In this study the effect of pH, adsorption behavior and the chemical struc-tures of two dyes (Methyl Orange and Bromothymol Blue) on the photo-degradation rate constant, was investigated. Adsorption isotherm shows tha...In this study the effect of pH, adsorption behavior and the chemical struc-tures of two dyes (Methyl Orange and Bromothymol Blue) on the photo-degradation rate constant, was investigated. Adsorption isotherm shows that the adsorption amount of dyes on TiO2 surface is highly related to the pH of the solution and to the pKa of each dye. In acidic medium the adsorption percentage of Methyl Orange on TiO2 surface was 76% facing 5% for Bromothymol Blue. The kinetic study shows compatibility between the degradation rate constant and the adsorption percentage on the surface. In basic medium the adsorption percentage of Methyl orange and Bromothymol Blue is similar while the degradation rate of Methyl orange is two times faster than that of Bromothymol Blue which reveals the role of chemical structure in the photodegradation rate.展开更多
Cadmium (Cd), one of the most toxic heavy metals added to soil after phosphate fertilizer treatment, was investigated. The effects of this metal on morphological and physiological changes of Lactuca sativa were studie...Cadmium (Cd), one of the most toxic heavy metals added to soil after phosphate fertilizer treatment, was investigated. The effects of this metal on morphological and physiological changes of Lactuca sativa were studied in addition to its partitioning in different parts of the crop. In parallel, Lactuca sativa was allowed to grow under hydroponic conditions with modifications of the Hoagland nutrient solution. This solution was submitted to five Cd concentrations, 0, 0.093, 0.186, 0.279 and 0.372 mg Cd/L and three P concentrations, 0, 299 and 1420 mg P/L. The study showed a positive effect of phosphorus on root elongation, surface area while cadmium inhibited plant growth and sometimes the death of the plants. Cadmium was found to be accumulated in roots while zinc was preferably accumulated in the leaves and stems. The increase of performance of Lactuca sativa under hydroponic condition and Hoagland contaminated solution with cadmium was found to be better than the ones grown in Cd amended soil with or without phosphorus.展开更多
Distribution of Cu, Zn, Pb, Cr, Ni, Mn concentrations and the activity of polonium-210 in the surrounding area of a phosphate fertilizer industry located on the eastern coast of the Mediterranean Sea has been determin...Distribution of Cu, Zn, Pb, Cr, Ni, Mn concentrations and the activity of polonium-210 in the surrounding area of a phosphate fertilizer industry located on the eastern coast of the Mediterranean Sea has been determined. Nineteen sampling sites were distributed around the industrial zone on a surface area of about 100,000 m^2. Atomic absorption spectroscopy and Alpha spectroscopy were used to quantify the heavy elements and polonium-210, respectively. Investigation on a particle scale was conducted by TEM and SEM coupled to EDX and X-ray cartography to determine the nature of heavy elements carriers and their distribution. Heavy elements were mainly concentrated inside the particle size fraction 〈 50 μm. Their levels decreased with distance increasing from the industry. According to the reference soil, enrichment factors were about 10, 15, 32 and 100 times for Zn, Pb, Cu, and Cr, respectively inside the particle size fraction 〈 50 μm on the closest sites to the industry. The main contaminant sources were transport and storage of row materials and the free release of phosphogypsum waste. Heavy elements were entrapped inside agglomerates of sulfates, phosphates and iron oxihydroxides in a diffused shape. Polonium-210 with an enrichment factor of about 56, showed the same behavior of the spatial distribution of the trace elements.展开更多
文摘In this study the effect of pH, adsorption behavior and the chemical struc-tures of two dyes (Methyl Orange and Bromothymol Blue) on the photo-degradation rate constant, was investigated. Adsorption isotherm shows that the adsorption amount of dyes on TiO2 surface is highly related to the pH of the solution and to the pKa of each dye. In acidic medium the adsorption percentage of Methyl Orange on TiO2 surface was 76% facing 5% for Bromothymol Blue. The kinetic study shows compatibility between the degradation rate constant and the adsorption percentage on the surface. In basic medium the adsorption percentage of Methyl orange and Bromothymol Blue is similar while the degradation rate of Methyl orange is two times faster than that of Bromothymol Blue which reveals the role of chemical structure in the photodegradation rate.
文摘Cadmium (Cd), one of the most toxic heavy metals added to soil after phosphate fertilizer treatment, was investigated. The effects of this metal on morphological and physiological changes of Lactuca sativa were studied in addition to its partitioning in different parts of the crop. In parallel, Lactuca sativa was allowed to grow under hydroponic conditions with modifications of the Hoagland nutrient solution. This solution was submitted to five Cd concentrations, 0, 0.093, 0.186, 0.279 and 0.372 mg Cd/L and three P concentrations, 0, 299 and 1420 mg P/L. The study showed a positive effect of phosphorus on root elongation, surface area while cadmium inhibited plant growth and sometimes the death of the plants. Cadmium was found to be accumulated in roots while zinc was preferably accumulated in the leaves and stems. The increase of performance of Lactuca sativa under hydroponic condition and Hoagland contaminated solution with cadmium was found to be better than the ones grown in Cd amended soil with or without phosphorus.
基金supported by the research grants program of the Lebanese Council for Scientific Research
文摘Distribution of Cu, Zn, Pb, Cr, Ni, Mn concentrations and the activity of polonium-210 in the surrounding area of a phosphate fertilizer industry located on the eastern coast of the Mediterranean Sea has been determined. Nineteen sampling sites were distributed around the industrial zone on a surface area of about 100,000 m^2. Atomic absorption spectroscopy and Alpha spectroscopy were used to quantify the heavy elements and polonium-210, respectively. Investigation on a particle scale was conducted by TEM and SEM coupled to EDX and X-ray cartography to determine the nature of heavy elements carriers and their distribution. Heavy elements were mainly concentrated inside the particle size fraction 〈 50 μm. Their levels decreased with distance increasing from the industry. According to the reference soil, enrichment factors were about 10, 15, 32 and 100 times for Zn, Pb, Cu, and Cr, respectively inside the particle size fraction 〈 50 μm on the closest sites to the industry. The main contaminant sources were transport and storage of row materials and the free release of phosphogypsum waste. Heavy elements were entrapped inside agglomerates of sulfates, phosphates and iron oxihydroxides in a diffused shape. Polonium-210 with an enrichment factor of about 56, showed the same behavior of the spatial distribution of the trace elements.
