Chemical characterization of imperata cylindrical (`Lalang`) and pennisetum purpureum (Napier grass) for bioethanol production in Malaysia

Grass is a candidate biomass producer because it is fibrous and it thrives well on poor soils. The chemical properties of two grass species growing naturally and abundantly on idle lands in Malaysia were investigated in this study. The grasses selected were Imperata cylindrical (`Lalang`) and Pennisetum purpureum (Napier grass). For the purpose of analysis, Napier grass was further divided into male and female plants, and stem and leaves. Lignin, hemicellulose and cellulose contents were determined using the TAPPI standard methods. `Lalang` was found not to be an attractive biomass producer because of its high lignin content (22%) (P<0.05). On the contrary, Napier grass, particularly the female stem, had low lignin content (13%) (P<0.05) and a favourably high level of cellulose (46%) (P<0.05). In the female leaf, lignin content was higher (20.7%), while the cellulose content (30.4%) was lower compared to the stem. Although the cellulose content in the male stem (51%) was slightly higher (P<0.05) than the female, its lignin was two-fold above that of the female stem, making it a less desirable biomass producer. Hence, it was concluded that female Napier grass has a good potential of becoming a biomass producer in bioethanol production in Malaysia

Effect of pretreatment process on bioconversion of kenaf (hibiscus cannabinus l.) core to glucose.

Kenaf (Hibiscus cannabinus L.) is a renewable carbon-rich lignocellulosic resource for fermentable sugars. In this study, kenaf cores cultivar V36 from four-month-old stems were pretreated by i) physical, ii) physical and thermal, and iii) physical and chemical methods. The celluloses of pretreated kenaf core particles were then hydrolyzed into fermentable sugars by cellulase from Trichoderma reesei (C2730). The pretreated kenaf core particles were incubated for 48 h at 37 °C. The efficiency of bioconversion was mainly dependent on the pretreatments applied prior to the hydrolysis process. The effects of the pretreatments on kenaf core’s lignin, holocellulose, and cellulose contents were also determined. Kenaf cores without pretreatment had 19.4% lignin, 86.2% holocellulose, and 47.4% alpha-cellulose. The combination of physical and chemical pretreatment on kenaf cores cultivar V36 resulted in a higher cellulose content (92.49%) and produced 50 times higher sugar concentration than the physical pretreatment

Conversion of lignocellulosic materials from local grass to bioethanol

Grass is a candidate biomass producer because it is fibrous and it thrives growing on poor soil. The chemical properties of two grass species growing naturally and abundantly in idle lands in Malaysia were investigated. Grass selected were ‘Lalang’ (Imperata cylindrica) and Napier grass (Pennisetum purpureum). For the analysis, Napier grass was further divided into male and female plants, and stem and leaves. Lignin, hemicellulose and cellulose contents were determined using the TAPPI standard methods. ‘Lalang’ appeared not to be an attractive biomass producer because of its high lignin content (22%). On the contrary, Napier grass, particularly the female stem had low lignin content (13%) and a favorably high level of cellulose (46%). In female leaf, lignin content was higher (20.7%) while cellulose (30.4%) was lower, when compared to the stem. Although cellulose content in the male stem (51%) was slightly higher than the female, its lignin was two-fold above that of the female stem, making it a less desirable biomass producer. With the results obtained it was concluded that female Napier grass in Malaysia has a good potential of becoming a biomass producer. Female Napier grass, the best grass candidate was selected to undergo two different pretreatments, alkali pretreatment and biological pretreatment. Alkali pretreatment was carried out at four different NaOH concentrations: 1%, 5%, 7% and 10%. Alkali pretreated materials were subjected to Trichoderma reesei ATCC 26921 enzyme hydrolysis; several hydrolysis parameters were tested to optimize glucose yield including temperature and agitation, by applying the Response Surface Method (RSM). HPLC revealed that samples pretreated with 5% NaOH had glucose content of 7.47g/L and 7 % NaOH yielded glucose content of 7.4g/L. There was no difference between 5% and 7% NaOH pretreated material. However between the two, 7 % NaOH can be considered as a better pretreatment because the glucose yield was consistent throughout the parameters of temperature and agitation; these two parameters can affect the optimum activity of cellulase in converting cellulose to glucose. From RSM analysis, glucose yield was optimal at 38.5˚C and 175rpm. When using the whiterot fungus, Phanerochate chrysosporium as biological pretreatment, followed by Trichoderma reesei ATCC 2692 enzyme hydrolysis at constant enzyme loading of 1ml with 1g of material, samples pretreated for three weeks gave the highest glucose yield (4.5g/L). However, the yield was lower than the alkali pretreated grass. On looking at the efficiency of these two pretreatments, alkali pretreatment was a better pretreatment as it yielded higher glucose content compared to biological pretreatment, despite the ease of handling and time consuming of the experiment conducted. Hydrolysates from the pretreatments were fermented using the ethanol insensitive strain Escherichia coli K011 at 35˚C and 100rpm, and the ethanol content was detected by Gas Chromatography (GC). After 24 hours of fermentation, alkali pretreated material yielded 37.7% ethanol while biological pretreated material yielded 24.4% ethanol. It was observed that alkali pretreated grass material gave out higher ethanol yield. These results indicated that Malaysia’s female Napier grass is capable of becoming an important biomass for producing bioethanol

Pretreatment methods on Malaysian weedy grass (Pennisetum purpureum) for bioethanol production.

Grasses are often regarded as weeds, yet they are abundant in lignocellulosic material. They can thrive throughout every climatic region, tolerate poor marginal soils and have no seasonal commitment. Here, we report the potential of a local Malaysian grass Pennisctum pirrpurmrn (Napier grass) as a biomass feedstock for bioethanol production. We compared two pretreatments on the raw plant material for the purpose of breaking-down lignin, a recalcitrant component in the fiber, which resist the release of cellulose in the plant cell wall. Lignin breakdown eventually enhances the efficiency of converting cellulose into glucose. Alkali pretreatment was carried out at four different NaOH concentrations: 1%, 5%, 7% and 10%. Alkali-pretreated materials were subjected to cellulase hydrolysis; several hydrolysis parameters were tested to optimize glucose yield including temperature and agitation, by applying the Response Surface Method (RSM). HPLC revealed that the glucose content in samples that were pretreated with 7% NaOH gave the highest yield (7.4 g/L). In addition, the glucose yield was not influenced by changes in hydrolysis parameters, therefore it was concluded as the most suitable pretreatment concentration. When using a white-rot fungus, Phanerochaebe chlysosporizrm as biological pretreatment followed by enzime hydrolysis, samples treated for the: weeks gave the highest glucose 1-ield (4.5 g/L). We demonstrated that Malaysian weedy grass is a potential lignocellulosic biomass that may serve as a cheap feedstock for bioethanol production

Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field