Thanapalan Murugesan

Pressure Drop and Flow Regimes in Cocurrent Gas-Liquid Upflow through Packed Beds

Abstract On the basis of the experimental results along with those available in the literature (1678 experimental data from five liquid systems, covering 10 different packings, from three sources) with a wide range of variables, a generalized approach is developed to identify the flow regime transitions viz., bubble flow, dispersed bubble flow and pulse flow in cocurrent two-phase (gas–liquid) upflow through packed beds. New correlations for the estimation of frictional pressure drop involving all the fundamental and operating variables are also presented for the three regimes of operation. This present correlations are more accurate than those previously reported.

The chlor-alkali process: Work in Progress

The chlor-alkali process has come a long way from the days of the diaphragm and mercury cell process to the present membrane cell process, with huge reduction in power consumption and hence its carbon footprint. Although there is reduction in the release of highly toxic mercury to the environment, there is increased release of less harmful substances such as chloride and chlorate because the membrane cell is less tolerant to contaminants, and hence requires higher purity brine. The technology providers have continued to improve upon the process to reduce power consumption and to reduce the plant’s footprint. This review looks briefly at the three technologies and attempts to look at where we currently are at. All new chlor-alkali plants being built are of the membrane process. This review mentions some of the areas where improvements can be made to the membrane process.

Effect of sulfonate-based anions on the physicochemical properties of 1-alkyl-3-propanenitrile imidazolium ionic liquids

In this paper, the physicochemical properties of a new series of ionic liquids (ILs) based on nitrile-functionalised imidazolium cations ([C2CN Cnim]+) with sulfonate-based anions were studied. The ILs were prepared by reacting imidazole with acrylonitrile, followed by butyl- and decyl bromide. The anions of the resulting bromide salts exchanged by metathesis to dioctylsulfosuccinate (DOSS), dodecylsulfate (DDS), benzenesulfonate (BS) and trifluoromethanesulfonate (TFMS). The densities of these ILs are lower compared to the those of other reported nitrile-functionalised ILs, while on the other hand, the viscosities of the ILs are higher due to the effects of the large anions and the long alkyl chain of the cations.

An Empirical Model for the Estimation of Moisture Ratio During Microwave Drying of Plaster of Paris

The drying characteristics of plaster of Paris (POP) under microwave irradiation were studied for different shapes of materials through various drying parameters like microwave power, initial moisture content, and drying time. An empirical model for the estimation of moisture ratio was developed using the drying kinetic data of POP. Further, the experimental data on moisture ratio of POP for different operating conditions were fitted with the nine basic drying model equations. Based on the observations, the constants and coefficients of the literature models were rewritten in the form of Arrhenius and logarithmic expressions considering microwave power as input variable. Fifty-eight new model expressions were derived by changing the constants and coefficients and tested using the present experimental data. From the analysis of RMSE, χ2, and EF parameters for the derived models, a suitable empirical model (Model No. 55, RMSE = 0.0874; χ2 = 0.0020; EF = 0.9999) was established to represent the present experimental data on microwave drying of POP.

Characterization and Process Optimization of Microwave Drying of Plaster of Paris

The changes in the characteristics of plaster of Paris (pop) during drying operation under microwave irradiation conditions, namely surface morphology, effective moisture diffusivity, and absorption of microwave, were studied. The drying characteristics and kinetics of the process during microwave drying of plaster were studied for rectangular-faced cuboids (80 × 70 × 15, L × B × H in mm) through various drying parameters like microwave power input, initial moisture content, and drying time. Further, the experimental data on moisture ratio of plaster for different operating conditions were obtained and the optimization of the microwave drying process parameters was performed with response surface methodology (RSM) by considering all the above-said independent variables. Based on the RSM analysis, the optimum values of the process variables were obtained as: initial moisture content (A) 60%; microwave power input (B) 180 W; and drying time (C) 480 S.

Hydrogen Storage of a Fixed Bed of Nanocrystalline Mixed Oxides

Nanocrystalline hydrotalcite derived mixed oxides containing magnesium, cobalt, and aluminum (MCAM) (M(1−x)AlxO(1

Partition Behavior of Bovine Serum Albumin in PEG2000‐Sodium Citrate‐Water Based Aqueous Two‐Phase System

Abstract The effect of phase forming components, pH, neutral salt (NaCl) addition on partitioning of bovine serum albumin (BSA) in PEG2000‐sodium citrate based aqueous two‐phase system was investigated at 25°, 35°, and 45°C. The systems were prepared by varying the phase forming components concentration at a pH of 5.0, 6.0, 7.0, 8.0, and 9.0 with different NaCl salt concentrations of 0.05 M, 0.1 M, 1.5 M, 0.2 M, 0.3 M, and 0.4 M. The affinity of the BSA for the lower phase increases with increase in pH, due to increase in ratio of trivalent to divalent citrate ions in the two‐phase system. It was confirmed that the partition of BSA depends on the relative hydrophobicity of the compounds as well as their charge. Optimum level of pH and NaCl concentration for the partitioning of bovine serum albumin was determined.

Thermal properties of different transition metal forms of montmorillonite intercalated with mono-, di-, and triethanolammonium compounds

In the present study, different transition metal forms of montmorillonite have been intercalated with mono-, di-, and triethanolammonium cations via d coordination mechanism to investigate their thermal behavior, structural characteristics, surface properties, and elemental composition using TG, XRD, BET, and CHNS techniques. Thermogravimetric analysis showed two thermal transition steps for transition metal-exchanged montmorillonites, which attributed to desorption of the physically adsorbed water and hydrated water, and dehydroxylation of the structural water; whereas for ammonium-montmorillonite complexes, the TG curves showed three thermal transition steps which attributed to desorption of the adsorbed water and dehydration, decomposition of the ammonium cations in the interlayer space of montmorillonite, and the dehydroxylation of the structural water. The thermal analysis of ammonium-montmorillonites affirmed that the molar mass of amine compounds used affects both desorption temperature (position) and the amount of the adsorbed water (intensity). XRD results revealed that the molar mass of amine used has linear relation with the basal spacings of the corresponding ammonium-montmorillonites, indicating structural changes. BET results showed that the molar mass of amines has an inverse effect on the surface area of the studied samples. CHNS analysis for the studied samples quantitatively confirmed the intercalation of ammonium cations into the interlayer space of montmorillonite.

Modeling of Thin Layer Drying of Banana (Nendran Spp) under Microwave, Convective and Combined Microwave-Convective Processes

Drying kinetics of microwave, convective and microwave assisted convective drying of thin layer Nendran banana was investigated on a modified microwave oven. The drying characteristics through the operating parameters of the drying process, such as power output, air temperature, slice thickness and sample mass in terms of drying rate equation, were analyzed. An appropriate empirical model to represent the drying process was established by analyzing the available literature models with current experimental data. The statistical analysis for the selected model was performed, parameters like Mean Bias Error, Root Mean Square Error, reduced chi square and t-stat were estimated to examine the consistency of the model to represent the present experimental results. Higher rates and shorter drying times were achieved at a higher temperature and microwave heating power and lesser sample thickness and load. Microwave drying resulted in a substantial decrease in the drying time with better quality product when dried at higher power (300 W) level compared to other processes.

Experimental investigation on the effect of wastewater matrix on oxytetracycline mineralization using UV/H2O2 system

Abstract Experiments on the mineralization of oxytetracycline in aqueous solutions using UV/H2O2 system were carried out. The mineralization process was monitored and measured as a function of total organic carbon (TOC) removal. Effect of five different water matrices on the mineralization efficiency, kinetics and the electrical energy per order was analyzed and reported. The present results showed that the percentage TOC removal, the rate constants and the electrical energy per order depend on the concentration of organics, inorganics and other impurities present in the water matrices. The value of electrical energy per order (EE/O) for the OTC mineralization is higher for more complex water matrices.Graphical Abstract