V. A. Astakhov

Bio: V. A. Astakhov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Langmuir adsorption model & Adsorption. The author has an hindex of 1, co-authored 1 publications receiving 233 citations.

Development of the concepts of volume filling of micropores in the adsorption of gases and vapors by microporous adsorbents

Abstract: 1. Synthetic zeolites of various compositions and crystal chemical structures differ extremely substantially in average density in the adsorption space of the cations accessible for direct interaction with the molecules being adsorbed, and in their number for a unit mass of the adsorbent. This determines the limiting cases of adsorption with a weakly or strongly expressed role of the electrostatic component in the total adsorption interaction. 2. The volume nature of the filling of the micropores of the zeolite and, in a satisfactory approximation, the temperature invariance of the characteristic equation of adsorption, are the experimental bases for the theory of the adsorption of gases and vapors on zeolites. 3. In the case of weakly expressed electrostatic interactions, the adsorption on zeolites is closest in nature to adsorption on microporous adsorbents, which do not contain active centers in the form of cations in the adsorption space.

Water and Metal-Organic Frameworks: From Interaction toward Utilization.

Abstract: The steep stepwise uptake of water vapor and easy release at low relative pressures and moderate temperatures together with high working capacities make metal-organic frameworks (MOFs) attractive, promising materials for energy efficient applications in adsorption devices for humidity control (evaporation and condensation processes) and heat reallocation (heating and cooling) by utilizing water as benign sorptive and low-grade renewable or waste heat. Emerging MOF-based process applications covered are desiccation, heat pumps/chillers, water harvesting, air conditioning, and desalination. Governing parameters of the intrinsic sorption properties and stability under humid conditions and cyclic operation are identified. Transport of mass and heat in MOF structures, at least as important, is still an underexposed topic. Essential engineering elements of operation and implementation are presented. An update on stability of MOFs in water vapor and liquid systems is provided, and a suite of 18 MOFs are identified for selective use in heat pumps and chillers, while several can be used for air conditioning, water harvesting, and desalination. Most applications with MOFs are still in an exploratory state. An outlook is given for further R&D to realize these applications, providing essential kinetic parameters, performing smart engineering in the design of systems, and conceptual process designs to benchmark them against existing technologies. A concerted effort bridging chemistry, materials science, and engineering is required.

Contribution of Different Sulfamethoxazole Species to Their Overall Adsorption on Functionalized Carbon Nanotubes

Abstract: Antibiotics pose environmental risks, but their adsorption mechanisms are still unclear. Identifying the contributions of different mechanisms is vital in predicting antibiotic environmental behavior and consequently understanding their environmental risks. This study used functionalized carbon nanotubes (CNTs), namely hydroxylized (MH), carboxylized (MC), and graphitized (MG) multiwalled CNTs, as adsorbents and sulfamethoxazole (SMX) as an adsorbate to study the adsorption mechanisms of ionizable organic contaminants on solid particles. At pH around 3.7, SMX always showed the highest adsorption on different CNTs and the adsorption followed the order of MH > MG > MC. Combining the results on SMX specie analysis, the pH-dependent adsorption is well-explained by hydrophobic and electron-donor-acceptor interactions. The adsorption of neutral SMX is always dominant by contributing generally over 80% to the overall adsorption. A significant contribution of cationic SMX at pH < 3.5 suggested significant contribution of hydrogen bonds to SMX adsorption. The strength of bisphenol A (BPA) inhibiting SMX adsorption was dependent on the concentration ratio of BPA to neutral SMX, instead of to the overall SMX concentration. This result emphasized the importance of identifying the dominant mechanisms or species for the adsorption of antibiotics.

Literature review on solar adsorption technologies for ice-making and air-conditioning purposes and recent developments in solar technology

Abstract: The primary objective of this review is to provide fundamental understandings of the solar adsorption systems and to give useful guidelines regarding designs parameters of adsorbent bed reactors,and the applicability ofsolar adsorption both in air-conditioning and refrigeration with the improvement of the coefficient of performance. Solar adsorption heat pump and refrigeration devices are of significance to meet the needs for cooling requirements such as air-conditioning and ice-making and medical or food preservation in remote areas. They are also noiseless, non-corrosive and environmentally friendly. For these reasons the research activities in this sector are still increasing to solve the crucial points that make these systems not yet ready to compete with the well-known vapor compression system. There is an increasing interest in the development and use of adsorption chillers due to their various economic and impressive environmental benefits, enabling solar energy or waste heat to be used for applications such as district networks and cogeneration plants. Compared to adsorption systems that require heat sources with temperatures above 100°C (zeolite–water systems, activated carbon–methanol systems) or conventional compressor chillers, a silica gel/water adsorption refrigerator uses waste heat with temperature below 100°C. This creates new possibilities for utilizing low temperature energy.