The effective adsorption of tetracycline onto zirconia nanoparticles synthesized by novel microbial green technology.

Pseudomonas aeruginosa bacteria have been used in this study for zirconia nanoparticles synthesis through green technology for adsorption driven bioremediation of tetracycline from wastewater. The characterization of synthesized nano zirconia has been performed by employing dynamic light scattering, field emission-transmission electron microscopy, energy dispersive X-ray, X-ray diffraction, fourier transform infrared spectroscopy, and point of zero charge analysis. The zirconia nanoparticles have shown average particle size ~15 nm, monoclinic and tetragonal crystal structure with 6.41 nm of crystallite size, the presence of elemental zirconium and oxygen, and the occurrence of functional groups like O-Zr-OH, Zr-O-Zr and Zr-O bonds. The zirconia nanoparticles mediated adsorption of tetracycline has been found to be effective at solution pH 6.0 and in a very less contact time 15 min. Strong electrostatic interaction between zwitterionic form of tetracycline and protonated surface of zirconia nanoparticles is the governing adsorption mechanism in this study. The kinetic study has been performed on the basis of the tetracycline adsorption process revealing that the adsorption phenomenon follows pseudo-second order kinetic, further suggesting chemisorption of tetracycline over zirconia nanoparticles. The Langmuir isotherm model has been found to be the best fitted model among the all isotherm models indicating the involvement of monolayer uptake of tetracycline on the surface of zirconia nanoparticles. Moreover, the maximum tetracycline adsorption capacity of zirconia nanoparticles calculated by the Langmuir isotherm model is close to 526.32 mg/g. This finding is quite reasonable to accept that zirconia nanoparticle may be used as an alternative adsorbent to mitigate the tetracycline contamination in wastewater.

Ultrasonic assisted enhanced adsorption of methyl orange dye onto polyaniline impregnated zinc oxide nanoparticles: Kinetic, isotherm and optimization of process parameters.

The fabrication of novel functionalized composite materials as adsorbent is considered to be the core research area in adsorption technology for environmental applications. Indiscriminate disposal of industrial effluents containing toxic dyes has become a serious environmental issue across the globe since last few decades. In view of above, this study focused on the performance evaluation of ZnO/polyaniline nanocomposite (ZnO-PANI-NC) for quick ultrasonic assisted adsorptive remediation of methyl orange dye from aqua matrix. ZnO nanoparticles were fabricated by a simple co-precipitation method and ZnO-PANI-NC was synthesized by in situ oxidative polymerization of aniline monomer in presence of ZnO nanoparticles. The nanocomposite was extensively characterized for its crystalline nature, morphological characteristics, surface chemical bonding, specific surface area and pore volume by employing XRD, SEM, TEM, FTIR, and BET analysis. The ZnO-PANI-NC has shown superior adsorptive performance as compared to pure PANI as well as ZnO nanoparticles and the maximum monolayer adsorption capacity of 240.84 mg/g was obtained for the ZnO-PANI-NC. Under ultrasonic environment the adsorption reaction reached to equilibrium (more than 98% MO dye removal) within 15 min of reaction. Adsorption process followed Langmuir isotherm model and second order kinetic model strictly and contribution of intra-particle diffusion was also observed. The ZnO-PANI-NC has shown its high regeneration ability (more than 86%) even after 5th consecutive cycles of adsorption-desorption. Response surface methodology based optimization was used to optimize the adsorption experimental data and maximum MO removal of 99.12% was observed at optimum sonication time 13 min, adsorbent dose 0.38 g/L and initial MO concentration at 28 mg/L.

Synthesis of MnFe2O4 and Mn3O4 magnetic nano-composites with enhanced properties for adsorption of Cr(VI): artificial neural network modeling.

This study reports adsorptive removal of Cr(VI) by magnetic manganese ferrite and manganese oxide nano-particles (MnF-MO-NPs) composite from aqueous media. The X-ray diffraction pattern of MnF-MO-NPs revealed a polycrystalline nature with nanoscale crystallite size. The prepared adsorbent with high Brunauer-Emmett-Teller specific surface area of 100.62 m2/g and saturation magnetization of 30.12 emu/g exhibited maximum Cr(VI) removal at solution pH 2.0 and was easily separated from water under an external magnetic field. Adsorption capacity as much as 91.24 mg/g is reported and electrostatic interaction between positively charged adsorbent surface and anionic metal ion species is the main driving force in this adsorption. Adsorption experimental data followed Langmuir isotherm and second order kinetics. Partial involvement of intra-particle diffusion was also observed due to the mesoporous nature of MnF-MO-NPs. The thermodynamic studies revealed that the process was favorable, spontaneous and exothermic in nature. An artificial neural network model was developed for accurate prediction of Cr(VI) ions removal with minimum mean squared error (MSE) of 15.4 × 10-4 and maximum R2 of 0.98. Owing to large surface to volume ratio, advantage of easy magnetic separation, and high adsorption capacity towards Cr(VI), the reported MnF-MO-NPs appear to be a potential candidate in Cr(VI) contaminated wastewater remediation.