Thermal behaviour of impregnated olive stones with phosphoric acid via TGA-MS

This study aims to investigate the thermal behaviour of raw and phosphoric acid impregnated olive stones via coupled thermogravimetric analysis-Mass spectrometry (TGA-MS) during pyrolysis. The impregnated material was prepared at three H$_{3}$PO$_{4}$/precursor weight ratio of 0.5; 1 and 1.5; for various impregnation time of 3, 6 and 9 h, which was then subjected for thermal analysis. TGA profiles were obtained under dynamic conditions in temperature range 25 °C to 750 °C with a heating rate of 10 °C/min, using pure nitrogen as an inert gas. Thermal degradation of olive stones was observed in three stages namely dehydration, active and passive pyrolysis. Two-steps degradation of raw olive stone occurred, whereas the impregnated material displayed only one step. Addition of phosphoric acid sharply reduced the onset temperature of the main decomposition step. Onset temperatures decreased with increasing rate or time of impregnation. It could conclude that 3 h is sufficient as time of impregnation for activated carbon production. Examination of the main gas products were carried out using coupled TGA-MS. The principal permanent gases detected were H$_{2}$, H$_{2}$O, CO, CO$_{2}$ and the light hydrocarbons C$_{2}$H$_{6}$ and CH$_{4}$. Different kinetic scenarios of raw and impregnated olive stones were observed. The above results should be useful to understand the pyrolysis mechanism of phosphoric acid impregnated olive stone for improving activated carbon production

Thermal behaviour of impregnated olive stones with phosphoric acid via TGA-MS

This study aims to investigate the thermal behaviour of raw and phosphoric acid impregnated olive stones via coupled thermogravimetric analysis-Mass spectrometry (TGA-MS) during pyrolysis. The impregnated material was prepared at three H$_{3}$PO$_{4}$/precursor weight ratio of 0.5; 1 and 1.5; for various impregnation time of 3, 6 and 9 h, which was then subjected for thermal analysis. TGA profiles were obtained under dynamic conditions in temperature range 25 °C to 750 °C with a heating rate of 10 °C/min, using pure nitrogen as an inert gas. Thermal degradation of olive stones was observed in three stages namely dehydration, active and passive pyrolysis. Two-steps degradation of raw olive stone occurred, whereas the impregnated material displayed only one step. Addition of phosphoric acid sharply reduced the onset temperature of the main decomposition step. Onset temperatures decreased with increasing rate or time of impregnation. It could conclude that 3 h is sufficient as time of impregnation for activated carbon production. Examination of the main gas products were carried out using coupled TGA-MS. The principal permanent gases detected were H$_{2}$, H$_{2}$O, CO, CO$_{2}$ and the light hydrocarbons C$_{2}$H$_{6}$ and CH$_{4}$. Different kinetic scenarios of raw and impregnated olive stones were observed. The above results should be useful to understand the pyrolysis mechanism of phosphoric acid impregnated olive stone for improving activated carbon production

APPLICATION OF ACTIVATED CARBON PREPARED FROM OLIVE STONES IN THE REMOVAL OF TWO BASIC DYES FROM WATER

Olive stones is produced in large quantities during the manufacture process of the olive oil in the Tunisian oleic industry. This by-product. have been converted to granular activated carbon by carbonisation in the nitrogen atmosphere followed by steam activation. Activated carbon so obtained with 1150 m2/g specific surface area and 0,53 cm3/g pore volume, essentially microporous, has been used for the adsorption of two basic dyes: Methylene Blue (MB) and Rhodamine B (RB) in aqueous solution. The equilibrium adsorption isotherms of the two dyes at 30°C shows Langmuir shape. The maximum adsorption capacity of MB and RB are found to be 303 mg/g and 217 mg/g respectively. Adsorbent affinity to tested dyes is related to electric and steric effects. KEY WORDS: Olive stones, activated carbon, Methylene Blue, Rhodamine B, adsorption Global Jnl Pure & Applied Sciences Vol.10(1) 2004: 91-9

Competitive adsorption of ibuprofen and amoxicillin mixtures from aqueous solution on activated carbons

This work investigates the competitive adsorption under dynamic and equilibrium conditions of ibuprofen (IBU) and amoxicillin (AMX), two widely consumed pharmaceuticals, on nanoporous carbons of different characteristics. Batch adsorption experiments of pure components in water and their binary mixtures were carried out to measure both adsorption equilibrium and kinetics, and dynamic tests were performed to validate the simultaneous removal of the mixtures in breakthrough experiments. The equilibrium adsorption capacities evaluated from pure component solutions were higher than those measured in dynamic conditions, and were found to depend on the porous features of the adsorbent and the nature of the specific/dispersive interactions that are controlled by the solution pH, density of surface change on the carbon and ionization of the pollutant. A marked roll-up effect was observed for AMX retention on the hydrophobic carbons, not seen for the functionalized adsorbent likely due to the lower affinity of amoxicillin towards the carbon adsorbent. Dynamic adsorption of binary mixtures from wastewater of high salinity and alkalinity showed a slight increase in IBU uptake and a reduced adsorption of AMX, demonstrating the feasibility of the simultaneous removal of both compounds from complex water matrices.The authors thank the financial support of MINECO (CTM2011/23378) and PCTI Asturias (Fondos Feder 2007-2013, grant PC10-002). HM, RJC and AGB thank the financial support of Univ. Gabes (mobility grant), PCTI Asturias (PhD Severo Ochoa fellowship) and MINECO (PhD fellowship BES-2012-060410), respectively. COA thanks C. Diaz for the help in the wastewater analysisPeer reviewe

Fast Production of Activated Carbon from Pomegranate Peels by Combining Microwave Heating and Phosphoric Acid Activation for Paracetamol Adsorption

Pomegranate peels, abundant raw precursor in Tunisia, were converted into activated carbon by means of microwave heating using phosphoric acid activation. The influence of the activation temperature and irradiation time on the process yield and porous texture of the resulting activated carbons was investigated. Textural properties were studied through the nitrogen adsorption-desorption isotherms and the scanning electron microscopy. The surface chemical properties were characterized by acid-base titration, point of zero charge, and Fourier-Transform Fourier transform infrared spectroscopy spectra. Paracetamol, a widely applied pharmaceutical, was selected to examine the adsorptive behavior of the activated carbon prepared in the optimum conditions. A series of experiments were conducted in a batch system to assess the influence of parameters, that is, pH, initial concentration, and adsorption temperature. The prepared activated carbons showed the high Brunauer-Emmett-Teller surface area (1,657 m2/g) and the important total pore volume (0.91 cm3/g) for an activation temperature and irradiation time of 450°C and 10 min, respectively. The adsorption performance illustrated an encouraging result. The Langmuir equilibrium adsorption capacity was 238 mg/g. Estimated thermodynamic parameters show a spontaneous and exothermic adsorption process. Microwave heating as a simple process provides a high-quality activated carbon in a short time. The obtaining results make microwave heating, combined with phosphoric acid, a feasible method for producing successful adsorbent for paracetamol removal.Peer reviewe

Competitive adsorption of ibuprofen and amoxicillin mixtures from aqueous solution on activated carbons

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