Permeation of Polybutylene Pipe and Gasket Material by Organic Chemicals

Abstract

Recent investigations have found that organic chemicals may contaminate drinking water by permeating buried plastic pipes and gasket materials. Pipe-bottle direct-exposure experiments and microbalance experiments were conducted in order to determine the susceptibility of polybutylene (PB) piping material and gasket materials to permeation by a wide range of organic chemicals. Many lipophilic compounds tested were found to permeate to a detectable level in consumers' tap water within a month at one third of their aqueous solubilities. It was also found that PB was more permeable than low-density polyethylene to toluene and that chlorinated hydrocarbons permeated PB faster than unchlorinated hydrocarbons. Gasoline compositions such as benzene, toluene, ethyl benzene, and xylenes appeared to be highly permeable to PB and gasket material. The organic chemicals were approximately 5 to 100 times more permeable in gasket materials than in PB.The development of plastic extrusion years. The polymers commonly used for technology has led to the extensive use these purposes have been polyvinyl of plastic water conduits and pipe gaskets chloride (PVC), polyethylene (PE), polyin the potable water industry in recent butylene (PB), and acrylonitrile-butadi-ene-styrene (ASS) for water pipe and tubing and styrene-butadiene-rubber (SBR) for the push-on type of pipe gasket used to connect PVC, ductile iron, steel, or concrete water pipes. SBR is used in more than 90 percent ofthe applications.' Other types of polymers such as Neoprene (chlorinated rubbers), ethylenepropylene-diene-monomer (EPDM), nitrile rubbers, and fluorinated rubbers are also used in the manufacture of pipe gaskets. These materials are immune to corrosion, easy to install, ductile, durable, and energy efficient to manufacture. They are not, however, impervious to many organic chemicals, which allows contamination of the potable water.

Salt rejection and water flux through a tubular pervaporative polymer membrane designed for irrigation applications

“…deionized water or salt solution), covered and periodically removed and weighed [11][12][13][14][15][16]. This was used to measure the rate at which the solution was absorbed by the polymer, as well as the diffusivity coefficient, D. Eight pieces of the polymer tube of length 14.7 cm, amounting to a total average surface area of 850 cm 2 , were inserted in a bottle and immersed in an excess of solvent.…”

Rejection of organic micro-pollutants from water by a tubular, hydrophilic pervaporative membrane designed for irrigation applications

“…In addition, Berens [22] found that diffusion coefficient (D) decreases with increasing permeate weight, size (molecular volume) and cross sectional area of the penetrant. Similarly, Shao and Huang [11], reported that the diffusion coefficient of a permeate through a polymer is a strong function of the size and shape of the permeate, and Park et al [23] Hydrogen-bonding interaction has also been proposed as a dominant factor controlling the selectivity toward water in hydrophilic pervaporation process [27]. In this study, an enhanced propensity for hydrogen-bonding influenced the rejection of phenol (δh = 14.9) and 2-phenoxyethanol (δh = 14.3), as these compounds had the lowest removal of 47% and 58% respectively, whereas fluorene, which has the second lowest hydrogen bonding parameter among the seven studied compounds (δh = 1.7), was best rejected.…”

Permeation of BTEX compounds through HDPE pipes under simulated field conditions

“…The case of benzene demonstrates that knowledge of environmental fate and transport is essential for evaluating the potential permeation risk of contaminants because the distribution of chemicals among environmental media determines the contaminant levels that plastic pipes might encounter in the field. In the unsaturated soil, plastic pipe permeation was believed to occur from the vapor phase (Holsen et al, 1991b;Park et al, 1991). The current study did not collect vapor samples for BTEX analysis, and thus the exact concentration of BTEX in soil gas was unknown during the experimental period.…”

“…No previous study specifically investigated the permeation of organic contaminants through PE pipe buried in unsaturated soil. In addition, comparing the diffusion coefficients obtained from the three permeation tests (free product gasoline, gasoline-contaminated water, and gasoline-contaminated unsaturated soil) on the basis of the values of activity is a challenge because of the lack of consistent definitions of activity (Park et al, 1991).…”