Reportedly, the yield of photobioreactors (PBR) system ranges from 0.02 to 3.22 g/L per day and are used to cultivate algae in closed environment under manageable conditions. Efficiency of this system can be appreciated by considering the fact that it does not permit the algae to be exposed to the external environment. There are various configurations of the PBR systems like:

1. Vertical tank

2. Polybag

3. Helical tube

4. Horizontal tube

5. Inclined tube

6. Flat-plate

7. Vertical-column photobioreactor

13.3.2.1 Tubular PBR

A tubular PBR is constructed by arranging linear tubes made up of plastic or glass. This configuration can be easily manipulated to form arrangements like helical tubes and fence-like PBR. The ability of this configuration to expose the culture to maximum sunlight makes it suitable to use during outdoor cultivation. A slight glitch in tubular PBR is the settling of algae at the bottom of the tubes. Sedimentation can, however, be avoided by utilizing an airlift propeller to maintain an exceedingly turbulent flow. Tubular PBR are the largest in terms of size with areas reaching up to 750 m3.

Md. Abul Kalam Azad, Md. Saiful Islam, and Latifah Amin

Contents

16.1 Introduction…………………………………………………………………………………………………… 276

16.2 Sugarcane Straw Availability and Quality……………………………………………………………….. 277

16.3 Straw Recovery………………………………………………………………………………………………. 278

16.3.1 Straw Recovery Way 1…………………………………………………………………………. 278

16.3.2 Straw Recovery Way II………………………………………………………………………… 278

16.3.3 Straw Recovery Way III……………………………………………………………………….. 279

16.4 Improvement of Soil Properties Through Sugarcane Straw……………………………………………. 279

16.4.1 Erosion of Soil………………………………………………………………………………….. 279

16.4.2 Moisture Content……………………………………………………………………………….. 280

16.4.3 Soil Carbon Stock……………………………………………………………………………… 280

16.5 Ethanol Production from Sugarcane Straw………………………………………………………………. 281

16.5.1 Pretreatment of Biomass……………………………………………………………………….. 281

16.5.2 Enzymatic Hydrolysis of Cellulose…………………………………………………………. 282

16.5.3 Detoxification of Hemicellulosic Hydrolysate………………………………………………. 283

16.5.4 Fermentation of Biomass into Ethanol Production……………………………………… 283

16.5.5 Distillation of Ethanol………………………………………………………………………… 283

16.6 Bio-Oil Production from Sugarcane Straws……………………………………………………………… 284

16.7 Sugarcane Straw as Textile Fiber Production…………………………………………………………… 284

16.8 Sugarcane Straw for Bioelectricity……………………………………………………………………….. 285

16.9 Conclusion………………………………………………………………………………………………….. 285

References …………………………………………………………………………………………………………. 285

Md. A.K. Azad (*)

Centre for General Studies, Universiti Kebangsaan Malaysia,

Bangi, Selangor 43600 , Malaysia

Department of Agricultural Extension, Khamarbari, Farmgate, Dhaka 1215, Bangladesh e-mail: azad. dae@gmail. com

Md. S. Islam

Faculty of Science, Department of Chemistry, Universiti Putra Malaysia, Serdang, Mala; L. Amin

Centre for General Studies, Universiti Kebangsaan Malaysia,

Bangi, Selangor 43600 , Malaysia

K. R. Hakeem et al. (eds.), Biomass and Bioenergy: Processing and Properties,

DOI 10.1007/978-3-319-07641-6_16, © Springer International Publishing Switzerland 2014

Abstract Sugarcane straw is destroyed through burning before harvest or left on the ground for decomposition. Sugarcane straw is composed of cellulose (33.30-36.10 %), hemicelluloses (18.40-28.90 %), lignin (25.80-40.70 %), ashes (2.10-11.70 %), and extractives (5.30-11.50 %). Sugarcane straw availability depends on the sugar­cane variety and age of harvesting. It can be used for alternative energy production and improvement of soil properties such as soil erosion, moisture content, and soil carbon stock. The biomass of sugarcane straw can be converted into biofuel through pyrolysis. The sugarcane straw has potentiality that could produce textile fibers. Bioelectricity is environmentally friendly produced from sugarcane straw which contributes to economic development.

Keywords Sugarcane straw • Biofuel • Bioelectricity • Ethanol

16.1 Introduction

Sugarcane is the main source of sugar in the world. It is native to Southeastern Asia (Daniels and Roach 1987). Brazil is the largest sugarcane-producing country through­out the world. In 1532, it was first introduced in Brazil. Brazil has favorable climate and soil conditions for sugarcane cultivation and is considered an important sugarcane exporting country to European Union (Dinardo-Miranda et al. 2008). It may be adapted in different parts in Brazil and 85 % of sugarcane currently cultivated at Sao Paulo and adjacent states in Brazil (Goldemberg 2007). Sugarcane can accumulate vigorous bio­mass due to C4 photosynthesis in nature. Sugarcane is a highly productive C4 photo­synthesis plant, which bestows higher light, water, and efficient nitrogen use compared to C3 pathway of plant (DeSouza and Buckeridge 2010). It is clonally propagated by stem cutting and semi-perennial with life cycle. Sugarcane takes 12-18 months for maturity from planting to harvest during cultivation. Sugarcane has been used as ratoon crops that can allow up to five harvests. About 70 % raw table sugar has been produced from sugarcane in the world (Contreras et al. 2009). Generally, sugarcane stalks are used during dry season for cattle when pastures are unavailable for grazing. The sugar­cane is consisted of two parts such as stem and straw. The sugar and ethanol has been processed from stem while energy is obtained from burning the straw in industry. According to Saad et al. (2008) and Moriya et al. (2007), the thing which is removed from sugarcane is considered as straw. Sugarcane straw is composed of dried and fresh leaves as well as top of the plant, and 150 kg straw can be obtained from one ton of cultivated sugarcane (Saad et al. 2008).

The sugarcane straw is generally burnt before harvesting. The practice of burning the sugarcane residues to facilitate harvest and transport operation of straw has been wide­spread in the world for reducing the harvesting cost in nonmechanical area. Andrade et al. (2010) reported that sugarcane field is burnt to facilitate the manual harvesting for increasing the content of sugar content by weight. Sugarcane straw is burnt by the indus­try to generate local energy for producing sugar and alcohol (Costa et al. 2013).

Now the manual operation has been replaced by mechanical operation gradually for maintaining the straw on the ground under green cane management. Franga et al.

(2012) reported that burning practice is being reduced day by day for preventing major health problems which have been created from the cloud of smoke and ash released during sugarcane straw burning.

The collection of sugarcane straw is being improved technically that would increase the amount of sugarcane straw. Sugarcane straw can be considered as alter­native energy production in the world. Carrier et al. (2011) reported that sugarcane straw can be used for energy production through pyrolysis and vacuum. On the other hand, Brazil has introduced a law to avoid the burning of sugarcane residues. Other countries like South Africa are trying to consider the application of sugarcane straw in energy production. The straw of sugarcane is composed of three main mac­romolecules such as cellulose, hemicellulose, and lignin. Cellulose-based fibers have mechanical and physical properties that are widely used as biodegradable filler (Toriz et al. 2005; Sun et al. 2004). Pyrolysis is an alternative way of burning in order to produce ashes, bio-oil, biogas, and charcoal by using the sugarcane straw. The sugarcane straw is used for energy production which is environmentally friendly (Cortez and Lora 2006). Biodiesel and petrochemicals can be produced through pyrolysis of sugarcane straw.

Here we discuss the nuts and bolts of microalgal biomass production using waste water.

The heat resistance of bamboo fibers is extremely good. The thermal resistance of fibers is increased by reinforcing it with epoxy resins (Shih 2007). The chemically modified water bamboo fibers when reinforced with biodegradable PBS show an improvement in thermal resistance of the resultant composite (Shih et al. 2006). Cotton/bamboo fiber composites when subjected to heat reveal that as the concen­tration of bamboo increases, their thermal conductivity reduces and resistance increases (Majumdar et al. 2010). Thermogravimetric analysis reveals that thermal stability of polypropylene bamboo/glass fiber reinforced hybrid composites increases as the amount of bamboo increases in the composite (Nayak et al. 2009).

2.4.6 Weight

Bamboo fibers are lightweight fibers and due to this property they can be used for the formation of composites (Rao and Rao 2007). Bamboo fiber strips when treated with sodium hydroxide solution show that increase in the percent of alkali results in decreasing the weight of strips (Das et al. 2006). Bamboo fibers have high strength to weight ratio. This ratio can be increased by reforming the bamboo (Yao and Li 2003). Increase in bamboo weight is directly related to aging (Li 2004).

Agricultural biomass, also referred to as lignocellulosic are produced in billions of tons around the world every year. There are various types of agricultural biomass across the world that can be a potential candidate as raw material in different appli­cations such as oil palm trunks, bagasse, coconut coir, bamboo and kenaf. Mostly, this biomass is found in the form of residual stalks from crops, leaves, roots, seeds, seed shells, etc. They can be divided into main groups depending on the part of the plant which they are extracted, i. e. bast (stem), leaf, fruit (seed) and straw as shown in Fig. 5.1. The composition of these organic fibres varies from one plant species to another. In addition, the polymer constituent composition in a single plant var­ies among species and even different parts of the same plant. It depends on the plant age, development growth, environment and other condition (Kumar et al.

2008) . The properties of biomass vary considerably depending on the fibre diam­eter, structure, degree of polymerization, crystal structure and source and on the growing conditions.

Since decades ago, biomass raw materials have been historically used for ancient tools, food source, construction materials and textiles and as a source of energy. However, there has been a dramatic increase in the use of plant fibre recently for the development of environmental renewable materials especially as a reinforcing agent in polymeric composite materials in substitution of synthetic fibres like glass fibres. This situation is largely spurred by environmental awareness, ecological consider­ation and technological advances. Figure 5.2 depicted an example of different types of agricultural biomass raw materials that has been used in various applications.

Fig. 5.1 Classification of agricultural biomass

Bamboo

Fig. 5.2 Various types of agricultural biomass

8.2.1 Pure Splitting Method

Initially, ID leaves are washed with huge quantity of water and are dried for a period of 150 days at ambient conditions (Fig. 8.2). The dried leaves are again cleaned using soft cloth to remove fine particulates. A splitter with a needle of 0.5 mm

diameter is used for extracting filaments from the leaves. The extracted fiber is placed in an oven at 70 °C to take away moisture before fabricating the composites, as shown in Fig. 8.3.

Okra fibres, which are cropped in a number of countries across several continents, may represent a suitable example of by-product from an agricultural productive system involving mainly food-related applications. This offers a low cost availability of ligno — cellulosic fibres, which may be used for different possible purposes. In this regard, a number of issues were investigated, in particular their possible introduction as a filler, possibly with some reinforcement effect, both in conventional thermosetting and bio­degradable thermoplastic matrices. This involved an evaluation of the effectiveness of different chemical treatments in modifying the resistance and morphology of the fibres, which, as microscopical investigation demonstrated, is rather variable with regard to diameters, lumen dimensions and overall shape. A possible alternative to application of okra fibres in the dimensions of technical fibres, therefore on the microscale, is their use as sources of CNC with the idea of providing a filler, usually applicable in small amounts, for biodegradable matrices, such as poly(vinyl alcohol) (PVA).

In general terms, the results obtained suggest that most suitable fields of applica­tions for okra fibres in the material sector may refer to their use in the packaging industry, therefore mainly linked to the application of biodegradable matrices in short life products.

Abou El Kacem Qaiss, Rachid Bouhfid, and Hamid Essabir

Contents

14.1 Introduction………………………………………………………………………………………………….. 226

14.2 Natural Fiber Characterizations……………………………………………………………………………. 227

14.3 Processing Techniques for Polymer Composites……………………………………………………….. 228

14.4 Problematic…………………………………………………………………………………………………… 231

14.5 Mechanical Properties………………………………………………………………………………………. 233

14.5.1 Tensile Properties………………………………………………………………………………. 235

14.6 Dynamic Mechanical Thermal Analysis………………………………………………………………….. 236

14.7 Interface Fiber/Matrix……………………………………………………………………………………….. 238

14.7.1 Techniques to Improve the Interface Adhesion……………………………………………… 238

14.8 Conclusions and Future Perspective………………………………………………………………………. 243

References ………………………………………………………………………………………………………….. 244

Abstract Natural fibers have recently become attractive to researchers, engineers, and scientists as an alternative reinforcement for fibers-polymer matrix composites. This interest comes from the combination of several advantages of natural fibers such as low cost, low density, non-toxicity, high specific properties, no abrasion during processing, and the possibility of recycling. The lack of compatibility between hydrophilic fibers and hydrophobic polymers (thermoplastics and thermo­sets), results a poor interfacial adhesion, which may negatively affect the final prop­erties of the resulting composites. The tensile properties of composites based on natural fibers are mainly influenced by the interfacial adhesion, dispersion/distribu — tion of fibers, and fibers loading. Several chemical modifications are used to enhance the interfacial adhesion resulting in an improvement of thermal and mechanical properties of the composites. This chapter presents a description of the natural fiber

A. Qaiss (*) • R. Bouhfid • H. Essabir

Moroccan Foundation for Advanced Science, Innovation and Research (MAScIR), Institute of Nanomaterials and Nanotechnology (Nanotech), Rabat, Morocco e-mail: a. qaiss@mascir. com

K. R. Hakeem et al. (eds.), Biomass and Bioenergy: Processing and Properties,

DOI 10.1007/978-3-319-07641-6_14, © Springer International Publishing Switzerland 2014 reinforcement composites/polymer matrix, and the context for the development and use of these products. The fibers used as reinforcement of thermoplastics matrix are Alfa, Doum, Pine cone, Hemp, Coir, and Bagasse. The knowledge of the structure and chemical composition of each component is required to understand the study of interactions between the reinforcing fibers and matrix.

Keywords Natural fibers • Matrix • Thermal properties • Mechanical properties • Interfacial properties

14.1 Introduction

In recent years, the polymer materials are widely used in various applications, such as automotive, construction, aerospace, and sports, the most important polymer benefits are ease in processing, the productivity and reduce costs. Fibers reinforced polymers matrix, such as aramid, basalt, carbon, and glass fibers are most com­monly used in industry applications due to their low cost, ease of production, and their important specific mechanical properties (Ku et al. 2011; Wambua et al. 2003; Pickering et al. 2007). However, the problem encountered in the use of these materi­als is their negative impacts to humans and the environment. Although, addition of renewable resources as reinforcement in materials composite is becoming more frequent (Beckermann and Pickering 2008; Torres and Cubillas 2005). Markets are becoming more oriented to demand more environmentally friendly products. Natural fibers are now promising as replacements for usual synthetic fibers for various applications such as aerospace, automotive parts and applications of high perfor­mance, etc. (Ofomaja and Naidoo 2011; Yanjun et al. 2010). The industry of natural fiber composite has widely invaded the world; the automotive industry is the prime driver of “green composites” because the industry is faced with issues for which green materials offer a solution. These new materials are called eco-materials, bio-composites, or eco-designed materials. The natural reinforced composites have therefore attracted attention more high due to their availability as renewable, and ecological material (Cao et al. 2006). They exhibit advantages such as low cost, low density, biodegradability, availability, good thermal and mechanical properties (Malha et al. 2013), ease of implementation (Arrakhiz et al. 2012a), their ability to be recycled (Essabir et al. 2013 a) and to their environmental friendliness (Arrakhiz et al. 2012b; Essabir et al. 2013c). Polymers reinforced with natural fibers have been shown to exhibit enhancements in thermal (Essabir et al. 2013b), mechanical (Arrakhiz et al. 2012c), and rheological properties (Arrakhiz et al. 2013a; Essabir et al. 2013c). Fibers are often added to a plastic matrix to reduce the cost of a com­ponent and to improve some mechanical properties such as stiffness. In terms of markets and applications, it is particularly the automotive industry, the building and construction industry which have expressed interest in using such materials.

A better understanding of the morphological, structural and chemical composition of natural fibers is essential to developing materials composites. Lack on compatibility

between fibers and matrix is the biggest challenge in developing these composite materials (Freire et al. 2008; Sawpan et al. 2011). Natural fibers are hydrophilic, they are essentially composed of lignocelluloses, which contain hydroxyl groups (Freire et al. 2008) . These hydrophilic fibers are therefore incompatible with hydrophobic thermoplastic matrix, such as polyolefin and have low resistance to humidity (Arrakhiz et al. 2012a). Another important factor to obtain high mechan­ical properties is the fiber dispersion/distribution in matrix. These problems are the main limitations in polymers composites based on natural resources (Essabir et al. 2013b) Several reports show that the properties of composites were improved when the surface of the natural fibers or the polymer was modified (Arrakhiz et al. 2013a, c ).

Bio-oil from straw is a complex mixture that contains different organic compounds formed by the thermal degradation of cellulose, hemicelluloses, lignin, and other biomolecules which are presented in sugarcane straw biomass. Biofuel can be obtained from pyrolysis method from sugarcane straw. Pyrolysis is one kind of thermo-degradation technique that can be used for transformation of the biomass in bio-oil. The biomass has been converted into a liquid product such as bio-oil through pyrolysis which can be used as feedstock for fuels and valuable chemicals (Maiti et al. 2006; Li et al. 2011). Thermal pyrolytic conversion is the promising method that can be used for biomass conversion (Strezov et al. 2008). The medium tempera­ture (550 °C) leads to the production of a pyrolysis gas composed by H2 and CO (Morf et al. 2002) . Mesa-Perez et al. (2013) investigated on biofuel production through pyrolysis using sugarcane straw. They obtained 35.5 % bio-oil at 470 °C temperature that has low oxygen content and high heating value. The pyrolysis of sugarcane straw is an environment-friendly method for the production of bio-oil because it does not have another important use (Cortez and Lora 2006). The develop­ment of biorenewable agro-industry needs to integrate the coproducts obtained through pyrolysis process (Arbex et al. 2004). Bio-oil is a good coproduct of pyroly­sis and an energy carrier and feedstock for biodiesel and petrochemical production. Bio-oil is a complex nature that requires the usage of high-resolution chromato­graphic techniques. The multidimensional chromatography specially GC x GC/ TOFMS is a powerful technique for analysis of bio-oil. This technique has some advantages for separation capacity, resolution, sensitivity, and selectivity. Sfetsas et al. (2011) have used the GC x GC/FID and GC x GC/TOFMS for quantification of bio-oils. Fullana et al. (2005) reported that 70 % chromatogram could be obtained using GC x GC.

There are several studies being carried out on kinetics modeling for biomass gasifi­cation using air-steam gasification, but limited studies on pure steam gasification. Corella and Sanz (2005) developed a reaction kinetics model based on pyrolysis and gasification in circulating fluidized bed gasifier. Several reactions have been consid­ered in the modeling including fast pyrolysis reaction, oxidations reactions, steam reforming of methane, tar reforming, char reforming, and water gas shift reaction. The char gasification reaction is presented as follows:

char [CH0.20O0.13 ] + 0.38H2O ® 0.54CO + 0.45H2

The kinetics for all reactions has been considered first order based on the easiest or simplest kinetics available in the literature. For example the kinetics for the char gasification reaction was selected from the literature (Gonzalez-Saiz 1988) as follows:

Г10 = k1oCchai2CH20 k10 = 2.0 x105exp (-6,000/T)

Furthermore, the all rate equations for all reactions were solved using Chemical Reaction Engineering rules. For example the overall volumetric rate equation for hydrogen was presented as follows:

RH2 _ 1 + d8 ‘Г8 + d9 ‘Г9 + d10 ‘Г10 — r4

Nikoo and Mahinpey (2008) have presented a comprehensive model for biomass air-steam gasification in fluidized bed using pine saw dust as biomass. Both kinetics and hydrodynamics parameters have been considered with few assumptions.

For the reactions kinetic model, the reaction equations for combustion (CO) and steam gasification (SG) given by Lee et al. (1998) were chosen as follows:

(1 — —со Г

——SG = k exp l-^SG I Pn

d*cO + d^SG Y, Pc£SYC dt dt 0 Mc

Furthermore, the model was validated with the experimental data taken from the literature and the mean error calculated between the experimental value and the predictions. The parametric studies have been done with temperature, steam/bio — mass ratio, equivalence ratio, and particle size on the product gas composition and carbon conversion efficiency.

Lu et al. (2008) considered fluidized bed reactor for kinetics model of biomass air-steam gasification using assumptions of isothermal and steady state conditions. Furthermore, pyrolysis has been considered as instantaneous process. The wood powder has been taken as biomass and the following eight reactions (adopted from Lu et al. (2008)) have been solved in MATLAB.

C + O2 —— CO2

C + CO2 —— 2CO

C + H2O —— CO + H2

C + 2H2 —— CH4

CO + H2O —— CO2 + H

CO + H —— CO + HO
2CO + O2 —— 2CO,

CH4 + H2O —— CO + 3H.

The all kinetics constants (k0-k7) have been chosen from the literature. Furthermore, the model has been validated with experimental data of pine sawdust taken from the literature.

Ji et al. (2009) presented a kinetics model for steam gasification of biomass for enriched hydrogen gas production from biomass. A simplified flow sheet has been also presented to get pure hydrogen based on fluidized bed gasifier, steam reformer, and H2 membrane water gas shift reactor. Several reactions have been considered in all reactors. The rate of reactions for all reactions has been solved using the kinetics data from the literature. Furthermore, the model has been validated with the experi­mental data taken from the literature. The effect of temperature and steam/biomass ratio has been studied on the hydrogen purity and yield. The temperature and steam/ biomass range was taken 960-1,120 K and 0.5-3.0, respectively. The hydrogen purity was predicted more than 60 mol% at 1,023 K and steam/biomass ratio of 3.0. Furthermore, they reported that the lower heating value of the product gas decreased by increasing both temperature and steam/biomass ratio due to the increase of hydrogen in the product gas.