Huazhen Cao

A nanostructured nickel–cobalt alloy with an oxide layer for an efficient oxygen evolution reaction

A nanostructured nickel–cobalt alloy with an oxide layer was fabricated and its superior catalytic activity towards the electrochemical oxygen evolution reaction in alkaline media was investigated. Firstly, a NiCo–SiO2 composite film was prepared via a potentiostatic electro-codeposition method. Then the SiO2 template was etched and the NiCo component was activated leading to the generation of a NiCoOx layer during consecutive CV scans in concentrated alkaline solution. The results show that this nanostructured NiCo alloy with the oxide layer can provide a current density of 100 mA cm−2 in 1.0 M KOH at a low overpotential of 326 mV and exhibits good stability towards water oxidation. The excellent OER performance is enabled with the unique metal-oxide structure, which allows high electrical conductivity in the metal and high catalytic activity on the oxide.

Preparation of pure SbCl3 from lead anode slime bearing high antimony and low silver

A novel treatment process of lead anode slime bearing high antimony and low silver was developed by a potential-controlled chloridization leaching and continuous distillation. The experimental results show a high Sb3+ concentration, 489.2 g/L, in the leaching solution for two-stage countercurrent leaching process, and the leaching rates of Sb, Cu, Bi more than 99% when the potential is controlled at 450 mV. When the leaching solution is distillated and concentrated at 120 °C, almost all the silicon compound is evaporated into the concentration distillate and exists as amorphous hydrated silica. By the continuous distillation, high pure SbCl3 could be prepared, and AsCl3 is enriched in the distillate while metals Bi, Cu are enriched in the continuous distillation residue. As a result, the recovery rate of Sb is more than 95%.

Thermodynamic analysis of separating lead and antimony in chloride system

In chloride system, thermodynamic analysis is a useful guide to separate lead and antimony as well as to understand the separation mechanism. An efficient and feasible way for separating lead and antimony was discussed. The relationships of [Pb(superscript 2+)][Cl(superscript -)]^2-lg[Cl](subscript T) and E-lg[Cl](subscript T) in Pb-Sb-Cl-H2O system were studied, and the solubilities of lead chloride at different antimony concentrations were calculated based on principle of simultaneous equilibrium. The results show that insoluble salt PbCl2 will only exist stably in a certain concentration range of chlorine ion. This concentration range of chlorine ion expands a little with increasing the concentration of antimony in the system while narrows as the system acidity increases. The solubility of Pb(superscript 2+) in solution decreases with increasing the concentration of antimony in the system, whereas increases with increasing the concentration of total chlorine. The concentration range of total chlorine causing lead solubility less than 0.005 mol/L increases monotonically.

Electrodeposition of As–Sb alloy from high arsenic-containing solutions

Abstract As–Sb alloy was electrodeposited from high arsenic-containing solutions. The influences of current density, Sb 3+ concentration, reaction temperature and HCl concentration on the electrolyte composition, cell voltage and current efficiency were investigated. The surface morphology, composition and structure of the deposits were analyzed by scanning electron microscopy (SEM), inductively coupled plasma mass spectrometry (ICP-MS) and X-ray diffraction (XRD), respectively. The results show that the prepared As–Sb alloy shows an amorphous structure under all conditions. Under the optimized condition, i.e., 10 g/L As 3+ , 2 g/L Sb 3+ , 4 mol/L HCl, current density of 4 mA/cm 2 and temperature of 20 °C, desired As–Sb alloy with a composition of 70.26% As and 29.74% Sb (mass fraction) is obtained. What is more, the current efficiency is as high as 94.74% and high arsenic removal rate is achieved under this condition.

Highly porous copper ferrite foam: A promising adsorbent for efficient removal of As(III) and As(V) from water

A novel copper ferrite foam fabricated on Fe-Ni foam substrate was synthesized via a simple hydrothermal method to efficiently remove arsenic from aqueous solution. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-Ray diffraction pattern (XRD) and Raman spectra were used to characterize the morphology and surface composition of the copper ferrite foam (CFF). The adsorption behavior of As(III) and As(V) onto this CFF is studied as a function of solution pH, temperature, contact time, and different concentrations. Results shown that this CFF has high adsorption capacity and excellent recyclability. Adsorption isotherms study indicates Langmuir model of adsorption. The maximum adsorption capability of As(III) and As(V) on CuFe2O4 foam is observed about 44.0 mg g-1 and 85.4 mg g-1, respectively. Regeneration experiment indicates that arsenic could be easily desorbed from CFF with 0.10 mol L-1 NaOH and the high adsorption capacity can be maintained for six regeneration cycle.

Effective cementation and removal of arsenic with copper powder in a hydrochloric acid system

This work investigated the removal and cementation of arsenic from a hydrochloric acid system with copper powder. Thermodynamic analysis and cyclic voltammetry test were conducted to evaluate the feasibility of cementation. The effect of reaction temperature, mole ratio of Cu to As(III), stirring rate, reaction time and HCl concentration on the cementation efficiency of arsenic were investigated systematically. 94.75% of the arsenic could be removed under optimized conditions: mole ratio of Cu/As = 8 at 45 °C for 60 min. The structure and morphologies of the cement products were characterized by X-ray diffraction and scanning electron microscopy, respectively. The results show that the reaction temperature has little influence on the morphology of the cement products which consist of particles with various sizes, but has a great influence on the cementation efficiency. During the cementation process, the rate-controlling mechanisms are changed at different temperatures. It is diffusion controlled at the high temperature region (45–50 °C) with an activation energy of 26.7 kJ mol−1, while it is surface reaction controlled at the lower temperature region (30–45 °C) with an activation energy of 145.7 kJ mol−1. Ammonium citrate can efficiently inhibit the evolution of arsane, while has little influence on the cementation efficiency of arsenic.

Nucleation/growth mechanism of electrocrystallization for As–Sb alloy in hydrochloric acid system

Abstract The initial electrocrystallization of As–Sb alloy on glass carbon (GC) electrode in hydrochloric acid system was studied via cyclic voltammetry (CV) and chronoamperometry measurements. Current transients were presented in dimensionless formation, which showed that the initial nucleation/growth process of As–Sb alloy followed three-dimensional nucleation model with diffusion-controlled growth. Relevant nucleation parameters were calculated by analyzing related current transients. Particular attention was paid to the effect of Sb(III) concentration on the nucleation process during the co-electrodeposition. The quantitative results showed that Sb(III) played a positive effect on enhancing the nucleation rate of As–Sb alloy, leading to the evolution of alloy surface morphology from grain structure to compact layer structure.