Organoclays for Wastewater Remediation

The organoclay project is new in my lab. We haven’t published on it yet, but we recently received funding from the National Science Foundation to pursue lots of exciting work on it.

The basic idea is to better understand the chemistry governing the uptake of organic environmental contaminants, especially compounds that disrupt the hormone system of humans and wildlife, from wastewater by an engineered natural clay (an organoclay). Ultimately, the goal would be to use the organoclay as a purification filter, just like the activated carbon filters in your home Brita pitcher or in your fish tank. As is the case for activated carbon, this could be scaled up or down, as needed. The basic idea isn’t new, but there’s still a lot of chemistry about what works, what doesn’t, and why that we don’t understand.

Here’s how I described the project to the NSF — students, if you are interested in working on this project, be in touch!

RUI: Elucidating interlayer chemistry for design of

novel, nontoxic organoclays for contaminant remediation

Contamination of environmental waters with organic chemicals poses a significant challenge to human and environmental health worldwide. Ubiquitous detection of industrial chemicals, pharmaceuticals, and personal care products, including endocrine disrupting chemicals, in treated wastewater receiving streams, groundwater, and drinking water wells reveals that conventional wastewater treatment processes do not fully remove these compounds.  Increased industrialization, population growth, and often lax environmental regulations result in a global need to remediate chemical contamination, which is only magnified by ongoing challenges of freshwater scarcity, biodiversity loss, and climate change.

This project seeks to better understand the chemistry of surfactant-modified clay minerals (organoclays) and to improve their efficacy for removing organic contaminants from environmental waters. The PI will use multiple spectroscopic techniques (XRD, FTIR), sorption isotherms for select model contaminants, and additional characterization tools (TCN, GC/MS) to understand the variables that influence the chemical environment of the organoclay interlayer and, in turn, the magnitude of contaminant uptake into the clay. This understanding will enable the design of novel non-toxic organoclays. This project will enhance the fundamental understanding of the organoclay interlayer chemistry and our ability to control that chemistry to improve remediation of aqueous organic contaminants.

Using organoclays to remove organic contaminants from waste and environmental waters shows great promise as an effective and affordable approach. Montmorillonite clay modified with long-chain alkyl-ammonium cationic surfactants has been extensively studied and demonstrated to effectively sorb petroleum hydrocarbons, phenols, nitro- and chloro-substituted aromatics, PAHs and other organic pollutants from water. Although a good deal is known about the sorption mechanisms of contaminant uptake into the interlayer of organoclays, fundamental questions remain regarding the organoclay interlayer chemistry and how it can be used to optimize contaminant remediation. Moreover, the toxicity of conventional surfactants used in organoclays has not been addressed. This work will elucidate and apply critical organoclay chemistry to design effective, non-toxic organoclays that will help realize the potential of organoclays to promote human and environmental health.



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