Abstract

This dissertation investigates potential methods for enhancing biomass pyrolysis by examining different process conditions and the feasibility of mixing feedstock through the utilization of nitrogen-rich biomass. The biomass selection is based on species strategic to the Kingdom of Saudi Arabia and consists of (1) Salicornia bigelovii (SB), a halophyte that can thrive in harsh environments and has a high tolerance to salinity and (2) algal biomass which has high productivity and is able to grow in non-arable land and waste streams. This thesis begins with understanding the composition of the pyrolysates of SB pyrolysis in N₂ atmosphere. The bio-oil produced from SB was found to have various oxygen- and nitrogen-containing compounds, resulting in a corrosive and chemically unstable fuel. Additionally, the biochar was found to have a low surface area, limiting the possible applications of the biochar. Three enhancement methods were used to improve the quality of biochar and bio-oil from conventional pyrolysis in the N₂ atmosphere. First, the effect of changing the pyrolysis environment to a CO₂ atmosphere was explored by performing a detailed kinetic analysis and investigating the pyrolysis products. The CO₂ atmosphere resulted in a more stable biochar with a larger specific surface area compared to that produced in a N₂ atmosphere. Second, co-pyrolysis of SB with heavy fuel oil (HFO), a hydrogen rich feedstock, was explored through an investigation of yields, kinetics, interactions, and quality of bio-oil and biochar produced. The bio-oil collected from the mixtures had a reduced amount of oxygenated compounds and an increased amount of aliphatic and aromatic hydrocarbons. Finally, microwave-assisted heating was adopted to replace the conventional heating system previously used for SB pyrolysis. Biochar was produced by microwave-assisted pyrolysis (MAP) of SB, seaweed and 8 microalgae species, Spirulina platensis (SP), Chlorella vulgaris (CV), Tetraselmis chuii (TC), Haematococcus pluvialis (HP), Nannochloropsis oceanica (NO), Phaeodactylum tricornutum (PT), Dunaliella salina (DS), and Chlamydomonas reinhardtii (CR). The produced biochar was pretreated with water and activated with potassium hydroxide (KOH) to further enhance the biochar surface for adsorption applications. A detailed characterization of the biochar confirmed the enhancement results of the MAP and KOH activation. The biochar samples were tested for the removal of Pb and As from synthetic wastewater