Chemical binding

About: Chemical binding is a research topic. Over the lifetime, 1822 publications have been published within this topic receiving 52516 citations.

Lignin Nanoparticle-Coated Celgard Separator for High-Performance Lithium-Sulfur Batteries.

Abstract: Tremendous efforts have been made toward the development of lithium–sulfur (Li–S) batteries as one of the most reasonable solutions to the rapidly increasing demand for portable electronic devices and electric vehicles, owing to their high cost-efficiency and theoretical energy density. However, the shuttle effect caused by soluble polysulfides is generally considered to be an insurmountable challenge, which can significantly reduce the battery lifecycle and sulfur utilization. Here, we report a lignin nanoparticle-coated Celgard (LC) separator to alleviate this problem. The LC separator enables abundant electron-donating groups and is expected to induce chemical binding of polysulfides to hinder the shuttle effect. When a sulfur-containing commercially available acetylene black (approximately 73.8 wt% sulfur content) was used as the cathode without modification, the Li–S battery with the LC separator presented much enhanced cycling stability over that with the Celgard separator for over 500 cycles at a current density of 1 C. The strategy demonstrated in this study is expected to provide more possibilities for the utilization of low-cost biomass-derived nanomaterials as separators for high-performance Li–S batteries.

Physicochemical and Mechanical Properties of Portland Cements

Abstract: The microstructural nature of Portland cement-based products is complex and gives rise to time-dependent physical and mechanical properties, with significant changes taking place over periods of many months or even years. These effects are more fundamental than the continuing hydration reaction of the initial unhydrated cement, and involve slow ageing processes in the colloidal hydration products. In addition, the chemical binding of water in the hydrates takes on a series of energies which result in ready loss of moisture over a wide range of humidities, and a readjustment of water molecules between different sites within the microstructure in response to small changes in environmental temperature and humidity. All such changes, some of which are irreversible, are reflected in changes in physical and mechanical properties. Conventional physical and mechanical attributes suitable for describing the behaviour of solids are allotted to hardened cement pastes and concretes, for example, thermal expansivity or elasticity, but it should be recognised that these functions have only approximate validity for these systems and are dependent on the length of time for which the external stimulus is applied.

Biosorption of Metals and Metalloids

Abstract: Industrial activities such as mining operations, refining of ores and combustion of fuel oils play a relevant role in environmental pollution since their wastes contain high concentrations of toxic metals that can add significant contamination to natural water and other water sources if no decontamination is previously applied. As toxic metals and metalloids, including arsenic, cadmium, lead, mercury, thallium, vanadium, among others, are not biodegradable and tend to accumulate in living organisms, it is necessary to treat the contaminated industrial wastewaters prior to their discharge into the water bodies. There are different remediation techniques that have been developed to solve elemental pollution, but biosorption has arisen as a promising clean–up and low–cost biotechnology. Biosorption is one of the pillars of bioremediation and is governed by a variety of mechanisms, including chemical binding, ion exchange, physisorption, precipitation, and oxide-reduction. This involves operations (e.g. biosorbent reuse, immobilization, direct analysis of sample without destruction) that can be designed to minimize or avoid the use or generation of hazardous substances that have a negative impact on the environment and biota, thus following the concepts of “green chemistry” and promoting the environmental care. Furthermore, it has to be specially considered that the design of a biosorption process and the quality of a biosorbent are normally evaluated from the equilibrium, thermodynamic, and kinetic viewpoints. Therefore, a successful biosorption process can be only developed based on multidisciplinary knowledge that includes physical chemistry, biochemistry and technology, among other fields.