Nanocomposite Dosage Research Articles

RSM-CCD optimized In-air synthesis of photocatalytic nanocomposite: Application in removal-degradation of toxic brilliant blue

The present research work describes the synthesis of a nanocomposite hydrogel [BFO/Mr-cl-poly(AAm)-IPN-poly(AA)] from nano bismuth iron oxide (BFO) synergistically coupled with interpenetrating network (IPN: Mr-cl-poly(AAm)-IPN-poly(AA)) of acrylic acid (AA) created within crosslinked network of a semi-IPN (Mr-cl-poly(AAm)). Semi-IPN was previously synthesized from N, N′-methylene bisacrylamide (MBA) crosslinked (cl) network of polyacrylamide (poly(AAm)) grafted onto aqueous extract of Commiphora mukul (Mr). The synthesized sample was efficient in removal-degradation of Coomassie brilliant blue G-250 (CBB) dye. Nanocomposite (NC) was magnetic as well as photocatalytic. Initially, optimization of the reaction parameters was carried out using Response Surface Methodology (RSM) design. Significant variables were accessed using Minimum Resolution V design and further optimized conditions were evaluated with central composite design (CCD). Semi-IPN showed maximum % swelling of 833.8% showing interdependence of time-temperature and solvent-crosslinker concentration. IPN synthesized gave maximum swelling of 285.8%. On insertion of BFO nanoparticles, the NC synthesized could remove-degrade a maximum of 90.4% dye in sunlight and 88.6% in UV–visible light under optimized parameters: 600 mg NC dose, 10 ppm initial dye concentration, pH 7.0, removal and degradation time 25 h and 4 h, respectively. The whole process showed second order kinetics with Elovich model criteria and followed Langmuir adsorption isotherm. GC-MS analysis gave low molecular weight products as an evidence of degradation process. Also, the NC synthesized can be recycled for industrial use.

Efficient photocatalytic oxidation of arsenite from contaminated water by Fe2O3-Mn2O3 nanocomposite under UVA radiation and process optimization with experimental design

The efficiency of photocatalytic oxidation process in arsenite (As(III)) removal from contaminated water by a new Fe2O3-Mn2O3 nanocomposite under UVA radiation was investigated. The effect of nanocomposite dosage, pH and initial As(III) concentration on the photocatalytic oxidation of As(III) were studied by experimental design. The synthesized nanocomposite had a uniform and spherical morphological structure and contained 49.83% of Fe2O3 and 29.36% of Mn2O3. Based on the experimental design model, in photocatalytic oxidation process, the effect of pH was higher than other parameters. At nanocomposite concentrations of more than 12 mg L−1, pH 4 to 6 and oxidation time of 30 min, photocatalytic oxidation efficiency was more than 95% for initial As(III) concentration of less than 500 μg L−1. By decreasing pH and increasing the nanocomposite concentration, the photocatalytic oxidation efficiency was increased. Furthermore, by increasing the oxidation time from 10 to 240 min, in addition to oxidation of As(III) to arsenate (As(V)), the residual As(V) was adsorbed on the Fe2O3-Mn2O3 nanocomposite and total As concentration was decreased. Therefore, Fe2O3-Mn2O3 nanocomposite as a bimetal oxide, at low doses and short time, can enhance and improve the efficiency of the photocatalytic oxidation and adsorption of As(III) from contaminated water resources. Furthermore, the energy and material costs of the UVA/Fe2O3-Mn2O3 system for photocatalytic oxidation of 1 mg L−1 As(III) in the 1 L laboratory scale reactor was 0.0051 €.

Synergetic enhancement of Cr(VI) removal from aqueous solutions using polyaniline@Ni(OH)2 nanocomposites adsorbent

Novel polyaniline@Ni(OH)2 nanocomposites, designated as PANI@Ni(OH)2 NCs, were synthesised by depositing Ni(OH)2 nonoparticles onto 2-napthalene sulfonic acid doped PANI nanotubes surface. Characterization tools confirmed the presence Ni(OH)2 nanoaprticles onto the reactive PANI nanotubes surface. Greater surface area (26.85 m2/g), and multiple sorption sites of PANI@Ni(OH)2 NCs facilitated higher performance towards removing Cr(VI) from aqueous solution when compared with its PANI nanotubes counterpart. Acidic pH (optimum pH-4.0) and nanocomposite dosage at and above 0.5 g/L yielded the highest Cr(VI) recovery from aqueous solutions. Kinetic experiments with PANI@Ni(OH)2 demonstrated fast Cr(VI) removal and the kinetic mechanism followed with pseudo-second-order kinetic model. Sorption isotherm data for Cr(VI) removal using PANI@Ni(OH)2 fitted well with both linear and non-linear Freundlich isotherm model, whereas a maximum of 625 mg/g Cr(VI) removal capacity was obtained at 25 °C using linear Langmuir isotherm model. Assessment of thermodynamic data with enthalpy change, ΔH0 = 17.895 KJ/mol and entropy change, ΔS0 = 0.135 KJ/mol/K suggested the endothermic and spontaneous nature of the Cr(VI) removal with PANI@Ni(OH)2. Cations and anions commonly present as co-existing ions in industrial wastewater showed negligible impact on abatement of Cr(VI) using PANI@Ni(OH)2. Surface complexation and reduction of noxious Cr(VI) species to less poisonous Cr(III) species onto PANI@Ni(OH)2 surface were identified as the major Cr(VI) removal mechanism associated with the present nanocomposite structures. Meanwhile, using this present simple synthetic route, a number of polymer/metal oxide and/or hydroxide nanocomposite structures can be fabricated for various applications.

Imprinting “Nano-SiO2-Crosslinked Chitosan-Nano-TiO2” Polymeric Nanocomposite for Selective and Instantaneous Microwave-Assisted Sorption of Hg(II) and Cu(II)

An imprinting polymeric nanocomposite-like structure was synthesized by bonding crosslinked chitosan to nano-SiO2 and nano-TiO2 simultaneously via bifunctional glutaraldehyde linker. The structure of this “nano-SiO2-crosslinked chitosan-nano-TiO2” nanocomposite was confirmed and characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The surface area (6.47 cm3 g–1), porosity (0.193 cm3 g–1), and particle size (14–40 nm) were confirmed from scanning electron microscopy (SEM) studies, high-resolution transmission electron microscopy (HR-TEM) studies, and surface area measurements. This nanocomposite announced selective and enhanced sorption for Hg and Cu ions with high performance using microwave techniques. Different factors that affected the metal sorption capacity were monitored, including microwave-contact time, pH, nanocomposite dosage, temperature, and initial metal concentration. Maximum capacity values of 8000 and 4000 μmol g–1...

Magnetic CoFe 2 O 4 @ melamine based hyper-crosslinked polymer: A multivalent dendronized nanostructure for fast bacteria capturing from real samples

Polymeric compounds are main types of advanced materials to prepare antibacterial coating as well as water treatment system hence this work was aimed to prepare a polymeric nanostructure with excellent bacteria capture efficiency. Dendronized melamine – resorcinol was synthesized by a condensation reaction. To simplify polymer collection from aqueous solutions, a magnetic nanocomposite of the polymer was also prepared. For this purpose, CoFe2O4 nanoparticles were synthesized by solid-state combustion route using cellulose as fuel. Bacteria removal efficiency was studied by uptake of Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) bacteria from water, milk and fruit juice samples. Effective parameter on the capturing efficiency including; solution pH, contact time and nanocomposite dosage were optimized. Results confirmed the positive role of presented nanostructure for fast capturing of bacterial pathogens with high efficiency (more than 99%).

Adsorption and photocatalysis for methyl orange and Cd removal from wastewater using TiO 2 /sewage sludge-based activated carbon nanocomposites

Nanocomposite TiO2/ASS (TiO2 nanoparticle coated sewage sludge-based activated carbon) was synthesized by the sol-gel method. The changes in surface properties of the TiO2/ASS nanocomposite were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray fluorescence. The prepared TiO2/ASS nanocomposite was applied for simultaneous removal of methyl orange dye (MO) and Cd2+ from bi-pollutant solution. The factors influencing photocatalysis (TiO2 : ASS ratios, initial pollutant concentrations, solution pH, nanocomposite dosage and UV irradiation time) were investigated. The results revealed that high removal efficiency of methyl orange dye (MO) and Cd2+ from bi-pollutant solution was achieved with TiO2/ASS at a ratio (1 : 2). The obtained results revealed that degradation of MO dye on the TiO2/ASS nanocomposite was facilitated by surface adsorption and photocatalytic processes. The coupled photocatalysis and adsorption shown by TiO2/ASS nanocomposite resulted in faster and higher degradation of MO as compared to MO removal by ASS adsorbent. The removal efficiency of MO by ASS adsorbent and TiO2/ASS (1 : 2) nanocomposite at optimum pH value 7 were 74.14 and 94.28%, respectively, while for Cd2+ it was more than 90%. The experimental results fitted well with the second-order kinetic reaction.

Removal of malachite green from the aqueous solutions using polyimide nanocomposite containing cerium oxide as adsorbent

ABSTRACTIn this study polyimide nanocomposites containing cerium oxide were prepared through sol-gel method. Morphology of the particles was investigated using scanning electron microscopy (SEM) and the average size of the composite particles was obtained as 41 nm. Structural characteristics of the nanocomposites were investigated using X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. These nanocomposites were used as an adsorbent for removal of the malachite green (MG) as pollutant. During investigating the activity of the dosage of adsorbent polyimide nanocomposite containing cerium oxide, time, pH and concentration of the pollutant were studied and the results demonstrated the high activity of the prepared nanocomposites as adsorbent. The highest removal percentage is obtained at pH = 5, and the optimum dosage of the nanocomposite so as to removal of malachite green was chosen as 0.7 g.

A Novel Nanocomposite as an Efficient Adsorbent for the Rapid Adsorption of Ni(II) from Aqueous Solution.

A sulfhydryl-lignocellulose/montmorillonite (SLT) nanocomposite was prepared using a chemical intercalation reaction. The SLT nanocomposite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Transmission Electron Microscopy (TEM), the results demonstrated that an intercalated-exfoliated nanostructure was formed in the SLT nanocomposite. Batch experiments were conducted to optimize parameters such as SLT nanocomposite dosage, the initial concentration of Ni(II), solution pH, temperature, and time. The results indicated that the attractive adsorption capacity reached 1134.08 mg/g with 0.05 g of SLT at an initial concentration of Ni(II) of 700 mg/L, solution pH of 5.5, adsorption temperature of 50 °C, and adsorption time of 40 min, meanwhile, the Ni(II) adsorption capacity significantly decreased with the increase in ionic strength. The pseudo-second order kinetic model could describe the whole adsorption process well, and the isotherm adsorption equilibrium conformed to the Freundlich model. The adsorption mechanism of SLT was also discussed by means of FTIR and Energy-Dispersive X-Ray (EDX). Dramatically, the introduction of sulfhydryl achieves the increased activated functional groups content of SLT nanocomposite, leading to remarkably higher adsorption amount on Ni(II). The desorption capacity of SLT was dependent on parameters such as HNO3 concentration, desorption temperature, and ultrasonic desorption time. The satisfactory desorption capacity and desorption efficiency of 458.21 mg/g and 40.40% were obtained at an HNO3 concentration, desorption temperature, and ultrasonic desorption time of 0.4 mol/L, 40 °C, and 30 min, respectively. The regeneration studies showed that the adsorption capacity of SLT was consistent for four cycles without any appreciable loss and confirmed that the SLT was reusable. Owing to such outstanding features, the novel SLT nanocomposite proved the great potential in adsorption for Ni(II) removal from aqueous solution, and exhibited an extremely significant amount of Ni(II), compared to pristine lignocellulose/montmorillonite and the conventional spent adsorbents.

Photocatalytic degradation of pefloxacin in water by modified nano-zinc oxide

Nanocrystalline La-doped ZnO powders were synthesized by homogeneous precipitation method and characterized by various sophisticated techniques such as XRD, UV–vis DRS and SEM. Experimental results show that the La-doped ZnO could make ZnO particle size decrease and make specific surface area large, so the photocatalytic activity of La-doped ZnO was increased compared with pure ZnO. The optimal conditions for maximum efficiency of pefloxacin degradation under 6h UV irradiation were found as 1g/L dosage of La-doped ZnO nanocomposite, pefloxacin concentration of 15mg/L, and pH = 7.0. Under optimal operating conditions, degradation efficiency was reached to 93%.

Photocatalytic degradation of Direct yellow 86 diazo dye using sulfanilic acid-modified TiO2 in aqueous suspensions.

This study synthesized sulfanilic acid (SA)-modified TiO2 nanocomposites and used them as an effective photocatalyst for Direct yellow 86 diazo dye removal from aqueous solution. This novel nanocomposite (SA/TiO2) was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and X-ray diffraction. The results showed the formation of SA/TiO2 nanocatalyst. The photocatalytic activity of the modified photocatalyst was examined by degradation of Direct yellow 86 (GE) under UV and visible light. The effects of five parameters, the concentration of GE, dosage of SA/TiO2 nanocomposite, UV light irradiation intensity, pH and visible light illumination, on the removal of GE using SA/TiO2 nanocomposite were studied. The highest GE removal was determined at pH of 9, nanocomposite dosage of 0.15 g/l and initial GE concentration of 50 mg/l at the constant temperature of 25 °C. However, the results showed that the GE removal rate increased as the UV light intensity increased. In addition, an enhancement in the photodegradation rate was observed with visible light illumination. The adsorption trends of GE at various initial concentrations followed the Langmuir isotherm model.

Super high removal capacities of heavy metals (Pb2+ and Cu2+) using CNT dendrimer

This research demonstrates the capability of carbon nanotubes (CNT) modified with four generations of poly-amidoamine dendrimer (PAMAM, G4) to remove Cu2+ and Pb2+ heavy metals from aqueous solution in single and binary component systems. Uniquely high adsorption capacities for copper and lead, which are 3333 and 4870mg/g respectively, were achieved. FTIR, H1 NMR, Zeta potential, SEM and TEM techniques were employed for characterizing the synthetic nanocomposite and indicated that the dendrimer functionalized CNTs have been synthesized. The effects of several parameters including initial metal ion concentration, solution pH and the nanocomposite dosage were studied. The experimental data were analyzed by the Langmuir and Freundlich isotherms and the pseudo-first order and pseudo-second order kinetics models. The maximum adsorption occurred at pH=7. The adsorption process for Cu2+ and Pb2+ in single and binary component systems fit the Langmuir and extended Langmuir models respectively. This study also tested the kinetic sorption of the metals on PAMAM/CNT in single and binary component metal systems at various metal ions concentrations. The results showed that PAMAM/CNT nanocomposite was a super-adsorbent, able to uptake uniquely large quantities of heavy metal from single and binary component liquid phase.

Enrichment of lanthanides in aqueous system by cellulose based silica nanocomposite

Synthesis of cellulose based silica (CLx/SiO2) nanocomposite was successfully carried out and employed for the removal of Eu(III), La(III) and Sc(III). Nanocomposite was characterized by TEM, AFM, SEM, XRD, FTIR and BET. TEM analysis indicated that the particle diameter of nanocomposite was in the range of 9–15nm and silica particles was uniformly distributed throughout the nanocomposites. The presence of mixed phases of cellulose and SiO2 was observed by FTIR and XRD. Experimental results showed that CLx/SiO2 nanocomposite produced by sulfuric acid modification possess higher surface area than that of citric acid modified. Various parameters including contact time, pH, nanocomposite dosage, initial concentration, and temperature were optimized to achieve maximum adsorption capacity. The kinetics results revealed that the surface chemical sorption for Eu(III) and La(III) and physisorption for Sc(III). Also, the film diffusion was the rate-determining step of the adsorption process. Importantly, the isotherms fitted better to Langmuir for Eu(III) and La(III) than Freundlich. The positive values of ΔH0 indicates that the adsorption process was endothermic and negative value of ΔG0 indicates the feasibility of Eu(III), La(III) and Sc(III) removal by adsorption on CLN/SiO2 nanocomposite and suggests the spontaneous nature of adsorption on nanocomposite. Desorption of adsorbate loaded on nanocomposite during adsorption process was easily carried out up to three cycles. The results indicate that the nanocomposite is an efficient adsorbent with good adsorption capacity for Eu(III), La(III) and Sc(III).

Immobilization of chitosan nanolayers on the surface of nano-titanium oxide as a novel nanocomposite for efficient removal of La(III) from water

A novel nanocomposite has been designed and synthesized via surface crosslinking of chitosan nanolayers (NChit) with titanium oxide nanoparticles (NTiO2) using glutaraldehyde (Glu) as the crosslinking agent. A simple and green surface chemical reaction was accomplished by the aid of microwave heating process to enforce surface encapsulation and functionalization for the production of the aimed NTiO2-Glu-NChit nanocomposite. The average particles size of nanocomposite was characterized in the range of 52–58nm using SEM and confirmed by the HR-TEM. The XRD, TGA and FTIR were also employed to assure the immobilization and crosslinking processes. NTiO2-Glu-NChit was studied to estimate the sorption efficiency towards La(III) from aqueous solution by the batch technique under different experimental controlling physicochemical parameters such as, initial pH of metal ion solution, contact time, nanocomposite dosage and initial metal ion concentration. The optimum sorption condition for La(III) as the target metal ion was identified at pH=1.0, 3.0 and 6.0. The adsorption process of La(III) was characterized to follow the postulates of Langmuir and Freundlich isotherm models and the adsorption mechanisms were identified to obey the pseudo-second order kinetic model based on the best compatible results with the experimental data.

Magnetic cobalt ferrite composite as an efficient catalyst for photocatalytic oxidation of carbamazepine.

A magnetic spinel cobalt ferrite nanoparticle composite (CFO) was prepared via an ultrasonication-assisted co-precipitation method. The morphological structure and surface composition of CFO before and after reaction were investigated by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, and Fourier transform infrared spectroscopy, indicating the consumption of iron oxide during photodegradation. X-ray photoelectron spectroscopy and vibrating sample magnetometry confirm the preparation of the ferrite nanoparticle composite and its magnetic properties. The prepared CFO was then used for the photocatalytic degradation of carbamazepine (CBZ) as an example of pharmaceuticals and personal care products (PPCPs) from aqueous solution. The effects of the nanocomposite dosage, contact time, and solution pH on the photodegradation process were investigated. More than 96% of the CBZ was degraded within 100min at 0.2g·L-1 CFO in the presence of UV light. The reactive species for CBZ degradation in the CFO/UV system was identified as hydroxyl radicals by the methanol scavenging method. Combined with the detection of leached iron ions during the process, the CBZ degradation mechanism can be presumed to be heterogeneous and homogeneous photocatalytic degradation in the CFO/UV system. Furthermore, iminostilbene and acridine were detected as intermediate products by GC-MS.

Synthesis and characterization of PAMAM/CNT nanocomposite as a super-capacity adsorbent for heavy metal (Ni2 +, Zn2 +, As3 +, Co2 +) removal from wastewater

The water cleaning applications of carbon nanotubes (CNT) have generated much research interest since their initial discovery. However, in the early stages of research, the efficiency of CNTs for the removal of heavy metal ions has been severely limited because of the intense agglomeration of CNTs and their deficiency of functional groups. In this research, a new method has been discovered for the preparation of dendrimer functionalized CNTs and a PAMAM/CNT nanocomposite was prepared. FTIR, SEM, TEM, Raman spectroscopy, zeta potential measurements, and dispersion observing methods have been employed for characterizing the synthetic nanocomposite and these techniques indicated that the dendrimer functionalized CNTs have been favorably synthesized. In addition, the uniquely high adsorption capacities properties of PAMAM/CNT nanocomposite for Ni2+, Zn2+, As3+, Co2+ were examined. The effects of several parameters including initial metal ion concentration, temperature, solution pH, the nanocomposite dosage and contact time were studied. The experimental data were analyzed using equilibrium isotherm relationships (Langmuir, Temkin and Freundlich) and the uniquely high adsorption capacities and rates were studied using (pseudo-first order, intraparticle diffusion and pseudo second-order) adsorption kinetics models. The results indicated that the maximum adsorption occurred at pH=8. With increasing nanocomposite dosage and increasing contact time, there was increased adsorption capacity. Analysis of the adsorption process demonstrated that the Langmuir isotherm and pseudo-second order kinetics are the most appropriate models for heavy metal ions adsorption onto PAMAM/CNT nanocomposite.

Synthesis of malachite@clay nanocomposite for rapid scavenging of cationic and anionic dyes from synthetic wastewater

Synthesis of malachite@clay nanocomposite was successfully carried out for the removal of cationic (Methylene Blue, MB) and anionic dyes (Congo Red, CR) from synthetic wastewater. Nanocomposite was characterized by TEM, SEM, FT-IR, EDS analysis and zeta potential. TEM analysis indicated that the particle diameter of nanocomposite was in the range of 14 to 23nm. Various important parameters viz. contact time, concentration of dyes, nanocomposite dosage, temperature and solution pH were optimized to achieve maximum adsorption capacity. In the case of MB, removal decreased from 99.82% to 93.67% while for CR, removal decreased from 88.55% to 75.69% on increasing dye concentration from 100 to 450mg/L. pH study confirmed the higher removal of CR in acidic range while MB removal was higher in alkaline range. Kinetic study revealed the applicability of pseudo-second-order model for the adsorption of both dyes. Negative values of ΔG0 for both systems suggested the feasibility of dye removal and support for spontaneous adsorption of CR and MB on nanocomposite. Nanocomposite showed 277.77 and 238.09mg/g Langmuir adsorption capacity for MB and CR respectively. Desorption of dyes from the dye loaded nanocomposite was easily carried out with acetone. The results indicate that the prepared malachite@clay nanocomposite is an efficient adsorbent with high adsorption capacity for the aforementioned dyes.

Visible light photocatalytic activity of chitosan/poly(vinyl alcohol)/TiO2 nanocomposite for dye removal: taguchi‐based optimization

This work describes the preparation of chitosan/poly (vinyl alcohol)/titanium dioxide (CS/PVA/TiO2) nanocomposite for its use as a photocatalyst under visible light irradiation. The prepared nanocomposite was characterized by Fourier transform infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activity of CS/PVA/TiO2 was evaluated by photocatalytic removal of acid red 14 (AR14) in aqueous solution as a model pollutant. A Taguchi orthogonal array experimental design with an L16 matrix was employed to optimize the factors affecting the photocatalytic efficiency of CS/PVA/TiO2 nanocomposite such as: pH, irradiation time, initial dye concentration, and nanocomposite dosage. The optimum conditions were found to be as follows: pH = 3; irradiation time = 120 min; initial dye concentration = 10 mg L−1, and nanocomposite dosage = 400 mg L−1. The pH was found to be the most effective factor for dye removal, followed by the nanocomposite dosage. The dye removal during visible‐CS/PVA/TiO2 process under optimal conditions followed the pseudo‐first‐order reaction model with the rate constants of 0.0188 min−1. The photocatalytic activity of CS/PVA/TiO2 nanocomposite dropped very slightly in five consecutive reaction cycles. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 66–72, 2017

Response surface modeling of lead (׀׀) removal by graphene oxide-Fe3O4 nanocomposite using central composite design.

BackgroundMagnetic graphene oxide (Fe3O4@SiO2-GO) nanocomposite was fabricated through a facile process and its application as an excellent adsorbent for lead (II) removal was also demonstrated by applying response surface methodology (RSM).MethodsFe3O4@SiO2-GO nanocomposite was synthesized and characterized properly. The effects of four independent variables, initial pH of solution (3.5–8.5), nanocomposite dosage (1–60 mg L−1), contact time (2–30 min), and initial lead (II) ion concentration (0.5–5 mg L−1) on the lead (II) removal efficiency were investigated and the process was optimized using RSM. Using central composite design (CCD), 44 experiments were carried out and the process response was modeled using a quadratic equation as function of the variables.ResultsThe optimum values of the variables were found to be 6.9, 30.5 mg L−1, 16 min, and 2.49 mg L−1 for pH, adsorbent dosage, contact time, and lead (II) initial concentration, respectively. The amount of adsorbed lead (II) after 16 min was recorded as high as 505.81 mg g−1 for 90 mg L−1 initial lead (II) ion concentration. The Sips isotherm was found to provide a good fit with the adsorption data (KS = 256 L mg−1, nS = 0.57, qm = 598.4 mg g−1, and R2 = 0.984). The mean free energy Eads was 9.901 kJ/mol which confirmed the chemisorption mechanism. The kinetic study determined an appropriate compliance of experimental data with the double exponential kinetic model (R2 = 0.982).ConclusionsQuadratic and reduced models were examined to correlate the variables with the removal efficiency of Fe3O4@SiO2-GO. According to the analysis of variance, the most influential factors were identified as pH and contact time. At the optimum condition, the adsorption yield was achieved up to nearly 100 %.

Adsorption of brilliant green dye by polyaniline/silver nanocomposite: Kinetic, equilibrium, and thermodynamic studies

Polyaniline/silver nanocomposite (PANI/AgNPs) was synthesized by the chemical oxidative polymerization of aniline with ammonium peroxydisulphate in acidic medium of sulfuric acid (1M). The surface of polyaniline is modified by silver nanoparticles. Samples were prepared at various molar ratios of silver nitrate to PANI ranging from 1 to 2.5. The emeraldine base was oxidized to pernigraniline, where the silver nitrate was reduced to metallic silver. The modified surface of PANI was confirmed by the scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), FT-IR and thermogravemetric analysis (TGA). The efficiency of polyaniline/silver nanoparticles for the adsorptive removal of brilliant green (BG) from aqueous solutions, has been evaluated with respect to several experimental conditions. These conditions are contact time, initial BG concentration, temperature and nanocomposite dosage. The experimental data were analyzed by the Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm fits the experimental data very well due to the homogeneous distribution of active sites onto PANI/AgNPs surface. The thermodynamic parameters such as Gibbs free energy, entropy and enthalpy changes of the ongoing adsorption process indicated the feasibility and endothermic nature of BG adsorption. The kinetics study revealed that adsorption of BG onto PANI/AgNPs follows the pseudo-second order kinetic model.

Photodegradation of Erythromycin antibiotic by γ-Fe2O3/SiO2 nanocomposite: Response surface methodology modeling and optimization

Efficient adsorbent γ-Fe2O3/SiO2 nanocomposites were synthesized using sol–gel method. The developed adsorbent was well characterized using various analytical techniques such as XRD, TEM, SEM, BET and DRS techniques. The obtained XRD pattern that revealed a strong Si (111) peak at 28.1°. On the other hand, the patterns of display representative γ-Fe2O3 peaks were centered at 2θ=31.2°, 33.9°, 44.1°, 52.5°, 57.6°, and 63.9°, due to (220), (311), (400), (422), (511), and (440) planes, respectively. The DRS analysis of γ-Fe2O3/SiO2 nanocomposite that shifted to a lower wavelength (blue-shift), reveals the high photocatalytic activity of the developed adsorbent. The central composite design superimposed with the response surface methodology (RSM) was used for the optimization of the influential parameters and photocatalytic removal of Erythromycin antibiotic. The obtained optimized values for the rapid removal of Erythromycin antibiotic were as follows: γ-Fe2O3/SiO2 nanocomposite dosage of 500mgL−1, initial RhB concentration of 6mgL−1, the irradiation time of 6min, and pH=8.