Solvent Free Lipase Catalysed Synthesis of Ethyl Laurate: Optimization and Kinetic Studies

The current research work represents solvent free enzymatic synthesis of fatty acid ethyl ester; ethyl laurate. Immobilized lipase Fermase CALB?10,000 was used for the synthesis of ethyl laurate from ethanol and lauric acid. The influence of process parameters such as catalyst loading, speed of agitation, mole ratio, molecular sieves and temperature were studied. Fermase CALB?10,000 offered a conversion of 92.46 % at 60 °C in 4 h at optimized condition. The experimental data was best fitted by the Random Bi-Bi model with inhibition of both the substrates i.e. lauric acid and ethanol. The following kinetic parameters were retrieved from the model: V_max = 1.243 × 10³ mmol/min/g enzyme; K_A = 0.1283 mmol; K_B = 8.51 mmol; K_iA = 5.098 mmol; and SSE = 0.0142. The activation energy for the enzymatic esterification was also determined and calculated to be 28.49 kJ/mol. A maximum conversion of 71 % was obtained after 5 successive reuse of Fermase CALB?10,000 lipase.     

Evaluation of rheological constitutive equations for branched polymers in step shear strain flows

The pom-pom rheological constitutive equation for branched polymers proposed by McLeish and Larson is evaluated in step shear strain flows. Semianalytic expressions for the shear-stress relaxation modulus are derived for both the integral and approximate differential versions of the pom-pom model. Predictions from the thermodynamically motivated differential pompon model of ?ttinger are also examined. Single-mode integral and differential pom-pom models are found to give qualitatively different predictions, the former displays time–strain factorability after the backbone stretch is relaxed, while the latter does not. We also find that the differential pompon model gives quantitatively similar predictions to the integral pom-pom model in step strain flows. Predictions from multimode integral and differential pom-pom models are compared with experimental data on a widely characterized, low-density polyethylene known as 1810H. The experiments strongly support time–strain factorability, while the multimode pom-pom model predictions show deviations from this behavior over the entire range of time that is experimentally accessible.     

Palladium incorporated on carbonaceous catalyst for Suzuki coupling reaction in water

A new palladium incorporated carbonaceous catalyst Pd@CCSO₃HNH₂ was synthesized by introducing palladium on glucose derived carbocatalyst. The catalyst was well characterized and was used for the Suzuki coupling of phenyl boronic acid with different aryl halides under aqueous conditions. This green methodology represents a ligand free, cost-effective and operationally convenient method for the synthesis of a variety of biaryl’s under the conditions that are tolerant for a broad range of functional groups with good to excellent yields. Moreover, the catalyst could be easily recycled and reused at least five times without any significant loss of its catalytic activity.     

Method for determination of radium in seawater using MnO<Subscript>2</Subscript> co-precipitation technique

Radium is considered to be a useful tracer for studying various physical processes of seawater. There are several methods for analysis of radium; however, analysis of radium in seawater by those analytical techniques is a tedious job. Thus a new methodology was optimized for analysis of radium in sea water using MnO₂ co-precipitation followed by gamma spectrometry. The method produced good yield which ranged from 85–98%. The method is simple and requires less amounts of chemicals and no use of acids. Seawater from different western Indian coastal environments viz. Tarapur, Mumbai and Goa were collected and analysed for ²²⁶Ra and ²²⁸Ra using this method.     

The renaissance in redox flow batteries

Although redox flow batteries were invented as early as 1954, no system development took place until NASA demonstrated an Fe/Cr redox flow battery system in 1970s. In hibernation for several years, redox flow battery systems have begun to catch the attention of policy makers globally. The resurrection of redox flow batteries rests heavily on their techno-economic feasibility as large-scale energy storage systems for emerging grid network that are being developed by climate change mitigation industries, namely, wind and solar. This article reviews various redox flow battery technologies with a cost and market prognosis.     

Ultrasound-assisted synthesis of ethyl hexanoate using heterogeneous catalyst: Optimization using Box-Behnken design

Ultrasound-assisted synthesis of ethyl hexanoate was studied in a solvent-free system using Amberlyst-15 as a heterogeneous catalyst. The effect of reaction parameters was evaluated by employing Box Behnken Design. Maximum conversion was obtained as 83.9% experimentally with operating temperature 60 °C, ethanol to hexanoic acid molar ratio as 3, 60% duty cycle, 11% catalyst loading, 10% molecular sieves, and 80 W input power which were optimized through one parameter at a time. The optimal conditions for maximum 86.66% conversion obtained by Box Behnken Design operated in Response Surface Methodology were 62.8 °C temperature, 3.31 ethanol to hexanoic acid molar ratio, and 51.58% duty cycle. The absence of external mass transfer resistances was proved by evaluating Mear's criterion. Thiele modulus and effectiveness factor were determined to study the influence of internal mass transfer resistance qualitatively. The kinetics of the heterogeneous reaction was modeled using Langmuir-Hinshelwood model. The activation energy was calculated as 24.61 kJ/mol.     

LC–MS Determination of Gabapentin from Human Plasma

Gabapentin is an anticonvulsant drug used for the treatment of epilepsy. It is not bound to plasma protein and is not metabolized. A high performance liquid chromatography–mass spectrometric micro method is described in this report for its determination from human plasma. Chromatography was performed on a 50 × 4.6 mm, 4 μm nitrile column and the parent ion detected in the positive ionization mode on single quadrupole analyzer (Q1MI) with atmospheric pressure ionization source. Extraction was carried out on C₁₈, 100 mg/3cc cartridge using 10 μL sample volume. The mean extraction recovery was 97% and within batch and between batch coefficients of variation were <9%. Lack of interference from endogenous substances helped in achieving a highly sensitive method without the need for monitoring fragment ions. The lowest concentration injected on column for calibration curve was 195 pg (range 0.5–64 ng). The method was applied for analysis of samples from a cross-over bio-equivalence study comparing two formulations.

     

Valorization of Food and Agricultural Waste: A Step towards Greener Future

With the progress in technology and population, an enormous amount of agricultural and food waste is being generated throughout the world. In the past, food and agro‐wastes were either burnt off or allowed to rot in fields, but this can be potentially hazardous to the environment. Therefore, approaches with respect to their utilization, reuse, and processing need to be developed to enable the sustainable utilization of feedstock and reduce pollution. Agricultural wastes mainly comprise of cellulosic fibres possessing high fixed carbon content and multifunctional groups. Agricultural waste shows considerable applicability due to its high strength, environmentally benign nature, low cost, and ease of availability and reusability. All these characteristics have been researched upon in the past, in the sector of waste water management for the removal of heavy metals and dyes. Similarly, a variety of food and agro‐waste has been adopted as sources for new drug leads or important phytochemicals with different therapeutic benefits. Agro‐waste can also be employed for enzyme immobilization after proper modification. Apart from this waste cooking oil comes under the category of food waste and can be processed to prepare alternate energy source such as biodiesel. This personal account summarizes the development, processing, and application of food and agro‐waste in the production of biodiesel, environmental remediation, curative medicine, and in the development of biocatalysts, by researchers in our laboratory.