Papers by Keyword: Rainwater Runoff

Abstract: For the treatment of contaminated rainwater runoff, the synthesis of manganese dioxide and its coating onto buoyant polypropylene granule was done with accompanying adsorption experiments. Results showed 35-45 m oxide coating was stable under severe hydrodynamic conditions, had 37 mg of Mn attached per gram of granules, moreover, consisted of mixed birnessite and cryptomelane forms of manganese dioxide. Adsorption capacity of each gram of media was 4.9, 3.9, 0.98, 0.75 mg of Pb , Cu , Cd , and Zn , fitting well to the Freundlich adsorption model. Manganese-dioxide-coated polypropylene granules had favorable engineering advantages and excellent adsorptive properties, being challenging alternative to other practically-oriented in situ or centralized rainwater treatment media.

Abstract: Modified polypropylene granules (MDPG) were coated by manganese dioxide and their surface and adsorptive characteristics were studied. Surface characteristics of the adsorbent were investigated by B.E.T. surface area and mercury porosimetry. Coating has significantly increased the surface area of granules from 0.12 m 2 /g B.E.T. N 2 to 15.42 m 2 /g. Gas pycnometry measurements resulted in low density of 0.13 g/cm 3 for uncoated granules, the fact ascribed to 0.65 porosity measured. Coating increased micro pore volume of raw granules by a factor of 58. Adsorption experiments were conducted in column flow-through reactors at pH 6.0 and 10 g/L sorbent dosage for mixture of four metal species, each having 5 mg/L initial concentration. More than 60 % of Pb and Cu was removed within first 20 min, whereas just over 29 and 13 % for Cd and Zn respectively. Furthermore, more than 99, 84, 40, 16 % of Pb, Cu, Cd, and Zn was removed within 1 h. Adsorption efficiencies for 5 ppm of initial metal concentration at pH 5.0 and 10 g/L sorbent/solute ratio resulted in 4.9, 3.9 mg of Pb and Cu sorbed per gram of sorbent. And these ratios for separate metal ions were substantially higher than those for the mixture of the four metal ions. For 5 g/L of sorbent under the same parameters, removal efficiencies of Cd and Zn were respectively 0.98, 0.75 mg/g, correlating well with Freundlich adsorption model. Adsorption kinetics showed relatively fast removal rates within first 5 h of sorption. Desorption resulted in eluting 57, 70, 76, 78 % of the initial feeding concentrations for Pb, Cu, Cd, Zn, respectively.