Search

In the present work, magnetic nickel ferrite (NiFe2O4) have been synthesised using low temperature combustion method and then modified with Cetyltrimethylammonium bromide (CTAB) to form a magnetic composite. Prepared composite (CTAB-NiFe2O4) was used as an adsorbent for removing brilliant green dye from aqueous solution. Adsorbent was investigated by using various techniques like Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, energy-dispersive spectra, thermogravimetric analysis and pH of point zero charge. Different parameters such as effect of contact time, pH, adsorbent dose and initial dye concentration were studied for the adsorption of dye. The optimum values observed were 170 minutes equilibrium time at pH 6 and adsorbent dose 0.6 g. Various adsorption kinetic models such as pseudo first-order kinetic model, pseudo second-order kinetic model and Elovich model were used to determine the nature of adsorption. Pseudo second-order kinetic model fitted better with higher R2 value which indicated that the adsorption was chemical in nature. Langmuir isotherm was best fitted to experimental data for the adsorption of brilliant green dye with maximum adsorption capacity 'Qe' 250 mg/g. It revealed that the adsorption in this study takes place on homogenous surface and follows monolayer pattern. Therefore, for the removal of Brilliant green dye from wastewater using composite (CTAB-NiFe2O4) can be considered as an effective adsorbent. [ABSTRACT FROM AUTHOR]

Standard purification systems have mainly demonstrated the inefficient removal of neonicotinoid insecticides with high persistence in the environment. In the present work, a new magnetic adsorbent composed of Fe3O4 and CuO nanoparticles impregnated with activated carbon (AC) has been used to remove imidacloprid (IMCP) as the most common neonicotinoid insecticide from the water solutions. Various techniques such as Fourier Transform infrared spectroscopy, x-ray diffraction, field emission scanning electron microscopy, energy-dispersive x-ray diffraction, and vibrating sample magnetometer were employed to characterise the fabricated composite. The main affecting parameters, including adsorbent amount, solution pH, agitating time, initial pesticide concentration, and temperature, were examined to obtain the optimised conditions. According to the obtained results from kinetic and isotherm modelling, the adsorption mechanism of IMCP on Fe3O4/CuO@AC nanocomposite (NC) is a combination of chemisorption and physisorption phenomena. The presence of heterogeneous sites for IMCP adsorption was shown by fitting the experimental data to the Freundlich isotherm model. In addition, the adsorption process was well consistent with the pseudo-second-order kinetic model, which indicates that chemisorption is the determining step in the adsorption process. Thermodynamic data showed the exothermic and spontaneous nature of the adsorption process. Under optimal conditions (initial concentration of pesticide 10 mg L−1, pH = 7, and contact time of 10 min), 99.6% of IMCP was effectively removed, indicating the excellent ability of the adsorbent to adsorb this insecticide from aqueous solutions. [ABSTRACT FROM AUTHOR]

In this study, the leaves of juglans regia chemically treated with acetic acid and L-arginine were used as adsorbents for removal of crystal violet dye from aqueous solution. The adsorbents were characterised using powder x-ray diffraction, Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller techniques. The adsorption isotherm, kinetics and thermodynamic parameters were examined for adsorption of dye on various adsorbents. The effect of initial dye concentration on adsorption capacity was studied and maximum adsorption capacity of adsorbents as per Langmuir linear fit was found for (JRACD: 263.85 mg g−1, JRACCHR: 273.97 mg g−1 and JRLRG: 290.70 mg g−1) at an initial dye concentration of 300 ppm, pH of dye solution 8, dosage of adsorbent 0.3 g, contact time of 70 minutes and at temperature of 303.15 K. It was observed that Freundlich isotherm fitted well for adsorption of dye on all the adsorbents compared to Langmuir isotherm. The kinetics of adsorption was found to follow the linear pseudo-second-order rate equation (R2 ≥ 0.9967). The Gibbs free energy was spontaneous in nature for the three adsorbents. The response surface methodology was also applied for all the adsorbents and optimisation of initial dye concentration (100, 200, 300) ppm, dosage of adsorbent (0.1, 0.3, 0.5) g and pH of dye solution (2, 5, 8) led to the development of quadratic models. The maximum adsorption capacity as per response surface model was found as 260.12 mg g−1 for JRLRG under optimum conditions. The significance of these models was also characterised by analysis of variance test. Additionally, density functional theory was used to support the experimental analysis and using Fukui function analysis the site for adsorption has been proposed. [ABSTRACT FROM AUTHOR]

Industrial effluents contain many toxic heavy metal ions and they are the main source for water pollution. Different methods are adopted for the purification of infected water. Among the diverse techniques, ion exchange method using conducting polymer based ion exchange material has several advantages over than other traditional methods like adsorption. In the present work, polyaniline/Ti(IV) iodosulphosalicylate (PANI/Ti(IV) ISS) a conducting polymer based ion exchange material was synthesised by sol–gel method via the mixing of inorganic precipitate of Titanium(IV) iodosulphosalicylate (Ti(IV) ISS) into the matrix of organic conducting polymer polyaniline (PANI). The PANI/Ti(IV) ISS conducting polymer based ion exchange material was well characterised using techniques such as Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction studies (XRD), scanning electron microscopy (SEM), energy dispersive X-Ray (EDAX), transmission electron microscopy (TEM) and thermal (TGA/DTG) analysis. The ion exchange capacity, elution behaviour, elution time and pH titration studies were also investigated. Furthermore a.c. electrical conductivity studies and impedance spectrum of this material also carried out. Some binary separations of heavy metal ions were achieved by the column packed by PANI/Ti(IV) ISS conducting polymer based ion exchange material. PANI/Ti(IV) ISS conducting polymer based ion exchange material showed an ion exchange capacity values (IEC) for Li+, Na+ and K+ which were found to be 1.98, 2.49 and 2.68 meq/g respectively. Based on the distribution coefficient values, PANI/Ti(IV) ISS conducting polymer based ion exchange material was found to be selective for the removal of Pb2+ ion, and the Kd value of 493.02 mL/g for Pb2+ ion from a mixture of toxic metal ions. Pb(II)ion from a synthetic mixture can be removed quantitatively by using PANI/Ti(IV) ISS and it is a promising candidate for ion selective electrode membrane studies. [ABSTRACT FROM AUTHOR]

The bio-sorption is the using of biological biomasses, live or dead form, for heavy metals removal from polluted wastewater. In the current work, live planktonic Nostoc sp. cells were used for hexavalent Chromium [Cr(VI)] elimination from Cr-contaminated wastewater. Optimisation process was achieved in order to obtain the optimum conditions that help achieving the highest Cr(VI) removal efficiency. For instance, One Factor At a Time 'OFAT' experiments were performed for the determination of the coded factors levels (low/high levels) that can be included in the Full factorial design experiment 'many interacted factors at a time'. Afterwards, a small reactor design was implemented to develop Nostoc sp. algal biofilm. After that, the algal biofilm was applied in the Cr(VI) removal process to facilitate harvesting and dewatering of the biomass after the treatment process. Results showed that, live planktonic Nostoc sp. achieved the highest Cr(VI) removal efficiency of 98.16%at 100 ppm after 7 days contact time. Furthermore, Nostoc sp. stated its great ability to form a biofilm on polystyrene substrate which achieved the highest Cr(VI) removal of '86.498%' at a concentration of 100 ppm after 7 days contact time. Some characterisation techniques such as Fourier Transform Infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) analyses were applied on the developed biofilm of Nostoc sp. Isotherm and kinetics were investigated for the Cr(VI) removal process using Nostoc sp. biofilm. [ABSTRACT FROM AUTHOR]

In this article, a highly sensitive electrochemical sensor is introduced for direct electro-oxidation of bisphenol A (BPA). The novel nanocomposite was prepared based on multi-walled carbon nanotube/thiol functionalised magnetic nanoparticles (Fe3O4-SH) as an immobilisation platform and gold nanoparticles (AuNPs) as an amplifying electrochemical signal. The chemisorbed AuNPs exhibited excellent electrochemical activity for the detection of BPA. Some analysing techniques such as Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and energy-dispersive x-ray diffraction exposed the formation of nanocomposite. Under optimum conditions (pH 9), the sensor showed a linear range between 0.002-240 μM, with high sensitivity (0.25 μA μM−1) along with low detection limit (6.73 × 10−10 M). Moreover, nanocomposites could efficiently decrease the effect of interfering agents and remarkably enhance the utility of sensor at detection of BPA in some real samples. [ABSTRACT FROM AUTHOR]