With this award, the Environmental Chemical Sciences Program of the Division of Chemistry is funding Professor Molly Constanza-Robinson of Middlebury College to clarify the chemistry of organoclays and apply this understanding to the design and characterization of novel, nontoxic organoclays for effective contaminant remediation. Potentially harmful chemicals, including pesticides and pharmaceuticals, are routinely detected in treated wastewater, receiving streams, groundwater, and drinking water wells. Using modified clay mineral (organoclays) as an adsorbent represents a promising approach for removing harmful contaminants from environmental waters, but fundamental questions remain. This research team uses spectroscopic techniques to study the details of the organoclay interlayer chemical environment to understand how the molecular-level properties of the clay influence its sorption efficiency. In addition to developing fundamental knowledge and the societal benefit of promoting human and environmental health, this project supports the training and mentoring of a diverse group of undergraduates in interdisciplinary environmental chemical research and additional students through an associated course-based laboratory project.
Montmorillonite clay modified with long-chain alkyl-ammonium cationic surfactants has been extensively studied and demonstrates the ability to effectively sorb petroleum hydrocarbons, phenols, nitro- and chloro-substituted aromatics, and other organic pollutants from water. Although much is known about contaminant uptake into the interlayer of organoclays, unanswered questions hinder optimization of the organoclays for use in contaminant remediation. Moreover, the potential toxicity of conventional surfactants used in organoclays has not been addressed. Using multiple spectroscopic techniques, sorption isotherms, and additional characterization tools, this project investigates factors that govern the organoclay interlayer chemical environment, including its size, crystallinity, and hydration, and how these properties influence the sorption efficiency of the organoclays. This insight is then applied to the design and characterization of novel, effective, and non-toxic organoclays.
