Facile Electrochemical Synthesis of Bifunctional Needle-like Co-P Nanoarray for Efficient Overall Water Splitting.

The development of low-cost and high-performance bifunctional electrocatalysts for overall water splitting is still challenging. Herein, we employed a facile electrodeposition method to prepare bifunctional cobalt phosphide for overall water splitting. The needle-like cobalt phosphide (Co-P-1) nanoarray is uniformly distributed on nickel foam. Co-P-1 exhibits excellent electrocatalytic activity for hydrogen evolution reaction (HER, 85 mV at 10 mA/cm2, 60 mV/dec) and oxygen evolution reaction (OER, 294 mV at 50 mA/cm2, 60 mV/dec). The cell-voltage of 1.60 V is found to achieve the current density of 10 mA/cm2 for overall water splitting in the two-electrode system, comparable to that of previously reported Pt/C/NF||RuO2/NF. The excellent electrocatalytic performance can be attributed to the needle-like structure with more active sites, accelerated charge transfer and evolved bubbles' release. This work can provide new approach to the development of a bifunctional electrocatalyst for overall water splitting.

Roles of the mineral constituents in sludge-derived biochar in persulfate activation for phenol degradation.

Biochar as an environmental-friendly and low-cost catalyst has gained increasing attention in the catalytic degradation of organic pollutants. However, the roles of endogenous mineral constituents in biochar in the catalytic degradation are still unclear. In this study, the mineral-rich biochar produced from sewage sludge at 400 °C (SS400) and 700 °C (SS700) and their corresponding demineralized biochar (DSS400 and DSS700) were used to be the persulfate (PS) activator for phenol degradation. Results showed that the mineral-rich biochar + PS system had negligible phenol degradation (≤12.6 %), whereas distinct degradation of phenol were obtained in the demineralized biochar + PS system where DSS400 + PS and DSS700 + PS exhibited 36.3 % and 57.8 % degradation, respectively. Different minerals in mineral-rich biochar exhibited varying functions on phenol degradation. Mg and K in biochar had less effect on the phenol degradation, while Fe-containing minerals favored the phenol degradation. However, Ca-containing minerals more greatly reduced the formation of hydroxyl radical, resulting in more inhibited degradation of phenol. Thus, the overall degradation of phenol was reduced by the mineral-rich biochar. The findings indicated that the inherent minerals in biochar were not favorable for the phenol degradation, which guides us the application of biochar containing different minerals in the remediation of organic pollutants.

Performance evaluation of anaerobic baffled reactor (ABR) for treating alkali-decrement wastewater of polyester fabrics at incremental organic loading rates.

In this study, an anaerobic baffled reactor (ABR) with four compartments was employed to treat alkali-decrement wastewater of polyester fabrics under different organic loading rates. The stable operation of this reactor was achieved in 70 days at a hydraulic retention time of 36 h and mesophilic temperature of 35 ± 1 °C. It is found that the chemical oxygen demand removal and decolorization of this system can be as high as 79.0% and 87.7%, respectively. The different acidogenesis and methanogenesis in four compartments was acclimated by the variation of pH, oxidation reduction potential values and operational conditions in the spatial distribution of the first to fourth compartments of the ABR system. In addition, the dehydrogenase activity (DHA) and coenzyme F420 concentrations along the four compartments ranged from 67.8 to 185.21 µgTF/(gVSS·h) (TF: triphenyl formazan; VSS: volatile suspended solids) and 0.123 to 0.411 µmol/g, respectively. These results indicated that the ABR could separate acidogenesis and methanogenesis in longitudinal distribution and treat well the alkali-decrement wastewater.

[Study on the start-up of the anaerobic baffled reactor for treating alkali-deweighting and dyeing-printing wastewater].

The start-up of treating alkali-deweighting and dyeing-printing wastewater by anaerobic baffled reactor (ABR) was investigated. Through seeding with the anaerobic granular sludge, the start-up with low organic loading was started by using artificial alkali-deweighing and dyeing wastewater as influent with the condition of temperature 32 degrees C-35 degrees C and pH 7.8-8.3. After continuously running 70 days, the start-up had been completed to reach the stabilization. The results showed that the pH of effluent kept stable around 7.3 and the average COD removal rate was up to 78% while the average volume loading rate was 1.93 kg x (mm3 x d)(-1). After the start-up, a separating function of each compartment was observed and meanwhile the anaerobic granular sludge with good properties was achieved. Relative to the start, the size of granular sludge particle was increased and the sludge sedimentation performance became better and the value of f (MLVSS/MLSS) was up to 0.65 at the end of the experiment. In addition, high activity of the microorganism was observed that the average value of dehydrogenase activity (DHA) with TF expression and the coenzyme F420 concentration were x (g x h)(-1) and 0.18 micromol x g(-1), respectively.