Fatiha Abdelmalek

Post-discharge plasma-chemical oxidation of Iron(II) complexes

The plasmachemical properties of an electric discharge in humid air are considered by examining the oxidation of Fe(II) to Fe(III) aquo-ions in a solution exposed to the discharge. The reaction product is characterised and quantified by means of the thiocyanate complex FeSCN2+. The reaction mechanism shows two distinct steps: a rapid step directly depending on the treatment time and a slow post-discharge step, which are both ascribed to species formed in the discharge (i.e., respectively to OH radical and to hydrogen peroxide or nitrate ions). These concerned species are able to react either at the liquid surface (OH) or to diffuse into the solution and react as solutes. Experimental arguments in favour of zero and first order reaction steps are given. A particular reactor design involving a multibladed electrode is tested at the juncture and its use considered for further industrial applications.

The Adsorption of Pentachlorophenol from Aqueous Solutions onto Exchanged Al-MCM-41 Materials

The ability of a mesoporous molecular sieve to adsorb chlorinated phenols was studied experimentally. Thus, the adsorption isotherms of pentachlorophenol (PCP) from aqueous solutions were measured on (M)Al-MCM-41 (M = Na+, K+, Cu2+, Cr3+) at intervals of 10 K between 303 K and 323 K. The experimental isotherms obtained were of the S-type in terms of the classification of Giles and co-workers. The best fit of the adsorption isotherm data was obtained using the Freundlich model. The adsorption affinity of PCP increased in the order (K)Al-MCM-41 < (Cr)Al-MCM-41 < (Na)Al-MCM-41 < (Cu)Al-MCM-41. At the same temperature, the adsorption of PCP on (Cu)Al-MCM-41 was more pronounced compared to its adsorption on alumina-pillared montmorillonite and mesoporous alumina aluminium phosphates. Analysis of the isosteric curves showed that (Cu)Al-MCM-41 and (Na)Al-MCM-41 presented a heterogeneous profile. In contrast, (K)Al-MCM-41 and (Cr)Al-MCM-41 did not exhibit energetic heterogeneity throughout the entire range of coverage.

Plasmacatalytic removal of lead acetate assisted by precipitation.

The Gliding Arc Discharge (GAD) is an efficient non-thermal plasma technique able to degrade organic compounds dispersed in water at atmospheric pressure. The degradation of the organometallic lead acetate (PbAc) in aqueous solution was performed by two distinct plasmageneous processes: GAD and GAD/TiO2. The global oxidation of the organic matter was followed by Chemical Oxygen Demand (COD) and the mineralization was determined by the Total Organic Carbon (TOC). The Pb(2+) ions released during the degradation process were measured by Atomic Absorption Spectroscopy (AAS). For 2h of GAD treatment, the degradation rate of PbAc (10mM) reached 83% and for the same duration of GAD/TiO2 process ([TiO2]=1gL(-1)), it reached 93%. The release of Pb(2+) ions in the solution was respectively of 95% and 57% for GAD and GAD/TiO2 processes. The released Pb(2+) ions were removed by precipitation process in a basic medium at pH=11.1. A reaction mechanism was proposed to explain the PbAc molecule degradation and the Pb(2+) elimination.

GIS-based approach for optimised collection of household waste in Mostaganem city (Western Algeria)

This work proposes an optimisation of municipal solid waste collection in terms of collection cost and polluting emissions (carbon oxides, carbon dioxides, nitrogen oxides and particulate matter). This method is based on a simultaneous optimisation of the vehicles routing (distance and time travelled) and the routing system for household wastes collection based on the existing network of containers, the capacity of vehicles and the quantities generated in every collecting point. The process of vehicle routing optimisation involves a geographical information system. This optimisation has enabled a reduction of travelled distances, collection time, fuel consumption and polluting emissions. Pertinent parameters affecting the fuel consumption have been utilised, such as the state of the road, the vehicles speed in the different paths, the vehicles load and collection frequencies. Several scenarios have been proposed. The results show the importance of the construction of a waste transfer station that can reduce the cost of household waste collection and emissions of waste transfer pollutants. Among the proposed five scenarios, we have noticed that the fourth scenario (by constructing a waste transfer centre) was the most performing. So, the routes of optimised travelled distance of the new circuits have been reduced by 71.81%. The fuel consumption has been reduced by 72.05% and the total cost of the collection has been reduced by 46.8%. For the polluting emissions, the reduction has been by 60.2% for carbon oxides, by 67.9% for carbon dioxides, by 74.2% for nitrogen oxides and by 65% for particulate matter.

Competitive Contribution of Catalyst and Adsorption Roles of TiO 2 on the Degradation of AO7 Dye During Plasma Treatment

In order to investigate the role of TiO2 during plasma treatment, the degradation of the dye AO7 has been studied by gliding arc discharge in the presence of a TiO2 catalyst (CGAD). The results revealed that the adsorption of the dye on TiO2 is a physical adsorption in accordance with Langmuir isotherm, with a constant of adsorption KL = 0.52 mg/L and a maximum adsorption capacity b = 18.1 mg/g. The temperature variation of the reaction medium made it possible to consider thermodynamic parameters. Indeed, the adsorption is exothermic (enthalpy: ΔH < 0), and spontaneous (free enthalpy: ΔG < 0). The negative entropy (ΔS < 0) confirms the affinity of the dye molecules for TiO2. 20 min of CGAD treatment in the presence of an optimal quantity of TiO2 (2 g/L enabled us to bleach the solution of AO7 (100 μM) completely. The discoloration rate with and without the addition of TiO2 was 100% and 28%, respectively. 40 additional minutes of treatment allowed a total abatement of the chemical oxygen demand. The elimination of AO7 molecules during the plasma-catalytic treatment follows Langmuir-Hinshelwood (L-H) model kinetics. According to this model, the speed constant is kr = 14.97 mg L−1 min−1 and the adsorption coefficient is KL—H = 0.010 L/mg. The latter being negligible compared to kr, adsorption is therefore weakly performed during the plasma treatment.

Search for a new economic optimum in the management of household waste in Tiaret city (western Algeria).

In household waste matters, the objective is always to conceive an optimal integrated system of management, where the terms ‘optimal’ and ‘integrated’ refer generally to a combination between the waste and the techniques of treatment, valorization and elimination, which often aim at the lowest possible cost. The management optimization of household waste using operational methodologies has not yet been applied in any Algerian district. We proposed an optimization of the valorization of household waste in Tiaret city in order to lower the total management cost. The methodology is modelled by non-linear mathematical equations using 28 variables of decision and aims to assign optimally the seven components of household waste (i.e. plastic, cardboard paper, glass, metals, textiles, organic matter and others) among four centres of treatment [i.e. waste to energy (WTE) or incineration, composting (CM), anaerobic digestion (ANB) or methanization and landfilling (LF)]. The analysis of the obtained results shows that the variation of total cost is mainly due to the assignment of waste among the treatment centres and that certain treatment cannot be applied to household waste in Tiaret city. On the other hand, certain techniques of valorization have been favoured by the optimization. In this work, four scenarios have been proposed to optimize the system cost, where the modelling shows that the mixed scenario (the three treatment centres CM, ANB, LF) suggests a better combination of technologies of waste treatment, with an optimal solution for the system (cost and profit).

Optimization of Cost and Pollutant Emissions from MSW Collection Using GIS. The Case Study of Mostaganem, Western Algeria

The collection and transport of household wastes are among the most important factors in the management of wastes, hence representing a major part of the budget.

Metallic Contamination of Water and Sediments of “Hillil River” (North-West of Algeria) Near Wild Dump Site

In the North West of Algeria, wastes represent a serious problem for environment and a potential risk for the population health.