The feasibility of using raw diatomite and aluminum hydroxide-modified diatomite (Al-diatomite) for removal of aniline and phenol from water was investigated. Their physicochemical characteristics such as pHsolution, point of zero charge (pHPZC), surface area, Fourier transform infrared (FT-IR) and scanning electron microscopy was determined. After the raw diatomite was modified, the surface area of Al-diatomite increases from 26.67 to 82.65 m(2) g(-1). The pHPZC and pHsolution (10%) occurred around pH 5.2 and pH 8.6, respectively. The removal rates of aniline and phenol on diatomite and Al-diatomite decreased with increasing solution pH, while surface charge density decreased. The adsorption of aniline and phenol on diatomite presented a good fit to the Langmuir and Freundlich models, but the models are not fit to forecast the adsorption of aniline and phenol on Al-diatomite. The study indicated that electrostatic interaction was a dominating mechanism of aniline and phenol sorption onto Al-diatomite.
A B S T R A C TThe combination of H 2 O 2 and hydrodynamic cavitation has been used to degrade phenol in water. The effects of parameters including inlet pressure (P1), orifice geometries of hydrodynamic reactor, initial concentration of H 2 O 2 , the presence of dissolved gases and catalysts (CuO, Fe, and TiO 2 ) have been discussed. It revealed that increased P1, more number of holes on plates, optimum initial H 2 O 2 concentration, the higher flow rate of oxygen, and the presence of Fe or CuO are more favorable in phenol degradation. Nitrogen has different effect on cavitation from oxygen. Furthermore, the identification of primary intermediates of the reaction (hydroquinone, catechol, benzoquinone, and resorcin) indicated that hydroxyl radicals are involved in phenol degradation mechanisms.
In this paper, a novel predictive direct power control (PDPC) strategy is proposed for three-phase AC/DC converters, which is based on a straightforward regulation of instantaneous active and reactive power. The converter controlled by the proposed strategy realizes operations without line-side voltage sensors by introducing the virtual flux (VF) concept and a grid voltage estimation method based on the instantaneous power. A constant converter switching frequency is achieved by employing the space vector modulation, which simplifies the design of the line filter. Simulation results show that the improvement of power ripple elimination and sinusoidal line currents can be observed in the proposed PDPC at a lower switching frequency. Comparative studies reveal that the steady behaviors of the proposed PDPC are superior to that of the conventional look-up-table DPC (LUTDPC) and PDPC, moreover the transient process of which is more shorter compared with that of the conventional LUTDPC.Index Terms-Predictive direct power control (PDPC), virtual flux (VF), voltage sensorless control, AC/DC converters, space vector modulation (SVM)
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