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Peat has been evaluated as an efficient sorbent. In this paper, peat for removal of Pb²⁺ ions from aqueous solution was studied. Peat samples were analyzed for total lead, pH, humidity, and TC (total carbon). Major factors involved, including initial Pb concentration, contact time, and pH, also were investigated. The aqueous solution of lead(II) (0.25 mg/L, 25.0 mg/L, 50.0 mg/L, 75.0 mg/L, and 100.0 mg/L) was agitated at a fixed speed of 20 rpm for 5, 10, 20, 45, 90, 180, and 360 minutes, respectively. At the end of each contact time, the solid was removed by filtration through a 0.45 µm glass filter and then analyzed with an atomic absorption spectrophotometer. Adsorption capacity of peat increases with increasing contact time, initial lead(II) concentration, and was significantly affected by initial pH value in the range from 4.0-7.0. The amount of Pb adsorbed on peat was greatest at pH 6.0, 360 min contact time, and 100 mg/L lead(II) concentration, i.e. 9.489 mg/g. The Freundlich and Langmuir models were used to interpret the sorption behaviour of Pb²⁺ ions, and the results showed that the Freundlich model shows a better fitting than the Langmuir model according to correlation coefficients (R²>0.98, Freundlich model, R² >0.58 Langmuir model).
Chemically modified and natural zeolite consisting of clinoptilolite and mordenite minerals (Sokirnica Mine, Ukraine) was selected for testing the adsorption ability of formaldehyde. Modified zeolite was produced from natural zeolite by chemical activation with sulphuric acid (H2SO4) 2M at 95-98°C for six hours. Synthetic wastewater was prepared by adding formaldehyde at concentrations equal to or higher than the maximum allowable concentration (MAC) values: 1 MAC = 2 mg/l, 2 MAC = 4 mg/l, 3 MAC = 6 mg/l, 5 MAC = 10 mg/l, and 10 MAC = 20 mg/l. The effects of adsorption time (5 min, 10 min, 30 min, 60 min, 3 h, 5 h, 8 h, and 12 h) were examined for the selected formaldehyde concentrations. Adsorption efficiency, adsorption capacity, and iodine numbers were evaluated for the selected adsorbents. The positive effect of natural zeolite chemical modification was obtained in the range of 5.4 to 24.0%, with an average value of 9.2 %. Iodine number was selected as a parameter for natural zeolite chemical modification with 2M sulphuric acid evaluation. The iodine number before sorption was 154.3 mg∙g-1 and after modification was 164.5 mg∙g-1
The aim of the current study is to investigate the relationship between physico-chemical parameters, and to determine levels of certain heavy metals (Pb and Cd) in bottom sediments of Lake Sudotėlis in Lithuania. Organic matter (OM) content and pH were measured. Both positive and negative correlations were detected between the lake bottom sediment content and physical-chemical parameters. The pH of the sediment in all sites was slightly alkaline, e.g. from 7.76±0.02 to 8.21±0.02. Quantity of organic matter in bottom sediments was 10.37±0.30 to 76.50±1.6%. The metals concentrations (in mg/kg of dry weight) ranged 0.42±0.02 to 12.73±0.60 for Pb, and 0.02±0.004 to 6.89±0.33 for Cd.
Emissions by rail transport account for around 1% of total pollutant emissions. The greatest negative influence on human health is made by PM, NOx, and others pollutants. Our article describes the methodology for measuring emissions (CO, NOx, PM, and CH) into the air by rolling stock on which the experimental measurements of emissions are based. Comparison of emissions by the stock company Lietuvos geležinkeliai old (TEP70BS), re-motorized (2M62K), modernized (2M62M, ČME3ME, ČME3MG), and new (ER20CF) locomotives, railcars (620 M), and diesel trains (RA-2) into the atmosphere is carried out. As the study carried out in 2009 shows, the tested emissions into the air by diesel locomotive engines (pollutant kg/fuel ton) decreased significantly (up to 40%) when compared to the study carried out in 2003. Emissions of sulphur dioxide into the air from rolling stock in 2009 significantly decreased against 2003 as the allowable sulphur content in diesel fuel decreased from 0.2% to 0.001%.
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