Platinum uptake from chloride solutions using biosorbents

Present work investigates platinum uptake from synthetically prepared, dilute platinum-bearing solutions using biomass residues, i.e. pistachio nut shell and rice husk, which are abundant in Turkey, and provides a comparison between these two biosorbents. Effects of the different uptake parameters, sorbent dosage, contact time, temperature and pH of solution on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell was activated, platinum uptake (%) was poor compared to the rice husk. However, after the pistachio nut shell was activated at 1000 °C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (original and activated) and rice husk were shown to be better than commercially available activated carbon in terms of adsorption capacity. These two sorbents have also been characterized by FTIR and SEM. Adsorption equilibrium data best complied with the Langmuir isotherm model. Maximum adsorption capacities, Qmax, at 25 °C were found to be 38.31 and 42.02 mg.g- 1for the activated pistachio nut shell and rice husk, respectively. Thermodynamic calculations using the measured ∆H°, ∆S° and ∆G° values indicate that the uptake process was spontaneous and endothermic. The experimental data were shown to be fit the pseudo-second-order kinetic model

Influence of polyvinyl alcohol amount on producing in situ photo-crosslinked thioamide functionalized nanofiber membranes

Poly(vinyl alcohol)/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM) photo-cured nanofiber membranes and pure PVA nanofiber membranes were produced by electrospinning technique. In situ UV radiation was applied during the electrospinning in order to provide polymerization during the jet flight and promote crosslinking of ATM and MA with PVA. The cross-linking was examined by Fourier-transform infrared spectroscopy (FTIR). The morphology and thermal behavior of electrospun nanofiber were characterized by scanning electron microscope (SEM) and thermogravimetric analysis (TGA), respectively. The surface area of nanofiber membranes was measured by Brunauer-Emmert-Teller (BET) analysis. Furthermore, water durability test was examined. Water durability test demonstrated that in situ photo-cured PVA/MA/ATM nanofiber membrane had the least average mass loss. The surface areas of PVA/MA/ATM nanofiber membranes were 160-280 m2/g. The surface area and diameter of PVA/MA/ATM nanofibers decreased as the PVA content increased. The diameter of nanofibers was obtained less than 100 nm. The results showed that the water-insoluble nanofiber membranes with better chemical and thermal resistance were obtained. These nanofiber membranes may be a promising candidate for the usage of water treatment

Synthesis of hydroxyethyl cellulose from industrial waste using microwave irradiation

The paper describes the synthesis of hydroxyethyl cellulose from industrial waste, namely, air particle vacuum dust (APVD). The selected reaction parameters were sodium hydroxide concentration, ethylene oxide proportion, reaction time, and reaction temperature in an attempt to understand their effects on the reaction. For this purpose, APVD was bleached and mercerized using sodium hydroxide and hydrogen peroxide solution to remove/dissolve non-cellulosic material. The modified waste material was then reacted with ethylene oxide under microwave irradiation to obtain hydroxyethyl cellulose. To determine the effect of each reaction parameter, the degree of substitution and viscosity were measured and compared in detail. The greatest values were achieved using 40% (w/v) sodium hydroxide, one gram ethylene oxide per gram of APVD, a 90 min reaction time, and a 70 °C reaction temperature. Process efficiency was evaluated by recording 1H-NMR (nuclear magnetic resonance), solid-13C-NMR, Fourier Transform Infrared Spectroscopy, Differential Thermal Analysis-Thermogravimetry, Differential Scanning Calorimetry and Scanning Electron Microscope of best samples. These helped elucidate the expected reaction. The proposed method, compared with the conventional method, was easy, fast, and straightforward. Keywords: Air particle vacuum dust, Synthesis, Microwave, Hydroxyethyl cellulos