The ZnO/ZnMn2O4 nanocomposite (ZnMn) was used as adsorbent for the removal of cationic dye Basic Yellow 28 (BY28) from aqueous solutions. The adsorbent was characterized by X-ray diffraction, scanning electron microscope, TEM, Fourier transform infrared ray, BET, particle size distribution and zeta potential measurements. The adsorption parameters, such as temperature, pH and initial dye concentration, were studied. Kinetic adsorption data were analyzed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The Langmuir and Freundlich isotherm models were applied to fit the equilibrium data. The maximum adsorption capacity of BY28 was 48.8 mg g?1. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were calculated. 相似文献
In this study, nanocomposite hydrogels from grafting of acrylamide onto kappa-carrageenan biopolymer were prepared in the presence of sepiolite clay. Methylenebisacrylamide and ammonium persulfate were used as cross-linker and initiator, respectively. The sepiolite nanoclay was introduced into hydrogel matrix without any chemical treatment. The structure of nanocomposites was investigated by FTIR, SEM, TEM, and TGA techniques. The TEM image showed that sepiolite exists as individual needle’s shape. The swelling of hydrogels were studied in distilled water, salt solutions, and various pHs. The obtained nanocomposites were evaluated to remove of cationic crystal violet (CV) dye from water. The kinetic and isotherm of adsorption of dye onto nanocomposites were studied and analyzed according to kinetic and isotherm models. The results showed that the pseudo-second-order adsorption kinetic was predominated for the adsorption of CV onto nanocomposites. The experimental equilibrated adsorption capacity of nanocomposites was analyzed using Freundlich and Langmuir isotherm models. The results corroborated that the experimental data fit the Langmuir isotherm the best. By varying the pH of initial dye solution, while the clay-free hydrogel showed relatively pH-independent adsorption behavior, the nanocomposites depicted pH-dependent adsorption. 相似文献
Nanocomposite superabsorbents were synthesized by simultaneously solution copolymerization of acrylamide (AAm) and sodium acrylate (Na-AA) in the presence of carrageenan biopolymer and sodium montmorillonite (Na-MMt) nanoclay. Potassium persulfate (KPS) and methylenebisacrylamide (MBA) were used as initiator and crosslinker, respectively. The structure and morphology of the nanocomposites were investigated using XRD, FTIR, scanning electron microscopy (SEM), and TEM techniques. The influence of nanoclay and carrageenan contents as well as monomer weight ratios on the degree of swelling of nanocomposites was studied. The optimum water absorbency was obtained at 10 wt% of clay, 10 wt% of carrageenan, and 1:1 of monomers weight ratio. The obtained nanocomposites were examined to remove of crystal violet (CV) cationic dye from water. The effect of carrageenan and clay content on the speed of dye adsorption revealed that while the rate of dye adsorption is enhanced by increasing the clay content up to 14 wt% of clay, it was decreased as the carrageenan increased in nanocomposite composition. The results showed that the pseudo-second-order adsorption kinetic was predominated for the adsorption of CV onto nanocomposites. The experimental equilibrated adsorption capacity of nanocomposites was analyzed using Freundlich and Langmuir isotherm models. The results corroborated that the experimental data fit the Freundlich isotherm the best. 相似文献
The adsorption of Methylene Blue (MB) and Acid Orange 7 (AO7) from aqueous solutions by acid treated coconut coir was investigated under laboratory conditions to assess its potential in removing cationic and anionic dyes. The acid treated coconut coir exhibited better adsorption capacity in cationic dye MB than anionic dye AO7 and the data obtained can be well described by both Langmuir and Freundlich isotherm models. According to the Langmuir isotherm model, the maximum adsorption capacities of MB and AO7 onto acid treated coconut coir were 121 mg/g and 10 mg/g, respectively. The adsorption behavior of MB and AO7 onto acid treated coconut coir was analyzed with first-order Lagergren model and pseudo-second order model. 相似文献
Novel hydrogel nanocomposites were synthesized by solution polymerization of acrylamide in the presence of carrageenan biopolymer and laponite RD clay. Laponite was used as an inorganic cross-linker. Ammonium persulfate was applied as an initiator. The structure and morphology of the nanocomposites were investigated using XRD, scanning electron microscopy, and transition electron microscopy techniques. The influence of both laponite nanoclay and the carrageenan content on the swelling degree of nanocomposites was studied and it was found that all nanocomposites containing carrageenan component have a high swelling degree compared to a nanocomposite without carrageenan. The obtained nanocomposites were examined to remove a cationic crystal violet (CV) dye from water. The effect of carrageenan and clay contents on the speed of dye adsorption revealed that while the rate of dye adsorption is enhanced by increasing the clay content, it was depressed as the carrageenan content increased in nanocomposite composition. The results showed that the pseudo-second-order adsorption kinetic was predominant in adsorption of CV onto nanocomposites. The experimental equilibrated adsorption capacity of nanocomposites was analyzed using Freundlich and Langmuir isotherm models. The results indicated that the experimental data fit the Langmuir isotherm best. Maximum adsorption capacity was obtained for carrageenan-free nanocomposite with 79.8?mg?g?1 of adsorbed CV onto nanocomposite. 相似文献
In this paper, the use of tamarind hull biosorbent (Tamarindus indica) has been investigated to remove cationic dyes from textile eflluent. Basic Violet 6 and Basic Red 18 were used as cationic dye models. The surface characteristics of tamarind hull were investigated using Fourier Transform–infrared and scanning electron microscopy. The influence of process variables such as adsorbent dosage, initial dye concentration and pH were studied. The presence of fuctional groups such as hydroxy and amine groups onto the tamarind hull surface were proved by Fourier Transform–infrared analysis. Data were evaluated for compliance with the Langmuir and Freundlich isotherm models. The results indicated that the data for adsorption of Basic Violet 6 and Basic Red 18 onto tamarind hull fitted well with the Freundlich isotherm model. Also, the adsorption kinetics of Basic Violet 6 and Basic Red 18 on biosorbent was studied. The rates of sorption were found to conform to pseudo‐second‐order kinetics with good correlation. Results indicated that tamarind hull could be used as a biosorbent to remove cationic organics from contaminated watercourses. 相似文献
This paper presents a study on the batch adsorption kinetics of seven cationic dyes, namely, Methylene Blue, Safranine T, Rhodamine B, Crystal Violet, Malachite Green, Brilliant Green, and Basic Fuchsine onto Jalshakti® (JS), a super absorbent polymer, from aqueous solution. The adsorption of dyes reaches equilibrium in 60–90 min. Equilibrium isotherms and intraparticle diffusion rate constants were measured for single component systems. It is found that uptake of dyes on JS follows the Langmuir and Freundlich isotherm models. The particle diffusion study showed that the initial boundary layer diffusion is followed by intraparticle diffusion effects. The flat and planar dye molecules are readily adsorbed as compared with the propeller shaped triphenylmethane dyes. Photocatalytic regeneration of spent JS using UV/TiO2 is more effective compared to conventional methods. Further, the regenerated JS exhibits 90% efficiency for subsequent adsorption cycle with Methylene Blue and Safranine T aqueous solutions. 相似文献
Abstract Adsorptive removal of the dyes C.I. Basic Blue 9, C.I. Basic Red 2, and C.I. Acid Blue 74 from aqueous solution onto the activated carbon cloth (ACC) has been investigated. The removal of each dye has been followed by in-situ UV-visible spectroscopic method using the so-called scanning kinetics technique. Kinetic data obtained in this way were tested according to pseudo-first order, pseudo-second order, Elovich, and intraparticle diffusion models. Pseudo-second order model was found to be the best in representing the experimental kinetic data. Adsorption isotherms at 30°C were derived for each dye. Isotherm data were found to fit best to Freundlich isotherm model among the three isotherm models tested; Langmuir, Freundlich, and Redlich-Peterson. High specific surface area of the ACC allowed almost complete removal of each dye under the experimental conditions applied. Adsorption capacity of the ACC for the three dyes was correlated with the dimensions of dye molecules and pore sizes of the ACC. 相似文献
A series of polystyrene (PS)/organomontmorillonite (OMMT) clay nanocomposites was prepared by effectively dispersing the inorganic nanolayers of OMMT clay in the organic PS matrix via the solvent blending method using xylene as a solvent. The resulting samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The XRD and TEM results show that the intercalation/exfoliation of OMMT can be divided into solvent swelling and layer breaking processes and is affected by several reaction parameters such as nanofiller loading, refluxing temperature, and refluxing time. TGA data show that the PS/OMMT nanocomposites have significant enhanced thermal stability. When 50% weight loss is selected as a point of comparison, the thermal decomposition temperature of PS/OMMT nanocomposite with 7 wt% of OMMT is 15°C higher than that of pure PS. The glass transition temperature (Tg) of PS/OMMT nanocomposites is about 5.0–6.2°C higher than that of pure PS. The water uptake capacity of PS/OMMT nanocomposites is negligible when compared with pure PS. 相似文献
In the present study, synthesis of poly(AAm-co-AMPS)/Na-MMT hydrogel nanocomposite with different amount of bis[2-(methacryloyloxy)ethyl] phosphate as a crosslinker was successfully carried out for the removal of crystal violet (CV), methylene blue (MB) and methyl red (MR) from aqueous solution. Hydrogel nanocomposite was characterized by FT-IR, SEM, EDS, XRD and TGA analysis. Several important parameters were investigated to obtain maximum adsorption capacity. Adsorption behavior of hydrogel nanocomposite was investigated for the adsorption of dyes and it was found to remove about 80% for CV, 89% for MB and 51% for MR in 50 mg/L of dyes solutions at pH 7 and about 86% for CV, 93% for MB and 23% for MR at pH 12. Kinetic studies revealed that the applicability of pseudo-first-order and pseudo-second-order model for the adsorption of CV, MB and MR. The adsorption isotherm was studied in 25, 35, 45 and 55 °C using Langmuir, Freundlich, Temkin and Jovanovic models and the adsorption data were well described by Freundlich isotherm model. Hydrogel nanocomposite showed 155, 176 and 113 mg/g maximum adsorption capacity for CV, MB and MR respectively. Negative values of ΔG0 for all three dyes suggested the feasibility of dyes removal and support for spontaneous adsorption of CV, MB and MR on hydrogel nanocomposite. Desorption of dyes from the dye loaded hydrogel nanocomposite was simply done in ethanol. The results indicate that the prepared poly(AAm-co-AMPS)/Na-MMT hydrogel nanocomposite is an efficient adsorbent with high adsorption capacity for the aforementioned dyes.
In this study, a series of poly acrylamide-co-acrylic acid/NaY zeolite, poly acrylamide-co-acrylic acid/MCM-41, and poly acrylamide-co-acrylic
acid/clinoptilolite nanocomposites were synthesized. These materials were characterized by using FT-IR spectroscopy, XRD,
TGA, and SEM. Removal capacity of Pb(II) and Cd(II) ions in aqueous solutions by using these nanocomposites was investigated
with controlled time, initial metal ions concentration, pH values, adsorbent content, and temperature by using atomic absorption
spectrometry. Results show that these nanocomposites have further adsorption related to NaY, MCM-41, and clinoptilolite. Poly(AAm-co-AAc)/NaY,
poly(AAm-co-AAc)/MCM-41, and poly(AAm-co-AAc)/clinoptilolite exhibit superior Pb(II) (about 90–99%) and Cd(II) (about 88–98%)
adsorption behavior at room temperature and the poly(AAm-co-AAc)/NaY nanocomposite had the best adsorption behavior. Finally,
the equilibrium removal performance of the composites is analyzed according to the Langmuir and Freundlich adsorption isotherm
model that shows result fitted to Langmuir model and have monolayer adsorption. 相似文献
Gum xanthan/psyllium-based nanocomposite was prepared by microwave-assisted synthetic method for the removal of toxic Malachite green (MG) dye from aqueous solutions. The nanocomposite was prepared by in situ incorporation of the K2Zn3[Fe(CN)6]·9H2O nanoparticles into the semi-IPN matrix in the presence of ammonium persulphate and glutaraldehyde as initiator-crosslinker system. Liquid uptake efficacy of the hybrid superabsorbent was enhanced through the optimization of different reaction conditions, including APS = 0.027 mol L?1; glutaraldehyde = 0.053 × 10?3 mol L?1; solvent = 8.0 mL; acrylic acid = 10.928 mol L?1; pH 7.0; reaction time = 60 s and microwave power = 100 % and its thermal behavior was evaluated using TGA-DTG-DTA technique. Candidate nanocomposite was characterized by FTIR, SEM, XRD and UV–visible spectroscopic methods. Various optimized parameters for the efficient removal (83 %) of the Malachite green were adsorbent dose of 800 mg, 14 mg L?1 initial dye concentration and contact time of 28 h. Further, Langmuir and Freundlich adsorption isotherms showed good applicability in adsorption process of MG onto the nanocomposite with maximum adsorption efficiency of 3.21 mg g?1. However, for Freundlich isotherm, R2 was around 0.9947 and value of 1/n was less than 1 for the synthesized nanocomposite which indicated that the Freundlich isotherm was more favorable than Langmuir isotherm model along with its usability for wide range of dye concentrations. The nanocomposite was found to be a potential product for dye removal from waste water and could prove to be a boon for textile sector. 相似文献
Adsorptive removal of Basic Blue 3 (BB 3) and Basic Red 18 (BR 18) by a clinoptilolite-type natural zeolite from their single-component solutions has been studied in the temperature range of 298–328 K. Experimental equilibrium results are well described by the Freundlich and the Langmuir isotherm models. The model parameters obtained for single-solute systems at 298 K have been used for the prediction of adsorption isotherms in binary dye solutions using multicomponent isotherm models. Competitive adsorption results between BB 3 and BR 18 in binary solutions satisfactorily fit the extended Freundlich, extended Langmuir, and modified Langmuir models. A site distribution function that gives information about affinity of adsorption sites for competing species in binary systems has been mathematically calculated using the Freundlich parameters. Time-dependent results for single and binary dye solutions have been analyzed according to a pseudo-second-order kinetic model based on chemisorption and a McKay model assuming two resistance diffusion processes, respectively. The diffuse reflectance FT-IR spectra indicate that the dyes are adsorbed via electrostatic interactions in external rings of clinoptilolite by replacing the zeolitic water in a single system, and they diffuse through the liquid associated with zeolitic water in TO4 tetrahedra (T: Al, Si) in a mixed solution. 相似文献
Cyclodextrin-based materials containing carboxylic groups (CD/CMC adsorbents) are used for the removal of C.I. Basic Blue 9 (BB 9) from aqueous solutions. Studies concerning the sorption kinetics (i.e. the effects of contact time, dye concentration and mass of sorbent) are presented and discussed. Results of adsorption experiments showed that these adsorbents exhibited high sorption capacities toward C.I. Basic Blue 9. The adsorption capacity of BB 9 on CD/CMC material increased as the dosage of the material increased and the adsorption kinetics followed a pseudo-second order model. However, the sorption was dependent on the presence of carboxylic groups. Four isotherm equations have been tested in the present study, namely Freundlich, Langmuir, Temkin and generalized. The characteristic parameters for each isotherm have been determined. The monolayer adsorption capacity was 56.5 mg g−1. The Freundlich equation represented the best fit of experimental data than the other isotherm equations. 相似文献
Mesoporous MCM-41 was synthesized at room temperature using tetraethoxysilane (TEOS) with cetyltrimethylammonium bromide (CTAB) and employed as an effective adsorbent for the adsorption of methylene blue dye from aqueous solution. The as-synthesized MCM-41 was calcined at 250 and 550°C to study the relation between the surface area and pore volume with surfactant removal. The synthesized MCM-41 was characterized using thermo gravimetric analysis (TGA), X-ray diffraction (XRD) patterns, nitrogen adsorption/desorption isotherms and Fourier transform infrared (FT-IR) spectroscopy. The MCM-41 calcined at 550°C showed higher surface area (1,059 m2 g?1) with pore volume of 0.89 ml g?1 and was used for the investigation of adsorption isotherms and kinetics. The experimental results indicated that the Freundlich and Redlich-Peterson models expressed the adsorption isotherm better than the Langmuir model. In addition, the influence of temperature and pH on adsorption was also investigated. The decrease in temperature or the increase in pH enhanced the adsorption of dye onto MCM-41. A maximum adsorption capacity of 1.5×10?4 mol g?1 was obtained at 30°C. The kinetic studies showed that the adsorption of dye on MCM-41 follows the pseudo-second-order kinetics. 相似文献