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Tannin-immobilized cellulose was prepared by the phenolic reaction of the phenol ring of tannin with the aldehyde group of aldocellulose, where aldocellulose was prepared by the oxidization of cellulose with sodium periodate as oxidizing agent. The method of immobilized tannin is environmentally friendly due to the lack of crosslinking agent. The adsorption properties of cellulose were improved due to the introduction of tannin. The maximum adsorption capacity of the tannin-immobilized cellulose for berberine hydrochloride was 143.66 mg/g. The isothermal adsorption for berberine hydrochloride conformed to the Langmuir model well. The adsorption of tannin-immobilized cellulose for berberine hydrochloride was a weak chemical adsorption, and the adsorption process was exothermic. The adsorption equilibrium was reached within 90 min in the initial concentration 100 mg/L, and the sorption kinetics fitted well to a pseudo-first-order model. Tannin-immobilized cellulose has potential application prospect in the field of the separation and purification of alkaloids. [ABSTRACT FROM AUTHOR]

In this work, a novel Z-scheme CdIn2S4 nano-octahedron/BiOCl nanosheet (CIS/BOC) heterostructure was successfully designed and synthesized via a facile in-situ hydrothermal process, where the CdIn2S4 nano-octahedra grew on the surfaces of tiny BiOCl nanosheets in a face-to-face way. The structure, morphology and optical properties of as-prepared samples were characterized through various technologies. The photocatalytic activities were systematically evaluated by the degradation of methyl orange (MO), tetracycline hydrochloride (TCH) and rhodamine B (RhB) under simulated solar light irradiation. The degradation results displayed that all CIS/BOC composites exhibited significantly enhanced photocatalytic activities toward MO degradation in comparison with the bare CdIn2S4 and BiOCl. Simultaneously, the obtained CIS/BOC-2 with 6 wt.% BiOCl nanosheets loaded possessed the optimal photocatalytic performance, and its rate constant was about 3.6 and 2.59 times as high as those of bare CdIn2S4 and BiOCl. Furthermore, the CIS/BOC-2 nanocomposite with superior photostability and repeatability also presented high photocatalytic activities for the removal of both antibiotics (TCH) and dyestuff (RhB). The unique Z-scheme face-to-face heterostructure with intimate contacted interface in CIS/BOC-x nanocomposites provided more charge transfer nanochannels, shortened the migration distance and boosted the separation of photoinduced charge carriers, resulting in the excellent photocatalytic activities. Our study may provide a promising strategy to develop and synthesize other Z-scheme face-to-face composite photocatalysts with good photocatalytic performance. [ABSTRACT FROM AUTHOR]

Abstract This paper aims to study the hydropower system operation stability considering the coupling effect of water potential energy in surge tank and power grid. Firstly, the mathematical formulation for hydropower system with surge tank that connected to power grid is established. Then, the hydropower system operation stability is investigated. The coupling effect mechanism of surge tank and power grid on stability is revealed. Finally, the formula for critical stable sectional area (CSSA) of surge tank considering power grid is derived and analyzed. The results indicate that the free vibration equation for hydropower system with surge tank that connected to power grid under step load disturbance is a ninth order linear homogeneous differential equation. The domain at the bottom left corner of the critical line on the Proportional-Integral plane is the stable domain. The proposed novel analytic solution of stable domain has a high precision and is feasible for practical applications. The formula for CSSA of surge tank considering power grid realizes the unity of the coupling effect of water potential energy in surge tank and power grid. The CSSA contains four terms, i.e. headrace tunnel term, penstock term, governor term and power grid term. Highlights • Model for hydropower system with surge tank connecting to power grid is established. • Hydropower system operation stability is investigated by stable domain. • Coupling effect mechanism of surge tank and power grid on stability is revealed. • A novel analytic solution of stable domain for hydropower system is proposed. • Critical stable sectional area of surge tank considering power grid is derived. [ABSTRACT FROM AUTHOR]

In view of the restricted performance in terms of accuracy, anti-disturbance, and robustness of the current road lane recognition algorithm for Lane Departure Warning System, tensor voting–based road lane recognition algorithm with road lane geometric constraints is presented in this paper. It extracts road lane information from random images using voting decayed function optimized from geometric constraints of road lanes. The entire framework of the algorithm consists of pre-processing, vote-processing, and post-processing. First, white points which represent the potential road lanes are selected and remaining points are discarded for reducing noise and computation burden in binary image. Next, the most likely connection between voters and receivers can be characterized as decayed function. Road lane geometric constraints determined by calibration results of the camera are utilized to optimize decayed function in tensor voting in order to emphasize road lane points in vote-processing. At last, these points are clustered and fitted into road lanes in post processing. The experimental results indicate that accuracy of this method is superior in terms of traditional road lane extraction in complicated traffic condition. [ABSTRACT FROM AUTHOR]

Abstract This paper aims to study the saturation characteristics for stability of hydro-turbine governing system with surge tank. Firstly, the mathematical model of hydro-turbine governing system under load disturbance is established, and the equivalent independent stability discriminants are presented. Then, the saturation characteristics for stability are analyzed. Using analytical stability discriminants and stable domain, the generation mechanism of saturation characteristics is revealed, and a distinguishing method of critical saturation state is proposed. Finally, the concept of saturation sectional area of surge tank is proposed. The distribution and partition for stability states is illustrated, and a combined tuning method of sectional area of surge tank and governor parameter is proposed. The results indicate that, for hydro-turbine governing system with surge tank, the fourth-order discriminant boundary is always the critical boundary of stable domain. The second-order and third-order discriminant boundaries determine the stable domain under saturation state. The equality for fourth-order discriminant has two real solutions when the system is saturated. The saturation sectional area of surge tank is the sectional area that makes the system reach critical saturation state. Domain C of the distribution and partition figure for stability states is the most favorable domain for the system stability. Highlights • Stability discriminants for hydro-turbine governing system are presented. • Generation mechanism of saturation characteristics for stability is revealed. • A distinguishing method of critical saturation state is proposed. • Concept and calculation of saturation sectional area of surge tank are proposed. • A tuning method of sectional area of surge tank and governor parameter is proposed. [ABSTRACT FROM AUTHOR]

Biochars prepared from agricultural and forestry biomass resources have been widely used to remove wastewater pollutants. However, the theoretical analysis of the role of biochar functional groups in pollutant removal and the visualization of the adsorption mechanism is still in its initial stage. In this study, a kind of biochar with satisfied adsorption potential was prepared from Fructus Aurantii Immaturus residues (FAIR). A Fructus Aurantii Immaturus residue biochar (FRB) structural model was constructed based on its physicochemical characterization, and the adsorption mechanism of FRB for methylene blue (MB) was clarified at the molecular level through the adsorption experiments, adsorption models and DFT calculations. The results indicated that the FRB prepared by NaOH activation has abundant functional groups, higher porosity and specific surface area, and its saturated adsorption capacity for MB reached 298.90 mg/g. The adsorption process of the FRB for MB can be suitably described by the pseudo-second-order kinetic model and the Freundlich isothermal adsorption model, and it is an endothermic entropy-driven non-spontaneous process. The adsorption mechanism depended on the electrostatic attraction, hydrogen bond, π–π interaction and van der Waals force formed by the interaction between the -COOH, -OH and -NH-CO- in the FRB structure and the amino groups in the MB structure. Notably, the results of the DFT calculations were highly consistent with the theoretical analysis of the adsorption experiments and adsorption models. [Display omitted] • A biochar from phytoextraction residues of Citrus aurantium L. was prepared. • Saturated adsorption capacity of biochar for MB reached 298.90 mg/g. • Adsorption mechanism of biochar for MB was analyzed via experiments and models. • Role of biochar functional groups for dye adsorption was explained. • Interaction between the MB and biochar surface was verified by DFT calculations. [ABSTRACT FROM AUTHOR]

Despite their high potential for solar energy conversion into chemical fuels, most artificial all-solid-state Z-scheme photosystems have disordered structures and focus on power photocatalytic water splitting applications rather than photoelectrochemical (PEC) cells. Herein, an innovative pure Z-scheme heterostructure, CdS/Au/SnO 2 -S, composed of one-dimensional (1D) oriented CdS nanorods modified with SnO 2 -wrapped Au nanoparticles (NPs), was designed as a photoanode for highly efficient PEC hydrogen evolution. Systematic characterization confirms that the incorporated Au NPs not only act as the host platform to support the SnO 2 layer growth but also play a key role as the electron mediator for strengthening the vectorial charge transfer from SnO 2 to CdS. This reinforced Z-scheme charge transportation channel is favorable for suppressing the bulk charge recombination process, increasing the overall carrier density, and preserving the strong redox capability, ultimately resulting in a considerably improved photocurrent density and photo-to-current conversion efficiency with better corrosion resistance. [Display omitted] • A pure Z-scheme CdS/Au/SnO 2 heterojunction photoanode is well-designed. • A spectrum-defined hydrolysis-precipitation approach is used for sample synthesis. • The embedded Au NPs as electron mediators and strengthen vectorial charge transfer. • CdS/Au/SnO 2 exhibits lengthened electron lifetimes and better photostability. • Interfacial charge transfer and PEC enhancement mechanism are discussed in detail. [ABSTRACT FROM AUTHOR]

Active removal of recalcitrant antibiotic contaminants for wastewater purification and hydrogen evolution from water splitting using hollow-structured photocatalysts has attracted considerable interest in the field of environmental governance and energy conversion. Herein, 0D Ta3N5 nanoparticles anchored on 3D TiO2 hollow nanosphere composites (0D/3D Ta/Ti) were designed and fabricated via a feasible surface self-assembly process for the first time. Various techniques were employed to characterize the structure and optical properties of the as-prepared samples. The photocatalytic activities of Ta3N5/TiO2 hybrids were systematically evaluated via both photodegradation of levofloxacin (LEV) and water splitting for hydrogen evolution under solar light irradiation. The degradation results showed that the x-Ta/Ti composites exhibit remarkably better performances for LEV degradation than pristine TiO2. The 3 wt% Ta3N5 nanoparticle-loaded hollow TiO2 composite material exhibited optimal photocatalytic activity (92.79%), and its degradation rate constant was 3.04 times that of TiO2. Simultaneously, the 3-Ta/Ti composite also possessed high ability to degrade other antibiotics such as ciprofloxacin (CIP) and tetracycline hydrochloride (TCH) and colored organic dyes such as Rhodamine B (RhB). Besides, x-Ta/Ti composites exhibited higher photocatalytic hydrogen evolution activities compared with TiO2 hollow spheres. The efficient charge transfer and separation between the close heterogeneous interfaces, broadened spectral response range and improved specific surface area were mainly responsible for the superior photocatalytic performance of the x-Ta/Ti nanocomposite. Our study provides an effective strategy for the design of hollow structure composite photocatalysts with excellent photocatalytic performances not only for pollutant removal, but also for efficient solar-to-fuel conversion. [ABSTRACT FROM AUTHOR]