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The Hofmeister series characterizes the ability of salt anions to precipitate polyampholytes/proteins. However, the variation of protein size in the bulk solution of acids and the effect of salts on the same have not been studied well. In this article, the four acids (CH3COOH, HNO3, H2SO4, and HCl) and their effects on the hydrodynamic radius (RH) of gelatin in the bulk solution are investigated. The effects of Na salt with the same anions are also considered to draw a comparison between the interactions of acids and salts with polyampholytes. It is suggested that the interactions of polyampholytes with acids are different from those of salts. The interaction series of polyampholytes with acids with respect to the RH of the polyampholyte is C H 3 CO O − > N O 3 − > C l − > S O 4 2 − whereas the interaction series with salts is S O 4 2 − > C H 3 CO O − > C l − > N O 3 − . These different interactions are due to equilibration between acid dissociation and protonation of polyampholytes. Another important factor contributing to the interactions in weak acids is the fact that undissociated acid hinders the movement of dissociated acid. Experiments and simulations were performed to understand these interactions, and the results were identical in terms of the trend in RH (from the experiments) and the radius of gyration (Rg) (from the simulations). It is concluded that the valence of ions and dissociation affect the interaction in the case of acids. However, the interactions are influenced by the kosmotropic and chaotropic effect, hydration, and mobility in the case of salts. [ABSTRACT FROM AUTHOR]

The depolymerization of lignin to produce renewable value-added building block chemicals has received increased attention from both industry and academia, as its facilitation is a key in the development of future biorefinery technologies. The main challenge in lignin depolymerization relies on its complex structure. Numerous efforts have shown that catalysts, solvents, reaction parameters, and physiochemical properties of lignin significantly affect the depolymerization reaction of lignin. Solvents are crucial components of the reaction system and affect the performance of the lignin depolymerization process. A good solvent can promote the solubility of lignin and enhance the catalyst–lignin interactions, and could also stabilize the reactive intermediates. However, the relationship and dependence of the molecular structure of lignins with its solubility and reactivity in different solvents are poorly understood. Thus, it is important to understand the influence of solvents on the reaction mechanism, the thermodynamic state of lignin, intermediates, products, and catalysts' stability. In this article, various solvents used in the depolymerization of different types of lignin reactions are extensively overviewed. Special attention is paid to comparing the conversion of lignin, yield of bio-oil, and yield of monomers in the presence of different polarity-categorized solvents and binary solvents. [ABSTRACT FROM AUTHOR]

A model has been developed based on the available experimental data for propylene polymerization with long-chain branching. The system considered is a bicatalyst system, where the first catalyst produces the atactic polypropylene macromonomer and second one grafts the atactic polypropylene macromonomers to isotactic polypropylene backbone. Pareto optimal solutions for long-chain branched polypropylene with the binary catalyst system are obtained by adapting nondominated sorting genetic algorithm for a particular multiobjective setup. Optimization objective is to produce polymer of maximum weight average molecular weight and maximum grafting density (expressed as number of macromonomers per 1000 backbone monomer units) in minimum polymerization time. Two catalysts and one cocatalyst concentration, second catalyst addition time are taken as decision variables with relevant process constraints that take care of model validity over prescribed operating range. A wide variety of process choices have been obtained for the optimization setup which shows betterment in process performance (e.g., ~17% improvement in grafting density and 1% improvement in weight average molecular weight with the same polymerization time attained as compared to the processes reported in the literature Ye and Zhu, 2013)., INTRODUCTION Polypropylene (PP) can be preferred to many other thermoplastics for the applications which need light weight and reasonable thermal resistant properties. Highly linear PPs can be produced by Ziegler-Natta [...]

Since coal washeries generate huge quantities of high-ash rejects as waste, effective utilization of coal rejects help in sustainable coal preparation. Out of different coal rejects, tailings from froth-flotation process can be a potential material for the extraction of clean coal due to its fine size, availability in the slurry form, presence of good carbon values, and better liberation properties. In the present study, three different methodologies i.e., chemical method, chemico-physical method, and physical method are explored to separate clean coal with >49.8% yield for their utilization in coke making process. The chemical method of demineralization by alkali-acid leaching shows a high clean coal yield of 65.4%; however, the alteration of vitrinite-group macerals makes it unsuitable for coke making process. Chemico-physical method of clean coal separation by hydrothermal extraction followed by density separation results in clean coal at 49.8% yield with an increase in vitrinite group macerals, which shows a positive impact on rheological and coking properties. The physical separation method by ultrafine grinding followed by density-gradient-centrifugation resulted in 58.2% of clean coal yield with coking properties similar to the clean coal obtained in conventional coal beneficiation plants. By adopting chemico-physical method and physical method of coal cleaning, the overall clean coal yield of the washery can be improved by >5.1%. Also, there is no deterioration in coke properties such as coke strength after reaction and coke reactivity index by using the prepared clean coal in coal blend. [ABSTRACT FROM AUTHOR]

'Conducting polymeric (CP) membrane based controlled molecular release under applied electrical potential' is an important futuristic application in 'drug delivery'. A validated Poisson-Nernst-Planck based framework has been used in this study for the purpose of performance mapping for such a system. Leaking of the molecules during loading time and retention of molecules at the end of each voltage cycle have been identified here as the major bottlenecks in the use of this system in a sustainable basis. Peak flux of ionic molecules delivered is a key objective to be maximized along with minimum retention and leakage. Results reveal that parameters like time of voltage span, effective diffusivity, polymer film thickness need to be tightly maintained. At the same time, a wide variety of CP-drug combinations can be acceptable. This opens the possibilities of utilizing this system for large range of therapeutic applications for controlled drug delivery. POLYM. ENG. SCI., 51:2001-2012, 2011. ©2011 Society of Plastics Engineers, INTRODUCTION Conducting polymeric (CP) membrane based controlled molecular release phenomenon can be applied in drug delivery applications. These are porous polymeric membranes inside which oxidation-reduction reactions can occur. The entire [...]

Handling and disposal of high volume of fine coal tailings is a biggest challenge for coal washeries. Separation of clean coal by density separation and flotation shows limited yields of 23–28% and 13–14% respectively. Chemical leaching process has a challenge with the formation of insoluble salts. The present investigation aimed to separate clean coal by a combination of chemical-physical separation technique, i.e. alkaline hydrothermal process followed by density separation. Hydrothermal extraction of humic substance causes dissociation of coal aggregated structure (Mineral-Maceral-Pore structure), thus improves the separation. Experiments performed as per design of experiments and reduced design of experiments, where 100 µ particle size, 50% (w/w) pulp density, 4.5% KOH (w/w), and 140°C reaction temperature found to be optimum, at which 16.2% ash clean coal at 40.7% yield and humic acid by-product at 18.3% yield were obtained. Use of swelling agent such as tetrahydrofuran shown negative impact on clean coal recovery. Material balance and cost data were presented to show the techno-commercial viability of this technology. [ABSTRACT FROM AUTHOR]

Ionic inclusion inside thin conducting polymer (CP) film is a major and common feature for actuator as well as membrane-based drug release. In this study, an electro-active polymeric thin-film system has been conceptualized. PNP-electro-neutrality (Poisson-Nemst-Planck) based modeling framework with customized boundary conditions is used to depict the electrochemical phenomena. In dynamic model, kinetics of probable redox reactions is included along with electro-migration and diffusion terms in the overall PNP framework. At steady state, interfacial voltage seems to hold the critically important role, while ionic migration and reaction kinetics play very crucial roles in determining the dynamics of such systems. The validated model predicts that lowering in the standard potential of the polymeric electrode accelerates the process of ionic ingress. Higher ionic flux is obtained using slower voltage scan. Variation of diffusivity shows the large spectrum of relatively unexplored dynamics for such electro-active thin-film-based system. The significance is in designing actuator- or membrane-based controlled molecular release systems. POLYM. ENG. SCI., 48:2229-2237, 2008. [C]2008 Society of Plastics Engineers, INTRODUCTION Currently, increasing applications of conducting poly rners (CP) such as bioclcctronic devices, drug delivery systems enhance the scope of investigating underlying phenomena of microcleclrode and nanoelcctrode processes (1), (2). [...]