Graphene-based Nanomaterials as a Novel Dual Sorbent for Organic Chemicals

Abstract

Graphene-based nanomaterials (GBNMs) in different forms (e g as stacked graphene oxides single-walled and multi-walled nanotubes) are known for their superior electronic and thermal conductivities This study shows that GBNMs perform as a dual sorbent to sorption organic chemicals (contaminants) through (competitive) adsorption and (noncompetitive) partition Extensive sorption data from various solutes on various GBNMs suggest that the well detached and structurally loose graphene monolayers develop a liquid-like motion in water at room temperature to enable them to attract organic solutes as a “solvent” in concomitance with the solute adsorption on the aggregated graphene phase Because of the concurrent solute adsorption and partition the observed GBNM sorption data cannot be reconciled by a conventional adsorption model For GBNMs possessing a large amount of detached graphene monolayers that gives rise to a relatively large BET-N2 surface area this gives GBNMs a huge advantage to sequester an exceptionally large combined amounts of coexisting organic species (especially liquids) over the limits posed by the conventional adsorbents e g activated carbon Moreover the postulated GBNM dual-sorbent concept clarifies many previously unresolved issues such as the highly concentration-dependent solute competitive effect and the highly variable “adsorbed capacities” per unit surface area of different organic solutes on a GBNM versus a conventional adsorbent (e g graphite or AC) The partition hypothesis with a GBNM may be scrutinized by the experimental sorption data of liquid benzene (BEN) versus solid naphthalene (NPL) or phenanthrene (PHN) on a GBNM The partition capacity of BEN (as a dissolved liquid) with a GBNM is expected to be sharply higher than that of either NPL or PHN (as a dissolved solid) because of the melting-point effect on the solute activity (a) (where a = 1 for a pure liquid and < 1 for a pure solid) The large range of solute adsorption and partition capacities gained with selected GBNMs offers a crucial account of the postulated novel GBNM behavior

Date of Award	2020
Original language	English
Supervisor	Tsair-Fuh Lin (Supervisor)