Modeling the Influence of Coastal Site Characteristics on PFAS in Situ Remediation.

The potential performance of a hypothetical colloidal-activated carbon (CAC) in situ remedy for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in groundwater in coastal zones was evaluated using estimated hydrogeologic and geochemical parameters for a coastal site in the United States. With these parameters, a reactive transport model (ISR-MT3DMS) was used to assess the effects of tidal fluctuations and near-shore geochemistry on CAC performance. The average near-shore ionic strength of 84 mM at the site was conservatively estimated to result in an increase in the adsorption of PFOA to CAC by about 50% relative to non-coastal sites with ionic strength <10 mM.

Quantifying remediation of chlorinated volatile compounds by sulfidated nano zerovalent iron treatment using numerical modeling and CSIA.

Sulfidated nanoscale zerovalent iron (S-nZVI) has demonstrated promising reactivity and longevity for remediating chlorinated volatile compounds (cVOC) contaminants in laboratory tests. However, its effectiveness in field applications remains inadequately evaluated. This study provides the first quantitative evaluation of the long-term effectiveness of carboxymethyl cellulose-stabilized S-nZVI (CMC-S-nZVI) at a cVOC-contaminated field site.

The journey of toluene to complete mineralization via heat-activated peroxydisulfate in water: intermediates analyses, CO monitoring, and carbon mass balance.

Our study has thoroughly investigated the complete mineralization of toluene in water via heat-activated peroxydisulfate (PDS) by: (1) monitoring concentrations/peak areas of various intermediates and CO throughout the reaction period and (2) identifying water-soluble and methanol-soluble intermediates, including trimers, dimers, and organo-sulfur compounds, via non-target screening using high-resolution mass spectrometry. Increased temperature and PDS dosage enhanced toluene removal/mineralization kinetics and increased the rate/extent of benzaldehyde formation and its further transformation. Artificial groundwater and phosphate buffer minimally impacted toluene removal but significantly decreased benzaldehyde formation, indicating a shift in transformation pathways.

A high-throughput and cost-effective microplate reader method for measuring persulfates (peroxydisulfate and peroxymonosulfate).

Frequent use of persulfates as oxidants, for in situ chemical oxidation and advanced oxidation processes, warrants the need for developing a fast and efficient method for measuring persulfate concentrations in aqueous samples in the lab and on site. Here, we propose a modified method, based on Liang et al.'s (2008) spectrophotometric method, for measuring both peroxydisulfate (PDS) and peroxymonosulfate (PMS) in the aqueous samples.

Effect of low permeability zone location on remediation of Cr(VI)-contaminated media by electrokinetics combined with a modified-zeolite barrier.

Research on electrokinetics-permeable reactive barrier (EK-PRB) remediation to date has mainly focused on homogeneous soils or soils with micro-scale heterogeneities. The potential impact of macro-scale physical heterogeneities, such as stratified layers or lenses, on EK-PRB remediation has not received much attention. This study investigates the effect of a low permeability stratum on EK-PRB remediation of hexavalent chromium (Cr(VI)).