PRODUCTION AND CHARACTERIZATION OF BIODIESEL FROM LUFFA CYLINDRICA SEED OIL

ABSTRACT

Biodiesel  was  produced  from  the  seed  oil  of  Luffa  cylindrica.  The  oil  obtained  was transesterified to produce methyl-esters and glycerol. The percentage oil yield of 36.32% was obtained from Luffa cylindrica seed. Biodiesel properties of methyl-esters were determined using American Society for Testing and Materials (ASTM) Standards and compared with that of petrodiesel. The methyl-ester yield of 92.06 % was obtained from Luffa cylindrica seedoil. Higher viscosity at 40oC (15.50 mm2/s) was obtained for the seed oil whereas  it  was reduced to 3.80 mm2/s after transesterification  which is comparable with that of  biodiesel standards.  Lower  heating  value  (29.39  MJ/kg)  was  obtained  for  methyl-ester  of  Luffacylindrica compared to 42.85 MJ/kg obtained for petro diesel. Higher pour, cloud and flash points of 4 oC, 8 oC and 150 oC respectively were obtained for Luffa cylindrica seed methyl- ester, compared to -12 oC, -16 oC and 74 oC respectively obtained for petrodiesel. Biodiesel produced from Luffa cylindrica seed oil had cetane number (71.93), refractive index (1.465 nm)  and  relative  density  (0.88  kg/m2)  which  is  comparable  to  biodiesel  standard.  The chemical  properties  acid  value  (0.52  mgKOH/g)  and  iodine  value  (57.87  mgI2/g)  also compared well with most standard biodiesel. The seed oil of Luffa cylindrica could be a good source of biodiesel.

CHAPTER ONE

INTRODUCTION

Biodiesel is an alternative fuel made from renewable biological sources such as vegetable  oil and animal fats (Raja et al., 2011). Due to the depleting  world’s petroleum reserves, threatening to run out in the foreseeable future and the increasing environmental concerns, there is a great demand for alternative sources of petroleum- based  fuel  including  diesel  and  gasoline  (Sambo,  1981;  Munack  et  al.,  2001). Indiscriminate  extraction and increased consumption of  fossil fuels have led to the reduction  of  the  underground-based   carbon  resources  (Ramadhas  et  al.,  2004). Biofuels are produced from renewable sources; they do not add to the stock of total carbon-dioxide in the atmosphere. These plant forms remove carbon-dioxide from the atmosphere  and give up the  same amount when burnt within a few years. Hence, biofuels are considered  to  be “CO2  neutral” (Ramadhas et al., 2004). The primary goals of National Energy Policy are to increase the energy supplies using mixtures of domestic resources and to reduce our dependency on imported oil or petroleum. As a domestic  renewable  energy  source,  biomass  offers  an  alternative  to  conventional energy  sources  and  supplements  national  energy  security,  economic  growth  and environmental benefits (Ma and Marcus, 1999). Currently, biodiesel is considered a promising  alternative   due  to  its  renewability,  better  gas  emission,  non  toxicity and  its biodegradability (Hossain et al., 2010). Plant oil and animal fats contain three ester  linkages  between  fatty acids and glycerol  which makes  them  more viscous. Among  the  techniques  applied  to  overcome  the  difficulties  encountered  in using vegetable  or animal oil in engines, transesterification  of oil to biodiesel seems  the most  promising  (Zhang  et  al.,  2003).  The  high  viscosities  of  vegetable  oils  are reduced   through  the  process  of  transesterification   (Alamu   et  al.,   2008).  The production of biodiesel from edible and non edible oil has progressively affected food uses, price, production and availability (Rashid et al., 2008). Vegetable oil seeds that do  not  compete  with  traditional  food  crops  are  needed  to  meet  existing  energy demands (Xu and Marcus, 2009). Reducing the cost of the feedstock is necessary for biodiesel’s  long-term  commercial  viability.   In  order  to  achieve  production  cost reduction  and  make  biodiesel  more  competitive  with  petroleum  diesel,  low  cost feedstocks, such as non-edible oils, waste vegetable oils could be used as raw material (Xiaohu and Geg, 2009). In this research therefore, attempt is being made to explore the  oil  of  Luffa  cylindrica  seed  from  Nigeria  in  an  industrial  process  for  the production of biodiesel.

1.1      Luffa cylindrica plant.

Loofa is derived from the cucumber and marrow family, and originates from America (Mazali and Alves, 2005). Luffa commonly called sponge  gourd,  loofa, vegetable sponge, bath sponge or dish cloth gourd, is a member of cucurbitaceous family. The number of species in the genus Luffa varies from 5 to 7. Only 2 species L. cylindrica and L. acutangula are domesticated. 2 wild species are L. graveolens and L. echinata. Loofa   sponge   is   a   lignocellulosic   material   composed   mainly   of   cellulose, hemicelluloses  and lignin (Rowell  et  al., 2002). The fibers are composed  of 60% cellulose, 30% hemicelluloses and 10% lignin and the fruits smooth and cylindrical in shape.

Luffa cylindrica has alternate and palmate leaves comprising petiole. The leaf is 13 and 30 cm in length and width respectively and has the acute-end lobe. It is hairless and has serrated  edges.  The flower  of L. cylindrica  is yellow  and  blooms during August-September. The plant is cultivated in many countries, including Brazil, where its  cultivation  has an  increasing  economic  importance  (Mazali  and  Alves,  2005).

Luffa  cylindrica   is  a  sub-tropical  plant,  which  requires  warm   summer temperatures  and long frost-free  growing  season  when grown  in temperate regions. It is an annual climbing plant which produces fruit containing fibrous vascular system. It is a summer season vegetable. It is difficult to assign with accuracy the indigenous areas of Luffa species.  They have a long history of cultivation in the tropical countries of Asia and Africa. Indo-Burma is reported to  be  the  center  of  diversity  for   sponge  gourd.  The  main  commercial production countries are China, Korea, India, Japan and Central America (Bal et al., 2004).

The oil extracted from L. cylindrica is finding increasing use in the production of  biodiesel  which  is  now  gaining  wide  acceptance  because  of  low  CO2 emission and other considerations (Ajiwe et al., 2005).The plant is classified as follows:

Luffa cylindrica Linn.

Kingdom         :          Plantae Division          :           Mangoliophyta Class               :           Mangoliosida Order              :           Cucurbitales Family            :           Cucurbitaceae Genus             :           Luffa

Specie             :          Cylindrica

Vernacular Names

Hindi               :          Ghiatarui Sanskrit            :          Rajakoshataki Bengali            :          Dhundul Tamil               :          Pikku

Telungu           :         Guttibira Bombay state   :         Ghosali Malayalam       :          Tureippirku

Fig.1.1. Luffa cylindrical seed. (Moser, 2009)             Fig. 1.2. Luffa cylindrical Fruit. (Moser,

2009)

In  oriental  medicine,  L.  cylindrica  has  effect  on  the  treatment  of  fever, enteritis and swelling etc. The extracts from its vines are used as an ingredient in  cosmetics  and  medicine  (Lee  et  al.,  2006).  Immature  fruit  is  used  as vegetables,  which is good for diabetes (Bal et al.,  2004).  In Nigeria, Luffa cylindrica plant grows in the wild and on abandoned building structures and fenced walls in towns and villages (Ndukwe et al., 2001).

1.2       Biodiesel

Biodiesel  is  a  mono-alkyl  ester  of  long  chain  fatty  acid  derived   from renewable  biological  sources  (ASTM,  2008a).  It  is  used  directly  in  the compression ignition engine (Knothe et al., 1997). Biodiesel is a clean burning alternative fuel that comes     from 100% renewable resources. Many people believe that biodiesel is the fuel of the future; it is occasionally referred to as biofuel. Biodiesel which is derived from triacylglycerol by transesterification and from the fatty acids by esterification has attracted considerable attention during the past decade as a renewable, biodegradable, eco-friendly and non- toxic fuel (Knothe  et al., 2006; Demirba, 2008). Recently, it is    used as a substitute for petroleum based diesel due to environmental considerations and

depletion of vital resources like petroleum and coal (Ma and Marcus, 1999). The   possible use of renewable resources as fuels and as a major feedstock for the chemical industry is currently gaining growth.

The    majority    of    biodiesel    today    is    produced    by    alkali-catalyzed transesterification with methanol, which results in a relatively short reaction time. However, the vegetable oil and alcohol must be substantially anhydrous and have low free fatty acid content, because  the presence of water or free fatty acid  or both promote  soap  formation.  Generally,  transesterification  is used to produce biodiesel from vegetable oil or animal fat containing low free fatty acid (FFA) through a reaction involving alcohol and an alkaline catalyst (Ma et al., 1998;  Gerpen et  al., 2004;  Prateepchaikul  et al., 2007).  When biodiesel is produced from high FFA oils by transesterification, the high FFA content in the oils reacts with the metallic alkoxide to produce soap (Brown et al., 2003;  Gerpen  et  al.,  2004).  In  addition,  if oils  contain  high  moisture content,  saponification  and hydrolysis occur. These reactions cause a lower yield  and washing difficulty.  The problem can be solved via four methods: enzymatic-catalyzed   transesterification,  acid-catalyzed  transesterification,  a supercritical  carbon  dioxide  technique  and  a  two-stage  process  (Ma  and

Marcus, 1999).

Fig. 1.3: Production of biodiesel. Source: (Moser, 2009a)

Three moles of biodiesel and one mole of glycerol are produced  for  every mole    of    triacylglycerol    that    undergoes    complete    conversion.    The transesterification   reaction   is   reversible,   although   the   reverse   reaction (production of monoacylglycerols from fatty acid alkyl esters and glycerols) is negligible largely because glycerol is not miscible with fatty acid alkyl esters

especially  fatty  acid  methyl  esters  (FAME)  when  using  methanol  as  the alcohol component. The reaction system is biphasic at the beginning and at the end of biodiesel production as methanol, vegetable oil glycerol and fatty acid methyl  esters  are  not  miscible.  The  chemical  composition  of  biodiesel  is dependent upon the feedstock from which it is produced, as vegetable oils and animal fats of differing origin have different fatty acid compositions. The fatty ester composition of biodiesel is identical to that of the parent oil or fat from which it is produced. Vegetable oils such as soybean oil, rapeseed oil (canola oil) and in countries with more tropical climates, tropical oils (palm oil and coconut oil) are the major sources of biodiesel (Demirbas, 2006). However, in recent years, animal fats and recycled greases as well as used vegetable oils have found increasing attention as sources of raw materials for the production of biodiesel, as the latter primarily is inexpensive feedstocks (Mittelbach and Tritthart, 1988).

In all the feedstocks, transesterification  reactions are carried out to  produce biodiesel.  The  vegetable  oil  production  and  biodiesel  feedstock  usage  are intimately  related.  Feedstocks  for  biodiesel  production  vary  with  location according to climate and availability (Demirbas, 2006).  Generally, the most abundant commodity oils or fats in a particular region are the most common feedstocks. Thus, rapeseed and sunflower oils are principally used in Europe for biodiesel production, palm oil which predominates in tropical countries are widely  used  in  tropical  countries,  soybean  oil  and  animal  fats  are  most common  in  the  United  States  of  America  (Demirbas,  2006).  During  the transesterification process, intermediate glycerols, mono- and diacylglycerols are formed;  small amounts  can remain  in the final  biodiesel  (methylester) product.    Besides    these    partial    glycerols,    unreacted    triacylglycerols, unseparated  glycerol,  free  fatty  acids,  residual  alcohol  and  catalyst  can contaminate the final product. The contaminants can lead to severe operational problems when using biodiesel such as engine deposits, filter clogging, or fuel deterioration. Therefore, in the United States, an ASTM (American Society for Testing  and  Materials)  standard  is developed  and  also,  in some  European countries,  such  as  Austria,  Czech  Republic,  France,  Germany  and  Italy, standards  have  been  developed  that  limit  the  amount  of  contaminants  in

biodiesel  fuel.  In these  standards,  restrictions  are  placed  on the  individual contaminants by inclusion of items such as free and total glycerol for limiting glycerol and acylglycerols, flashpoint for limiting residual alcohol, acid value for  limiting  free  fatty  acids  and  ash  value  for  limiting  residual  catalyst (Mittelbach, 1994).

1.2.1     Advantages and disadvantages of biodiesel.

The  advantages  of  biodiesel  as  a  diesel  fuel  are  portability,  availability, renewability, higher combustion efficiency, lower sulfur and aromatic content (Ma and Marcus, 1999; Knothe et al., 2006), higher cetane number and higher biodegradability (Mudge and Pereira, 1999; Speidal et al., 2000 ; Zhang et al.,

2003), as well as its potential for reducing a given economy’s dependency on imported petroleum, high flash point and inherent lubricity in the neat  form (Mittelbach and Remschmidt, 2004; Knothe and Steidly, 2005).  Biodiesel is better than diesel fuel in terms of sulfur content, flash point, aromatic content and biodegradability (Bala, 2005). The economic advantages of biodiesel are that it reduces greenhouse gas emissions, helps to reduce a country’s reliance on crude oil imports and supports  agriculture  by providing  new  labor  and market opportunities  for domestic  crops. In addition, it enhances lubrication and is widely accepted by vehicle manufacturers (Palz et al., 2002).

The major disadvantages  of biodiesel are its higher viscosity, lower  energy content, higher cloud and pour points, higher nitrogen oxide (NO) emissions, lower engine speed and power, injector choking, engine  compatibility,  high price and higher engine wear (Prakash,1998). When biodiesel is used instead of pure petro diesel, fuel consumption rises with the overall cost of application of  biodiesel  as  an  alternative  to  petro  diesel.  Biodiesel  neat  and  blends increase nitrogen oxide (NO) emissions compared with petroleum-based diesel fuel used in an unmodified  engine.  Peak torque is lower for biodiesel than diesels; on average it decreases power by 5% compared to diesel at rated loads (Demirbas,  2006).  The   technical  disadvantages   of  biodiesel/fossil  diesel blends include  problems with fuel freezing in cold weather, reduced energy density  and  degradation  of  fuel  under  storage  for prolonged  periods.  One additional  problem  is  encountered  when  blends  are  first  introduced  into

equipment that has a long history of pure hydrocarbon usage.  Hydrocarbon fuels typically form  a layer  of deposits  on the inside  of  tanks and  hoses. Biodiesel  blends  loosen  these  deposits  causing  them  to  block  fuel  filters. However, this is a minor problem easily remedied by proper filter maintenance during the period following introduction of the biodiesel blend. Many of these deficiencies  can be mitigated  through cold  flow improver  (Hancsok  et al.,

2008) and antioxidant (Tang et al., 2008) additives, blending with petro diesel (Benjumea  et al., 2008) and reducing  storage  time (Bondioli et  al., 2003). Additional methods to enhance the low-temperature performance of biodiesel include   crystallization,    fractionation   (Kerschbaum    et   al.,   2008)   and transesterification with long or branched-chain alcohols (Wu et al., 1998).

Strategies  to improve  the exhaust  emissions  of biodiesel,  petrol diesel  and blends of biodiesel in petro diesel include various engine or  after-treatment technologies   such   as   selective   catalytic   reduction   (SCR),   exhaust   gas recticulation  (EGR),  diesel  oxidation  catalysts  and  NO or particulate  traps (McGeehan,  2006).  However,  feedstock  acquisition  currently  accounts  for over 80% of biodiesel production expenses, which is a serious threat to the economic   viability  of  the   biodiesel   industry  (Retka-Schill,   2008).  One potential solution to this problem is employment of alternative feedstocks of varying type, quality and cost. These feedstocks may include soapstocks, acid oils, tall oils, used cooking oils, waste restaurant greases, various animal fats, non-food vegetable oils and oils obtained from trees and microorganisms such as  algae.  However,  many of these alternative  feedstocks  may contain  high levels  of  free  fatty  acids  (FFA),  water,  or  insoluble  matter,  which  affect biodiesel production (Moser, 2009a)

1.2.2    Alcohols used in the production of biodiesel.

As previously mentioned, methanol is the most common alcohol used in the production of biodiesel. Other alcohols may also be used in the preparation of biodiesel such as ethanol, propanol, iso-propanol and  butanol (Rodrigues et al., 2008). Methanol is used widely because it is relatively cheaper than other alcohols and has chemical and physical advantages over other alcohols (Ma and Marcus, 1999). Butanol may also be obtained from biological materials (Qureshi et al., 2008), thus yielding completely bio-based biodiesel as well as Methanol,  propanol  and  iso-propanol  which  are  normally  produced  from petrochemical materials such as methane obtained from natural gas.

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