| Author | Nguyen Minh Hoang |
| Call Number | AIT Thesis no.PP-06-6 |
| Subject(s) | Newsprint--Recycling
|
| Note | A thesis submitted in partial fulfillment of requirements for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Neutral de inking process promises a wide range application for recycled paper because of its positive effect on final product as well as its user-friendly technology. Many works have been done in the recent year cited that neutral deinking process not only produces high quality products but also reduces production cost, compared to alkaline process. Neutral process is not affected by yellow darkening in high pH environment, therefore no need to use other additional chemical to limit the yellow darkening in alkaline process. A major theme of this study is the effects of soaking time, repulping time and consistency at the repulping stage of neutral deinking process on the ERIC, brightness and flotation yield. The materials (30% ONP and 70% ONP) are collected from Vietnam. Handsheet is made after repulping stage, flotation stage and hyperwashing stage to measure ERIC and brightness. After flotation stage, yield is determined. The experiment was conducted by applying the factorial design method, which aimed to reduce the number of experiments and predict result of experiment. It was found that brightness decreased at both too high and too low consistency due to ink redeposition onto fiber and low ink detachment. The optimum consistency in this work is 4%. Moreover, soaking time and repulping time also have strong effect on brightness, ERIC, flotation yield and hyperwashing yield. The repulping time should not keep too long, especially at high consistency due to ink redeposition onto fiber. The result of experiments indicate that highest result is achieved at 4% consistency, 5 hour soaking time and 10 minute repulping time. Beside that, the effect of surfactants (nonanionic and anionic) on ERIC, brightness and flotation yield also are considered in this study. Several neutral processes have been done while only one typical alkaline process is conducted. The purpose of this work aims to evaluate and compare the result of the ERIC, brightness, flotation yield and hyperwashing yield between a typical alkaline process and a number of neutral experiments with variable conditions. After that, a peroxide bleaching stage is done to measure how much brightness units can gain from both alkaline process and neutral process. A selected sample of neutral process and alkaline process is bleached. The bleaching conditions and bleaching agents are unchanged for both alkaline process and neutral process. The effect of bleaching agents and bleaching conditions are not considered in this work. The results of this work indicate the important of surfactants in flotation deinking process. However, too high soap dosage may give negative brightness at flotation stage. At bleaching stage, the brightness of neutral process is better than alkaline process. Neutral process showed a slight gain in brightness (about one point) compared to alkaline deinking process after the bleaching stage |
| Year | 2006 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Pulp and Paper Technology (PP) |
| Chairperson(s) | Nazhad, Mousa M. |
| Examination Committee(s) | Lehtinen, Esa;Malinen, Raimo |
| Scholarship Donor(s) | Government of Finland - AIT Fellowship |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2006 |