Electronic Theses and Dissertations

Date of Award

1-1-2020

Document Type

Dissertation

Degree Name

Ph.D. in Engineering Science

First Advisor

Baharak Sajjadi

Second Advisor

Sasan Nouranian

Third Advisor

Daniell L Mattern

School

University of Mississippi

Relational Format

dissertation/thesis

Abstract

A series of my researches aim to develop an advanced suitable carbon activation techniques using ultrasound waves, and chemical functionalization for the application of environmental remediation. Ultrasound irradiation exfoliates the graphitic layers of biochar, and creates new/opens the blocked pores, thus creating active sites for chemical activation using amine. CO2 is one of the major air pollutants and a leading cause of the global warming. Thus, it is imperative to establish a proper CCS technology. Reductive photocarboxylation could be an effective way to attach CO2 on carbonaceous structure such as biochar. Biochars have highly porous structure, high surface area and graphitic oxide clusters that consist of the reactive oxygen functional groups such as ̶ COOH, C=O, ̶ OH that are susceptible to amine functionalization. Amine, a nucleophile, can react with CO2, which is an electrophie, to boost adsorption efficiency of the biochar. Furthermore, to identify the impact of amination, the work was carried out in the presence of two different activating agents carbodiimide-benzotriazole and potassium hydroxide and five different amines - tetraethylenepentamine, diethanolamine, monoethanolamine, polyethylenimine, piperazine and their binary and ternary mixtures. The work was further extended to investigate the role of different biomass origin on CO2 capture. Biochars were synthesized from herbaceous, agro-industrial and crop based biomasses and were subjected to three different treatment conditions that involved- I. physical activation, II. chemical activation and III. integrated ultrasonic-amine activation. The last step of this series of works involved investigating the synergistic and antagonistic impact of pyrolysis temperature (in the range of 500-800 ºC) on ultrasound activation and the subsequent CO2 adsorption. It is worth to mention that the conventional carbon activation requires elevated temperature (>700 ºC) and prolonged activation time (>3 hrs). While the method discussed in this dissertation was conducted at near ambient temperature for a very short duration (~30-60sec) and consumes a significantly lower level of energy than conventional carbon activation processes. In addition, this advanced carbon modification method can be adopted for other environmental applications, in addition to CO2 capture and pollutant removal from water and air.

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