Polyethylene pipes and epoxy or polyurethane linings are increasingly used in drinking water infrastructure. As a recent introduction to the water industry, there are still many unknowns about how polymers will behave in the distribution system specifically relating to sorption and desorption of chemical contaminants. This study is in response to a spill of 4-methylcyclohexane methanol (MCHM) that occurred in January 2014 contaminating the drinking water of nine counties in West Virginia. This study investigated sorption and desorption of the odorous chemical MCHM into polymer drinking water infrastructure and granular activated carbon (GAC). Experiments for sorption of non-polar toluene and polar 1-butanol were conducted as a comparison for MCHM sorption. Additionally, a brief odor analysis was done on the ability of activated carbon to remove odor from contaminated water and on leaching of MCHM from pipe material into clean water. The results show that MCHM diffusion and solubility in polyethylene pipe materials is low. Solubility in polyethylene ranged from 0.003-0.008 g/cm3 and was more similar to the polar contaminant n-butanol than the non-polar contaminant toluene. Desorption experiments indicated that MCHM sorbed to polyethylene diffused back into water at levels that produced odor. MCHM diffused very quickly into epoxy; its solubility was similar to polyethylene pipe. MCHM caused the polyurethane lining to swell and deform. Granular activated carbon effectively sorbed MCHM to below its odor threshold. The sorption properties of MCHM indicate the potential for contamination of infrastructure and the desorption indicates subsequent recontamination of drinking water. / Master of Science

A recent chemical spill of 4-Methylcyclohexanemethanol (4-MCHM) in West Virginia left 300,000 people without water. Officials claimed that this compound is not lethally toxic, but potentially harmful if swallowed or inhaled, and can cause eye and skin irritation. Sittig's Handbook of Toxic and Hazardous Chemical Carcinogens reports high exposures from skin contact or inhalation may cause damage to the heart, liver, kidneys, and lungs, and may result in death. However, no quantitative data seem to exist and no references can be found on neurotoxicity. We have investigated the neurotoxicity of 4-MCHM using mammalian nerve cell networks grown on microelectrode arrays. Network spontaneous activity from multiple units (range 48 – 120 per network) were used as the primary readout. Individual units were followed based on spike waveforms digitized at 40 kHz (Plexon MNAP system). Dose response curves show the effective inhibitory concentration at 50 percent decrease (EC50) to average 27.4 microM SD±6.17. However, in the presence of 40 microM bicuculline, a competitive GABAA antagonist, the EC50 shifts to 70.63uM SD ±4.3; implying that early, low concentration exposures to 4-MCHM involve GABA activation. Initial activity loss occurs without active unit loss (defined as 10 or more template threshold crossing per min), indicating functional interference with spike production. Full recovery has not been seen at concentrations above 130 microM, unless the culture was given bicuculline. Direct exposure to 400uM results in immediate, irreversible loss of spike production, followed by necrosis of glia and neurons.

Problematic organic pollutants in industrial and drinking water sources are a leading cause of water scarcity. Among the advanced oxidation processes, sonolytic degradation has received considerable attention because it combines oxidation processes initiated by reactive oxidant species and a pyrolysis processes associated with the high temperatures produced during cavitation. The degradation of the semi-volatile compound, MCHM, was rapid and followed pseudo-first order kinetics. The Freundlich kinetic model for heterogeneous systems was successfully applied to describe the non-uniform distribution of MCHM at the gas-liquid interface during ultrasonic treatment. Two primary products were confirmed by GC-MS. Computational studies were also applied to assist in a better understanding of the conformational effects and the pyrolytic pathways. The first-generation antihistamine, diphenhydramine (DPH), was also readily degraded by ultrasound. The heterogeneous process was best fit to a Langmuir-Hinshelwood kinetic model, which indicated a uniform partitioning at the gas-liquid interface. The degradation of DPH was achieved primarily via the addition reaction with hydroxyl radicals to the aromatic rings. Computational studies supported the observed products and the proposed reaction pathways for the pyrolytic and oxidation degradation pathways. Ultrasound was shown to be a rapid and effective method to remediate cetirizine (CET), a second-generation antihistamine. Addition of different hydroxyl radical scavengers into the solution prior to treatment as the competition studies indicated that CET reacted with hydroxyl radicals at the gas-liquid interface and the bulk solution. When the solution was saturated by O2, CET degraded the most rapidly. Degradation products were confirmed by LC-MS analyses. Treatment of the emerging problematic perfluorinated alkyl substance, “GenX” with steady state gamma-radiation under various conditions did not lead to significant degradation. However, “GenX” does react with eaq- at near diffusion-controlled rate, k = 5×1010 M-1·s-1. Titanium dioxide photocatalysis did not lead to appreciable degradation of “GenX” under a variety of conditions even in the presence of oxalic acid or ethanol as the valence band hole quencher. Sonolysis was a promising method and led to the effective mineralization of “GenX” under argon saturated conditions. A detailed computational study of the pyrolytic degradation pathways was carried out using density function in Gaussian 09.