Sengupta, Angan

This work contributes to the estimation of new and complementary density data for carbon dioxide (CO2) confined in carbon slit pores at different conditions. Grand canonical Monte Carlo (GCMC) simulations were employed to predict the CO2 adsorption capacities in carbon slit pores of height 20, 31.6, 63.2, 94.85 and 126.5 Å at 673.15 and 873.15 K over a pressure range of 500–4000 kPa, which corresponds to steam reforming of methane process. The bulk densities of CO2 at these temperature and pressure conditions have been estimated via isothermal–isobaric ensemble MC simulations using the Elementary Physical Model. The predicted density shows an excellent agreement with the experimental data. The adsorption capacities of CO2 in all the aforementioned pores at 673.15 and 873.15 K over the pressure range of 500–4000 kPa have also been estimated in the presence of wall–fluid interactions, in addition to the fluid–fluid interactions. The study on the thermodynamic phase behaviour of confined CO2 in the presence of wall–fluid interactions showed the existence of vapour–liquid equilibria at high temperature and pressure conditions.

Date palm (Phoenix dactylifera L.) is the most commonly cultivated fruit tree in the Middle East and North Africa. Date fruits are an excellent source of nutrition due to their high sugar content and high levels of phenols, minerals, and antioxidants. This work aimed to prepare a soluble natural sweetener from date fruit extract using colloidal gas aprons (CGAs) generated with a food-grade non-ionic surfactant (Tween 20). Various process parameters, such as the flow rate of the CGAs, the volume of the feed, the temperature of the CGAs, and the feed solution, were varied to obtain the optimal parameters. In the foam phase, the maximum soluble sugar enrichment of 92% was obtained at a flow rate of 50 mL/min of CGA and a solution temperature of 23 °C. The formation of intermolecular hydrogen bonding between the glucose molecules and the surfactant Tween 20 was confirmed by molecular modeling studies.

Batch reactors with polymerisation reaction and ineffective cooling arrangements are prone to thermal runaway. In the present case study, we have investigated such a thermal runaway scenario in case of thermally initiated free radical styrene polymerisation reaction inside adiabatic and non-adiabatic batch reactors. We found that our developed process model for the well-mixed batch reactor along with the reported kinetic model in the literature; aptly describes the thermal runaway polystyrene formation reaction conditions (critical temperature for runaway, Tcr and the critical time for runaway, tcr). We have also deployed the well-studied Extended Kalman Observer (EKO) to provide online estimates of the runaway reaction process parameters, by using reaction temperature as the only measurement to the observer. It is noted that the non-linear EKO with this one temperature measurement provides accurate estimates of all runaway process parameters from an early time interval. We have also shown that an accurate online estimate of the critical process variables of the polystyrene formation reaction by using the EKO algorithm helps in effective manipulation of initiator concentration that increases the operational safety of the non-adiabatic batch reactors by delaying the attainment of Tcr at a higher monomer conversion.

Increasing demand for wearable sensors for multipurpose applications have made it an essential part of our everyday life. In such a scenario; reusability, flexibility, cost effectiveness, and integrability of such sensors are among the top desirable features. Using our casual clothing as sensors can be one of the most effective ways for various therapeutic, diagnostic, and continuous monitoring functionalities. Conducting yarns, possibly, have the capability to deeply influence the 4th industrial revolution and rule the e-textile based smart wearables for wide range applications. Herein, we present a comparative experimental study of three different capacitive sensor structures for humidity sensing applications. These structures have been explored using conducting yarns having tungsten metal as core conducting materials.

In present work, we have performed the Grand Canonical Monte Carlo (GCMC) simulations to quantify CO2 capture inside porous silica at high operating temperatures of 673.15 K and 873.15 K; and over a operating pressure range of 500 kPa – 4000 kPa that are methane steam reforming process parameters. Related chemical potential values at these thermodynamic conditions are obtained from the bulk phase simulations in the Canonical ensemble in conjunction with Widom's insertion technique, where the CO2 has been accurately represented by TraPPE force field. Present structure of the porous silica is a single slit pore geometry of various heights (H = 20 Å, 31.6 Å, 63.2 Å and 126.5 Å), dimensions in which possible vapour-liquid equilibria for generic square well fluids has been reported in literature. Estimation of the pore-fluid interactions show a higher interaction between silica pore and adsorbed CO2 compared to the reported pore-fluid interactions between homogeneous carbon slit pore and adsorbed CO2; thus resulting in an enhancement of adsorption inside silica pores of H = 20 Å and H = 126.5 Å, which are respectively 3.5 times and 1.5 times higher than that in homogeneous carbon slit pores of same dimensions and at 673.15 K and 500 kPa. Estimated local density plots indicate the presence of structured layers due to more molecular packing, which confirms possible liquid-like and vapour-like phase coexistence of the supercritical bulk phase CO2 under confinement.

Diglycolamine (DGA), one of the alkanolamine solvent used in natural gas sweetening unit, produces total organic acid (TOA) anions as degraded products that has detrimental effects over the operational units. In this study, calcium alginate carbon (CAC) adsorbents were used to remove TOA anions from industrial lean DGA solvent. The adsorbents were characterized by TGA, DSC, Raman, FTIR, and SEM analysis. Effects of different parameters such as the adsorption time, adsorbent dosage, and solution temperature were examined in the batch adsorption experiments. The kinetic data were best fitted to the pseudo-second-order model, highlighting chemisorption as the rate-limiting step. This was also validated using molecular modeling by predicting the intermolecular hydrogen bond formation between the organic acid anions and the calcium alginate molecules. The TOA uptake increased with the increase in the solution temperature from 49.9 mg/g at 25 °C to 72.5 mg/g at 55 °C. The CAC beads were regenerated effectively for six adsorption–desorption cycles in a fixed-bed column. The environmentally friendly CAC adsorbent exhibited significant application potential for the removal of TOA anions from lean DGA solvents.