Five different activated carbons (ACs) have been prepared from dried date pits using air and phosphoric acid as activating agents. The used phosphoric acid:date pit ratio dictated the characteristics of the prepared ACs; the equivalent BET-nitrogen surface area varied from 794 m2/g for a ratio of 5:1, to 1707 m2/g for a ratio of 2:1, whereas the micropore volume changed in value from 0.24 cm3/g for the 5:1 ratio to 0.59 cm3/g for the 2:1 ratio. The prepared ACs were tested to remove 4-chlorophenol (4-CP) from aqueous solutions by means of batch adsorption process. The prepared 2:1 AC exhibited the highest uptake with a maximum of 525 mg/g. Equilibrium pH studies showed that 4-CP removal was pH dependent; the maximum uptake occurred at an equilibrium pH value of 5.5. Dynamic studies showed that 4-CP uptake on 2:1 AC is rapid, with 80% of the maximum uptake achieved during the first 40 min. Both surface adsorption and intraparticle diffusion were identified to be effective adsorption mechanisms. Kinetic studies indicated a pseudo second-order reaction. Results of equilibrium adsorption experiments showed that the adsorption of the 4-CP on 2:1 AC is best described by the Langmuir model. The thermodynamics parameters of the adsorption (ΔG0, ΔH0, and ΔS0) were determined by studying the adsorption equilibrium at different temperatures. The values of these parameters indicated the spontaneous and endothermic nature of the adsorption phenomenon of 4-CP on the prepared ACs.
Experimental investigation of supercritical fluid extraction (SFE) of active ingredients from rosemary herb has been performed. Carbon dioxide (CO₂) was used as a solvent with ethanol as a trapping agent. This work showed that the SFE can be an exceptional alternative to the use of chemical solvents. The effect of temperature and pressure on the extraction process was investigated to increase the yield of the extracted essential components. The types of extracted compounds from rosemary were specified and analyzed using GC-MS. The results indicated that several essential active ingredient compounds were extracted. Furthermore, the pressure affects the extraction, as the composition of some compounds increases with a pressure increase. SFE can be used to extract valuable active ingredients from rosemary. Two process parameters were investigated, namely, pressure and temperature, which indicate that SFE is a selective process for the production of certain constituents. Some of the main components of the essential oil of Jordanian rosemary obtained in this study have important applications in pharmaceutical and cosmetic products. For instance, α-pinene is one of the main raw compounds used in the perfume industry.
A qualitative analysis of supercritical fluid extraction (SFE) of the medically useful compound, sage <i>(Salvia officinalis)</i> is presented in this study. Carbon dioxide was used as a supercritical solvent. Effects of operating conditions such as temperature, pressure, and extraction time were investigated. The effect of addition of cosolvents was also studied. The extracted useful compounds were identified and analyzed using GC-MS chromatography. The analysis of the extract obtained by SFE showed certain significant major compounds that are considered medically important. These major compounds are 1R-.alpha.-Pinene, D-Limonene, l-Camphene, and b-Pinene, and Eucalyptol. Although, there was no consistent trend with respect to the effect of the studied parameters on the composition of the extract, the selectivity of these major compounds are dependant on the operating conditions, manily the operating pressure. An increase in the pressure resulted in an increase in herb extraction yield; this is true for certain group of extracts, while the inverse is also true for other group of compounds. The effect of certain cosolvents on the extractability of sage showed a significant improvement of the yield of some particular constituents of sage
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