Study On Pulping & Papermaking Characteristics Of Plant Fiber Residues Of Rabdosia Amethystoides

The utilization of the Earth's large amounts of plant fiber residues as effective resources is of significant importance for both environmental conservation and as alternative raw materials for energy and manufacturing. This paper reviews the research on plant fiber residue resources in terms of their classification, biomass and the present status of their application. The aim of this study is to provide some valuable information on the raw material and processing techniques for the application of traditional Chinese medicine residue, as well as the other types of plant fiber residue. Additionally, the constant search of raw materials for the pulping and papermaking industry is expected to be mitigated through the discovery of substitute materials and the development of corresponding techniques.In this study, the plant Rabdosia amethystoides, which is an important and typical traditional Chinese medicinal plant , and its manufacturing residues, have been selected as the experimental example. To fully understand the feasibility of this waste material in pulping and papermaking, the biological characteristics , chemical composition and fiber morphology of raw R. amethystoides and its corresponding processed waste were studied and compared. In addition, the general process of cooking, and the cooking properties utilizing the alkaline-anthraquinone method (AP-AQ process) were systematically examined. The optimum bleaching characteristics utilizing HP, D/CED, D/CEpD, D/CEpDP and D/CED1ED2 bleaching conditions were determined. The lignin FTIR spectra were measured and analyzed before and after the cooking process. In addition, the beating parameters, and pulping and papermaking physical properties were studied.The following results were obtained from the present study:(1) The chemical composition of the stem of R. amethystoides was: ash content 3.80%, hot water extractives 10.90%, 1% NaOH extractives 32.80%, benzene-alcohol extractives 1.95%, Klason lignin 21.01%, holocellulose 71.83% and pentosan 16.09%. The chemical composition of R. amethystoides residue was: ash content 3.01%, hot water extractives 3.70%, 1% NaOH extractives 25.9%, benzene-alcohol extractives 1.33%, Klason ligin 20.17%, holocellulose 72.60% and pentosan 18.57%. The fiber morphology characteristics were: the stem of R. amethystoides: fiber length 0.68mm, length/width ratio 44.8. The ratio of cell wall thickness to lumen is 0.37. For the R. amethystoides residue: fiber length 0.68mm, length/width ratio 44.5. The ratio of cell wall thickness to lumen is 0.38. These results indicate that, R. amethystoides is a viable raw material for the papermaking industry.(2) The pulping properties of R. amethystoides by the Alkaline- Anthraquinone method were studied. The results indicate that the sequence of variables affecting the various cooking properties was, in order of increasing effect: (i) for yield: retention time, total active alkali charge and anthraquinone charge; (ii) for Kappa number: total active alkali charge, retention time and anthraquinone charge; (iii) for residual alkali: total active alkali charge, retention time and anthraquinone charge. The optimum cooking conditions of the AP-AQ method were as follows: total active alkali charge 22% (NaOH), and retention time 120 min; maximum temperature 160℃; liquor to o.d. (oven-dried) chips ratio 1:4. The optimal cooking results are: yield 35.40%, Kappa number 59.29 and residual alkali 15.17g/L (NaOH).(3) The optimum D/CEpD bleaching conditions, the bleaching characteristics of alkaline-anthraquinone R. amethystoides pulp, and the physical strength of the unbleached pulp were studied. The results indicate that the optimum bleaching conditions for D/CEpD pulp were: total effective chlorine charge 10% (all based on o.d. pulp), which was distributed in a ratio of 7.0:3.0 to the D/C and D stages, and H2O2 charge 1.1%. The characteristics of the bleached pulp were: brightness of AP-AQ 75.8% ISO, P.C. number 1.1. The optimum bleaching conditions for D/CEpDP pulp are: total effective chlorine charge 10% (all based on o.d. pulp), which was distributed in a ratio of 7.0:3.0 to the D/C and D stages, and H2O2 charge 1.1% in Ep stages,H2O2 charge 1.6% in P stages。The characteristics of the bleached pulp were: brightness of AP-AQ 80.5% ISO, P.C. number 0.6. The optimum bleaching conditions for D/CED1ED2 pulp were: total effective chlorine charge 10% (all based on o.d. pulp), which was distributed in a ratio of 7.0:3.0 to the D/C and D1 stages, and effective chlorine charge 0.9% in the D2 stage. The characteristics of the bleached pulp were: brightness of AP-AQ 81.7% ISO,P.C.number 0.7;The optimum bleaching conditions for HP pulp were: NaClO3 charge 12% in H stage,H₂O₂ charge 2.5% in P stage. The characteristics of the bleached pulp were: brightness of AP-AQ 70% ISO, P.C. number 1.0.(4) The physical strength data of the pulp with a beating degree 40°SR were: tear index of AP-AQ 8.0mN·m2/g, burst index of AP-AQ 1.3kP·m2/g and breaking length of AP-AQ 2315.4m.(5) The analysis of the lignin FTIR spectra indicated that carboxyl groups and cymene with oxygen were produced in considerable amounts in the cooking process.Although the resulting pulp yield was somewhat lower than for other papermaking materials, the use of R. amethystoides residue in pulp and papermaking nevertheless represents a viable way to utilize the residue, which is otherwise discarded.