Optimization and mechanism of the novel eco-friendly additives for solidification and stabilization of dredged sediment.

Solidification/stabilization technology is commonly used in the rehabilitation of dredged sediment due to its cost-effectiveness. However, traditional solidification/stabilization technology relies on cement, which increases the risk of soil alkalization and leads to increased CO2 emissions during cement production. To address this issue, this study proposed an innovative approach by incorporating bentonite and citrus peel powder as additives in the solidifying agent, with the aim of reducing cement usage in the dredged sediment solidification process. The research results showed that there is a significant interaction among cement, bentonite, and citrus peel powder. After response surface methodology (RSM) optimization, the optimal ratio of the cementitious mixture was determined to be 14.86 g/kg for cement, 5.85 g/kg for bentonite, and 9.31 g/kg for citrus peel powder. The unconfined compressive strength (UCS) of the solidified sediments reached 3144.84 kPa. The reaction products of the solidification materials, when mixed with sediment, facilitated adsorption, gelation, and network structure connection. Simultaneously, the leaching concentration of heavy metals was significantly decreased with five heavy metals (Zn, As, Cd, Hg, and Pb) leaching concentrations decreasing by more than 50%, which met the prescribed thresholds for green planting. This study demonstrated the ecological benefits of employing bentonite and citrus peel powder in the solidification process of dredged sediment, providing an effective solution for sediment solidification.

Accessing the Inaccessible: Analyzing the Oxygen Reduction Reaction in the Diffusion Limit.

The oxygen reduction reaction (ORR) is one of the key processes in electrocatalysis. In this communication, the ORR is studied using a rotating disk electrode (RDE). In conventional work, this method limits the potential region where kinetic (mass transport free) reaction rates can be determined to a narrow range. Here, we applied a new approach, which allows us to analyze the ORR rates in the diffusion-limited potential region of high mass transport. Thus, for the first time, the effect of anion adsorption on the ORR can be studied at such potentials.

Pt-group bimetallic nanocrystals with high-index facets as high performance electrocatalysts.

Bimetallic nanocrystals bound by high-index facets are promising catalysts, as they have both electronic effects from alloying and surface structure effects from high-index facets. Herein, we mainly focused on electrochemical preparation of two new Pt-Rh nanocrystals with high-index facets: {830}-bound tetrahexahedron and {311}-bound trapezohedron, and their excellent electrocatalytic properties for ethanol oxidation, especially the ability to break C-C bonds. Combining previous results about surface-modified tetrahexahedral Pt nanocrystals, we discuss the correlation of alloy and surface effects of the bimetallic system.