Biofuels produced from various lignocellulosic materials, such as wood, agricultural, or forest residues, have the potential to be a valuable substitute for, or complement to, gasoline. Many physicochemical structural and compositional factors hinder the hydrolysis of cellulose present in biomass to sugars and other organic compounds that can later be converted to fuels. The goal of pretreatment is to make the cellulose accessible to hydrolysis for conversion to fuels. Various pretreatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. During the past few years a large number of pretreatment methods have been developed, including alkali treatment, ammonia explosion, and others. Many methods have been shown to result in high sugar yields, above 90% of the theoretical yield for lignocellulosic biomasses such as woods, grasses, corn, and so on. In this review, we discuss the various pretreatment process methods and the recent literature that has reported on the use of these technologies for pretreatment of various lignocellulosic biomasses.

Nanoscience has matured significantly during the last decade as it has transitioned from bench top science to applied technology. Presently, nanomaterials are used in a wide variety of commercial products such as electronic components, sports equipment, sun creams and biomedical applications. There are few studies of the long-term consequences of nanoparticles on human health, but governmental agencies, including the United States National Institute for Occupational Safety and Health and Japan’s Ministry of Health, have recently raised the question of whether seemingly innocuous materials such as carbon-based nanotubes should be treated with the same caution afforded known carcinogens such as asbestos. Since nanomaterials are increasing a part of everyday consumer products, manufacturing processes, and medical products, it is imperative that both workers and end-users be protected from inhalation of potentially toxic NPs. It also suggests that NPs may need to be sequestered into products so that the NPs are not released into the atmosphere during the product’s life or during recycling. Further, non-inhalation routes of NP absorption, including dermal and medical injectables, must be studied in order to understand possible toxic effects. Fewer studies to date have addressed whether the body can eventually eliminate nanomaterials to prevent particle build-up in tissues or organs. This critical review discusses the biophysicochemical properties of various nanomaterials with emphasis on currently available toxicology data and methodologies for evaluating nanoparticle toxicity.

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