An improved mole ratio method for the dual-wavelength spectrophotometric determination of the equilibrium concentration of a chromogenic ligand L in an aqueous binary system is proposed. Techniques involving the k factor and isoabsorbance points can be used to mask instrumentally the absorbance of the product formed. By varying x, the concentration of the metal ion M, and fixing y, that of L, added in excess to ensure virtual completion of the reaction under study, a set of AL values, the absorbance of free L, can be measured under conditions free from any side reaction. As AL=εLl(y – xn/m), where ε is the molar absorptivity, l is the optical pathlength and n/m is the mole ratio of M and L in the reaction product MmLn, a linear graph can be plotted with AL as the ordinate and x as the abscissa. By extrapolation it intersects the abscissa at x0(x=x0 when AL= 0). Once x0 has been found, the mole ratio n/m can be readily obtained from the above equation as y is known and AL= 0. This is an absolute method. Its special features are as follows. (1) A linear plot gives more reliable results. (2) Dispensation with the use of a reference solution ensures a precise correction for any concomitant interfering absorbance possibly present in the same solution. (3) It is feasible to determine AL, one of the two interdependent variables of absorption under the specified conditions, hence it is applicable also to systems in which the absorption spectra of L and MmLn cross or overlap each other.
This paper proposes a method and system for calibrating the SOC characteristics of a satellite battery array simulator. The calibration system consists of a battery array simulation module, a simulator SOC curve acquisition module and a curve comparison module. The battery array simulation module uses the second-order RC equivalent circuit model to model the satellite battery array simulator, and calculate the parameters of the battery simulator model dynamically. The standard model of the satellite battery array simulator is established, and then the standard SOC curve is collected for reference. The simulator SOC curve acquisition module utilizes an improved adaptive Kalman filtering algorithm to process battery test data, and the ampere hour integration method is used to acquire the SOC characteristic curve of the satellite battery array simulator; The curve comparison module uses curve convolution to achieve the similarity between the standard SOC curve and the simulator SOC curve, which could achieve the accurate calibration of the satellite battery array simulator.
The removal of tetracycline (TC) from solution is an important environmental issue. Here we prepared an adsorbent hydrous ferric oxide (HFO) by adjusting a FeCl3·6H2O solution to neutral pH. HFO was characterized by a surface area analyzer, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), and was used to remove TC from solution. The influence of pH, solid-to-liquid ratio, ionic type, and strength on TC removal was investigated. Adsorption kinetics and isotherms were also determined. HFO after adsorption of TC was analyzed by FTIR and XPS to investigate the adsorption mechanism. The results showed that the adsorption of TC increased from 88.3% to 95% with increasing pH (3.0–7.0) and then decreased. K+ ions had little effect on TC adsorption by HFO. However, Ca2+ and Mg2+ reduced the adsorption of TC on HFO. When the concentrations of Ca2+ and Mg2+ were increased, the inhibitory effect was more obvious. Pseudo-second-order kinetics and the Langmuir model fitted the adsorption process well. The maximum adsorption capacity of TC on HFO reached 99.49 mg·g−1. The adsorption process was spontaneous, endothermic, and increasingly disordered. Combination analysis with FTIR and XPS showed that the mechanism between TC and HFO involved electrostatic interactions, hydrogen interactions, and complexation. Therefore, the environmental behavior of TC could be affected by HFO.
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