Natural product based composite for extraction of arsenic (III) from waste water.

Natural based composites of hydroxyapatite/Gum Arabic designed for removal of toxic metal arsenic (III) from waste water were synthesized and evaluated. Several composites with various compositions were prepared by the wet chemical method and analyzed using various spectroscopic and analytical methods such as: Fourier transform infrared spectroscopy, total organic carbon production, XRD analysis and scanning electron microscope. The rates of weight loss and water absorption of the HAp/GA composites as a function of time were evaluated in phosphate-buffered saline solution at 37 °C and a pH of 7.4. The effects of several variables on adsorption of arsenic (III) by HAp/GA composites were evaluated. The variables include arsenic (III) concentration, contact time (t) and complex surface nature of HAp/GA composite. Three surface complexation models were used to study the mechanisms controlled the adsorption. The models were Langmuir, Freundlich and Dubinin Radushkevich. The adsorption kinetic of arsenic (III) on the composite surface was described by three modes: pseudo first order, pseudo second order and the intra particle diffusion. The results revealed that, the rate of adsorption of arsenic (III) by HAp/GA composites was controlled by two main factors: the initial concentration of arsenic (III) and the contact time. The kinetic studies also showed that, the rate of adsorption is a second order. The results indicate that, composite offered in this study could be a valuable tool for removing toxic metals for contaminated water by adsorption. Graphical abstract .

Square wave voltammetric determination of paracetamol at chitosan modified carbon paste electrode: Application in natural water samples, commercial tablets and human urines.

A novel analytical approach has been developed and evaluated for the quantitative analysis of paracetamol (PCT). The anodic peak currents of paracetamol on the CS-CPE were about 200 fold higher than that of the unmodified electrodes. The influence of various parameters on the CS-CPE was investigated. Under the optimized working conditions, the oxidation peak current is linear to the paracetamol concentration in the ranges of 1.0 × 10(-3)-4.0 × 10(-4)mol L(-1) and 2.0 × 10(-4)-8.0 × 10(-7)mol L(-1) with a detection limit of 5.08 × 10(-7)mol L(-1). The repeatability of the method expressed as relative standard deviation (RSD) is 1.73% (n=8). Possible interferences were tested and evaluated in 1.0 × 10(-4)mol L(-1) paracetamol in the presence of inorganic ions, dopamine, ibuprofen, ascorbic acid and uric acid. The proposed method was successfully applied to PCT determination in natural waters, tablets and urine samples.

Synthesis and structure of a new copper(II) complex with 3,4'-bi-1,2,4-triazolate.

The salt diaquo-diammine-bis(3,4'-bi-1,2,4-triazolate) copper(II) of the formula [Cu(bTA-)2(NH3)2(H2O)2] has been synthesized and structurally characterized by X-ray single crystal diffraction analysis. This complex adopts a monomeric structure. This monomer crystallizes in the triclinic system, space group P1 with a=5.9657 Å; b=6.8975 Å; c=9.9892 Å; α=106.181°; ß=97.868°; γ=90.800° and Z=1. The Cu atom is coordinated by two nitrogen atoms of two monodentate bitriazolate ligands, two nitrogen atoms of NH3 and two water molecules in a distorted octahedral geometry. The complex has been also characterized by elemental analysis and studied by electronic and vibrational spectroscopy. The obtained results are in good agreement with the structure determined by X-ray diffraction analysis.