Emerging Trends of Computational Chemistry and Molecular Modeling in Froth Flotation: A Review.

Froth flotation is the most versatile process in mineral beneficiation, extensively used to concentrate a wide range of minerals. This process comprises mixtures of more or less liberated minerals, water, air, and various chemical reagents, involving a series of intermingled multiphase physical and chemical phenomena in the aqueous environment. Today's main challenge facing the froth flotation process is to gain atomic-level insights into the properties of its inherent phenomena governing the process performance. While it is often challenging to determine these phenomena via trial-and-error experimentations, molecular modeling approaches not only elicit a deeper understanding of froth flotation but can also assist experimental studies in saving time and budget. Thanks to the rapid development of computer science and advances in high-performance computing (HPC) infrastructures, theoretical/computational chemistry has now matured enough to successfully and gainfully apply to tackle the challenges of complex systems. In mineral processing, however, advanced applications of computational chemistry are increasingly gaining ground and demonstrating merit in addressing these challenges. Accordingly, this contribution aims to encourage mineral scientists, especially those interested in rational reagent design, to become familiarized with the necessary concepts of molecular modeling and to apply similar strategies when studying and tailoring properties at the molecular level. This review also strives to deliver the state-of-the-art integration and application of molecular modeling in froth flotation studies to assist either active researchers in this field to disclose new directions for future research or newcomers to the field to initiate innovative works.

A comprehensive review on current technologies for removal of endocrine disrupting chemicals from wastewaters.

In the recent years, endocrine disrupting compounds (EDCs) has received increasing attention due to their significant toxic effects on human beings and wildlife by affecting their endocrine systems. As an important group of emerging pollutant, EDCs have been detected in various aquatic environments, including surface waters, groundwater, wastewater, runoff, and landfill leachates. Their removal from water resources has also been an emerging concern considering growing population as well as reducing access to fresh water resources. EDC removal from wastewaters is highly dependent on physicochemical properties of the given EDCs present in each wastewater types as well as various aquatic environments. Due to chemical, physical and physicochemical diversities in these parameters, variety of technologies consisting of physical, biological, electrochemical, and chemical processes have been developed for their removal. This review highlights that the effectiveness of EDC removal is highly dependent of selecting the appropriate technology; which decision is made upon a full wastewater chemical characterization. This review aims to provide a comprehensive perspective about all the current technologies used for EDCs removal from various aquatic matrices along with rising challenges such as the antimicrobial resistance gene transfer during EDC treatment.

Surface Speciation of Brucite Dissolution in Aqueous Mineral Carbonation: Insights from Density-Functional Theory Simulations.

Aqueous mineral carbonation of brucite is an important mineralization route for carbon capture and sequestration. Prerequisite to mineral carbonation are the simultaneous CO2 absorption and brucite dissolution which imply, in the first place, the formation and release in the liquid phase of CO32-, HCO3-, Mg2+, MgOH+, and MgHCO3+ ions. To gain insights on the nature of adsorption sites and resulting surface complexes, the affinity of water and of dissolved species for pristine and partially dissolved brucite (001) cleaved surfaces in aqueous mineral carbonation has been investigated using density-functional theory (DFT) simulations. The species' affinity for uptake by the brucite (001) surface is predicted to obey the trend: Mg2+ > MgHCO3+ > MgOH+ > HCO3- > CO32-, whereas the surface acid/base behavior controls affinity following the order: dehydroxylated (001) surface > deprotonated (001) surface > neutral and protonated (001) surfaces. Covalent bonds have been predicted for the following (charge-determining) ion-(001) brucite surface sites: CO32- ≡ dehydroxylated site, HCO3- ≡ dehydroxylated site, MgOH+ ≡ dehydroxylated/deprotonated sites, MgHCO3+ ≡ dehydroxylated/(de)protonated sites, and Mg2+ ≡ neutral/(de)protonated/dehydroxylated sites. Congruent dissolution of (001) brucite surface leads to a diverse population of coordination-deficient Mg and O centers which are more active to form covalently bonded surface complexes with aqueous CO32-, HCO3-, Mg2+, MgOH+, MgHCO3+ as compared to the undissolved surface. However, although affinity of the altered surfaces for dissolved ions increases conspicuously, the same affinity trend is predicted for the dissolving surfaces as compared to the pristine (001) brucite surface.