Studies of the Polar and Apolar Liquid Film Properties of Pure and Modified Activated Carbons by Thermal Analysis and Sorptiometric Methods

Thermal analysis was used to investigate the adsorbed water layers and surface properties of various pure and modified commercial activated carbons. In addition, the thermodesorption of n-butanol, n-octane and benzene from samples saturated in a vacuum desiccator was studied under quasi-isothermal conditions. The mass loss Q-TG and differential mass loss Q-DTG curves obtained consisted of steps and inflections which were associated with the mechanism of wetting, adsorption and porosity properties of the studied surfaces. Adsorption/desorption isotherms of nitrogen on the activated carbon samples were measured using a sorptiomatic method. The specific surface areas, pore sizes, pore volumes and pore-size distribution functions have been calculated for the various samples. A correlation between the porosity parameters obtained from thermogravimetric and sorptiometric methods is presented

pH driven physicochemical conformational changes of single-layer graphene oxide

Single-layer graphene oxides (SLGOs) undergo morphological changes depending on the pH of the system and may account for restricted chemical reactivity. Herein, SLGO may also capture nanoparticles through layering and enveloping when the pH is changed, demonstrating potential usefulness in drug delivery or waste material capture

Driving forces of conformational changes in single-layer graphene oxide

The extensive oxygen-group functionality of single-layer graphene oxide proffers useful anchor sites for chemical functionalization in the controlled formation of graphene architecture and composites. However, the physicochemical environment of graphene oxide and its single-atom thickness facilitate its ability to undergo conformational changes due to responses to its environment, whether pH, salinity, or temperature. Here, we report experimental and molecular simulations confirming the conformational changes of single-layer graphene oxide sheets from the wet or dry state. MD, PM6, and ab initio simulations of dry SLG and dry and wetted SLGO and electron microscopy imaging show marked differences in the properties of the materials that can explain variations in previously observed results for the pH dependent behavior of SLGO and electrical conductivity of chemically modified graphene-polymer composites. Understanding the physicochemical responses of graphene and graphene oxide architecture and performing selected chemistry will ultimately facilitate greater tunability of their performance