Reginald E. Rogers

Removal of Copper Ions from Aqueous Solutions via Adsorption on Carbon Nanocomposites

The development of technologies for water purification is critical to meet the global challenges of insufficient water supply and inadequate sanitation. Among all wastewater treatments, adsorption is globally recognized as the most promising method because of its versatility and economic feasibility. Herein, the removal of copper ions (Cu(II)) from aqueous solutions through adsorption on free-standing hybrid papers comprised of a mixture between graphene and different types of carbon nanotubes (CNTs) was examined. Results indicate that the rate of adsorption and long-time capacity of the metal ions on the nanocomposites significantly exceeds that of activated carbon by a factor of 4. Moreover, the combination of graphene with CNTs endows an increase in the uptake of Cu(II) up to 50% compared to that of CNTs alone, with a maximum adsorption capacity higher than 250 mg·g(-1). The removal of Cu(II) from water is sensitive to solution pH, and the presence of oxygen functional groups on the adsorbent surface promotes higher adsorption rates and capacities than pristine materials. These hybrid nanostructures show great promise for environmental remediation efforts, wastewater treatments, and separation applications, and the results presented in this study have important implications for understanding the interactions of carbonaceous materials at environmental interfaces.

Binder free graphene-single-wall carbon nanotube hybrid papers for the removal of polyaromatic compounds from aqueous systems

The time-dependent adsorption of 1-pyrenebutyric acid, a model compound for polyaromatic carbon adsorption, onto graphene nanoplatelet-single-wall carbon nanotube hybrid papers is investigated experimentally based upon changes in optical absorption spectra.

Fixed bed adsorption of diquat dibromide from aqueous solution using carbon nanotubes

While carbon nanotubes (CNTs) are increasingly studied as attractive adsorbents for wastewater treatments, research on adsorption characteristics of these materials is mostly restricted to batch studies. However, it is well known that continuous flow techniques can be more efficient in removing contaminants. The present work exploits the attributes of different types of CNTs in a fixed bed column for the dynamic uptake of diquat dibromide from aqueous solutions.

Enhanced adsorption of carbon nanocomposites exhausted with 2,4-dichlorophenoxyacetic acid after regeneration by thermal oxidation and microwave irradiation

Graphene nanoplatelet–single-walled carbon nanotube hybrid papers exhausted with 2,4-dichlorophenoxyacetic acid were recovered by a combination of thermal oxidation and microwave irradiation. The recycling efficiency investigated after multiple saturation/regeneration cycles based upon changes in optical absorption spectra significantly exceeded the adsorption capacity of the original nanocomposites.

Emerging investigators series: highly effective adsorption of organic aromatic molecules from aqueous environments by electronically sorted single-walled carbon nanotubes

The use of electronically sorted (i.e. semiconducting or metallic) single-walled carbon nanotubes (SWCNTs) for the removal of organic compounds from aqueous environments is investigated. Chromatography techniques are used to separate the semiconducting type from the metallic type. Spectroscopy (including UV-visible) is employed to measure the uptake of 1-pyrenebutyric acid, diquat dibromide, and 2,4-dichlorophenoxyacetic acid onto the sorted SWCNTs. Kinetic and equilibrium analysis show that the semiconducting type is capable of adsorbing up to 70.6% more adsorbate compared to the metallic type. This is likely attributed to the favorability of these compounds interacting with the semiconducting type due to a lack of electron density around this type of SWCNT. Moreover, a comparison of the material separated in-house by chromatography to those purchased from a commercial source shows that the in-house material is capable of adsorbing 26.5 to 60% more adsorbate versus the commercial material in which the SWCNTs were separated using density gradient ultracentrifugation methods. This demonstrates that chromatography techniques potentially yield a more effective separation of the semiconducting and metallic SWCNTs. Such opportunities can be influential in the development of new adsorbent systems towards removal of targeted compounds from aqueous environments.