Marwan M. Batiha

MAFRAM-A new fate and risk assessment methodology for non-volatile organic chemicals

The main goal of this paper was to introduce an environmental fate and risk assessment methodology for comparing and establishing the general features of new and existing non-volatile organic chemicals (NVOCs) used in agricultural activities, based on simple and readily available properties. This methodology is a computer program called the multimedia agricultural fate and risk assessment model (MAFRAM). This model is a combination of the EQC-2V model, which describes the fate of NVOCs, with the ecological relative risk (EcoRR) approach, which assesses the ecotoxicological risk to agro-ecosystems. MAFRAM divides the agricultural environment into two main zones, which are the on- and off-farm zones. Each zone is subdivided into six compartments, including the air, water, soil, sediment, aboveground plants, and roots. The required input data are the chemical-physical properties of the pesticide, biota data, and environmental properties. The MAFRAM output includes the inter-compartmental transport and transfer rates, the primary loss mechanisms, chemical concentration, amount, residence time, and the rank of risk in each compartment. In addition, it can provide several secondary results. The MAFRAM application was illustrated using typical homogenous region properties and was run with an illustrative emission rate of 1 kg/h into air, using spinosad as a case study.

The effect of reaction conditions on the precipitation of sodium hexafluorosilicate produced from waste hexafluorosilicic acid

The effect of reaction conditions on the precipitation of sodium hexafluorosilicate produced from waste hexafluorosilicic acid The purpose of the study is to investigate the optimum conditions for the precipitation of sodium hexafluorosilicate (Na2SiF6) from waste hexafluorosilicic acid, an effluent from the phosphoric acid industry. Sodium chloride and sodium hydroxide were used as reactants to produce Na2SiF6. The effect of various parameters on the precipitation was investigated and includes; the molar ratio of the reactants, contact time, the temperature and the effect of seeding. The optimum reaction conditions were found to be as follows; excess sodium chloride or sodium hydroxide to hexafluorosilicic acid of 25%, contact time 40 minutes and a reaction temperature of 40°C. The reaction of hexafluorosilicic acid with an aqueous solution of sodium chloride at optimum conditions gave a maximum yield of 94.26% Na2SiF6 while the reaction of hexafluorosilicic acid with the aqueous solution of sodium hydroxide at optimum conditions gave a maximum yield of 97.3% Na2SiF6. The X-Ray diffraction (XRD) analysis reveals that the only crystals present in the precipitate are Na2SiF6. Also, Scanning Electron Microscope (SEM) analysis shows that the different morphology of these crystals depend on the precipitation conditions.

Removal of Sulfur Dioxide by a Slurry of Jordanian Oil Shale Ash

Abstract This work presents a study on the capacity of oil shale ash to remove sulphur dioxide from air streams before escaping into the atmosphere. Slurries of different concentrations of this ash showed an uptake capacity of 4 × 10−4 mol SO2/g ash obtained after 250 sec. This value increases with the increase of solution pH, temperature, and ash concentration, and decreases the ash particle size. The process of uptake seems to be coupled with both adsorption of SO3 2− on the surface of metal oxides and reaction with alkali and alkali earth metal hydroxides.