FABRICATION, CHARACTERIZATION AND OIL SPILL REMEDIATION PROPERTIES OF EXFOLIATED GRAPHITE

FABRICATION, CHARACTERIZATION AND OIL SPILL REMEDIATION PROPERTIES OF EXFOLIATED GRAPHITE

ABSTRACT

Severe damages frequently occur each year worldwide due to the effect of oil spills, where  crude oil is considered as one of the most aggressive liquids to the environment especially when accidentally spilled in large amounts. Suez Canal, Egypt, was one of the water sheds that suffered from the impact of crude oil spill especially the one dated December 14, 2004 10,000 tons of spilled crude oil. The aim of this research was to synthesize, test and develop a sorbent material capable of adsorbing crude oil spilled from water. Previous studies showed that exfoliated graphite (EG) is a promising material that can be used to adsorb hydrocarbon compounds. However, finding the proper way to utilize the EG is still a challenging problem. Also, the effect of some parameters such as temperature and type of the crude oil has not been widely investigated. The research herein had the following goals: (1) assess the effect of the exfoliation temperature on the sorption efficiency and the properties of the product; (2) assess and compare the effect of two different exfoliation time on the sorption efficiency and the properties of the product; and (3) find an applicable form of the exfoliated graphite for the oil spill remedy application.

To this end, the exfoliation time was found to have a great impact on the exfoliation volume and consequently on the crude oil sorption capacity, where the rate of expansion increases gradually and then decreases until the exfoliation temperature reaches 800 ⁰C. After this temperature, there is no significant impact for the exfoliation time, however the exfoliation volume continues to increase with a very low rate. Also, the exfoliated graphite density was found to decrease gradually from 44 g/l at 400C to 3.10 g/l at 1000C for the samples exfoliated for 60 seconds, and from 45.44 g/l at 300C to 3.31 g/l at 1000C for the samples exfoliated for 120 seconds. The x-ray diffraction (XRD) for the graphite exfoliated for 60 seconds showed that the sulfur still exists in the exfoliated sample at 950C. However, there no sulfur was detected after exfoliation at 1000C with the XRD data did not show any sulfur content for the tested samples exfoliated for 120 seconds starting from 650C. On the other hand, SEM/EDS detected sulfur content in all the samples exfoliated for 60 s and 120 s, which decreases as the exfoliation temperature increases, even after exfoliation for 120 s at 1000C. The maximum sorption capacity achieved is ~ 82 (kg of oil/kg of sorbent) which is about double the capacity of any other natural sorbent material reported so far. It was expected that the sorption capacity would increase with increasing the atmospheric temperature, however an interesting finding was that there is a minimal effect of atmospheric temperature on the sorption capacity of the exfoliated graphite when tested for Pennsylvania crude oil sorption. It was found also that the applicability of the EG is greatly modified by using fiber glass as a packaging material giving a maximum adsorption capacity of ~ 68 kg of crude oil per kg of the new composite material introducing the maximum sorption capacity for the applicable form of the exfoliated graphite.

 

TABLE OF CONTENTS

LIST OF FIGURES ………………………………………………………………………………………………….. v

LIST OF TABLES ……………………………………………………………………………………………………. vi

ACKNOWLEDGEMENTS ……………………………………………………………………………………….. vii

Chapter 1  Introduction ……………………………………………………………………………………………… 1

Chapter 3  Materials and Methods ………………………………………………………………………………. 11

Chapter 4  Results and discussion ……………………………………………………………………………….. 18

Chapter 5  Conclusions ……………………………………………………………………………………………… 41

Chapter 6  Future Work …………………………………………………………………………………………….. 42

Appendix  ………………………………………………………………………………………………………………… 43 References ……………………………………………………………………………………………………………….. 45

Chapter 1

 

Introduction

Millions of tons of crude oil are transported every year from the origin to the points of distillation and then to the consumers which may also pass through another one or more processing operations before consumption. These long ways of transportation increase the risk of spills. According to the Oil Spill Intelligence Report (1), almost  every week there is a new oil spill hits a water shed or country coast causing sever damages to the environment which accordingly lead to spending millions of dollars for a partial remediation of the problem. Nineteen years ago, the Exxon Valdez oil spill hit the reef of Prince William Alaska with 262,000 barrels containing more than 40,000 tons of crude oil. The estimated payout for the damages was 383.4 million dollars (1). However, the total cost of the cleanup exceeded 9.00 billion USD (21). Since this accident, a lot of precautions have been taken to avoid facing such a problem again.

However, no complete prevention of the serious spills was adapted till now. For example, later in December 7, 2007 a huge crude oil carrier in South Korea named Hebei Spirit spilled over 10,000 tons of crude oil which caused an economic disaster for 40,000 persons along a 375 kilometers of the western coast of the country, The government expected that the cost of the damages would exceed 500 million dollars (1).

The Suez Canal is one of the most important transportation ways in the world which connects the red sea to the Mediterranean Sea. It is a shortcut for those who are coming from America and Europe targeting the crude oil sources at the Middle East region. The way around

Africa is thousands of miles longer which increases the fuel consumption, labor cost and dangers. For these reasons, The Suez Canal hosts over 500 million tons of crude oil and its products every year. Accordingly, the risk of oil spills in this area is higher than any other place in the world.

One of the most severe oil spills that hit Suez Canal water shed was at December 14, 2004, when more than 10,000 tons of crude oil was spilled in the 365 meters maximum width canal, extremely affecting the fishery resources, wild life, the recreation resorts and the livelihoods of the families in a some villages along the canal who totally depend on fishing as the only source of income. Therefore, the need of rapid and efficient treatment techniques is essential.

To this end, the objectives of this research were to synthesize, test and develop a sorbent material capable of adsorbing crude oil spilled from water. Exfoliated graphite (EG) is expected to be a promising material to remove spilled crude oil. The effect of some parameters such as temperature and type of the crude oil are expected to be determinant factors for its efficiency. Therefore, the goals behind this research were to: (1) assess the effect of the exfoliation temperature on the sorption efficiency and the properties of the product; (2) assess and compare the effect of two different exfoliation time on the sorption efficiency and the properties of the product; and (3) find an applicable form of the exfoliated graphite for the oil spill remedy application.

FABRICATION, CHARACTERIZATION AND OIL SPILL REMEDIATION PROPERTIES OF EXFOLIATED GRAPHITE

Sharing is caring!