REV. CHIM. (Bucharest) ♦ 63 ♦ No. 2 ♦ 2012 http://www.revistadechimie.ro 153 Kinetic Aspects of Transport para-aminophenol through Agitated Bulk Liquid Membrane IOANA DIACONU * , IONUT ZAHARIA, ELENA RUSE*, DOINA ANTOANETA RADU *University Politehnica Bucharest, Faculty of applied Chemistry and Material Science, Department of Analytical Chemistry and Instrumental Analysis, 1-4 Polizu, 011061, Bucharest , Romania This paper presents experimental results regarding the transport through agitated bulk liquid membrane of para-aminophenol, a highly toxic chemical reagent. The influence of a group of carriers para-tert-butyl- calix[n]arenes (n=4,6,8) in the transport of para-aminophenol through a chloroform membrane was studied. In the presence of the carrier an increase of the efficiency transport takes place. Thus the transport efficiency increases from 26% without carrier to over 73% in the presence of the carrier para-tert-butyl-calix[8]arene. Assessing the kinetic parameters of transport process (entry and exit flow through the membrane, mass transfer coefficients), it was established that the transport efficiency increases in the order: para-tert-butyl- calix[4]arene < para-tert-butyl-calix[6]arene < para-tert-butyl-calix[8]arene. Also it has been observed an increase of exit flow from the membrane and also for mass transfer coefficients. Keywords: para-aminophenol, para-tert-butyl-calix[n]arene, kinetic model * diaconuioana12@yahoo.com, elenaruse29@yahoo.com Organic compounds with phenolic structures are products commonly found in industrial aqueous waste and are the most common forms of chemical pollutants from industrial wastewater. More than that, because of their toxicity to microorganisms in high concentrations, the state of degradation is limited [1, 2]. Aminophenols are considered a special class of pollutants because of high toxicity at low concentrations. Almost all aminophenols and their derivatives are toxic and carcinogenic for the organisms. It is know that para- aminophenol can produce the increase of human body temperature but also show chronic effects on aquatic organisms similar to the toxicity of phenol and aniline, the limit being 50 ppb in drinking water and sea water [3]. It is reported that para-aminophenol presents significant nephrotoxic and teratogenic effects [4]. Is a toxic compound, irritable to eyes, skin and respiratory system, which can cause irreversible damage to blood and kidneys. Para-aminophenol is used to obtain azo, sulfur, acid wool and leather dyes. From medical point of view, it is used to produce paracetamol and other drugs [5 - 8]. It also presents applications as a photodeveloper, in the rubber and petroleum additives [9]. Due to its using as an important intermediary in different processes the water pollution degree has grown [10 - 14]. Therefore its removal from wastewater is a very important activity with direct applications in environmental protection. For this purpose many studies designed to remove or treat the waste water of aminophenols were realized [15 - 18]. Such studies have been performed for the treatment of para-aminophenol with granular sludge in methanogenic conditions at a temperature of 30 o C, under stirring over a period of 150 days. Biodegradability test was performed by measuring the methane gas composition. It was found that methanogenic bacteria led to complete mineralization of para-aminophenol [18]. Oxidative methods have frequently been used to treat wastewater containing aminophenol. The use of hydrogen peroxide in the presence of Fe 2+ , has reduced the content of para-aminophenol in aqueous medium at a rate of 98% to 99,5% [17]. Very good results were obtained in the case of oxidation with hydrogen peroxide using the enzyme as a catalyst; degradation was virtually complete, up to CO 2 and H 2 O [19]. A special focus was put on the use of methods of separating para-aminophenols from different aqueous systems. Classical methods for selective separation of organic compounds, such as fractional distillation, solvent extraction processes and others, involve considerable costs of energy and large amounts of waste [20]. Treatment of wastewater using emulsion or supported liquid membranes, is an intense process, with a huge application potential but is still under development [21, 22]. These liquid membranes can be used as a viable alternative, because they involve low energy consumption, high sensitivity and rapid extraction with high efficiency due to the large contact surface for the mass transfer [23]. Because of instability of these membranes, the literature does not show very many applications of liquid membranes [24, 25], despite multiple uses available, both at laboratory, but also at pilot and industrial scale. Liquid membranes are considered a promising alternative technology for separation of pharmaceutical importance [26, 27]. In this context, in this work we studied the transport of para-aminophenol through bulk liquid membrane focusing on the role of transporters para-tert-butyl-calyx[n]arenas [28-32]. Experimental part Reagents All reagents used in transport experiments were of analytical grade and were used without further purification. HCl and para-aminophenol were purchased from Merck. The feed/donor (d) source and receiving/acceptor (a) phase were prepared using distilled water saturated in membrane solvent. The feed source is an aqueous solution of para-aminophenol 10 -3 mol/L. The receiving phase (acceptor aqueous phase) consists of a 10 -2 mol/L solution of HCl (pH=2). The membrane (m) is prepared from a