Adsorptive removal of malachite green and Rhodamine B dyes on Fe3O4/activated carbon composite

This study demonstrates the adsorption experiments of toxic dyes malachite green (MG) and Rhodamine B (RB) on Fe3O4-loaded activated carbon (AC). AC, which is known to be a high-capacity adsorbent, was aimed to be easily separated from aqueous media by loading it with Fe3O4. Fe3O4-loaded AC was prepared by the coprecipitation method and named magnetic activated carbon (M-AC), and the produced M-AC was characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), and pH(pzc) analyses. MG and RB adsorption by the M-AC was performed separately by batch technique and the effects of adsorbent amount, solution pH, and initial dye concentration on the adsorption were explored. Maximum removal efficiencies were found to be 96.11% for MG and 98.54% for RB, and the Langmuir isotherm model was the most fitted isotherm model for the adsorption. The kinetic and thermodynamic studies showed that the adsorption proceeded via the pseudo-second-order kinetic model and endothermic in-nature for both dyes

Chitosan grafted SiO2-Fe3O4 nanoparticles for removal of antibiotics from water

The antibiotic wastes in environment are very dangerous for human being because of the spread of epidemics due to increasing of the antibiotic-resistant bacteria. For reducing the proliferation of these bacteria, an environmental-friendly, cheap and non-toxic adsorbent, chitosan-grafted SiO2/Fe3O4, was developed in this study. The chitosan-grafted SiO2/Fe3O4 (Chi-SiO2/Fe3O4) nanoparticles were prepared and characterised by different physical and chemical techniques such as X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), N-2 adsorption-desorption isotherms (BET), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and zeta-potential analysis. The prepared nanoparticles were used for ciprofloxacin (CPX) adsorption from water. The nonlinear Langmuir and Freundlich isotherms were applied to experimental data. And Langmuir isotherm showed the best fit. The nonlinear pseudo-first-order and pseudo-second-order kinetic models and Weber-Morris intraparticle diffusion model were applied to kinetic data. The adsorption process followed the pseudo-second-order kinetic model. And the rate-limiting step was intraparticle diffusion step. The most suitable eluent for CPX desorption was determined as phosphate buffer solution rather than ethanol, and NaCl solution. It desorbed the 100% of CPX solution in 5h

Removal of ciprofloxacin from aqueous solution using humic acid- and levulinic acid- coated Fe3O4 nanoparticles

Humic acid (HA)- and levulinic acid (LA)-coated magnetic Fe3O4 nanoparticles were prepared and subsequently characterized using scanning electron microscopy, X-ray diffraction spectroscopy, Fourier transformer infrared spectroscopy, thermogravimetric analysis, particle size distribution analysis, and zeta-potential analysis. These magnetic nanoparticles were used for ciprofloxacin adsorption from aqueous solutions. Non-linear Langmuir and Freundlich adsorption isotherm models were used to explain the adsorption equilibria. The Langmuir adsorption capacities (q(m)) were 101.93 mg/g for HA-coated Fe3O4 and 53.76 mg/g for LA-coated Fe3O4. The appropriate contact times were 40 min for HA-coated Fe3O4 and 60 min for LA-coated Fe3O4. The adsorption rates and mechanisms were determined using pseudo-first-order and pseudo-second-order kinetic models. After the adsorption studies, the loaded nanoparticles were used for desorption studies, and their desorption kinetics were investigated. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Preparation of magnetic MIL-101 (Cr) for efficient removal of ciprofloxacin

Metal organic frameworks are widely used as adsorbent materials in recent years. In this study, the most prepared metal organic framework MIL-101 was prepared by hydrothermal method and featured magnetic property using co-precipitation method Fe3O4. Then, the prepared composite (MIL-101/Fe3O4) was first characterized using XRD, FTIR, SEM-EDS, and surface area analysis, then was used for the adsorptive removal of the most used antibiotic, ciprofloxacin (CIP). The effect of different adsorption variables which may affect the removal of CIP by MIL-101/Fe3O4 was investigated, as well as their adsorbent quantity, initial CIP concentration, pH, temperature, and contact time. The non-linear Langmuir and Freundlich isotherm were applied to experimental data. It was observed that rising solution temperature decreases adsorption efficiency, as the maximum adsorption uptake value was 63.28 mg g(-1) at 298 K and 22.93 mg g(-1) at 313 K, indicating the exothermic nature of the adsorption. The adsorption was studied kinetically and found to follow the pseudo-second-order kinetic model. The desorption of CIP from the MIL-101/Fe3O4 was investigated using three different eluents, and the results showed that phosphate-buffered solution was the most effective desorption eluent

Synthesis of NiFe2O4/TiO2-Ag+ S-scheme photocatalysts by a novel complex-assisted vapor thermal method for photocatalytic hydrogen production

© 2022 Elsevier B.V.This work aims to design and develop a photocatalyst with the main three properties: i) reduced bandgap for solar activation of the photocatalyst, ii) retarded e- / h+ recombination rate for the enhanced photocatalytic activity, iii) magnetic separability from the reaction medium. In this study, NiFe2O4/TiO2-Ag+ photocatalysts were synthesized to modify the structural properties of TiO2. Firstly, NiFe2O4 nanoparticles were synthesized by a conventional co-precipitation method, then in the presence of NiFe2O4 nanoparticles, TiO2 was synthesized by a novel complex-assisted vapor thermal (VT) method via slow hydrolysis of Ti-complex. After the best wt% amount of NiFe2O4 in the NiFe2O4/TiO2 had been determined for photocatalytic activity, Ag+ was added by wet-impregnation. The photocatalysts were characterized by X-ray diffraction (XRD), UV–vis Diffuse Reflectance Spectroscopy (DRS), Photoluminescence Spectroscopy (PL), vibrating sample magnetometer analysis (VSM), transmission electronic microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Photocatalytic hydrogen production reactions were carried out in methanol/water solution under solar light illumination. Consequently, the best configuration of the photocatalyst was determined as 12 wt% NiFe2O4/TiO2-0.5 wt% Ag+ (12NFT-0.50Ag+) which had shown the maximum hydrogen (H2) production rate as 137 µmol/g-cat after 5 h owing to its reduced bandgap energy and delayed e- / h+ recombination

Efficient removal of antibiotics by a novel magnetic adsorbent: Magnetic activated carbon/chitosan (MACC) nanocomposite

A novel adsorbent, Fe3O4/activated carbon/chitosan (MACC: Magnetic activated carbon/chitosan) was prepared by a simple coprecipitation method. MACC was characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and surface area analysis. MACC adsorption ability was tested for three commonly used hazardous antibiotics: ciprofloxacin, erythromycin, and amoxicillin. Langmuir isotherm model and pseudo second order kinetic model were best fitted with experimental results. Superior uptake values were found with using MACC; 90.10, 178.57 and 52631 mg/g were calculated as the theoretical adsorption capacity (g,n) using Langmuir isotherm for ciprofloxacin, erythromycin, and amoxicillin, respectively. Finally, MACC is considered as a promising magnetically separable efficient adsorbent for antibiotics removal. (C) 2017 Elsevier B.V. All rights reserved

Synergistic effect of Pt-0 and M2+ (Cu2+, Ni2+, Co2+) on photo(electro) catalytic activity of TiO2 nanorod array thin films

M2+ (Cu2+, Ni2+, Co2+) and Pt-0-M2+ loaded TiO2 nanorod film samples were prepared on transparent conducting oxide glass (FTO/F:SnO2). Two step method was used consisting a hydrothermal method to grow TiO2 nanorods on the surface and an ultrasonic-assisted sequential cation adsorption method to modify the nanorods. The samples were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (DRS), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy. The photoelectrochemical properties of the samples were evaluated by linear sweep voltammetry, photocatalytic activities were tested by methylene blue degradation under visible light. M2+-TiO2/FTO samples were compared with Pt-0-M2+-TiO2/FTO samples; the synergistic effect of Pt-0 and M2+ was discussed. Pt-0-Ni2+-TiO2/FTO showed superior photoelectrocatalytic activity with 1.358 mA cm(-2) and 78.3% methylene blue degradation under visible light. Quantum yields were calculated separately as a sign for H-2 generation rate and as a conversion of methylene blue molecule per absorbed light. (C) 2015 Elsevier B.V. All rights reserved

Enhanced photoelectrochemical activity of magnetically modified TiO2 prepared by a simple ex-situ route

Modified TiO2 nanocomposites have been recognized as attractive photocatalytic materials in solar energy conversion. The aim of this study is to enhance the photoelectrochemical performance under visible light region by magnetically modified TiO2 nanocomposites (Fe3O4/TiO2 and NiFe2O4/TiO2) prepared by a simple ex-situ non-thermal route. The magnetic TiO2 nanocomposites were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectra (DRS), photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), vibrational scanning magnetometry (VSM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Photoelectrochemical analysis was performed; chronoamperometry and Mott-Schottky curves were obtained. Results indicated that these non-noble, low-cost photocatalysts have shown the desired features; NiFe2O4/TiO2 have a suitable band gap to harvest visible range of solar light; they have reduced electron-hole recombination; and it is magnetically separable from reaction media. The most promising nanocomposite was found as NiFe2O4/TiO2 with a maximum photocurrent density 132 mu A cm(-2). The possible mechanism accounting for the improved photoelectrochemical performance of NiFe2O4/TiO2 is proposed