Thermogravimetry (TG) is a special measure of thermal degradation, where weight losses are calculated with the increases of temperature and time. Sometimes, TG is used to examine the kinetics of the physicochemical change involved in thermal reaction. Figures 10.4 and 10.5 and Table 10.5 show the TG & DTG for comparison among untreated OBF, 9 wt% OBF-PFR, 19 wt% OBF-PFR, 29 wt% OBF-PFR, 38 wt% OBF-PFR composites and 100 % PFR. It is seen that initial decomposition temperature (7]) and final decomposition temperature (Tf) are found highest for PFR and lowest in case of OBF. Here, TG curve of composite samples shows two steps degradation: first is related to fibre degradation and the second is related to PFR degradation. Among the composite samples, 38 wt% OBF-PFR composite has the

lowest onset and decomposition temperature. It shows that 38 wt% OBF-PFR composites degrade in higher percentage than other composites, maybe due to moisture loss and more volatile content in fibre. The residual char or ash content at 600 °C temperature is higher in the case of OBF, and it decreases with the increases of PFR content in composites and the lowest value is found for pure PFR sample.

The first derivative of the sample weight with respect to time at constant tem­perature is termed as DTG. The DTG curves in Fig. 10.5 show rate of weight loss with temperature. The PFR gives single degradation peaks. On the other hand, fibre and composite samples show multiple degradation peaks due to weight loss in different stages of moisture and various constituents of fibre.

The main step after the bulk cultivation of algae is its harvesting, which performs a very vital part in shaping the process budget of algal biofuels. Despite the excessive presence of algal biomass, the harvesting of macro-algal biomass is considered as simpler and less costly as compared to the harvesting of algal biomass. Due to the diluted nature of algal culture cells and small size, the operating expenses of dewa­tering and harvesting of algal biomass is high. The typical size of single-celled eukaryotic algae is measured around 3-30 pm (Grima et al. 2003), and the range of cyanobacteria is 0.2-3 pm (Chorus and Bartram 1999) . The improvement and wide-scale application of different technologies for energy generation is currently a great challenge and of a significance to the scientists and the machinists of active systems. It is generally believed that numerous roots, properties, and active transfor­mation of biomass are the main bases of renewable energy (McKendry 2002; Goyal et al. 2008). A number of procedures including chemical as well as mechanical can be performed, which includes centrifugation, flotation, flocculation, filtration, screening and gravity sedimentation, and electrophoresis for harvesting of algal biomass (Uduman et al. 2010). There are critical parameters to consider for the selection process of algae for harvesting. Such parameters include density, size, and value of the desired products. Two-step processes are usually used for the har­vesting of algae:

1. Bulk harvesting: This step is performed for the separation of algal biomass from the bulk suspension. The techniques that can be used to complete this process are flocculation, flotation, or gravity sedimentation.

2. Thickening: the second step required for harvesting of algae is thickening which is performed to thicken the slurry by filtration or centrifugation (Brennan and Owende 2010).

The most important and the most operative method used for the separation of algal biomass is by centrifugation technique in algae harvesting, but it is only done on high-valued products due to high operational and functional cost (Grima et al. 2003).

13.5.1 Flocculation

This is the process in which circulated algae cells are combined together to form bulky biomass collection for settling. The precipitate of carbonates with algal cells at high pH, due to CO2 ingestion by the algae, results in auto-flocculation (Sukenik and Shelef 1984).

Sugarcane straw can help to increase the moisture content and reduce soil evapora­tion that improve the water use efficiency. Sugarcane has been covered by straw up to 90 days after transplantation due to the increase in the moisture holding capacity for good emergence. Tominaga et al. (2002) reported that soil moisture content was higher in sugarcane field without straw burning than other sugarcane plots burned before harvest and bare soil plots. On the other hand, higher sugarcane production was observed in the unburned management using the APSIM model in South Africa which was related to higher soil moisture content (Thorburn et al. 2002). Shrivastava et al. (2011) reported that sugarcane straw covered on interrow spaces around 0.1 m thick exhibited the highest efficient use of irrigation water by reduc­ing the evaporation loss from the surface of soil. They found that the sugarcane straw maintained the water content of soil at maximum level for a longer duration than the uncovered soil surface. Therefore, sugarcane straw without burning enhanced around 10 % yield.

16.4.2 Soil Carbon Stock

The soil carbon stock increases when the sugarcane straw is left on the ground without burning. Wood (1991) reported that soil carbon stock was 20 % higher in the

0. 0-10.00 cm depth in areas without burning than burned areas under straw man­agement experiments in Australia. Canellas et al. (2003) reported that concentrations of carbons were 22.34 g kg-1 in the cane with straw management and 13.13 g kg-1 in the burned cane in the 20 cm soil depth in Southeastern Brazil. The soil carbon stocks increase about 15 % in the 0.1 m layer after 6 years of green cane management, compared to the burning management (Razafimbelo et al. 2006) . Galdos et al. (2009) reported that soil carbon stocks increased up to 30 % after 8 years of conver­sion due to mechanizing harvest with crop residue management on the field. It is revealed that sugarcane straw is capable to increase the soil carbon stocks in the soil under straw management.

Keeping in view the bio-extraction potential of microalgae along with biomass pro­duction, such integrated systems that use microalgae for treating waste water and producing oil for biodiesel and chemical products are gaining interests globally. It has demonstrated that dual-use of microalgae cultivation for waste water treatment coupled with biofuel generation is an attractive option for reducing energy, fertil­izer, and freshwater costs of production along with reduced GHG emissions (Pittman et al. 2011; Park et al. 2011; Menger-Krug et al. 2012). A group of researchers have claimed that microalgae-mediated CO2 fixation coupled with biofuel production is more sustainable if we integrate biomass production with wastewater treatment (Kumar et al. 2010). Actually, cultivation of microalgae consumes more fertilizers as compared to the most common oleaginous plants. For instance, N-fertilizer consumption in the range of 0.29-0.37 kg kg-1 oil is reported, which is higher than that for Jatropha and palm oil where 0.24-0.048 kg of fertilizer is required per kg oil production, respectively (Lam and Lee 2012). So, use of waste water enriched with nutrients will undoubtedly decrease the cost of production.

Moreover, although microalgae grow in an aquatic medium yet they require less water than terrestrial oleaginous crops while making use of saline, brackish, and/or coastal seawater (Kliphuis et al. 2010; Rodolfi et al. 2009). This allows the production of algal biomass without competing for valuable resources such as arable land, land­scapes, and freshwater. The microalgae Nannochloropsis sp., Dunaniella salina, Chlorella sp., and Etraselmis sp. were found suitable for a multiple-product algae crop. The tropical and sub-tropical microalgae display a variety of fatty acid profiles making algal biomass production more attractive to obtain oil-based bio-products, including biodiesel and omega-3 fatty acids (Lim et al. 2012). Conclusively, a biore­finery approach (integration of waste water treatment and algal biomass production) for microalgae would make the process economically feasible but challenges remain there regarding the efficient harvesting and extraction processes for some species.

Preface

Since the early times of human civilizations, biomass has been a major source of energy for the world’s people. Biomass energy or bioenergy, the energy from organic matter, is being used by human beings since thousands of years, ever since people started burning wood to cook food or to keep warm. Today still non-wood, forest residues, and agricultural biomass are our largest biomass resources. Biomass includes plants, residues from agriculture or forestry materials. So, the proper utili­zation of biomass can be environmentally friendly because, it will not only be able to solve the disposal problem but also can create value-added products from this biomass. It is also a renewable resource because plants to make biomass can be grown over and over and certainly as alternative source of energy. The use of agri­cultural biomass is constantly growing and will likely to continue to grow in future. It is estimated that utilization of biomass can also reduce global warming compared to fossil fuel. Energy crops, such as fast-growing trees and grasses, are called bio­mass feedstocks. The use of biomass feedstocks can also help to increase profits for the agricultural based industries.

Biomass obtained from agricultural residues or forest can be used to produce different materials and bioenergy required in a modern society. As compared to other resources available, biomass is one of the most common and widespread resources in the world. Thus, biomass has the potential to provide a renewable energy source, both locally and across large areas of the world. It is estimated that the total investment in the biomass sector will reach up to $104 billion from 2008 to 2021. Presently bioenergy is the most important renewable energy option and will remain so in the near and medium-term future. Previously several countries try to explore utilization of biomass in bioenergy and polymer composite sector. Biomass has the potential to become the world’s largest and most sustainable energy source and will be very much in demand. Bioenergy is based on resources that can be utilized on a sustainable basis all around the world and can thus serve as an effective option for the provision of energy services. In addition, the benefits accrued go beyond energy provision, creating unique opportunities for regional development.

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The present book “Biomass and Bioenergy,” volume 1, provides an up-to-date account of processing and properties of non-wood, forest residues, agricultural biomass (natural fibers) and its composites and bioenergy to ensure biomass utiliza­tion and reuse.

We wish to express our gratitude to all the contributors from all over the world for readily accepting our invitations and sharing their knowledge and expertise. We are thankful to authors for helping us to formulate diverse fields and also admirably integrating their scattered information from diverse fields in composing the chapters and enduring editorial suggestions to finally produce this venture that we hope will be a success. We greatly appreciate their commitment.

We are highly thankful to Springer-Verlag team for their unstinted cooperation at every stage of the book production.

Selangor, Malaysia Khalid Rehman Hakeem

Mohammad Jawaid Umer Rashid

Grass bamboo can be used in preparation of musical instruments like wind, string, and percussion instruments. Bamboo is ideally suited for manufacture of xylophone bars and chimes, flutes and organs, violins and zithers and violin bows. Bamboo plates can be used for forming body and neck of acoustic guitar as it is easily avail­able and is economical (Wegst 2008) . Bamboo is nearly immutable, and hence resistant to change. Bamboo is straight and cylindrical; this structure is best suited for production of musical instruments like flute (Grame 1962). Bamboo used for formation of musical instruments should be harvested at 3-5 years of age for high strength and durability (Diver 2001). Bamboo culms are also used for production of wind chimes (Perdue 1958).

The use of agricultural biomass has been proven in the laboratory scale and has been commercialized as an alternative to wood material. Characteristics, properties and compatibility of the fibres are essential for biomass integration into existing indus­trial production for various products. Studies conducted on the relationship between structure, network, physical and mechanical properties of biomass fibres shows that they are closely related to each other. These factors have influenced the use and application of biomass fibres, as for example in pulp and paper, textile and biocom­posite industry.

The IDL FRP composites under flexural loading beyond 15.55 % fiber volume fraction exhibited decreasing trend of flexural strength due to the lack of bond between the fibers and matrices. Figure 8.12 represents flexural strength against fiber volume fraction, where IDL CT FRP composite flexural strength is increasing with increase in volume fraction of the fiber. All the IDL CT FRP composites failed due to bend­ing only at the outer surface of the specimen. Though the IDL CT fiber volume fraction is 8.48 % less when compared with IDL fiber, the flexural strength of IDL CT FRP composites is 17.38 % more when compared with untreated fiber reinforced composites at maximum fiber volume fraction. From the Fig. 8.13, it is observed that the specific flexural strength of IDL CT FRP composites is 13.41 times higher than IDL FRP composites at maximum fiber volume fraction.

The flexural modulus of IDL CT FRP composites crossed its value after 15.5 % fiber volume fraction when compared with IDL fiber reinforced composites, as

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40 20 0

0 5 10 15 20 25 30 35

Volume fraction (%)

evidenced from Fig. 8.14. The determined flexural properties from the experimental results show the flexural modulus of treated and untreated FRP composites is increas­ing with increasing fiber content. In PALF fiber reinforced composites, the flexural properties at 30 % fiber content are very good, and its specific stiffness is 0.25 m x 106

(Uma Devi et al. 1997). The specific flexural modulus of IDL CT FRP composites have shown very good performance when compared with the composites reinforced with untreated IDL fibers, which is evident from Fig. 8.15.

For the energy production, the amount of biomass used by a specific power plant is limited by the quantity at which the high grade biomass can be delivered at a feasi­ble cost. The charges associated with the given amount of woody biomass were determined by the costs of stumpage, regression, harvesting, chipping and transpor­tation. For any organization, the quantity of biomass available at a given cost is also influenced by the transportation distance to some extent (Goerndt et al. 2013). The following subsections describe the ways and conventions used for the estima­tion of the woody biomass available for the power plants during energy production process. It also mean to provide the cumulative information regarding the costs associated with the purchase of woody biomass and other associated charges including delivery in the successive larger procurement and consumption areas.

14.7.1 Techniques to Improve the Interface Adhesion

The biggest challenge in developing of material composites based on natural fibers is the incompatibility between the hydrophilic fibers and the hydrophobic matrix. This incompatibility leads to a poor homogenization between fibers and the

polymer chains (Nazrul et al. 2010); as a result, a poor adhesion between both com­pounds is often seen (Pickering et al. 2007; Ku et al. 2011). Most studies refer to the modification of the interface of natural fibers or polymer matrix, to ensure compat­ibility between the fiber and the matrix (Huu Nam et al. 2011; Arrakhiz et al. 2012a). The treatment parameters used is a factor that influences the properties and characteristics of the result composites. Therefore, appropriate treatment tech­niques and parameters must be carefully selected to produce an optimal composite product. These techniques can be divided into two categories: physical and chemi­cal methods.

The physical treatments do not alter the chemical composition of the cellulose fiber and they are expensive (Belgacem et al. 1995). Stretching, calendering, ther­mal treatments are considered as an example of physical treatment (Belgacem et al. 1996; Liu et al. 1998). Other types of physical treatment are also found in the litera­ture as the electric discharge (corona, cold plasma). For example the electrical discharge treatment can modify the fiber surface from hydrophilic to hydrophobic by changing the surface energy (Belgacem and Gandini 2005; Kato et al. 1999).

The use of chemical treatments is for removing the non-cellulosic components in the fiber surface or for adding functional groups to increase connection with

polymer chains. Several chemical techniques were considered to improve the adhesion interfacial such as, grafting compatibilizer groups, addition of a coupling agent or cleaning the fiber’s surface. The alkali treatment is one of the standard chemical treatments using sodium hydroxide to remove amorphous and non-cellu — losic components from the fibers’ surface. The estherification or etherification of the hydroxyl groups found on the fibers’ surface is a possible technique to graft a func­tional group (Arrakhiz et al. 2012a). The use of maleic anhydride modified polypro­pylene (MAPP) as a coupling agent is another pathway to enhance the interface adhesion between fibers and matrix (Arrakhiz et al. 2012c). Fiber surface treatment may also increase the strength of the fiber; reduce the water absorption and surface tension between fiber and matrix.

The use of maleic anhydride grafted polypropylene; SEBS-g-MA as compatibil — izer between fibers and matrix improves the water resistance of fibers and enhance the wettability of fibers in the polymer matrix, also the use of SEBS-g-MA create a strong ester bonds between polymer and hydroxyl groups of fibers. Figure 14.9 shows the FTIR curves of PP/Pine cone composites with and without coupling agent. The peaks at 1,703, 1,652, and 1,560 cm-1 were observed after addition of compatibilizers, these peaks are the main characteristic peaks of ester bonds formed. These formed ester bonds between matrix and hydroxyl groups of fibers enhance the thermal and mechanical properties of composites.

SEM micrographs analysis of fracture surfaces of composites with coupling agent (Fig. 14.10) confirm that the addition of coupling agent improves the interface adhesion between doum fibers by absence of decohesion zones (pull out fibers), and reduction of the fiber/fiber contact.

The comparative thermal analysis between the composites with compatibilizer and without compatibilizer is found in the literature Arrakhiz et al. (2012a, b, c). Table 14.1 illustrates the comparative thermal analysis of Doum and Hemp fibers and their composites with and without compatibilizer. It was seen that the compos­ites compatibilized exhibit a higher temperature degradation than composites without compatibilizer.

The improvement in the fiber-matrix adhesion enhances the mechanical prop­erties of composites (Elkhaoulani et al. 2013). Figure 14.11 shows the compara­tive tensile properties of the fibers as Pine cone, hemp and Doum. Addition of

fibers increases Young’s modulus, until it reached one maximum value at 25 wt.% (for all composites). On the other hand, the tensile strength of various composites compatibilized is stabilized at a high value, except PP/hemp which shows a slight decrease. The tensile strength properties are higher in the composites compatibil­ized than composites without compatibilizer, this is due to the good interfacial adhesion (fibers/matrix). The maleic anhydride molecules grafted to PP construct a strong ester bonds with the hydroxyl groups (OH) present on the fibers’ surface (Elkhaoulani et al. 2013).

A good dispersion and interfacial adhesion between the matrix and fibers are both critical factors for the resulting composites to achieve improved mechanical properties. Chemical treatment of the fibers’ surface was used to improve interfacial adhesion in the composite. Table 14.2 illustrates influence of chemical treatments and fictionaliza — tion on two composite systems with different fibers (Alfa and Coir), at 20 wt.%, and thermoplastics matrix (PP and HDPE). The chemical modifications used in this work, namely NaOH, etherification (C12 (Dodecane bromide)), Estherification (Palmitic acid N-succinimidyl), and silane (3-(trimethoxysilyl) propylamine) exhibit a different inter­action mechanism with both fibers and polymer matrices.

The results show that chemical treatments improve the mechanical thermal pro­prieties of fibers, leading to improvement in properties of composites reinforced with these treated fibers. Alkaline treatment shows higher values in terms of young’s modulus, also composites with fibers fictionalized with silane and C12 shows a sig­nificant tensile modulus when compared to raw fibers reinforced polymer.