Volume 17, No. 2 (2016)
Articles
UV/VIS SPECTROMETER DETERMINATION OF CAFFEINE IN GREEN COFFEE BEANS FROM HARARGHE, ETHIOPIA, USING BEER-LAMBERT’S LAW AND INTEGRATED ABSORPTION COEFFICIENT TECHNIQUES
EPHREM G. DEMISSIE(1*), GIRMA W. WOYESSA(1), ARAYASELASSIE ABEBE(2)
A total of fifteen samples of green coffee (Coffea arabica L.) beans from the major producing region of Hararghe Ethiopia were studied using UV-Vis spectrometer measurement caffeine quantitative analysis from coffee beans. The number density of caffeine in green coffee beans has been reported using Beer-Lambert’s law and integrating absorption coefficient technique. Our results obtained using integrated absorption and Beer-Lambert’s law has a good agreement and we observed a maximum difference of 10.4 %. Based on their low caffeine concentrations among the samples collected were found in Jarso coffee. Coffee beans from the Harar Aboker were characterized by higher concentrations of caffeine. The determined concentration for caffeine in coffee beans (% w/w) ranged 0.601 % to 0.903 %. The concentrations of the caffeine varied significantly, depending on the geographical origin of the beans. The concentrations of caffeine in coffee collected from in Hararghe region were noticeably lower than their counterpart (1.0 - 1.2 %) grows in the other parts of Ethiopia.
FLUX PROFILES AND MATHEMATICAL MODELING OF FOULING MECHANISM FOR ULTRAFILTRATION OF KONJAC GLUCOMANNAN
NITA ARYANTI(1*), DYAH H. WARDHANI(1), SUPANDI SUPANDI(2)
This study was focused on principles and fouling analysis of konjac glucomannan (KGM) separation using ultrafiltration system. Two Polyethersulfone membranes (PES) having molecular weight cut-off of 10 and 20 kDa were used. It was found that membrane having larger pore size provided higher flux profiles. Evaluation of different transmembrane pressures resulted on possibility of more severe fouling at higher membrane pressure. With the increase of konjac glucomannan concentration, decrease of profile flux was observed. Further, a simple mathematical modelling of fouling mechanism was analyzed based on Hermia’s model. The images of membrane surfaces and cross-sections obtained by scanning electron microscopy (SEM) were examined and being compared with the model. The research found that the fouling mechanisms of KGM ultrafiltration using membrane with pore size of 10 kDa was complete blocking. On the contrary, cake/gel layer formation was a fouling mechanism for ultrafiltration system with pore size of 20kDa.
MONITORING OF ORGANIC POLLUTION AND MATURITY OF ORGANIC MATTER FROM SLUDGE LANDFILLING
SLIMANE LAHSAINI(1*), MOHAMMED CHATOUI(1), ANAS AGUELMOUS(1), LOUBNA EL FELS(2,3), LEILA IDRISSI(1), SALAH SOUABI(1), MOHAMED ZAMAMA(2), MOHAMED HAFIDI(2)
The biotransformation during the 3 years of sludge landfilling was evaluated by physicochemical analysis and phytotoxicity test. The final product exhibited a high degree of decomposition rate (51.06 %) than the controls as shown by a decrease of C/N ratio of about 19.67. The results showed that the lipid, surfactant and polyphenol as main compound of the sludge were breakdown over time. The concentrations decreased from 29.9 to 11.8 mg·g-1 and 3.4 to 0.6 mg·g-1, respectively for surfactant and polyphenols after 3 years of landfilling. This corresponds to a reduction of 80.2 % for polyphenols and 60.4 % for surfactant, due to the microorganisms activity. Total lipids decrease from 16.5 to 6.27 mg·g-1 of dry matter, representing an abatement rate of about 62 %. The evolution of organic matter reflects the progress of the humification process, which judging by the increase in the polymerization degree, is about 20 %. The landfilling efficiency to reduce phytotoxicity of sludge was confirmed by the germination index, which reached 52 and 59 %, respectively for alfalfa and cress after 3 years of landfilling. These results are promising and pave the way for agricultural spreading of sludge.
REMOVAL OF CRYSTAL VIOLET BY BIOSORPTION ONTO DATE STONES
NOUREDDINE EL MESSAOUDI, MOHAMMED EL KHOMRI, SAFAE BENTAHAR, ABDELLAH DBIK, ABDELLAH LACHERAI(*)
The biosorption has the advantage that it can be applied to effluent disposal and thus brings various responses to the regulatory requirements for environmental protection. This study presents the results obtained from the use of date stones (DS) for the elimination of crystal violet (CV) from aqueous medium. Several analysis techniques were used to determine the different characteristics of biosorbent studied (FTIR, TGA-DTA, SEM and pHzpc).The physico-chemical parameters influence of the biosorption such as biosorbent dosage, contact time, temperature, biosorbent particles size and initial dye pH were investigated under static conditions in order to evaluate the process system. The test results show that a gram of date stones may set a maximum amount adsorbed 90.89 mg·g-1 of CV at 50 °C according to the Langmuir isotherm with pseudo-second-order kinetic. Thermodynamic calculations performed shows also that sorption is spontaneous, endothermic and increased randomness in the solid / solution interface.
NOVEL FREE LABEL BOTULINUM APTASENSOR BASED ON CAPACITANCE METHOD
JAMAL RASHIDIANI(1-2), SAYED JAEFAR MOOSAVI(1*), KHADIJEH ESKANDARI(2*), FIROOZ EBRAHIMI(1)
A feasible and fast method to fabricate Botulinum neurotoxin serotype A (BoNT/A) biosensor was investigated by graphene-carbon paste nanocomposite electrode. In the present work, the graphene was synthesis by chemical method and characterized by SEM. The nanocomposite shows a high conductive and sensitivity for BoNT/A determination as shown by cyclic voltammetry and electrochemical impedance spectroscopy. Graphene-Carbone paste electrode was used for immobilization of aptamer in 0.1 M phosphate buffer solution at pH = 7. Aptamer was trapped in graphene modified carbon paste (Cp) electrodes. The electrodes were applied as indicator electrodes for capacitance determination of BoNT/A. Through this method, BoNT/A was detected in a concentration range from 0.16 to 0.68 ng·mL-1 with a correlation coefficient of 0.964 and detection limit of 0.09 ng·mL-1. Also, the life time of sensor is in finite.
SULFUR DIOXIDE AND AMMONIA GAS REDUCTION USING COCONUT CELLULOSE AND ACETYLATED CELLULOSE
SURJANI WONORAHARDJO(*), MUHAMMAD S. IBNU, ENDANG BUDIASIH
Some adsorbent materials were employed to reduce ammonia and carbon dioxide gases. Cellulose materials from nata de coco and grated coconut meat were packed in a column to be used as gas adsorbent. The effect of surface modification of cellulose by acetylation in order to enhance the sorption ability and capacity was also studied. Another factor that was tested was the column length. The characteristics of cellulose materials were done by electron microscopy, infrared spectroscopy, and physical parameters such as water and ash contents as well as iodine sorption ability. The amount of ammonia and sulfur dioxide gases absorbed by the materials were analyzed by visible spectroscopy. The results showed that the cellulose material can be good adsorbent for basic gas like ammonia as well as acidic sulfur dioxide gases. Acetylation as a method of surface modification gave the proof of better sorption for both gases but was greater for ammonia. However, the column length gave greater impact in ammonia compared to sulfur dioxide. This study provides a better explanation of dynamics at surfaces, in the search for better adsorbents.
THE INFLUENCE OF TEMPERATURE AND TIME ON THE ANTIOXIDANT ACTIVITY AND COLOR PARAMETERS OF DOG-ROSE (ROSA CANINA) ETHANOLIC EXTRACT
ELENA CRISTEA
This paper presents the study of the stability of antioxidant activity and color of the 50 % ethanolic extract of dog-rose (Rosa canina) from the Republic of Moldova with the main objective to test a food dye of natural origin. The extract was submitted to: -2 °C for 12 hours; 4 °C for 12 hours; 40 °C for 15 minutes, 60 °C for 15 minutes, 80 °C for 15 minutes and 100 °C for 2 minutes, after which the antioxidant activity and the color (CIELab) parameters were measured. Three sets of extracts were kept for 2 weeks at -2 °C; 4 °C and 25 - 30 °C and afterwards the parameters mentioned above were measured once again. Moreover, the total content of polyphenols was determined by Folin-Ciocalteu method. The results were expressed in mg gallic acid equivalents per liter. The antioxidant activity was determined using the method based on the interaction with the ABTS radical, the results being expressed in mmol trolox equivalent per liter. Thermal treatments have not influenced antioxidant activity, but have significantly affected the extract by increasing its luminosity and changing the red/green parameter towards more red tones, while storage at -2 °C caused the decrease of yellowness. Storage at 4 °C was found to be optimal for the preservation of the antioxidant activity.
EVALUATION OF THE ANTIMICROBIAL EFFECTS OF NEW HETEROCYCLIC BIS-QUATERNARY AMMONIUM COMPOUNDS ON BIOFILMS
Oana E. Constantin(1), Bianca Furdui(2*), Gabriela Bahrim(1), Rodica M. Dinică(2)
Considering the well-known mechanism of adaptable resistance of microorganisms to chemical compounds through biofilms formation and the widespread use of N-heterocyclic quaternary ammonium salts (QAC) as disinfectants, in this study we have evaluate the effect of 8 newly synthesized symmetrical and unsymmetrical diquaternary ammonium salts of 1,2-bis-(4-pyridil)-ethane on bacterial biofilms produced by three different bacterial strains. The effect of the exposure to quaternary ammonium salts on biofilm communities was investigated within biofilms obtained in a conventional testing system, on stainless steel and glass surfaces. Differential plate counts were used to characterize the developed communities and the effects of QAC exposure and the results were correlated with epifluorescence microphotographs. The data obtained revealed a significant reduction of bacterial cells in the biofilms tested with 4-7 log CFU for all the QAC.
CPE OF URANIUM (VI) USING IONIC LIQUID
SANAA NAÏT-TAHAR(1), MOHAMED A. DIDI(1*), DIDIER VILLEMIN(2)
Cloud point extraction (CPE) was used to extract uranium (VI) from an aqueous solution in acetate media. The methodology used is based on the formation of uranyl-ionic liquid (I) complexes and uranyl-D2EHPA soluble in a micellar phase of non-ionic surfactant (Triton X-100). The uranium (VI) complexes are then extracted into the surfactant-rich phase at ambient temperature. The ionic liquid (IL) used as a chelating agent was synthesized and characterized in this study. It is composed of N-butyl N’-triethoxy methyl imidazolium cation and diethylhexylphosphate (D2EHPA-H) as anion. The effect of the IL on the extraction efficiency was studied in presence and in absence of IL’s cation in acetate medium.