1. IntroductionCatastrophic oil spi

1. Introduction
Catastrophic oil spills such as those in Gulf of Mexico remind us of the necessity of prompt action to develop an environmentally friendly and cost-effective technology for minimizing environmental consequences. Oil absorbent is a promising way to deal with oil spillage with high clean-up efficiency. The sorbent materials used for oil spill clean-up can be classified into three typical groups: synthetic polymers, natural fiber materials and inorganic minerals. Commercially available oil absorbents are non-biodegradable synthetic organic products (e.g. polypropylene and polyurethane) and may cause serious disposal problems after their usage. The inorganic absorbents such as vermiculite (Machado et al., 2006), exfoliated graphite (Wang et al., 2010 and Yue et al., 2009), zeolite (Sakthivel, Reid, Goldstein, Hench, & Seal, 2013), silica (Yang et al., 2007) and calcium carbonate powder (Arbatan, Fang, & Shen, 2011) have poor buoyancy and oil absorption capacity. In this case, the utilization of organic natural materials such as agricultural waste is much more attractive due to their high biodegradability and low cost. Agricultural waste such as cellulosic fibers (Payne, Jackson, Aizpurua, Rojas, & Hubbe, 2012), rice husk (Genieva, Turmanova, Dimitrov, Petkov, & Vlaev, 2012), cotton (Zhang et al., 2013 and Zhou et al., 2013), kapok fibers (Wang, Zheng, & Wang, 2012), sawdust (Li, Pan, Huang, & Scholz, 2013), corn straw (Peng, Lan, Guo, Yang, & Dang, 2013), milkweed (Rengasamy, Das, & Karan, 2011) and banana fiber (Teli & Valia, 2013) all exhibit good oil absorbency.