N. Abdi

Anticancer activity of chemically prepared shrimp low molecular weight chitin evaluation with the human monocyte leukaemia cell line, THP-1

In the present study, anticancer activities of chitin, chitosan and low molecular weight chitin were evaluated using a human tumour cell line, THP-1. A molecular weight-activity relationship and an electrostatic interaction-activity relationship were determined. The cytotoxic effects of chitin and derivatives were also evaluated using a normal human foetal lung fibroblastic cell line, MRC-5 and the specific cytotoxicity of chitin and derivatives to tumour cell lines was demonstrated. The high antitumour effect of low molecular weight of chitin was established.

Equilibrium, kinetic and thermodynamic studies on aluminum biosorption by a mycelial biomass (Streptomyces rimosus).

This work focused on kinetic, equilibrium and thermodynamic studies on aluminum biosorption by Streptomyces rimosus biomass. Infrared spectroscopy analysis shows that S. rimosus present some groups: hydroxyl, methyl, carboxyl, amine, thiol and phosphate. The maximum biosorption capacity of S. rimosus biomass was found to be 11.76 mg g(-1) for the following optimum conditions: particle size, [250-560] μm, pH 4-4.25, biomass content of 25 g L(-1), agitation of 250 rpm and temperature of 25 °C. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherms at free pH (pH(i) 4) and fixed pH (pH(f) 4). Langmuir model is the most adequate. With fixed pH, the maximum biosorption capacity is enhanced from 6.62 mg g(-1) to 11.76 mg g(-1). The thermodynamic parameters (ΔG°, ΔH° and ΔS°) showed the feasibility, endothermic and spontaneous nature of the biosorption at 10-80 °C. The activation energy (Ea) was determined as 52.18 kJ mol(-1) using the Arrhenius equation and the rate constant of pseudo-second-order model (the most adequate kinetic model). The mean free energy was calculated as 12.91 kJ mol(-1) using the D-R isotherm model. The mechanism of Al(III) biosorption on S. rimosus could be a chemical ion exchange and carboxyl groups are mainly involved in this mechanism.

Electrodialysis with bipolar membrane for regeneration of a spent activated carbon

The main purpose of the present work was to develop a treatment method to regenerate granular adsorbent beds saturated with H(2)S by utilizing three electrodialysis compartments equipped with a cation or an anion exchange membrane or a bipolar membrane. Three electrodialysis compartments were utilized under various experimental parameters to determine the optimum conditions for the recovery of column particles saturated by H(2)S. The desulphurization operation is achieved with the extent of extraction close to 90% and an electric current density of about 30%. Use of the bipolar membrane makes it possible to regenerate the saturated adsorbent granules without adding chemical products. Since the only reagent was electricity, the projected economics are very attractive.

Enzymatic saccharification of solid residue of olive mill in a batch reactor.

This paper describes the enzymatic hydrolysis of solid residue of olive mill (OMRS) in a batch reactor with the Trichoderma reesei enzyme. Before enzymatic saccharification, crude lignocellulosic material is submitted to alkaline pre-treatment with NaOH. Optimum conditions of the pre-treatment (temperature of T=100 degrees C and OMRS-NaOH concentration ratio of about R=20) were determined. The optimum enzymatic conditions determined were as follows: pH of about 5, temperature of T=50 degrees C and enzyme to mass substrate mass ratio E/S=0.1g enzyme (g OMRS)(-1). The maximum saccharification yield obtained at optimum experimental conditions was about 50%. The experimental results agree with Lineweaver Burks formula for low substrate concentrations. At substrate concentrations greater than 40gdm(-3), inhibitory effects were encountered. The kinetic constants obtained for the batch reactor were K(m)=0.1gdm(-3)min(-1) and V(m)=800gdm(-3).

Modeling of the adsorption of metribuzin pesticide onto electro-activated granular carbon

AbstractThe main purpose of the present study is to investigate the mechanism which governs the adsorption of the pesticide onto electro-granular activated carbon (GAC). The operating conditions assessed are: electrical potential, electro-activation time, the initial metribuzin—electro-activated GAC concentration ratio (R = Cp/CGAC). In the first step, it has been confirmed using an experimental design that the C/C0 ratio is much more affected by the electrochemical potential application than by R ratio. The mathematical model indicates that the electrochemical potential has a significant effect during the metribuzin adsorption during the first half an hour on GAC and thereby demonstrates the electroactivation beneficial effect. In the second step, a mass transfer model has been applied in order to evaluate the effect of the electro-activation of GAC on the kinetic constant. Indeed, the results showed that the electro-activation accelerates the process with kinetic constants 2–3 times higher than those ob...

Economic study of groundwater defluoridation of the North African Sahara

AbstractThe economic evaluation of defluoridation of Sahara groundwater is presented for three processes: electrodialysis, reverse osmosis and the electrochemical bipolar reactor (EBR). The economic study was accomplished for a drinking water unit production of 100 m3/h. One of the findings was that the costs per cubic metre of treated water obtained with different processes were not too costly for the states of the North African region. The results also indicated that the most efficient process uses the EBR, followed by the electrodialysis and reverse osmosis process. However, the water produced by the first process does not have the required quality for drinking water; therefore, it has to be utilised for agricultural purposes. On the other hand, the electrodialysis unit do produce quality drinking water and appears to be an interesting solution to the fluorisis disease. Reverse osmosis method technique provides higher quality of drinking water with a salinity not exceeding 0.1 gsalts/l.

Effectiveness of a Biological Insecticide Derived from Scorpion Fish Offal against the Chickpea Weevil

The aim of this study is to evaluate the biological activity of a crude chitinase extracted from fish offal (scorpion) on the chickpea weevil Callosobruchus maculatus (Coleoptera: Bruchidae) at various concentrations: 3%, 6%, 9%, 12%, 15%, 18%, 21% and 24% (V/V). The biological tests were performed under the typical experimental conditions: temperature and relative humidity at 28°C and 75%, respectively. The results have shown that the concentration of 24% of crude chitinase extracted has 100% of insecticide activity after a contact time of 1 h. The lethal dose (LD50) is estimated for every sample and for a range time from 1 to 72 h. The lower percentage of mortality (10%) is obtained for low values of concentrations and contact time (dose of 3% of crude chitinase and 1 h of contact time). The maximum mortality rate is observed for the high values of two parameters (dose of 24% of crude chitinase and 72 h contact time). However, it is observed that for a higher dose (24%) and for a lower contact time (1 h), the mortality rate increased rapidly. The novelty of this work consists in the use of a new bioinsecticide obtained from offal scorpion fish.

Biohydrogen production by dark and photo-fermentation processes

The hydrogen can be produced in a biological production process by dark and photo-fermentation of organic substrates. Under anaerobic conditions, hydrogen is produced during conversion of organic substrate into organic acids using fermentative bacteria and during conversion of organic acids into H2 and CO2 using photo- fermentative bacteria. This bioprocess has been studied with a number of microorganisms, it is a very complex process and influenced by many factors. In order dark and photo-fermentation process is an important approach for bio-hydrogen production. In this study, different factors haves been examined to enhance biohydrogen production by these organisms, either as a combined or sequential using dark and photo-fermentation process. The effect of each factor on biohydrogen production efficiency is reported. A comparison of hydrogen production efficiency between dark-fermentation, photo-fermentation and two stage processes was investigated.

Enhancement of Enzymatic Process by Electric Potential Application

The purpose of this study is to investigate a new bio-electrochemical technique based on the utilisation of electric potential to enhance the enzymatic reaction. The efficiency of bio-electrochemical reactor has been achieved by studying the production of reducing sugar by enzymatic hydrolysis of olive mill. The results indicate that the application of a continuous electric potential of about 50 mV allowed a significant increase of the saccharification efficiency by about 25% (compared to an enzymatic process without electric potential). For an electric potential higher than 60 mV, the saccharification efficiency decreased, suggesting that the enzyme, a biological substance, could be damaged at high electric potential. It has been shown that the kinetics of the bio-catalyzed reactions could be controlled by an applied electric potential.