ABSTRACT
The chemical resistance of chlorinated hydrocarbons in starch/polyvinyl alcohol (PVA) blends has been investigated using a permeation cell with an in-cell solid phase microextraction (SPME) sampling device. The chlorinated hydrocarbon with a large molecule size or lower polarity was found to be less permeable through the starch/PVA blends. The tensile strength and chemical resistance of chlorinated hydrocarbons decreased with an increase in the starch content of blends. For the starch/PVA blends, the solubility of chlorinated hydrocarbons was inversely proportional to their molecular weight, molar volume and log Kow. The diffusion coefficients and solubility of permeants were proportional to the content of starch in the starch/PVA blends. It is plausible that the blends will be inclined to the starch characteristics as the plasticizer (i.e. glycerin) disrupts the rigidity arrangements of the starch and PVA. The present work provides information on the extent of organic compound permeation through starch/PVA blends for the practical application.
Subject(s)
Hydrocarbons, Chlorinated/chemistry , Polyvinyl Alcohol/chemistry , Solvents/chemistry , Starch/chemistry , Diffusion , Glycerol/chemistry , Membranes, Artificial , Permeability , Plasticizers/chemistry , SolubilityABSTRACT
This study elucidates the behaviour of heavy metals in slag produced from four different sewage sludge ashes mixed with municipal solid waste incinerator fly ash and then co-melted. Experimental results indicate that sewage sludge ashes consisted of SiO(2), CaO, and Al(2)O(3). Fly ash consisted of CaO, Na(2)O and SO(3). The speciation of sewage sludge ashes indicates that the ashes contained quartz and AlPO(4). The speciation in fly ash consisted of anhydrite, microcline, calcium chloride, sylvite and halite. The leaching behaviours of sewage sludge ashes met the Taiwan Environmental Protection Administration's regulatory standards. The fly ash had high concentrations of Zn and Pb; however, the leaching of these metals was low. The major components of synthetic slags were SiO(2) (33.5-54.0%), CaO (21.4-36.7%), and Al(2)O(3) (8.1-15.7%). The X-ray diffraction patterns of co-melted slags demonstrate that the slags contained significant amounts of glass. Most heavy metals can be fixed in a net-like structure; thus, they can not be extracted easily. The toxicity characteristic leaching procedure (TCLP) leaching concentrations for target metals in all slags met the Taiwan Environmental Protection Administration's regulatory standards.
Subject(s)
Carbon/chemistry , Environmental Pollutants/chemistry , Incineration , Metals, Heavy/chemistry , Particulate Matter/chemistry , Refuse Disposal/methods , Refuse Disposal/standards , Sewage/chemistry , Carbon/analysis , Cities , Coal Ash , Environmental Pollutants/analysis , Hot Temperature , Metals, Heavy/analysis , Oxides/analysis , Oxides/chemistry , Particulate Matter/analysis , Sewage/analysis , Taiwan , X-Ray DiffractionABSTRACT
Incineration of municipal solid wastes (MSW) is the main method of waste management in Taiwan. Although the incineration of MSW processes the solid wastes at 850-950 degrees C and destroys most of the organics, the content of incineration ashes is still a problem for landfill. Moreover, acid precipitation is much worse than before in Taiwan, especially in the northern areas. For instance, the occurrence probabilities of acid precipitation measured from 1991 to 1998 in Taipei increase from 73% to 85%. Therefore, it is more important to get a series of data that will help explore the influence of acid precipitation during disposal on characterization of pollutants than to analyze the ash properties after the incinerators have been constructed and regularly used. In this investigation, the disposal site of incineration ashes is simulated in laboratory by test columns. An irrigation experiment is taken to simulate the acid precipitation at room temperature. In order to explore the exact influence on leachate quality of the main chemical composition of acid precipitation, columns are migrated with different concentrations of sulfate in acid precipitation. This investigation showed that the sulfate concentration of acid precipitation has an increasing effect on the accumulative release of heavy metals, such as Zn, Pb and Cu, from leachate. The sulfate concentration of acid precipitation, however, will not influence the trend of chemical oxygen demand (COD), biochemical oxygen demand (BOD(5)) and total organic carbon (TOC) in the leachate release.
