Palash Panja

Pressurised Hot Water as a Novel Extractant of Natural Products: A Review

Abstract Pressurised hot water extraction (PHWE) has emerged as a highly promising energy-efficient and environmentally benign technique for recovering bioactive molecules from natural materials using sub-critical compressed liquid water in the temperature range of 80-180°C. It is set to replace conventional solvent extraction, pressurised organic solvent extraction or supercritical fluid extraction (SCFE) to obviate their limitations. A critical review on variations in the characteristic properties of PHW and the factors influencing the performance of PHWE process reveals its great potential to improve the yield and quality, by proper optimisation of process parameters. This novel extractant can be utilised to efficiently obtain clean product from a variety of natural substances.

Factors controlling production in hydraulically fractured low permeability oil reservoirs

Fundamentals of fluid flow in ultra-low permeability reservoirs need to be examined to understand production behaviours. In this paper, we perform sensitivity studies of reservoir properties (matrix permeability, heterogeneity, rock compressibility and reservoir pressure), fluid properties (bubble point pressure and initial dissolved gas oil ratio), rock fluid properties (relative permeabilities), completion parameters (fracture spacing) and operating parameters (bottom hole pressure) on production performances. Matrix permeability, rock compressibility, fluid properties and fracture spacing have major impact on oil recovery and gas oil ratio (GOR). More oil is recovered from higher permeability reservoir in the expense of higher GOR. Recovery increases with increasing rock compressibility since the pressure decline is more gradual in higher compressibility rocks. Oil phase becomes less viscous and more mobile due to higher amount of dissolved gas. Higher initial GOR improves production of oil with higher produced GOR. Closer fracture spacing yields more oil recovery. [Received: April 2, 2015; Accepted: August 26, 2015]

Recovery of Phytochemicals from Kokum (Garcinia indica choisy) Using Pressurized Hot Water

A novel process has been developed for the recovery of phytochemicals such as, ? -HCA from kokum (Garcinia indica choisy) rinds using hot water pressurized with carbon dioxide, followed by its purification. The performance of the pressurized hot water extraction (PHWE) process has been evaluated to ascertain the optimum process parameters for maximizing the recovery of ? -HCA. A systematic parametric study has been undertaken by varying the important parameters in the ranges of 30-120 °C for temperature, 1-20 atm for pressure, 30-60 min of extraction time, 4 - 22 ml/g of water to feed ratio, 1-3 number of stages , 0-350 rpm of stirring, presence of salt, nature of feed, and grinding. Ethanol is added to the aqueous extract from kokum rinds for the removal of pectinous materials by precipitation. Quantification of ? -HCA in the product has been carried out by the titration method with 0.1N NaOH solution. The maximum recovery is obtained when PHWE is carried out at 90 °C above which the recovery decreases. Pressure does not have much effect on the recovery of ? -HCA beyond a certain pressure required to maintain the extractant in the liquid phase. More ?-HCA is recovered by 2-stage PHWE from ground dry kokum than from salty kokum rinds.