Chemistry and Structure Characterization of Bamboo Pulp with Formacell Pulping

  Abstract—Bamboo is one of the non-wood materials which can be utilized as raw materials of pulp. The purpose of this work was to study the effect of the ratio of acetic acid : formic acid on the chemical properties of pulp from bamboo. The results of the study showed that increasing of the ratio of formic acid able to degraded of cellulose, hemicellulose, lignin content and reduced the pulp yield. The best condition of this research showed on the ratio of acetic acid: formic acid = 90:10. This condition produced the pupl with composition ofcellulose 66,98%, hemicelluloses 16,83%, and lignin 3,59%, with the yield of pulp was 42,279%.

  Keywords—acetic acid, bamboo, formacell, formic acid I.

  I NTRODUCTION n addition Recently, there are growing interest in the utilization of alternative fibrous material derived from lignocellulose materials such as agricultural waste, and bamboo to pulp production. The advantages of using non- timber raw materials are ease to pulping, excellent fiber for the special type of papers and high quality bleached pulp [2]. Non wood material can also utilized as an effective substitute for the over-exploited forest wood resources [3]–[6]. There are several advantages of bamboo compared to other woody plants, such as grow rapidly (up to 120 cm per day), easily to spread, highly productivity and easily to harvest. [7]8. The productivity of bamboo is reach into 2-6 times higher than pine plants [9]. Moreover, the characteristic of bamboo almost similar with woody plant. It has high cellulose content which about 40% -60.and fibre lenght is about 2-3 mm. The fibre lenght is equivalent to red spruce wood, but longer than pine, with average of fibre length is 1980 μm. Bamboo chip consist of 22,4% lignins, 19,5% Xylans, 49,3% cellulose, 16,8% extractive and 1,5% - 3% ash [11], [12]. This properties suggests that bamboo is the best material for papermaking compared to other lignocellulosic materials such as bagasse and rice straw[10] [15]..

  The common process for pulp-making process in Indonesia using chemical pulping such as sulfate process or is known as Kraft pulping. This process is known as not an environmentally friendly cause its produce several waste problem [16], [17] mainly due to the presence of sulfur compounds [18]. in order to minimize the waste from the

  S. Hidayati is with the Department of Agroindustrial Technology, Faculty of Agriculture, Universitas Lampung, 35145 Indonesia (e-mail: srihidayati.unila@ gmail.com).

  E. Suroso is with the Department of Agroindustrial Technology, Faculty of Agriculture, Universitas Lampung, 35145 Indonesia (e-mail: erdi.suroso@fp.unila.ac.id).

  W. Satyajaya is with the Department of Agroindustrial Technology, Faculty of Agriculture, Universitas Lampung, 35145 Indonesia (e-mail: wisnu.satyajaya@fp.unila.ac.id).

  D. Iryani is with the Department of Chemical Engineering, Faculty of pulping process, it is necessary to find the alternative environmentally friendly pulping process. One of alternative enviromentally friendly paper making process is organosolv method. Organosolv pulping is a process for separation of macromolecular components, comprises the delignification which is the solubilization of the lignin fragments resulted from the breakage of chemical bonds of protolignin an organic solvents which is usually associated with water in the 10% to 50% ratio (by volume), such as acetone, ethanol, methanol, formic acid and acetic acid [5]. Most of organosolv process by using volatile solvent carried out at high temperatures (185 - 210ºC). However, organosolv by using an organic acids such as acetic acid and formic acid require lower temperatures and pressure which is closer to atmospheric pressure [19] – [21].

  The formacell process is one of the pulping methods using acetic acid and formic acid as a cooking chemical [22]. the formacell process has many advantages, ie: produce high pulp yield, low lignin content, high brightness and good strength[23] – [30]. product precious side effects include hemicellulose and lignin-free sulfur fragments. lignin can be used for the production of adhesives and other products due it high purity, and low molecular weight. furthermore, reagents organic is easy recycled. this process produces a low lignin content, so it can be bleached using ozone or peroxy acetic acid. Sundquist (2000) reported that the formacell pulping process for the annual plant produces better pulp strength compared to soda processes [19]. organic acid for pulping of herbacious material such as bagasse [20], bamboo [31], and wheat straw (triticumvulgare cv. horoshiri) [32]. there are several factors have to be considered on paper-making by using acetosolv pulping process, such as ratio of solvent to water, ratio of solvent to raw materials, concentration of catalyst, temperature and reaction time. [33]–[36]. The catalyst concentration is the important factor in order to degragraded of lignin during teh pulping process [8]. Mormanne (2009) reported that formacell pulping of

  cephalostachyum virgatum kurz bamboo produced pulp

  product with the characteristic is: 42.88% of yield, 22.6% of kappa number, 5,702.23 m breaking length, 431.43 kpa bursting strength, 88.8 cm tearing strength and 20.7% iso brightness [31]. however, this reseach is not reported the effect of acetic acid ratio: formic acid on the chemical properties and the morphology of pulp product. thus, the purposes of the present work was to evaluate, the effect of acetic acid: formic acid ratio on chemical characteristic and pulp yield. the scanning electron microscopy (sem) was also conducted in order to study the physical features of fibers as well as structures and pulp bamboo morphology.

  

Sri Hidayati, Erdi Suroso, Wisnu Satyajaya and Dewi Iryani

Chemistry and Structure Characterization of

Bamboo Pulp with Formacell Pulping

  I

II. MATERIALS AND METHODS A.

   Raw material

2 SO

  Figure 2. Effect of acetic acid: formic acid ratio on the contents of hemicellulose bamboo pulp.

  He m ic e llu lo se ( % ) ratio acetic acid:formic acid

  20 (100:1) (90:10) (85:15) (80:20) (75:25)

  15

  10

  5

  C e llu lo se ( % ) ratio acetic acid:formic acid

  70 (100:1) (90:10) (85:15) (80:20) (75:25)

  65

  60

  55

  50

  The results of the study showed that increased formic acid ratios can reduce hemicellulose levels (Figure 2). The result hemicellulose levels ranged from 7-18.52%. The decline is thought to be due to the hydrolysis of hemicellulose by acid. Sjostom (1981) report if hemicelluloses are relatively easily hydrolyzed by acids since their monomeric components consisting of D-glucose, D-mannose, D-xylose, L-arabinose, and small amounts of L-rhamnose Favored hemicellulose hydrolysis rather than cellulose hydrolysis, even though the total hemicellulose yield was less than at 170°C [41].

  This experiments were used bamboo Betung sp as raw material which colected from Bandar lampung area. All chemicals used in this study such as formic acid, glacial acetic acid, HCl, H

   Hemicellulose

  B.

  If the hydrolysis of glycosidic bonds in a homogeneous system is catalysed by anions, it may also influence the hydrolysis of cellulose. Kupiainenet al (2012) reported cellulose is hydrolysed slower in formic acid than in sulphuric acid chemical hydrolysis in the pulp-making process in the acidic atmosphere is a major characteristic of glycosidic glycosides in polysaccharides [39]. Thus long chains cellulose will be short and compounds degradation products such as hydroxyl acids will dissolve during leaching so that cellulose levels will become lower. Wanrosli et al. (2007) stated that high concentrations of formic acid not only dissolving lignin into organic solvents, but cellulose was also degraded [40].

  Figure 1. Effect of acetic acid: formic acid ratio on the contents of cellulose bamboo pulp.

  The result showed that the value of cellulose pulp from bamboo ranged from 57% to 66,98% (Figure 1). The highest levels of cellulose occur in the ratio of acetic acid: formic acid 90:10. The same result was reported by Hidayatiet al. (2017) on the ratio of acetic acid: formic acid 90:10 also produced the highest cellulose content in the pulp of empty palm oil bunches [36].Increased ratio of formic acid does not decrease cellulose significantly. This happens because formic acid can selectively delignify biomass with minor effects on cellulose [38].The decrease in cellulose levels is due to the degradation of cellulose by acid to a more soluble compound in water.

   Cellulose

  Composition of pulp i.e cellulose, hemicellulose, and lignin were determined, by using Chesson methods [37]. The pulping products were analyzed by Philips XL-40 Scanning Electron Microscope (SEM) to determine the effect of ratio of acetic acid: formic acid on the pulp morphology and fibre structural details. The samples were pre-treated for SEM analysis by sputter-coating with a thin layer of gold. The .

   Pulp characterization

  C.

  The pulping processes were performed in 1.3 liter lab-scale autoclave with type of flat-bottom, and wide-mouth flask equipped with a condenser. About 20 g of bamboo fibrous were mixtured with the cooking liquor in the ratio of 15:1. in varied ratio of acetic acid : formic acid as cooking liquor, i.e: 100: 1 (K1); 90:10 (K2); 85:15 (K3); 80:20 (K4); and 75:25 (K5). About 0,5% of HCl was added as the catalyst into the cooking liquor. The pulping processes were conducted in an hour cooking at temperature of 130ºC. When the pulping processes ended, the autoclave was cooled into room temperature. Furthermore, the cooking liquor was colected, separated by using filter paper. The filtered residue was then washed by using distilled water. The pulp residue was then dried into yielded the amount of pulp.

   Pulping

  B.

  4 were received from Merck.

III. RESULTS AND DISCUSSIONS A.

  Jahanet a.l (2006) reported that the use of formic acidand the duration of cooking 2 hours obtained by hemicellulose result is about 7.8% [42]. High concentrations of formic acid can lead to a decrease in hemicellulose levels [36], [40],[43]; due to the degradation experienced by hemicellulose. This was because the hemicellulose has properties similar to cellulose that is easily degraded with acid solution. Hemicellulose is bound to polysaccharides, protein and lignin and is more soluble than cellulose [44]. Clark (1985) reported thatpolysaccharide compounds such as cellulose and hemicellulose are glycoside bonds linking the chain of compounds [45]. Glycoside bonds are easy hydrolyzed by acid through a chemical reaction and this condition is accelerated by the heating. Hemicellulose will undergo oxidation and degradation reactions first than cellulose, because the hemicellulose molecular chains are shorter and branched. Hemicellulose is insoluble in water but soluble in dilute alkaline solutions and more easily hydrolyzed by acids than cellulose [46].

  3

  50 (100:1) (90:10) (85:15) (80:20) (75:25)

  40

  30

  20

  10

  lig n in ( % ) ratio acetic acid:formic acid

  7 (100:1) (90:10) (85:15) (80:20) (75:25)

  6

  5

  4

  2

  C.

  1

  Scanning Electron Microscope (SEM) was used to see the structure of bamboo pulp fibers. Testing was done using 500x magnification (Figure 5). This test was required to estimate the structure and mechanical properties produced by the fibers. The process of formacell pulping in bamboo by producing morphological changes in bamboo fiber. The fibers undergo randomization from a rigid or crystalline form to randomization.

  Assessment of the structure of bamboo pulp fibres

  Figure 4. Effect of acetic acid: formic acid ratio on the contents of yields bamboo pulp. Pulping process by acid solution has properties reactive, so it can break the complex ties lignin-polysaccharides that result in increasingly the low yield of the resulting pulp. According to Fatriasari and Risanto (2011), increased concentrations of tending chemicals decrease the total pulp yield. It happens because with the higher concentration, the number of degraded cellulose will become higher [50].

  The results showed that increasing the ratio of formic acid to a ratio of 20 can decrease the yield of bamboo pulp (Figure 4). The yield in this study ranged from 36.75 to 44.5%.This decrease was due to the degradation of cellulose and hemicellulose by formic acid. Delignification process by formacell has been ascribed to the hydrolysis of α-aryl-ether and lignin-cellulose bonds, and to conform to a pseudo first- order kinetics like yield losses.

   Yield

  D.

  Delignification process was caused by the acid hydrolysis o f α-aryl ether bond [47]. Thedissolution of lignin has been ascribed to the cleavage of α-aryl and aryl-glycerol-β-aryl- ether bonds in its molecule [48]. Hydrogen ion concentration plays a very important role in solvent pulping. This is because lignin dissolution is expected to be preceded by the acid- catalyzed cleavage of α-aryl and ß-aryl ether linkages in the lignin macromolecule. But the formic acidratio increasesis thought to cause the lignin to re-condensate resulting in high yielding lignin. This happens because the concentration of concentrated organic acids more concentrated encouraging the reactivation of lignin polymerization that has dissolved in the cooking liquid, so that pulp lignin levels increase [30], [49]. Hidayati et al.(2017) stated that the high lignin content of pulp cooking is thought to be due to the condensation process so that the lignin settles on the surface of the pulp so is formed by combining carbon chains that form longer chains in which the formed compounds are the intermediates of carbonium ions formed on the pulp [46].

  Figure 3. Effect of acetic acid: formic acid ratio on the contents of lignins bamboo pulp.

  The results showed that the increase of formic acid ratio to a ratio above 10 can increase the lignin level of bamboo pulp. In this study the resulting lignin content ranged from 3.59 to 6.375%. Lignin is smaller than lignin contained in the bamboo that has not been done pulping process is 22.4% [12].

   Lignins

  Y ie ld ( % ) ratio acetic acid:formic acid

b. Bamboo pulp by acetic acid:formic acid 75:25

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  Figure 4. Structure of bamboo pulp fibers Formic acid as an active agent was able to effectively penetrate into the interior space of the cellulose molecules, thus collapsing the rigid crystalline structure and allowing hydrolysis to occur easily in the amorphous zone as well as in the crystalline zone. The research showed that formic acid can affect the crystalline parts of cellulose [51]. Acid hydrolysis process of cellulose at bamboo pulp is heterogeneous and occurs on the structural surface of crystalline lattices of cellulose molecules [52].

  IV. C ONCLUSION The results of the study showed that the increasing of the amount of formic acid added can reduce levels of cellulose, hemicellulose, lignin and pulp yield or bamboo pulp . The best result of this research was the ratio ofacetic acid: formic acid = 90:10 which produced level ofcellulose 66,98%, hemicelluloses 16,83%, lignin content3,59%, and yield of 42,279%.

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