22 research outputs found
Adsorption of Humic Acid from Water Using Chemically Modified Bituminous Coal-based Activated Carbons
Humic acid (HA) impairs water quality due to its reactivity with many substances present in water. During the drinking-water treatment process and water distribution via water supply system, HA present in water may react with chlorine and other disinfects producing harmful disinfection by-products (DBPs), which are categorized by the International Agency for Research on Cancer (IARC) in groups 2A (probably carcinogenic to humans) or 2B (possibly carcinogenic to humans). Several studies have investigated and reported increased HA removal by iron-coated sorbents. Therefore, the aim of this study was to examine the removal of HA from water by two commercially available bituminous coal-based activated carbons (ACs), Cullar D (Cm) and Hydraffin 30N (Hm). Prior to testing the chosen adsorbents were chemically modified according to two protocols: (1) oxidation by acid mixture (m1), and (2) oxidation with acid mixture followed by
iron-ions impregnation (m2). The batch adsorption tests were used to test their efficiency in HA removal under various values of process parameters (initial HA concentration, pH, contact time, adsorbent mass, and temperature). The results showed that up to 96 % of HA removal can be obtained by Cullar D modification Cm1, while maximum uptake of HA by Hydraffin 30N modification was achieved with Hm1 (62.1 %). After surface saturation with Fe3+ –ions (m2), both activated carbons showed similar and lower performances in HA removal (Cm2 up to 66.5 %, and Hm2 up to 50.3 %). FTIR analysis confirmed differences in modified AC structures, as well as favorable structure of Cm1 for HA adsorption.
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NEIGHBORHOOD DYNAMICS AND PRICE EFFECTS OF SUPERFUND SITE CLEAN-UP
Numerous hedonic price analyses estimate price effects associated with hazardous waste site remediation or other environmental variation. This paper estimates a neighborhood transition model to capture the direct price effect from Superfund site clean-up and the indirect price effects arising from residential sorting and changes in investment in the housing stock following clean-up. First-difference models of neighborhood change and a national sample are used. This approach fails to find consistent positive direct price effects. Positive indirect effects, however, may arise through residential sorting and neighborhood investment spurred by remediation. The findings can be sensitive to policy endogeneity and model specification. Copyright Blackwell Publishing, Inc. 2007