KINETIKA REAKSI POLIMERISASI UREA-ASETALDEHID DALAM PROSES ENKAPSULASI UREA
One method to increase the effectiveness of urea utilization and thus reduce environmental pollution caused by urea is encapsulation of urea. With urea encapsulation, its releases in water can be controlled. Microcapsule shell is formed directly on surface of urea particles called in situ polymeriza...
Saved in:
| Main Authors: | , |
|---|---|
| 格式: | Theses and Dissertations NonPeerReviewed |
| 出版: |
[Yogyakarta] : Universitas Gadjah Mada
2012
|
| 主題: | |
| 在線閱讀: | https://repository.ugm.ac.id/97893/ http://etd.ugm.ac.id/index.php?mod=penelitian_detail&sub=PenelitianDetail&act=view&typ=html&buku_id=53827 |
| 標簽: |
添加標簽
沒有標簽, 成為第一個標記此記錄!
|
| 總結: | One method to increase the effectiveness of urea utilization and thus
reduce environmental pollution caused by urea is encapsulation of urea. With
urea encapsulation, its releases in water can be controlled. Microcapsule shell is
formed directly on surface of urea particles called in situ polymerization. This
research aimed to study the kinetics of the polymerization reaction of urea and
acetaldehyde in the urea encapsulation process. The proposed model considers
the diffusion of acetaldehyde and reaction in solid phase.
Urea and acetaldehyde in 1:1.2 ratio mol/mol were charged into
erlenmeyer equipped with a thermometer and cooler. The reaction was run for 2
hours and sample was taken every 20 minutes. The amount of remaining
acetaldehyde was determined by sodium sulfite method and grain size was
measured by optical microscope and image pro software. Variables investigated
were reaction temperatures (5 - 15°C), particle sizes (14, 18, and 25 mesh), and
pH (2 - 4). Reaction rate constants and diffusivity constants were determined by
minimizing SSE.
The results show that the higher temperature and grain size, the higher
conversion is. Lower pH (more acid) provides higher conversion. Urea particle
was seen slightly swelling during the reaction, and also slightly sticky The
proposed reaction kinetics model fits well to the experimental data and the value
of reaction rate constants vary around : k1 (addition) 6.975 - 242.7 mL/mmol/min,
k2 (condensation) 2.81 x 10-3 � 0.133 and k3 4.70 x 10-5 � 1.17 x 10-2 ml/mmol/min. The value of diffusion constants are DA = 9.06 x 10-7- 1.75 x 10-5cm2/min
and DH+= 3.18 x 10-6� 7.06 x 10-5cm2/min. The process is bestconducted at 15oC, 14 mesh, pH 4 and 120 minutes time of reaction which result
in 63.38% conversion. This can be seen from appearance of polymer product of
urea-acetaldehyde that is slightly tougher than that of in other condition. |
|---|