نتایج جستجو برای: kraft
تعداد نتایج: 2427 فیلتر نتایج به سال:
In this paper, the depolymerization of lignin was successfully achieved by the thermal treatment of kraft lignin in butyl-1,8-diazabicyclo[5.4.0]undec7-enium chloride ([DBUC4][Cl]) without a catalyst. The thermal treatment experiments were performed in an oven at 150, 200, and 250 °C for 1 h. The changes in kraft lignin structure over the course of depolymerization were characterized by gel per...
∈∆N ), (1.1) where the convention 0log(0)= 0 is adapted, (see Shannon [19]). Throughout this paper, ∑ will stand for ∑N i=1 unless otherwise stated and logarithms are taken to the baseD (D > 1). Let a finite set of N input symbols X = {x1, x2, . . . ,xN } be encoded using alphabet of D symbols, then it has been shown by Feinstien [6] that there is a uniquely decipherable code with lengths n1,n2...
Laboratory-obtained kraft lignins have been studied via elemental analysis (EA), 1H-NMR, FTIR, GPC to analyse the chemical structure. The kraft lignins were subjected to oxidation with H2O2 using Co(salen) as a biomimetic catalyst at mild condition (80oC, 240 min). The kraft lignins isolated from eucalyptus (EKL) and bamboo (BKL) had a low hydroxyl (oxygen) contents, a low molecular weights (~3...
The KRAFT project has defined a generic agent-based architecture to support knowledge fusion — the process of locating and extracting knowledge from multiple, heterogeneous on-line sources, and transforming it so that the union of the knowledge can be applied in problem-solving. KRAFT focuses on knowledge in the form of constraints expressed against an object data model defined by a shared onto...
raft pulp i s manufactured in the United States from nearly all commercially availK ble wood species. About 55 million tons per year are manufactured, 30 million of which are bleached and used mostly for printing and office papers and tissue products. Some kraft pulp is exported, and significant quantities are imported, mostly from Canada and South America. Pulps manufactldred by sulfite, mecha...
In this study, Eucalyptus globulus stumpwood samples collected from six different sites in Portugal were evaluated for their ease of pulping, using two delignification processes (kraft and alkaline sulfite-anthraquinonemethanol (ASAM)). Morphologically, the stumpwood included fibers with a mean length of 0.930 mm, diameter of 21.4 μm, lumen width of 9.1 μm, and cell-wall thickness of 6.1 μm. Th...
Kraft lignin, a by-product of the pulp and paper industry, was explored as an adsorbent for six dietary oils and was compared to chitosan, which is widely used in the pharmaceutical market. The dissolution and adsorption efficiency of kraft lignin were tested at an acidic pH corresponding to the stomach, as well as at a basic pH corresponding to the intestine. Results showed that kraft lignin i...
Knowledge fusion refers to the process of locating and extracting knowledge from multiple, heterogeneous on-line sources, and transforming it so that the union of the knowledge can be applied in problem-solving. The KRAFT project has defined a generic agent-based architecture to support fusion of knowledge in the form of constraints expressed against an object data model. KRAFT employs three ki...
This review analyses the advances of pretreatment with sulfide-containing liquors to modify kraft pulping. In the past several decades, modified kraft pulping has advanced rapidly, based on the principle that high sulfide content at the first stage of cooking would improve both pulp quality and the selectivity of delignification. Pretreatment of wood chips with sulfide-containing liquors (i.e.b...
one of the solutions to increase the applications of lignin molecules is increasing reactive functional groups by chemical modification. adding reactive functional groups into the lignin structures is one the best proposed methods. the aim of this study was to investigate change in structure as well as glass transition temperature (tg) of soda and kraft lignins after hydroxymethylation them wit...
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