Advances in characterisation, preparation and application of polysaccharide-derived mesoporous carbons for environmental remediation

• Main Author: Borisova, Aleksandra
• Other Authors: Clark, James
• Published: University of York 2015
• Subjects: 540
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675090

Starbons are a group of mesoporous carbonaceous materials derived from renewable and readily available gelling polysaccharides — starch, alginic acid and pectin. They possess a high mesopore volume, a developed surface area, and a wide range of surface properties, ranging from oxygen-rich and hydrophilic to carbon-rich and hydrophobic, achieved by controlled pyrolysis of mesoporous polysaccharide aerogels in the 300–800 ◦C range. The objective of the present work was to build on the existing knowledge and previous developments in characterisation and preparation of Starbons, and their application in adsorption of organic pollutants (phenolics, polycyclic aromatic hydrocarbons, dyes). The aim was to improve our understanding of the relationship between the material properties and application performance. This thesis presents a systematic investigation of the change in chemical and textural properties of alginic acid and pectin-derived Starbons in the thermal range of 25–800 ◦C, using a wide range of complementary analytical techniques, such as N2 adsorption/desorption porosimetry, IR spectroscopy, Raman spectroscopy, UV spectroscopy, TG-IR, elemental analysis, pH drift, SEM and TEM. Analysis of the data demonstrates the common features of the thermal degradation process between alginic acid and pectin aerogels, and a wide range of biomass, and provides a comprehensive understanding of the properties of carbonized materials at any given temperature. An advancement in the preparation of highly-porous polysaccharide aerogels, using a novel freeze drying route, is reported. This development promises to lead to faster, lower cost and lower waste production of Starbons. The process is universally applicable to starch, alginic acid and pectin-derived materials. Finally, this thesis reports a systematic in-depth investigation of adsorption of a range of phenols and naphthols on alginic acid-derived Starbons prepared at different temperatures and having different surface areas and pore volumes. The analysis of adsorption kinetics, isotherms, thermodynamics, and desorption provided a comprehensive understanding of the factors governing and influencing the adsorption processes. Starbons demonstrate quantitatively greater desorption than conventional activated carbons.