Synthesis, Characterization and Application of a Diatomite-Based Composite for the Adsorption of Anionic Dyes in Aqueous Solutions (original) (raw)
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2011
The adsorption of three cationic dyes (rhodamine B, RB; crystal violet, CV; and malachite green, MG) onto termite feces, a low-cost adsorbent, was investigated. The adsorbent was characterized by IR spectroscopy, point of zero charge measurement, and the Boehm titration method. The adsorption follows the pseudo-second-order kinetic model and the Langmuir-Freundlich isotherm with maximum adsorption capacities of 95.53 mg g À1 (RB), 75.71 mg g À1 (CV), and 44.78 mg g À1 (MG). The study of thermodynamics showed that the adsorption is a spontaneous and endothermic process. This work suggests that termite feces can be used as a new low-cost adsorbent for cationic dye removal.
In this study, polyaniline (PANI), composite of polyaniline with banana peel and composite of polyaniline with mushroom have been synthesized by chem-ical oxidation polymerization. This is a cost effective and simple method of preparing PANI and composites of PANI. The PANI and its composites were characterized by UV/Vis and IR analysis. These composite materials have been effectively used in adsorption of anionic dye from aqueous medium. It has been observed that these are good materials for adsorption of anionic dye. Detail equilibrium and kinetic studies have been reported here by taking Eosin Yellow as anionic dye. The experimental data for Eosin yellow adsorption was best fitted in Langmuir adsorption model. Adsorption of Eosin yellow follows 2nd order kinetic model.
Synthetic Metals, 2018
A new high surface area polyaniline (PANI) adsorbent was synthesized by matrix polymerization of aniline in the presence of a polyacid, poly(2-acrylamido-2-methyl-1propanesulfonic acid) (PAMPSA). Morphological and physicochemical properties of PANI-PAMPSA were characterized by field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), nitrogen adsorption/desorption and zeta potential measurement. Adsorption properties were evaluated using Methylene Blue (MB) and Rose Bengal (RB) as model dyes. The results showed that PANI-PAMPSA obtained a well-defined porous structure with a specific surface area (126 m 2 g −1) over 10 times larger than that of the emeraldine base PANI (PANI-EB) (12 m 2 g −1). The maximum adsorption capacities were 466.5 mg g −1 for MB and 440.0 mg g −1 for RB, higher than any other PANI-based materials reported in the literature. The FTIR analysis and zeta potential measurement revealed that the adsorption mechanisms involved π-π interaction and electrostatic interaction. The adsorption kinetics were best described by a pseudosecond-order model, and the adsorption isotherms followed the Langmuir model. The thermodynamic study indicated that the adsorption was a spontaneous endothermic process. Overall, the convenient synthesis and the high adsorption capacity make PANI-PAMPSA a promising adsorbent material for dye removal.
Journal of Nanostructure in Chemistry, 2012
Acid green 25 (AG) dye was adsorbed from water by using polyaniline nanotubes (PANI NT) salt/silica composite as adsorbent. Comparison between the removal of the dye by using PANI NT salt/silica composite and the conventional PANI salt/silica composite was investigated. This result was evidenced from the measurements of the UV-visible absorbance of AG dye solutions after different times. Experiments were conducted by varying parameters, namely initial concentration of the dye and contact time. The percentage of color removal decreased with increase in initial dye concentration. Adsorption equilibrium of color removal was reached after 60 min of contact time. Equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherms, and their constants were determined. Using the linear correlation coefficients showed that the Langmuir isotherm best fits the AG adsorption data on PANI NT salt/silica composite. The experimental data were fitted into the following kinetic models: pseudo-first-order, pseudo-second-order, and the intraparticle diffusion model. It was observed that the pseudo-second-order kinetic model described the adsorption process better than any other kinetic models. The results obtained indicate that PANI NT salt/silica composite could be employed as a much more efficient adsorbent than the conventional PANI salt/silica composite for dye removal from water.
In the present study, adsorptive properties of Polyaniline (PAn) were investigated for Amido Black 10B dye in aqueous solution. Different variables, including adsorption time, adsorbent dosage, solution pH and initial dye concentration were changed, and their effects on dye adsorption onto PAn nano-adsor-bent were investigated. The study yielded the result that an increase in pH decreases the adsorption efficiency of nano-adsorbent. Also, Dye adsorption capacity increased with increase in the initial dye concentration. Optimum adsorption time and nano-adsorbent dosage were obtained 30 min and 0.1 gr, respectively. Kinetic studies illustrated that the Amido Black 10B dye adsorption process onto PAn nano-adsorbent followed the pseudo-second-order model, which indicates that the adsorption process is chemisorption-controlled. Also, adsorption equilibrium data were fitted to Freundlich isotherm. The maximum dye adsorption capacity, predicted by the Langmuir isotherm, was 142.85 mg/g. Moreover , Dubinin-Radushkevich isotherm showed that the adsorption of dye onto PAn nano-adsorbent is a chemisorption process.
Acid-free synthesis of polyaniline nanotubes for dual removal of organic dyes from aqueous solutions
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018
Polyaniline nanotubes (PANI-NTs) were prepared by a green approach via the aniline oxidation using ammonium peroxydisulfate as an oxidant in the presence of methyl orange A C C E P T E D M A N U S C R I P T (MO) as a structure-guiding agent without any acid for the dual removal of anionic and cationic dyes from aqueous solutions. The structure, morphology and the physicochemical properties of the synthesized PANI-NTs were examined by different techniques such as Fourier transform infrared, X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), UV-Vis spectroscopy, nitrogen adsorption-desorption isotherms, and thermal gravimetric analysis. The TEM image reveals the nanotubular morphology of the synthesized PANI. The prepared PANI-NTs were effectively used for dual adsorption of anionic Acid green (AG) and cationic methylene blue (MB) dyes from aqueous medium. The effect of various parameters was studied to optimize the conditions of the adsorption process. The obtained results indicated that the optimum pH for adsorbing MB and AG dyes are 9.0 and 3.0, respectively. Based on the kinetic studies, the sorption dynamics followed the second-order model. In addition, the equilibrium data of the anionic and cationic dyes' adsorption were fitted well to the Langmuir isotherm. Furthermore, the maximum monolayer capacity, (qmax), for MB and AG was calculated from the Langmuir model to be 91.1 and 58 mg g-1 , respectively. The thermodynamic study showed that the adsorption process of MB onto PANI-NTs is spontaneous, feasible and exothermic process. The regeneration study indicated that PANI-NTs can be reused for multiple dye adsorption cycles. Therefore, the synthesized PANI-NTs can be considered as a highly efficient adsorbent for both of anionic and cationic dyes from aqueous medium.
Chitosan/polyaniline hybrid for the removal of cationic and anionic dyes from aqueous solutions
Journal of Applied Polymer Science, 2018
Nanostructured chitosan/polyaniline (CH/PANI) hybrid was synthesized via in situ polymerization of aniline in the presence of chitosan. The CH/PANI hybrid was characterized by FTIR spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The CH/PANI hybrid had a nanofibrous structure with an average diameter of 70 nm. This hybrid was employed as an ecofriendly and efficient adsorbent with high adsorption capacity for the removal of Acid Green 25 (AG) and methylene blue (MB) from aqueous solutions. AG and MB were used as anionic and cationic model dyes, respectively. The CH/PANI adsorbent showed high dependence on the pH of the medium with an excellent adsorption performance and regeneration manner. The kinetics and adsorption isotherms were studied. The CH/PANI hybrid follows the pseudo second-order adsorption kinetics and Temkin isotherm model for the adsorption of both AG and MB dyes. This assumes that the enthalpy of dyes molecules decreases with the adsorption on heterogeneous surface with various kinds of adsorption sites and as well as the ability to form multilayers of the dye. Also, intraparticle diffusion was found to play an important role in the adsorption mechanism. The maximum adsorption capacity was found to be 240.4 mg g −1 of AG at pH 4 and 81.3 mg g −1 of MB at pH 11.
Adsorption of Acid blue 25 dye on diatomite in aqueous solutions
Indian Journal of Chemical Technology
The adsorption of Acid blue 25 (AB 25) dye from aqueous medium on diatomite was studied. The effects of pH, contact time, initial dye concentration, calcinations and sorbent dosage on the adsorption process were examined and optimum experimental conditions were identified. The maximum removal of dye was obtained under acidic conditions, in particular, at pH 2, but pH 8 was more suitable for industrial purposes. The percentage removal of dye decreased with an increase in initial concentration. Also, the results indicated that an increase in temperature raised the percentage removal of dye. The maximum percentage removal of AB 25 dye from aqueous solution using raw diatomite at pH 2, temperature 25±1°C, agitation speed of 200 rpm, initial dye concentration of 50 mg/L, and for a mixing time period of 300 min was 72.81% (64.22% at pH 8). Furthermore, under same conditions, the maximum adsorption of dye on calcined diatomite was 54.5%. The experimental data showed that the adsorption of dye on raw diatomite follows the Langmuir model, but its adsorption on calcined diatomite followed the Freundlich model. The kinetics effect of the adsorbent was pseudo-second-order.
Applied Organometallic Chemistry, 2019
In recent times, polyaniline (PANI), a conducting polymer, has been studied widely for environmental remediation application due to its controllable electric conductivity with high surface area, which makes it a suitable adsorbent material. But lower mechanical stability of PANI is considered to be a serious drawback for its large-scale industrial application. To improve the mechanical strength of PANI, in this study, hematite nanoparticles were impregnated onto PANI by oxidative polymerization method in order to fabricate a novel organometallic nanocomposite (hematite-PANI-NC). The hematite-PANI-NC was used as adsorbent for removal of methyl orange (MO) and eosin yellow (EY) dye from binary dye matrix under ultrasonic-assisted adsorption. Excellent MO and EY dye removal (more than 98%) was observed from binary matrix at a wide solution pH from 2.0 to 6.0, and under ultrasound wave the adsorption equilibrium was achieved within 15 min only. Both MO and EY dyes adsorption experimental data strictly followed Langmuir isotherm, and maximum monolayer adsorption capacity of 126.58 mg/g and 112.36 mg/g was observed for MO and EY dye, respectively. The uptake mechanism of MO and EY dyes onto hematite-PANI-NC is governed by electrostatic interaction, π-π bonding and hydrogen bonding between dye molecules and nanocomposite. Response surface methodology analysis reveals maximum MO and EY removal of 98.43% and 99.35% at optimum experimental conditions. This study implies that the hybrid organometallic material hematite-PANI-NC has high potential for quick and enhanced sono-assisted uptake of anionic dyes from water near neutral solution pH. K E Y W O R D S binary dye matrix, hematite nanoparticles, optimization, polyaniline, ultrasonic-aided adsorption 1 | INTRODUCTION In recent years, one of the most serious environmental problems is water pollution, which affects both biotic as well as abiotic components of the ecosystem. Toxic dyes and pigments are considered to be the most withering water pollutants, which are broadly used in industries like textile, papermaking, food and cosmetics. [1] The industrial effluents containing toxic dyes not only affect the aquatic system by obstructing light penetration, they