Cellulose Aerogel from Paper Waste for Crude Oil Spill Cleaning Son T. Nguyen, † Jingduo Feng, † Nhat T. Le, ‡ Ai T. T. Le, ‡ Nguyen Hoang, ‡ Vincent B. C. Tan, † and Hai M. Duong* ,† † Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575 ‡ R&D Center for Petroleum Safety and Environment (CPSE), Vietnam Petroleum Institute (VPI), Ward 27, Binh Thanh District, Hochiminh City, Vietnam ABSTRACT: Polyprolylene is commonly used for crude oil spill cleaning, but it has low absorption capacity and is nonbiodegradable. In our work, a green, ultralight, and highly porous material was successfully prepared from paper waste cellulose fibers. The material was functionalized with methyltrimethoxysilane (MTMS) to enhance its hydrophobicity and oleophilicity. Water contact angles of 143 and 145° were obtained for the MTMS-coated recycled cellulose aerogel. The aerogel achieved high absorption capacities of 18.4, 18.5, and 20.5 g/g for three different crude oils at 25 °C, respectively. In the investigated temperature range of 10, 25, 40, and 60 °C for the absorption of the tested crude oil on the aerogel, a highest absorption capacity of 24.4 g/g was obtained. It was found that the viscosity of the crude oils is the main factor affecting their absorption onto the aerogel. The strong affinity of the MTMS-coated recycled cellulose aerogel to the oils makes the aerogel a good absorbent for crude oil spill cleaning. 1. INTRODUCTION Oil spills have been considered as one of the most serious disasters that are threatening the marine ecosystem. Recently, the explosion of a drilling rig in the Gulf of Mexico caused significant environmental damage. Oil spills are usually related to accidents in oil production, storage, and transportation. As long as fossil fuels are needed, oil spills are still a big problem that human beings are facing. 1-7 Therefore, it is essential to solve this environmental problem. There have been many ways for oil spill cleanup classified as chemical, biological, and physical methods. Dispersion, in situ burning, and solidification are considered to be chemical methods which are complicated and expensive. Use of microorganisms in the biological methods is effective but it requires a long time, and the microorganisms are affected by pH, temperature, oxygen content, etc. In physical methods, booms and skimmers are often used, but they cannot remove oil from sea effectively. Among these methods, sorption has been considered to be one of the most effective ways for oil spill cleaning due to its ability of collection and the complete removal of oil from oil spill sites. 6,8-15 There have been several materials used as absorbents for oil spill cleaning in research and real applications. The oil absorbents can be catergorized as inorganic mineral, synthetic organic, and natual organic materials. 9,10,12,13 Inorganic materials (i.e., vermiculite, exfoliated graphite, diatomite, fly ash, etc.) 16-18 have low oil absorption capacity. Meanwhile, synthetic organic materials (i.e., polypropylene, polyurethane, etc.) 10,12,13 possess high affinity to oil but cause a waste problem after use due to their slow degradation. Natural organic materials from plants and animal residues, such as kapok fiber, sugar cane bagasse, rice husk, coconut husk, cotton, wool, sawdust, chitosan, etc., have been examined for oil absorption. 19-21 However, most of the materials show low oil absorption ability and also absorb water. Therefore, there is a high demand for finding new environmentally friendly absorbents with high oil absorption capacity, good selective- ness, and low cost for oil spill removal. Aerogels are the world’s lowest-density solid materials, composed of up to 99.98% air by volume but also highly porous and extremely rigid, capable of bearing weight many times their own. Aerogels are a diverse class of amazing materials with advanced properties. Transparent superinsulat- ing silica aerogels exhibit the lowest thermal conductivity of any solid known. Ultrastrong, bendable x-aerogels are the lowest- density structural materials. 22-27 Normally aerogels are brittle and fracture under too much force. Overcoming the character- istic stiffness of the aerogels could open up a whole new range of uses such as oil absorption applications. In order to circumvent the stiffness, cellulose is chosen. Cellulose, better known as “plants, mostly”, is normally used to make products such as paper and cardboard, but some forms of cellulose can also be quite strong. 28,29 One of the best methods to make aerogel out of cellulose is to freeze-dry it, removing all moisture and leaving nothing but a web of pure, solid fibers. 25,30,31 The increase of paper comsumption has been creating a huge amount of paper waste which contributes 25-40% of global municipal solid waste. 32 Recycling paper waste will help to preserve forests as well as solve the environmental problem. Recycled cellulose fibers from paper waste are a cheap and abundant resource. A combination between aerogel structure and recycled cellulose fiber will form a new materialnamed “recycled cellulose aerogel”which is cost-effective and promising for oil absorption. Although there have been some studies on using cellulosic materials for oil absorp- tion, 4,6,29,33-36 no studies have been carried out on fabricating aerogels from paper waste cellulose fibers and investigating Received: October 1, 2013 Revised: December 4, 2013 Accepted: December 5, 2013 Published: December 5, 2013 Article pubs.acs.org/IECR © 2013 American Chemical Society 18386 dx.doi.org/10.1021/ie4032567 | Ind. Eng. Chem. Res. 2013, 52, 18386-18391