The characteristic of Cu2ZnSnS4 thin film solar cells prepared by sputtering CuSn and CuZn alloy targets

Recent study shows that the main reason for limiting CZTS device performance lies in the low open circuit voltage, and crucial factor that could affect the V_oc is secondary phases like ZnS existing in absorber layer and its interfaces. In this work, the Cu₂ZnSnS₄ thin film solar cells were prepared by sputtering CuSn and CuZn alloy targets. Through tuning the Zn/Sn ratios of the CZTS thin films, the crystal structure, morphology, chemical composition and phase purity of CZTS thin films were characterized by X-Ray Diffraction (XRD), scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS) and Raman spectroscopy. The statistics data show that the CZTS solar cell with a ratio of Zn/Sn = 1.2 have the best power convention efficiency of 5.07%. After HCl etching process, the CZTS thin film solar cell with the highest efficiency 5.41% was obtained, which demonstrated that CZTS film solar cells with high efficiency could be developed by sputtering CuSn and CuZn alloy targets.     

Degradation of chlortetracycline in wastewater sludge by ultrasonication,Fenton oxidation,and ferro-sonication

Residual emerging contaminants in wastewater sludge remain an obstacle for its wide and safe applications such as landfilling and bio-fertilizer. In this study, the feasibility of individual ultrasonication (UlS) and Fenton oxidation (FO) and combined, Ferro-sonication processes (FO) on the degradation of chlortetracycline (CTC) in wastewater sludge was investigated. UlS parameters such as amplitude and sonication time were optimized by response surface methodology (RSM) for further optimization of FS process. Generation of highly reactive hydroxyl radicals in FO and FS processes were compared to evaluate the degradation efficiency of CTC. Increasing in the ratio of hydrogen peroxide and iron concentration showed increased CTC degradation in FO process; whereas in FS, an increase in iron concentration did not show any significant effect (p > 0.05) on CTC degradation in sludge. The estimated iron concentration in sludge (115 mg/kg) was enough to degrade CTC without the addition of external iron. The only adjustment of sludge pH to 3 was enough to generate in-situ hydroxyl radicals by utilizing iron which is already present in the sludge. This observation was further supported by hydroxyl radical estimation with adjustment of water pH to 3 and with and without the addition of iron. The optimum operating UlS conditions were found to be 60% amplitude for 106 min by using RSM. Compared to standalone UlS and FO at 1:1 ratio, FS showed 15% and 8% increased CTC degradation respectively. In addition, UlS of sludge increased estrogenic activity 1.5 times higher compared to FO. FS treated samples did not show any estrogenic activity.     

Quantitative Analysis of Abamectin,Albendazole, Levamisole HCl and Closantel in Q-DRENCH Oral Suspension Using a Stability-Indicating HPLC-DAD Method

Combination therapy of many anthelmintic drugs has been used to achieve fast animal curing. Q-DRENCH is an oral suspension, containing four different active drugs against GIT worms in sheep, commonly used in Australia and New Zeeland. The anti-parasitic drugs are Albendazole (ALB), Levamisole HCl (LEV), Abamectin (ABA), and Closantel (CLO). The main purpose of this study is to present a new simultaneous stability-indicting HPLC-DAD method for the analysis of the four drugs. The recommended liquid system was 1 mL of Triethylamine/L water, adjusting the pH to 3.5 by glacial acetic acid: acetonitrile solvent (20:80, v/v). Isocratic elusion achieved the desired results of separation at a 2 mL/min flow rate using Zorbax C-18 as a stationary phase. Detection was performed at 210 nm. The linearity ranges were 15.15 to 93.75 μg/mL for ALB, 25 to 150 μg/mL for LEV, 30 to 150 μg/mL for ABA, and 11.7 to 140.63 μg/mL for CLO. Moreover, the final greenness score was 0.62 using the AGREE tool, which reflects the eco-friendly nature. Moreover, the four drugs were determined successfully in the presence of their stressful degradation products. This work presents the first chromatographic method for simultaneous analysis for Q-DRENCH oral suspension drugs in the presence of their stressful degradation products.     

Specific ionic interactions in the quaternary systems HCl−NaCl−KCl-water and HCl−NH4Cl−KCl-water at 25°C

Mean ionic activity coefficients of hydrochloric acid in the systems HCl–NaCl–KCl-water and HCl–NH₄Cl–KCl-water at constant total ionic strength of 1 mole-kg^–1 have been determined for various ratios of the added salts at 25°C. The electromotive force method was used. Both an extended form of the simple empirical Harned equations (see ref. 1) and the more complicated semiempirical Pitzer equations (see refs. 2–4) for multicomponent electrolyte systems were used in the treatment of the data. Specific ionic interaction parameters for both types of equations are reported. The effects of the added salts on the thermodynamic behavior of HCl in the two systems mentioned were compared by considering the variation of its trace activity coefficient with change in amounts of the added salts at constant total ionic strength of 1 mole-kg^–1.     

Optical sensing of HCl with phenol red doped sol-gels

A dye doped sol-gel for the sensing of hydrochloric acid in solution and/or gaseous phase is described. The sol-gel is obtained by acidic hydrolysis of tetraethoxysilane (TEOS) and phenyltriethoxysilane (Ph-TriEOS) in the presence of phenol red (PR) and further spin-coating onto glass slides. The sensitive response is based on an increase of the absorption band at 510 nm of phenol red entrapped in the sol-gel casting when exposed to HCl solution or gas, due to protonation of the dye. The detection limit of the sol-gel response to moisturized gaseous HCl is below 12 ppm, and its response to HCl in solution falls in the range of 0.01-6 M. The sol-gel coating has a response time of less than 40 s in steady-state, and life-time of more than a year. Weak acids such as acetic acid, benzoic acid, salicylate acid, citrate acid, and carbonic acid do not interfere the response. The responses in acid solutions are completely reversible. In the gaseous phase, response of HCl appears to be moisture sensitive.     

Flow injection spectrophotometric determination of europium using chlortetracycline

A flow injection (FI) spectrophotometric determination of europium (III) is described, based on the complexation between europium (III), and chlortetracycline (CTC) in a Tris-buffer pH 8.0 medium. The resulting yellow-coloured complex is measured at its absorption maximum of 400 nm after 100 μl of sample or standard solution containing europium (III) are injected into the merged streams of CTC and Tris-buffer solutions. Optimum conditions for determining μg amounts of europium (III) are achieved by univariate method. Various types of reactors are also investigated. It is shown that the use of a single bead string reactor gives rise to the enhancement of peak height. A linear calibration curve over the range of 0.10-0.60 μg ml⁻¹ europium (III) is established with the regression equation (n=6) Y=34.93X+0.01 and the correlation coefficient of 0.9994 is obtained. A detection limit (3σ) of 0.01 μg ml⁻¹ of europium (III) and the relative standard deviation (R.S.D.) of 4.32% for determining 1.0 μg ml⁻¹ of europium (III) (n=7) are obtained. The recommended method has been applied to the quantitation of europium (III) in spiked water and stream sediment samples with average recoveries of 99.9 and 97.5%, respectively. The sampling rate is found to be 85 h⁻¹.     

Densities and compressibilities of aqueous HCl and NaOH from 0 to 45°C. The effect of pressure on the ionization of water

The densities and sound speeds of aqueous HCl and NaOH solutions were measured from 0.1 to 1.0m and from 0 to 45°C. These data were combined with literature data and fitted to functions of molality and temperature. The apparent molal volumes V and compressibilities K of these solutions were fitted to functions of molality and temperature. The partial molal volumes and compressibilities of HCl and NaOH solutions were used to calculate the partial molal volume V and compressibility changes for the ionization of water. Combined with literature data these values of V adn were used to calculated the effect of pressure on the ionization constant of water K _w from 0 to 200°C. The effect of pressure on K _w calculated from partial molal quantities are in reasonable agreement with that determined directly from high pressure measurements taken from the literature up to 1000 bar. It is necessary to use the pressure dependence of K ⁰ to extend the calculated pressure dependence of K _w up to 6000 bar.     

Influence of cations on the proton leakage through anion-exchange membranes

In the recovery of acids from wastewaters or the regeneration of acids and bases from salts by electromembrane processes, the most important phenomenon which limits the current efficiency is the transport of protons through the anion-exchange membrane (AEM). In this work, the proton leakage through an AEM is studied with a system containing hydrochloric acid or sulfuric acid on the cathodic side and the mixture of acid with one homoanionic salt (Li⁺, Na⁺, K⁺, Cr³⁺, NH₄⁺, (CH₃)₄N⁺ and (C₂H₅)₄N⁺) on the anodic side. The proton leakage is quantified from the value of the proton transport number. The results are analyzed assuming that the rate determining step of proton leakage is the interfacial transfer reaction of protons from the aqueous anodic solution to the membrane. The proton leakage is enhanced by the polarizing power of the cation. The transfer of protons into the membrane seems to be catalyzed by the presence of a layer of adsorbed cations on the surface of the membrane. The presence of salt decreases the proton leakage but it is always greater with H₂SO₄ solutions compared to HCl solutions.     

An ab initio calculation of K-spectra in molecules HCl and HF

An ab initio calculation of energies and intensities of K-emission and K-absorption spectra in molecules HCl and HF are carried out. An electronic readjustment due to a hole in a molecular core is taken into account. A vibrational structure of K-emission and K-absorption spectra is also calculated. The calculation shows that it is possible to detect a vibrational structure of valence bonding levels in X-ray emission spectra. A good agreement with experiment is obtained.     

The stokes and robinson hydration theory: A modification with application to concentrated electrolyte solutions

The proposed extension to the Stokes and Robinson hydration theory is based on the premise that H₂O molecules of electrolyte solutions reside in two unique environments, the solvent environment and the hydration envelope (or sheath) environment. Changes to the chemical potential of H₂O in either environment result in redistribution of H₂O molecules between the environments; consequently hydration numbers of electrolytes decrease as the solvent activity decreases. An equation derived from the theory and containing two adjustable parameters reproduces electrolyte activity coefficients more accurately than does the original Stokes and Robinson equation.