POLYOLEFIN INTERPENETRATED NETWORK FOR OIL SPILL RECOVERY: SYNTHESIS, CHARACTERIZATION, AND APPLICATION

Open Access
Author:
Nam, Changwoo
Graduate Program:
Materials Science and Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
October 03, 2016
Committee Members:
  • Tze-Chiang Chung, Dissertation Advisor
  • Tze-Chiang Chung, Committee Chair
  • Ralph H Colby, Committee Member
  • Michael Anthony Hickner, Committee Member
  • Fred Scott Cannon, Outside Member
Keywords:
  • polyolefin
  • crude oil
  • interpenetrated polymer network
  • decene/DVB
  • oil cleanup
Abstract:
In light of BP (British Petroleum) oil spill in the Gulf of Mexico in 2010, and despite the government’s "all hands on deck" approach to combating the oil spill, there was no effective technology for removing, recovering, and cleaning up oil spills or oil slicks from the surface of sea water and shorelines. A new class of polyolefin copolymers with an interpenetrating network (IPN) structure is considered as a practical and comprehensive solution for oil spill recovery and cleanup. After discussing some background information (Chapter 1) and current sorbent technology (Chapter 2), I will explain my research approach and experimental results, involving various polyolefin absorbent materials for oil and hydrocarbon spill recovery. To understand the structure-property relationship in polyolefin absorption capacity and kinetics, a systematic study (Chapter 3) was first conducted using a series of semicrystalline ethylene/1-octene copolymers (LLDPE thermoplastics with a broad range of crystallinity) and amorphous cross-linked 1-decene/DVB (x-D/DVB) copolymers (elastomers with a wide variety of crosslinking density). They are swellable but not soluble in any hydrocarbon liquids under ambient temperature conditions. The absorption evaluation involved various hydrocarbon liquids, including solvents (hexane, cyclohexane, and toluene), refined oil products (gasoline, diesel, and petroleum oil) and Alaska North Slope (ANS) crude oil. In general, the absorption capacity is controlled by the network structure. The maximum absorption capacities of semi-crystalline LLDPE and amorphous x-D/DVB elastomer with toluene can reach 35 and 43 times that of the polymer mass, respectively. However, with the complex oils, the absorption profile is determined by a iv combination of absorbate composition and absorbent network structure and morphology. Both polymer systems exhibit poor absorption performance with ANS crude oil. The systematic study provides important information about how the polymer structure and morphology affects the hydrocarbon absorption capacity and kinetics. Thus, a new polyolefin IPN structure was designed and fabricated by the combination of two polyolefin copolymers, including semicrystalline LLDPE thermoplastics and amorphous x-D/DVB elastomers (Chapter 4). The IPN structure allows the formation of porous morphology with relatively high free volume between two intertwined rigid and soft polymer chains, which enhances the diffusion of highly viscous hydrocarbon liquids and the swelling capacity of the polymer matrix. Some resulting polyolefin IPN structures show a very high hydrocarbon absorption capacity (>40 times by weight) and fast kinetics for all examined hydrocarbon absorbates, independent on the type of organic solvents and oils. The selective oil absorption (without water) offers buoyancy, stability, and easy recovery on water surfaces. In addition, the recovered oil swollen gel, containing >97% oil and <3% polyolefin (which is completely thermally degradable to small hydrocarbon molecules), is suitable for the regular oil-refining process (an economical, no waste, and no pollutant approach). Once the desirable polyolefin IPN structure was validated in the laboratory, a scale-up study was performed with the target of developing a commercial process that can be used for the large-scale production (Chapter 5). More than 20 pounds polyolefin IPN material have been delivered to DOI BSEE for an operational test at the Ohmsett (NJ, USA) facility. They had successfully examined the recovery of ANS crude oil spilled in seawater (salinity 29-33 ppt) under outdoor cool weather environment with similar 40 times ANS oil v absorption capacity and fast kinetics. In addition, the tests were focused on the recovery of resulting absorbed oil adduct (gels) on the water surface by skimmers and the pumping ability of the fully swollen gel by common crude oil delivery methods. In economic considerations, polyolefins are the least expensive polymeric materials, with a large production capability in the United States and around the world. With a conservative estimate, the production cost of new polyolefin INP material may be below $2 per pound in the large-scale industrial production. One pound of this polymer with 40 times absorption capacity can recover more than 5 gallons of the spilled oil (that would become pollutant/waste) to be used as regular crude oil that is worth more than $8 (based on $60/barrel). Most importantly, it can mitigate the huge environmental impacts caused by oil spills. Overall, this new polyolefin IPN absorbent material exhibits a combination of benefits in oil recovery and cleanup, including (i) High oil absorption capability (over 30 g/g) (ii) Fast kinetics (30 times within 2 hr) (iii) No water absorption (iv) Easy recovery from water surface and transporting to storage tank (v) The recovered oil-swelled i-Petrogel as regular crude oil for refinery (vi) No waste in natural resources and no air/water pollutions (vii) Cost effective and economic feasible.