Abstract
The authors explored the possibility of using persimmon byproducts as raw materials for obtaining kraft pulps. Various unbleached and bleached kraft pulps via pulping and bleaching processes were prepared. Then, their characteristics were determined and compared with those of commercial kraft pulps. For the highest screened yield of persimmon byproduct unbleached kraft pulps, the optimal pulping conditions were a liquid ratio of 5:1, an active alkali concentration of 25%, a sulfidity of 30%, and a cooking time of 3 h. Furthermore, the authors obtained persimmon byproduct bleached kraft pulps (PB-BKPs) with an ISO brightness of 73% via three-stage bleaching using 3% ClO2, 1.5% NaOH, and 3.5% ClO2. Moreover, PB-BKP prepared under optimal pulping and bleaching conditions had physical characteristics similar to those of commercial mixed-hardwood bleached kraft pulp, but with relatively low ISO brightness. Therefore, as raw materials, persimmon byproducts can be used for manufacturing a bleached kraft pulp.
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The Manufacture of Bleached Kraft Pulp from Persimmon Byproducts
Hae Min Jo,a Ji Young Lee,b,* Su Ho Kim,a and Kyung Min Kim a
The authors explored the possibility of using persimmon byproducts as raw materials for obtaining kraft pulps. Various unbleached and bleached kraft pulps via pulping and bleaching processes were prepared. Then, their characteristics were determined and compared with those of commercial kraft pulps. For the highest screened yield of persimmon byproduct unbleached kraft pulps, the optimal pulping conditions were a liquid ratio of 5:1, an active alkali concentration of 25%, a sulfidity of 30%, and a cooking time of 3 h. Furthermore, the authors obtained persimmon byproduct bleached kraft pulps (PB-BKPs) with an ISO brightness of 73% via three-stage bleaching using 3% ClO2, 1.5% NaOH, and 3.5% ClO2. Moreover, PB-BKP prepared under optimal pulping and bleaching conditions had physical characteristics similar to those of commercial mixed-hardwood bleached kraft pulp, but with relatively low ISO brightness. Therefore, as raw materials, persimmon byproducts can be used for manufacturing a bleached kraft pulp.
Keywords: Agricultural byproduct; Persimmon byproduct; Kraft pulp; Yield; Pulping; Bleaching
Contact information: a: Department of Forest Products; b: Department of Environmental Materials Science/IALS, Gyeongsang National University, Jinju 52828, Republic of Korea;
* Corresponding author: paperyjy@gnu.ac.kr
INTRODUCTION
The Korean paper industry has been steadily growing with the development of various paper products and production technologies. However, it is essential to overcome limitations, such as the low pulp self-sufficiency rate of 20% and the shortage of fibrous natural and fossil fuel resources (Eom 2014; Jeong 2016) for the continued growth of the Korean paper industry. Generally, agricultural byproducts are obtained from agricultural produce. According to a report published by the Ministry of Agriculture, Food and Rural Affairs in the Republic of Korea (Kim et al. 2014), 8,909 thousand tons of agricultural byproducts were theoretically generated in 2013. The most common were rice byproducts (65%), such as rice husk and rice straw, followed by fruit byproducts (18%) and field byproducts (16%). Most agricultural byproducts are fibrous resources that have been evaluated for use in energy and materials industries (Fahmy et al. 2017; Jesus et al. 2017; Fillat et al. 2018; Wi et al. 2018; Iriondo-DeHond et al. 2019). However, the actual amount of such byproducts in various industries is low (El-Sakhawy et al. 1996; Bhardwaj et al. 2005). In particular, because of the lack of natural resources in the Republic of Korea, technological development for recycling agricultural byproducts that are currently being discarded is necessary.
Persimmon is one of the highest produced fruits in the Republic of Korea and forms a large proportion of the fruit market. In 2017, approximately 300,000 tons of persimmon were produced from an area of larger than 24,000 ha (Kang 2017). While cultivating persimmon, many byproducts are generated via pruning; however, these are crushed and used as compost or subsequently discarded. The use of persimmon byproducts in pulp and paper mills can positively affect the domestic environment and the Korean pulp and paper industry, which lacks natural fibrous resources.
Previously, studies have reported that many types of agricultural byproducts have chemical and physical characteristics that are suitable for producing kraft pulp (Lee et al. 2014; Kaur et al. 2017). Because persimmon byproducts are fibrous resources, they are expected to be used in both the pulp and paper industry. However, few studies have examined the pulping or papermaking technology of agricultural byproducts.
In the present study, the authors evaluated the possibility of using persimmon byproducts as raw materials for manufacturing bleached kraft pulp. Then the chemical composition of the persimmon byproducts was analyzed, several kraft pulping processes to prepare persimmon byproduct unbleached kraft pulps (PB-UKPs) under various pulping conditions were performed, and their pulp yields were measured. After preparing the PB-UKP, the authors performed three-stage bleaching to prepare the persimmon byproduct bleached kraft pulp (PB-BKP). Both PB-UKP and PB-BKP were characterized, and their characteristics were compared with those of commercial bleached kraft pulps (BKPs).
EXPERIMENTAL
Materials
After pruning, the persimmon byproducts from Dangam Farm, Micheon-myeon, Jinju-si, Gyeongsangnam-do (Republic of Korea) were collected. As a control, softwood bleached kraft pulp (SwBKP) obtained from pine and mixed-hardwood bleached kraft pulp (HwBKP) was used and supplied by Moorim Paper (Jinju, Republic of Korea). Various chemicals for chemical composition analysis, kraft pulping, and bleaching were used.
Methods
Preparation of persimmon byproduct and analysis of chemical composition
Some severely rotten portions of persimmon byproducts were removed and allowed to air dry for 24 h. As shown in Fig. 1, before the experiments, persimmon byproduct chips of approximately 0.5 to 1.5 cm thickness were prepared.