In this study, the removal of biophenols from olive mill wastewater by activated carbon of different particle sizes has been carried out using the batch adsorption technique. The effects of the sorbent specific surface area and concentration, temperature, initial biophenols concentration, and contact time on the adsorption efficiency have been analyzed independently. The sorbent yields higher removal efficiency of biophenols as its specific surface area increases. When increasing the sorbent concentration from 10 to 50 g L À1 , the sorbent uptake capacity increases from 20% to 41%, and it reaches a maximum value of 65 mg g À1 at 298.2 K. Adsorption of olive mill wastewater biophenols is moderately rapid, being about 38% to 40% of the initial phenolic content after 120 min. Kinetic analysis shows that the adsorption process can be approximated by a pseudo-second-order model for which pore diffusion is the essential rate-controlling step. Equilibrium modeling by linearized adsorption isotherms reveals that a Langmuir-type isotherm with a preferable monolayer sorption would likely proceed. Calculated thermodynamic parameters such as Gibbs energy, enthalpy, entropy, activation energy, and sticking probability indicate that adsorption is a typical endothermic yet spontaneous process with a preferable physisorption mechanism. An external mass transfer coefficient model has been developed to determine the rate of adsorption controlled initially by the boundary layer film, with particular focus on its predictive performance.

Isobaric vapour-liquid equilibrium data have been measured for the binary systems toluene (1) þ acetic acid (2) and toluene (1) þ methyl ethyl ketone (2) at atmospheric pressure. An all-glass Fischer-Labodest-type apparatus, capable of handling pressures from 0.25 to 400 kPa and temperatures up to 523.15 K was used. The data were correlated by means of the NRTL, UNIQUAC, WILSON models and the applied UNIFAC model with satisfactory results; the relevant parameters are given and results were tested with regard to thermodynamic consistency using the methods of a modified Redlich-Kister and Herington equations.

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Hypericum perforatum L. (Hypericaceae) is one of the medicinal plants whose value has increased rapidly in recent years. It is especially popular for its use in the treatment of mild and moderate depression, as well as for the treatment of skin diseases, internal and external inflammatory wounds, neurological disorders, and the metabolism-disrupting effects of free radicals. Besides, it shows inhibitory effects against different kinds of microorganisms such as bacteria, fungus, and protozoa. Antimicrobial biofilms generated by the plant are its most potent output, unlike its essential oil which does not have much value in itself as much as its ingredients that can be converted into more valuable products. Its usage as a folk remedy has a wide application area in various cultures. It is thought that compiling studies on various aspects of this plant will benefit future studies. The present paper reports on studies on the antibacterial, antioxidant, and therapeutic properties of Hypericum perforatum, as well as on the composition of its essential oil.

Carboxylic acids are biotechnological substances that are used extensively in many industries, thus production and separation of carboxylic acids from product mixtures are important scientific and economic problems. The aim of this work was to investigate the removal of acetic, citric, lactic, and tartaric acids from aqueous solutions. With this aim, first the effects of time, temperature, and mixing on separation of the carboxylic acids from aqueous solutions were investigated by experimental work. After the experimental conditions were determined, separation was undertaken for different initial acid concentrations at constant hydrogel concentration. The effect of different gel−acid mass ratios on adsorption at constant initial acid concentrations was determined. The removal of acetic acid was 59.74 %, of lactic acid was 55.45 %, of citric acid was 54.22 %, and of tartaric acid was 56.85 % with a 1.5 hydrogel/acid mass ratio at the lowest concentration of each acid. Results obtained from the experimental work have been used with the Freundlich isotherm.