Bromate Removal from Water Using Doped Iron Nanoparticles on Multiwalled Carbon Nanotubes (CNTS)

The raw carbon nanotubes (CNTs) were prepared by the floating catalyst chemical vapor deposition method. The raw carbon nanotubes were functionalized, impregnated with iron nanoparticles, and characterized using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and thermogravimetric analysis (TGA). The three types of these multiwalled carbon nanotubes were applied as adsorbents for the removal of bromate from drinking water. The effects of the pH, the concentration of BrO3- anion, the adsorbent dose, the contact time, and the coanions on the adsorption process have been investigated. The results concluded that the highest adsorption capacities were 0.3460 and 0.3220 mg/g through using CNTs-Fe and raw CNTs, respectively, at the same conditions. The results showed that the CNTs-Fe gives higher adsorption capacity compared with the raw CNTs and the functionalized CNTs. The presence of nitrate (NO3-) in the solution decreases the adsorption capacity of all CNTs compared with chloride (Cl-) associated with pH adjustment caused by nitric acid or hydrochloric acid, respectively. However, the adsorption of all MWNCTs types increases as the pH of solution decreases

Synthesis of tannic acid azo polyurethane sorbent and its application for extraction and determination of atrazine and prometryn pesticides in foods and water samples

AbstractA new inexpensive sorbent (PUF–azo–Tan) was prepared by the coupling of tannic acid with polyurethane foam. The PUF–azo–Tan was characterized using different tools. Two new bands at 1724.1 and 1596.8cm−1 assigned for CO and NN groups appeared in the IR spectrum of PUF–azo–Tan. The PUF–azo–Tan contains 0.95 and 0.15mmolg−1 of phenolic and carboxylic groups, respectively. The pHZPC value of PUF–azo–Tan is 6.4. The PUF–azo–Tan has a considerable stability toward acid, alkali, and organic solvents. Atrazine and prometryn pesticides were extracted and preconcentrate by PUF–azo–Tan column and then analyzed by gas chromatography (GC) coupled with mass spectrometry. The effects of different parameters including pH, sample volume, temperature, initial concentration of pesticides, and shacking time were studied to optimize the presented procedure. The sorption capacity of PUF–azo–Tan was 0.14mmolg−1 (32mgg−1) and the extraction of the pesticides was accomplished within 3–5min. Kinetics studies data fitted the pseudo-second-order model (R2=0.989). The average detection limit of triazine pesticides in solution was 0.6ngmL−1 (RSD=0.35%, n=3). The equilibrium process was well described by the Freundlich isotherm model (R2=0.993). The extraction of the tested pesticides was accomplished in a period range 3–5min. The proposal study reveals PUF–azo–Tan has the potential of application as an efficient sorbent for the extraction and preconcentration of pesticides in cucumber, guava and potato foods, and water samples

Selective separation of Light green and Safranin O from aqueous solution using Salvadora persica (Miswak) powder as a new biosorbent

AbstractIn this paper a novel solid phase extraction method to remove Light green (acid dye) and Safranin O (basic dye) using Salvadora persica (Miswak) powder as a new biosorbent is described. The adsorption conditions such as contact time, initial dye concentration, pH and temperature were studied by using batch system. After optimization, Miswak showed an excellent removal rate for dyes, the extraction of the dyes was accomplished in a period range of 1–10min. The adsorption kinetics data were in good agreement with the pseudo-second-order rate model (R2=0.98) and the initial sorption rate (h) was found to be 0.01gmmol−1min−1. The new adsorbent was found to have a maximum adsorption capacity of 17.3mmol/g. The adsorption isotherms could be adequately described by the Freundlich equation (R2=0.91) and the 1/n value is 0.9, which attributed to the heterogeneous surface structure of the Miswak. Study of the variation of the sorption of the tested dyes with temperature yielded values for ΔH, ΔS, and ΔG of −21.0, −0.056.3 and −4.2kJmol−1, respectively