The Kraft Pulp And Paper Properties of Sweet Sorghum Bagasse (Sorghum bicolor L Moench)

Abstract

Abstract. This study investigated the potency of sweet sorghum (Sorghum bicolor) bagasse as raw material for pulp and paper using kraft pulping. The effects of alkali and sulfidity loading on kraft pulp and paper properties were also investigated. The pulping condition of the kraft pulp consisted of three levels of alkali loading (17, 19 and 22%) and sulfidity loading (20, 22 and 24%). The maximum cooking temperature was 170°C for 4 h with a liquid to wood ratio of 10:1. Kraft pulping of this Numbu bagasse produced good pulp indicated by high screen yield and delignification selectivity with a low Kappa number (< 10). The unbleached pulp sheet produced a superior brightness level and a high burst index. The increase of active alkali loading tended to produce a negative effect on the pulp yield, Kappa number and paper sheet properties. Therefore, it is suggested to use a lower active alkaline concentration.Keywords: alkali and sulfidity loading; kraft pulping; pulp and paper properties; sweet sorghum bagasse. IntroductionThe deforestation rate in the world due to wood and paper demand is estimated at about 11.2 million hectares per year [1]. Therefore, the pulp and paper industry should find out alternative raw materials, particularly non-wood fiber coming from agricultural wastes [1,2] that are annually highly available. On the other hand, concerns about sustainable future fiber supplies and a potential increase in wood cost also stimulates the pulp and paper industry to find out other fiber sources, such as sorghum [2]. Sorghum is a C 4 crop characterized by very efficient photosynthesis, which can grow quickly [1,3] and has wide range adaptability. Sweet sorghum produces a high yield of green biomass and a huge amount of ligno-cellulosic residue [4,5]. This biomass is renewable, cheap and widely available. The residue produced by juice extraction from the stalk, the so-called bagasse, represents about 30% of the whole plant fresh weight [6] and is used for non-food applications containing carbohydrate polymers (cellulose and hemicellulose) and lignin. Sorghum bagasse contains 40-49% cellulose,which is important for pulp production, with a cutting cycle at 3 months after planting. Meanwhile, fast-growing species such as Acacia mangium and Eucalyptus urophylla, containing 60% of cellulose, need 7 years for producing 120 tons of cellulose/ha/7 years. The cellulose production of sweet sorghum can reach 15 tons/ha/3 months or 60 tons/ha/1 year or 420 ton/ha/7 years, which is considerably higher than the production of A. mangium and E. urophylla [7].Pulp of sweet sorghum can be used for the manufacture of fine quality writing paper, low luminosity printing paper and kraft paper as well as corrugated solid particleboard [1,2]. Investigation on sorghum fiber for pulp production has been conducted in India [1] using a conventional soda pulping process, where the average pulping yield was 45% and the Kappa number was 14-18. The pulp is characterized by short fibers and a high proportion of fines. The production of sorg...

Antifungal Activities of Wood and Non-Wood Kraft Handsheets Treated with Melia azedarach Extract Using SEM and HPLC Analyses

“…The results for the chemical compounds of the raw materials ( Table 2 ) show that benzene–alcohol extracts, lignin, holocellulose, and ash content were 1.73–13.16%, 16.66–42.33%, 53.37–63.40%, and 1.66–6.73%, respectively. The holocellulose content in S. bicolor stalks was in accordance with the range of values reported in the literature: 71.0% [ 16 ], 67.2% [ 23 ], 68.0% from depithed extraction [ 85 ], 61.6% extracted with 1% NaOH [ 85 ], 69.0% from depithed extraction [ 86 ], and 61.6% extracted with 1% NaOH [ 86 ]. The average pulp yield from S. bicolor stalks was 45%, and the average kappa number was 14–18 when 16–20% sodium (NaOH) and a 1.5 h cooking time at 160 °C were used [ 12 ].…”

“…The lignin content in both S. bicolor and Z. mays was lower than in bamboo (26%) [ 19 ], rice hulls (20.44%) [ 88 ], and lotus leaf stalks (25.4%) [ 87 ], and higher than that in smooth bromegrass (13.7%) and tall fescue (14.0%) [ 20 ]. The content was also partially in the range of that reported for switchgrass (17.4%), Miscanthus giganteus (17.8%) [ 20 ], sugar beet (17.67%) [ 88 ], and S. bicolor stalks (17.4%) [ 23 ]. The ash content was high, especially in S. bicolor , but others were within the range of tropical hardwood (1 to 3%) [ 89 ].…”

“…Previous studies have focused on the properties of pulp and paper produced from Zea mays and S. bicolor stalks and have shown them to have promising values in terms of mechanical properties, such as the tensile index, burst index, tear index, burst index, and double fold number [ 15 , 16 , 22 , 23 , 24 , 25 ].…”

Lignin as an Active Biomaterial: A Review

“…After the treatment, the ether bond of cellulose and lignin cleavage and the biomass were washed to remove residual lignin in the pulp. This process was followed by obtaining black liquor as a by-product pulping process rich in lignin content (Fatriasari et al 2015). Kraft lignin can be isolated by dropping acid into black liquor, and it will be precipitated in the bottom of the solution.…”

Ciri Anatomi, Morfologi Serat, dan Sifat Fisis Tiga Jenis Lesser-Used Wood Species Asal Kalimantan Utara, Indonesia

“…Meskipun memiliki keragaman dalam hal panjang serat dan nilai turunan dimensinya, hasil skoring (Tabel 1) memperlihatkan serat ketiga jenis kayu masuk dalam Kelas Mutu III. Menurut Soijonkari-Pahlaka (2001); Emerhi (2012); Sharma et al (2013); Fatriasari et al (2015); Amoo et al (2016), serat dengan Kelas Mutu III cenderung menghasilkan lembaran kertas yang tebal dan kasar dengan kekuatan robek yang tinggi, namun kekuatan tariknya rendah. Di antara ketiga jenis kayu, kayu nyatoh lebih berpotensi digunakan sebagai bahan baku pembuatan pulp dan kertas karena memiliki nilai skor yang lebih tinggi.…”