water lily (Nymphaea lotus) stem for adsorption of malachite green dye from aqueous solution

Activated biochar was prepared from water lily through combination of physical and chemical technique. The prepared adsorbent was characterized by thermogravimetric analysis (TGA), elemental analysis (CHN/O), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and Brunauer-Emmett-Teller model (BET). Batch technique was used for adsorption of 99.25% of MG dye onto prepared adsorbent with 102.35 mg/g maximum monolayer adsorption capacity (Qmax) at optimum conditions of initial dye concentration (100 mg/L), adsorbent dose (0.1 g/100 mL), contact time (30 min), temperature (301 K), and stirring speed (200 rpm). Kinetic and equilibrium models were best fit with pseudo-first order kinetic and Langmuir isotherm, respectively. Thermodynamic parameters showed∆Ho, ∆So, and ∆Go to be 1.154 kJ/mol, 3.139 kJ/mol K, and −943.685 kJ/mol, respectively. Positive value of ∆Ho and large value of ∆So indicated that adsorption process was endothermic and that there was high collision rate at adsorbent–dye interface. The negative value of ∆Goconfirmed that adsorption process was spontaneous and feasible. Comparison of water lily stem-derived activated biochar (WLSAB) Qmax with those reported for other plant-derived activated carbons affirmed WLSAB as a better potential alternative adsorbent for treatment of dye-contaminated wastewater.

Synthesis, characterization and adsorption of Malachite green dye using novel materiel produced from opuntia ficus indica

Opuntia ficus-indica was chemically activated to produce a novel material for malachite green disposal from liquid solutions. The adsorption kinetic, isotherms and the thermodynamic studies were conducted in batch experiment at optimum pH. Two models were analysed to study the kinetic data the Ho’s pseudo-second order model and the Lagergren’s pseudo-first order. The data has showed that the Ho’s model fits more with a (R2 = 0.983). For adsorption isotherms Freunlish and Langmuir models were studied, and the the results show that the Langmuir fits more with the highest R2. The thermodynamic study proved that the adsorption process is feasible and spontaneous, physical and reversible. Moreover, the positive value of ΔS° indicates that there is an increase in the randomness of the system of solid/solution interface during MG adsorption process by Opuntia ficus-indica’ s activated carbon.The activated carbon and raw material were analyzed by FTIR/ATR, SEM and EDX images. The infrared spectrums show that there were some changes in the functional groups surface. The chemical activation by the phosphoric acid leads to a peptization and dissolution of cellulose, hemicellulose, lignin, and polysaccharide in the raw material. However in the SEM images we can see clearly that the surface modification and the new pores is formed with the release of volatile matter by the H3PO4 activation process.

Adsorptive Removal of Malachite Green Dye onto Coal-Associated Soil and Conditions Optimization

The present research was investigated to eliminate the cationic dye (malachite green (MG)) from the water environment using coal-associated soil. The adsorbent material was characterized using scanning electron microscopy (SEM) and Fourier Transform Infrared Spectrophotometer (FTIR) analyses. Batch experiments were performed to investigate the different factors which affect the adsorption study. The maximum percentage removal of MG dye was attained as follows: adsorbent dose of 1.0 g/L (0.2 to 1.6 g/L), solution pH of 6.0 (2.0 to 9.0), temperature of 30°C (30 to 60°C), time contact of 60min (10 to 90 min), and dye’s concentration of 25 mg/L (25 to 150 mg/L). The adsorption isotherm was studied with four different isotherm models and results showed that the Freundlich isotherm model gave the best fit than the other nonlinear models to designate the isotherm behaviours with [Formula: see text] value of 0.9568, and the maximum adsorption capacity of coal-associated soil for MG dye adsorption is 89.97 mg/g. The evaluation of kinetic studies was performed by using three different kinetic models, where it exposed that pseudofirst order providing the best fit with [Formula: see text] value of 0.96 (25 to 150 mg/L). The thermodynamic parameters Gibbs free energy ( ΔG°), entropy ( ΔS°), and enthalpy ( ΔH°) were endorsing that the present adsorption system was exothermic. Thus, the experimental results state that coal-associated soil could be an alternative material for the exclusion of dyes from water.

Comparative adsorption study of malachite green dye on acid-activated carbon

ABSTRACT Activated carbon produced from coconut shells has been gaining interest in wastewater treatment as a potential carbon source for adsorption with desired porosity, surface area, and stability requirements. Acid activation has been preferred for activated carbon production due to its superiority over adsorption of malachite green dye. This study involved in the acid activation of coconut shell derived carbon and its characterisation was performed to study the surface functionalities, thermal stability, textural and structural morphologies. The activated carbon was used for the adsorption of malachite green dye from aqueous solutions and with a special insight by varying contact time (20–220 min) and initial dye concentration (20–80 mg L−1) for adsorption study. Phosphoric acid-activated carbon has shown maximum adsorption capacity (Xm) of 32.787 mg g−1 at initial malachite dye concentration of 20 mg L−1 after 3 hours. All the adsorbents followed Freundlich isotherm with intra particle diffusion model as the rate-limiting step.

Kinetic Study of Adsorption of Malachite Green Dye on Poly Aniline-Formaldehyde/Chitosan Composite

Poly aniline-formaldehyde/chitosan composite (PAFC) was prepared by the in situ polymerization method. It was characterized by FTIR spectroscopy in addition to SEM, EDS and TGA techniques. The adsorption kinetics of malachite green dye (MG) on (PAFC) were studied for various initial concentrations (20, 30 and 40) mg/L at three temperatures (308, 313 and 318) K. The influence factors of adsorption; adsorbent dose, contact time, initial concentration and temperature were investigated. The kinetic studies confirmed that adsorption of MG obeyed the pseudo-second-order model and the adsorption can be controlled through external mass transfer followed by intraparticle diffusion mass transfer. A study of the temperature effect was indicated that the adsorption process was endothermic. The activation energy value for each concentration of the dye was calculated, it is observed that it decreases with increasing initial dye concentration.

Titania modified gum tragacanth based hydrogel nanocomposite for water remediation

In this work, 2-hydroxyethyl methacrylate cross-linked gum tragacanth hydrogel (GumT-cl-HEMA) was systematically synthesized to attain maximum swelling (396.9 %) by simple microwave-assisted green polymerization technique. The prepared GumT-cl-HEMA hydrogel was further modified by using TiO2 nanoparticles to generate TiO2 loaded 2-hydroxyethyl methacrylate cross-linked gum tragacanth (GumT-cl-HEMA/TiO2) hydrogel composite. The GumT-cl-HEMA hydrogel and GumT-cl-HEMA/TiO2 hydrogel composite were characterized through XPS, BET, XRD, FTIR, TGA and SEM. The GumT-cl-HEMA hydrogel and GumT-cl-HEMA/TiO2 hydrogel composite were used to perform adsorption to separate the molecules of malachite green (MG) from water. Batch adsorption parameters were examined to analyze the pH effect, time effect and adsorbent dose for the adsorption of malachite green dye from aqueous solution. The inclusion of TiO2 particles inside the GumT-cl-HEMA hydrogel led to increased adsorption rates and stability. The adsorption was accurately followed the pseudo second order model and Langmuir isotherm model. The reported GumT-cl-HEMA/TiO2 hydrogel composite removal efficiency was 99.3 % adsorbent dose = 90 mg, MG = 50 ppm, pH = 7, volume = 50 mL and time = 80 min). The synthesized samples were regenerated and then reused for five repeated adsorption-desorption cycles. The construction of GumT-cl-HEMA hydrogel and GumT-cl-HEMA/TiO2 hydrogel composite gives a facile scheme for efficient adsorbents.

Functionalized Zea Mays Cob (FZMC) as low-cost agrowaste for effective adsorption of malachite green dyes data set

This dataset article presents the effective adsorption of Malachite Green (MG) dyes onto FZMC as low-cost agro-waste. The physicochemical parameters data of the FZMC (1329 m2/g surface area; 12% moisture content; 0.9% loss of mass on ignition; 0.386 g/cm3 bulk density) showed its suitability for sorption. Favorable adsorption of MG dye in a batch technique was achieved at pH 8, 120 min contact time through 100 – 600 ppm concentrations. With R2>0.98, the Pseudo second-order model best represented kinetic data. The mechanism was better represented by the intraparticle diffusion model. Equilibrium data were best described by Freundlich and confirmed by Halsey isotherm with R2>0.97 and physisorption nature of the d-R isotherm model (E (J/mol) <8 kJ/mol). Qmax of FZMC (64.52 mg/g) surpassed those previously reported. Surface chemistry and morphology were determined by FTIR and SEM. The dataset revealed FZMC as a promising biosorbent for the treatment of industrial wastewater.

Decolorization of Textile Dye by Halophilic Exiguobacterium sp.VK1: Biomass and Exopolysaccharide (EPS) Enhancement for Bioremediation of Malachite Green

AbstractThe salt pan soil screened for the exopolysaccharides (EPS) producing organisms for the decolourization textile dyes. The isolate was characterized and confirmed as Exiguobacterium sp. VK1 by 16S rRNA analysis. The enhanced production of EPS was obtained with the minimal medium which was supplemented with various carbon sources, and cassava peel which has shown a 5.9 fold increase in the EPS (7704.71 mg/L) production. Exiguobacterium sp. VK1 removed Malachite Green (MG) dye (684.38 mg/g) with the maximum biosorption capacity of 79.1% at pH 6 and 40°C. With the increased EPS production, by supplementing the cassava peel, the MG dye adsorption also increased up to 97.61%, when decolorized within 30 min by Exiguobacterium sp. VK1. It was found that Pseudo Second‐order kinetics and Freundlich isotherm is the best fit for the equilibrium adsorption process of MG dye by Exiguobacterium sp. VK1. The thermodynamic properties such as activation energy (12.993 kJ/mol), change in enthalpy (10.501 kJ/mol), change in entropy ‐254.07 J/(mol K) and change in Gibbs energy (84.945‐90.026 kJ/mol) were investigated by Arrhenius and Eyring equation using Pseudo‐second‐order kinetic model. The result revealed that the adsorption process was thermodynamically feasible.

Comparative studies on adsorption of dye and heavy metal ions from effluents using eco-friendly adsorbent

Chemically modified Phosphoric acid activated Chrysopogon zizanioides roots Activated Carbon (PCRAC) used as an alternative adsorbent for the removal of Malachite Green (MG) dye and heavy metals Cu(II) and Ni(II) from industrial wastewater. The untreated waste water contain MG and heavy metals can affect human health and environment. Adsorption characteristic of activated carbon was investigated through various parameter like pH, Adsorbent dosage, contact time, Initial dye concentration. Results from Scanning Electron Microscopic (SEM) and Transmission Electron Microscopy (TEM) for PCRAC showed that the presence of heterogeneous and porous morphology on the surface of adsorbent indicated effective adsorption of dye and metal ions. The adsorption of MG dye and heavy metals of Cu(II) and Ni(II) were observes Freundlich isotherm with correlation coefficient of 0.978, 0.963 and 0.963. The adsorption process follows pseudo second order kinetic model.

Two-stage optimisation for malachite green removal using activated date pits

Water pollution, from industry and agriculture, is a major threat to water security in the light of decreasing global potable water resources. Adsorption is one potential treatment technology for the removal of different contaminants from polluted water. Hard lignocellulose-containing materials with high carbon content, such as date stones, are excellent precursors for the production of activated carbons for adsorption activities. In this study, waste date stone biomass, from the seedless date products industry, was treated and activated chemically for the adsorption of malachite green dye, which is widely used in the plastics and textile industries. Phosphoric acid was used as an activating agent for the date stones, and its adsorption capability was measured and compared to the capacity of natural date stone powder. Experimental equilibrium data were analysed and correlated by four isotherm models: Langmuir, Freundlich, Temkin and Langmuir–Freundlich (also called SIPS). The best fit for the experimental data for both treated and natural date stone was the Langmuir–Freundlich isotherm. The surface areas and maximum malachite green adsorption capacities of the natural date stone and the phosphoric acid–treated date stone were 86 and 909 m2/g, respectively, and maximum malachite green adsorption capacities were 31.5 and 64.7 mg/g, respectively. A two-stage batch adsorber model was developed to optimize the two-step adsorption process to remove malachite green and minimize the amount of adsorbent used for both untreated and treated date stones. The benefits of the two-stage adsorber and chemically activated date stones are discussed in terms of designing for various percentages dye removal, various effluent discharge concentrations and various initial dye concentrations. The two-stage system resulted in a reduction of adsorbent compared with the one-stage system of 36 to 460% to remove the same amount of dye.

Removal of malachite green using carboxymethyl cellulose-g-polyacrylamide/montmorillonite nanocomposite hydrogel

In this study, carboxymethyl cellulose based graft poly(acrylamide) hydrogel (CMC-g-P(AAm)) and its nanocomposite with montmorillonite (CMC-g-P(AAm)/MMT) were produced by the free radical method and it was used to malachite green (MG) dye removal from aqueous solution. The properties and characterization of the adsorbents were investigated using FTIR, SEM, TGA, and XRD analyzes, and the results showed that MMT nanoparticles were successfully distributed in the hydrogel system. MMT nanoparticles were loaded into the hydrogel system with different weight percentages and the maximum adsorption efficiency of MG dye was determined at 10 wt% MMT. Also, the effect of temperature, contact time, initial concentration of MG dye and initial pH on the adsorption efficiency of MG dye was studied in a batch. Equilibrium behavior investigation of the adsorption process showed that the equilibrium data determined are in good agreement with the Langmuir isotherm model and the monolayer surfaces play an effective role in the adsorption process. The maximum monolayer adsorption capacity (qmax) determined using the Langmuir isotherm model for CMC-g-P(AAm) and CMC-g-P(AAm)/MMT were determined to be 158.1 mg/g and 172.4 mg/g, respectively. Also, the kinetic study showed that the pseudo-second- order kinetic model is more capable of describing the kinetic behavior of the process than other models. Also, the α parameter values for the MG dye adsorption process using CMC-g-P(AAm) and CMC-g-P(AAm)/MMT were determined to be 0.6337 mg/g·min and 31.04 mg/g·min, respectively. This indicates that the produced composite has a high adsorption value. Gibbs free energy (ΔG°) was negative for the adsorption processes in the range of 25–50 °C, indicating that the process was spontaneous. In addition, the enthalpy parameter (ΔH°) was determined for the adsorption process using CMC-g-P(AAm) and CMC-g-P(AAm)/MMT nanocomposite hydrogels at 39.859 KJ/mol and 74.736 KJ/mol, respectively. Positive ΔH° indicates that the process is endothermic in the range of 25–50 °C using both adsorbents. Also, the concentrations effect of Na+ and K+ ions on adsorption efficiency was investigated and it was concluded that the efficiency of the adsorption process decreased with the increase of ions concentration. Adsorption efficiency decrease can be due to the occupation of active sites and repulsive electrostatic interactions at the adsorbent surface with the MG dye molecule.

Synthesis of potential bio-adsorbent from Indian Neem leaves (Azadirachta indica) and its optimization for malachite green dye removal from industrial wastes using response surface methodology: kinetics, isotherms and thermodynamic studies

The response surface methodology has been extended to study the adsorption of malachite green dye (MG) on Indian Neem leaf powder (NLP), Azadirachta indica. The study was experimented by varying the solution concentration from 10 to 100 mg/l. The removal percentage of MG was determined by spectrophotometer at wavelength of 618 nm. Design Expert 11.0 was used as a tool to study the optimal conditions of MG adsorption (applying 2-factorial interaction model of central composite design) and evaluation of interaction effects of different operating parameters including pH, time, solute concentration, temperature and adsorbent dosage. Numerical optimization helped to identify the optimal conditions for achieving the targeted dye removal of 95.493% when the pH, time, solute concentration, temperature and adsorbent amount were set at the range of 6.868, 36.4 min, 27.899 mg/l, 308.477 K, and 4.3475 g/l respectively. The experimental results indicate that the maximum adsorption capacity of NLP depends on various operating parameter like, pH, dye concentration, particle size of adsorbents and it’s activation. It was noted that adsorption capacity of the NLP increases from 33.33 to 66.72 mg/g when it was activated with dilute HCl. The higher correlation coefficient value (R2) of Langmuir isotherm 0.996 and lower p value (0.01203) indicate the fitness of the response surface 2FI model developed. Kinetic studies displayed the suitability of pseudo second order reaction for this adsorption process. The thermodynamic study show that the sorption process is exothermic and spontaneous in nature. It was observed that the adsorbent NLP in the form of fine powder are very effective for the removal of MG from its aqueous solution. The satisfactory values of regression coefficients at different temperature, and fittings of adsorption isotherms indicate that Indian NLP is a promising adsorbent for treatment of textile dyes.

In-Situ Synthesis of ZnO Nanoparticles using Gum Arabic Based Hydrogels as a Self-template for Effective Malachite Green Dye Adsorption

The current study focused on the use of gum Arabic grafted polyacrylamide (GA-cl-PAM) hydrogel as a self-template for the in situ synthesize of zinc oxide nanoparticles (ZnO NPs) and the application of synthesized nanocomposite as a potential adsorbent to remove synthetic dyes especially malachite green (MG) from aqueous solution. Different characterization techniques supported in situ synthesis of ZnO NPs onto polymer matrix. The gum Arabic-crosslinked-poly(acrylamide)/zinc oxide nanocomposites (i.e., GA-cl-PAM/ZnO nanocomposite) exhibited much better surface properties as compared to the parental hydrogel matrix. The swelling abilities of the GA-cl-PAM/ZnO nanocomposites with different concentrations of acrylamide were also checked and the nanocomposite with 7.03 × 10–4 mol/L of acrylamide exhibited maximum swelling capacity of 2354%. The nanocomposite adsorbed approximately 99% MG dye with 0.4 g/L adsorbent dose at neutral pH. Adsorption kinetics and isotherm followed pseudo-second-order and Langmuir isotherm models, respectively with the high adsorption capacity of 766.52 mgd/gads at 25 °C. It was observed that the dye molecules were adsorbed onto GA-cl-PAM/ZnO nanocomposite mostly via electrostatic interactions, hydrogen-bonding and pore-diffusion mechanisms. Diffusion of dye molecules within the internal structure of GA-cl-PAM/ZnO nanocomposite followed the combination of both liquid film as well as intraparticle diffusion mechanisms. Furthermore, nanocomposite was applied ten times consecutively to adsorb MG dye from aqueous solution. Therefore, GA-cl-PAM hydrogel have capability to be used for the in situ ZnO NPs synthesis and thus synthesized nanocomposite can be used effectively to treat dyes polluted wastewater.

Activated biochar derived from Opuntia ficus-indica for the efficient adsorption of malachite green dye, Cu+2 and Ni+2 from water

Applicability of biochar in water treatment is gaining interest due to its sustainability and low production cost. Herein, the biochar (BC) and activated biochar (ABC) synthesized from the cladodes of Opuntia ficus-indica (OFI) cactus were evaluated as a renewable adsorbent for adsorption of organic as well as inorganic pollutants including malachite green (MG) dye, Cu+2 and Ni+2 heavy metals. The modification of biochar with NaOH resulted higher surface basicity regarding more oxygen containing functional groups on the surface. The maximum uptake of 1341 mg g−1, 49 mg g−1 and 44 mg g−1 onto activated biochar for malachite green dye, Cu+2 and Ni+2 was acquired through the best fitted Langmuir isotherm model. Pseudo-second-order and Elovich models were found to provide a suitable fit indicating towards the chemisorption of all three components. Film diffusion and chemisorption are the main steps in adsorption of MG dye and heavy metals on activated biochar. The adsorption mechanisms were also hypothesized for adsorption of MG dye, Cu+2 and Ni+2. The remarkable adsorption capacities with higher reusability characteristics for adsorption of organic pollutants as well as inorganic heavy metals entrusts this activated biochar as a potential cost-effective adsorbent to mitigate water pollution issue.

Mesoporous magnetic biochar composite for enhanced adsorption of malachite green dye: Characterization, adsorption kinetics, thermodynamics and isotherms

This study aimed to prepare a corn straw-derived biochar supported nZVI magnetic composite (nZVI/BC) and evaluate its efficiency in adsorption of malachite green dye (MG). The prepared nZVI/BC composite was characterized by XRD, FTIR, TEM, TEM-EDS, VSM, XPS, TGA, zeta potential and BET surface area. The prepared mesoporous composite showed enhanced efficiency for the adsorption of MG dye. Adsorption models and kinetic results indicated that the adsorption of MG onto nZVI/BC composite was more fitted to Langmuir isotherm and follows second order kinetics. Intraparticle diffusion model indicated that the adsorption follows a three steps mechanism. The maximum adsorption capacity of nZVI/BC composite (515.77 mg MG/g composite) was much higher than most of reported biochar adsorbents. The removal process of MG onto nZVI/BC composite does not only proceed via adsorption mechanism, but also through an oxidative degradation mechanism. The Magnetic character of the biochar enables its easy separation and reuse for many cycles.