Experimental investigations on biopolymer in enhancing the liquid flow in microchannel

Stabilization and solidification of arsenic contaminated silty sand using alkaline activated slag

Contamination of soils by arsenic represents a significant environmental and public health risk, making effective remediation strategies a pressing concern. One commonly employed technique is stabilization and solidification, which involves the addition of stabilizing binders such as cement to immobilize arsenic. This study investigates the potential of alkaline activated slag for stabilization and solidification of arsenic-contaminated soil, employing the toxic characteristic leaching procedure (TCLP) and unconfined compressive strength (UCS) tests. To assess the strength and leachability behavior, the research examines the effect of several factors, including binder content, curing time, curing conditions, alkaline activator solution to slag ratio, sodium silicate to sodium hydroxide ratio, and sodium hydroxide concentration. Additionally, field emission scanning electron microscopes (FE-SEM) in combination with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) tests are employed to analyze the stabilization and solidification mechanism. The study shows that increasing the slag content to 20% by weight after 28 days of curing at ambient temperature leads to a decrease of almost 92% in the concentration of leached arsenic and an increase in UCS from 80 kPa to approximately 19 MPa. The formation of albite and anorthite crystals, along with gels such as (N, C)-A-S-H and C-S-H, contributes to enhanced strength and reduced leachability. As a result, the use of alkaline activated slag is identified as an effective and environmentally friendly approach for the stabilization/solidification of arsenic-contaminated soils. This study highlights the use of alkaline activated slag as an effective solution for remediating arsenic-contaminated soils while simultaneously reducing waste, greenhouse gas emissions, and energy consumption. Slag, a byproduct of metal production, is often wasted due to a lack of value and landfill space. However, alkaline activated slag demonstrates the potential to stabilize soil, immobilize heavy metals, and provide efficient and sustainable soil remediation.

Thriving artificial underwater drag-reduction materials inspired from aquatic animals: progresses and challenges

In the past decades, drag-reduction surfaces have attracted more and more attention due to their potentiality and wide applications in various fields such as traffic, energy transportation, agriculture, textile industry, and military. However, there are still some drag-reduction materials that need to be deeply explored. Fortunately, natural creatures always have the best properties after long-term evolution; aquatic organisms have diversified surface microstructures and drag-reducing materials, which provide design templates for the development of thriving artificial underwater drag-reduction materials. Aquatic animals are tamed by the current while fighting against the water, and thus have excellent drag reduction that is unparalleled in water. Inspired by biological principles, using aquatic animals as a bionic object to develop and reduce frictional resistance in fluids has attracted more attention in the past few years. More and more aquatic animals bring new inspiration for drag-reduction surfaces and a tremendous amount of research effort has been put into the study of surface drag-reduction, with an aim to seek the surface structure with the best drag-reduction effect and explore the drag-reduction mechanism. This present paper reviews the research on drag-reduction surfaces inspired by aquatic animals, including sharks, dolphins, and other aquatic animals. Aquatic animals as bionic objects are described in detail, with a discussion on the drag-reduction mechanism and drag-reduction effect to understand the development of underwater drag-reduction fully. In bionic manufacturing, the effective combination of various preparation methods is summarized. Moreover, bionic surfaces are briefly explained in terms of traffic, energy sources, sports, and agriculture. In the end, both existing problems in bionic research and future research prospects are proposed. This paper may provide a better and more comprehensive understanding of the current research status of aquatic animals-inspired drag reduction.