Microporous activated carbon (AC) and zeolites are industrially applied for air and water pollution control, but pore blockage, irreversible adsorption, and co-adsorption of moisture reduce their contaminant removal efficiencies and/or prevent reuse. Porous polymers are gaining traction in environmental engineering because they can have tunable physical and chemical properties that allow tailoring for specific applications. Our previous studies show that hydrophobic styrene-divinylbenzene (St-DVB) polymers maintain their catalytic NO oxidation performance when moisture is present, while AC fails due to competitive water adsorption caused by increased hydrophilicity and surface oxidation during use. It was also observed that polymers provide faster adsorption/desorption kinetics and higher desorption efficiency than AC at low temperatures. However, commercial St-DVB polymers have low micropore (dp &lt; 2 nm) volume, reducing adsorption capacity for low concentration contaminants. To overcome, the Friedel-Crafts reaction is applied using different size dichloroalkanes to tailor pore size distribution by hyper-cross-linking polymer segments and reducing the network mesh size. In this work, commercial St-DVB polymers were first hyper-cross-linked to increase micropore volume by up to 333%, without sacrificing the inherent hydrophobicity of the material. Consequently, hexane adsorption capacity increased by up to 218% at relative pressure (p/p0) = 0.05 and, in a separate series of experiments, catalytic NO oxidation rate increased by 100% ([NO] = 500 ppmv). Next, microporous polymers were chemically modified by deposition of tertiary and quaternary amine groups to increase phenol adsorption capacity and kinetics. Overall, this work describes novel polymer modification and production processes that highlight opportunities to tailor the product’s physical and chemical properties. The overarching goal is to exploit this flexibility, in an effort to present microporous polymers as competitive materials for use in air and water pollution control applications.

Hyper-cross-linking styrenic polymers with dichloroalkanes for improved adsorption of pollutants

2019 Spring National Meeting

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