Abstract
Nanomaterials have been utilized extensively in different fields based on their excellent optical properties, magnetic properties, and high surface area per unit volume etc. Carbon nanotubes (CNTs) are one of popular nanomaterials and have been applied to many research fields in recent years. Modifying or decorating the surface of CNTs with desired functional groups is an important step for preparing CNTs-based materials. The surface of CNTs acidified with carboxylic acid in advance is indispensable to benefit the followed-up reaction. The structure of CNTs after acidification, i.e., the acidified amounts and sites on the CNTs’ surface was known to affect their analytical applications, such as gas adsorption or heavy metal extraction. This motivated us to further explore the preparation parameters that affect the amounts and sites of carboxylic acid on the CNTs’ surface, which benefits subsequent analytical application. Microwave-assisted acidification, being regarded as green chemistry method, was employed to acidify different kinds of CNTs in this study. Various experimental parameters for microwave acidification (temperature, amounts of acid, and duration of microwave) were tested. Acid-base titration was applied to evaluate the amounts of carboxylic acid modified on to CNTs’ surface. The structure of CNTs after acidification was determined by Raman spectroscopy. Acidified sites were investigated first by acidified CNTs grafted with magnetic nanoparticles (MNPs) of transmission electron microscopy (TEM) analysis. Preliminary results of gas adsorption respective gas and heavy metal extraction would be investigated in the new future by using appropriate CNTs after optimal acidified conditions were confirmed.