鍍鉻過程中因氣泡在液面破裂所產生的含鉻液滴之特性
Other Title
Characteristics of chromium droplets generated from bubble
bursting at the surface of chromic acid solutions
bursting at the surface of chromic acid solutions
Date Issued
1999-07-31
Date
1999-07-31
Author(s)
王秋森
DOI
882314B002048
Abstract
Generation of droplets from bubble
bursting at liquid surface is a common
process in the natural environment as well as
industrial applications such as chromium
electroplating/anodizing processes. The
droplet generating process has significant
health implications when it involves the
transfer of hazardous substances from liquids
to the atmosphere. This study has the
objective of evaluating the effects of
electrolyte concentration, gas flow rate, and
bubble rise distance on the characteristics of
droplets generated from bubble bursting at
liquid surface of chromic acid solutions in a
laboratory bubbling system. The ranges of
parameter value studied were: CrO3
concentrations in the range of 31.25 to 375
g/L, liquid depths of 15 and 30 cm, and air
flow rates of 4 to 8 L/min.
The experimental results show that
droplets generated from bubbles bursting at
liquid surface varied from submicrometer
range to several tens of micrometers in
diameter for the studied ranges of parameter
value. The count median diameters (CMDs)
of droplets were in the range of 0.15-0.31 mm
in the measured size range of 0.1-30 mm.
The droplet volume distributions calculated
from the number distribution data were
bimodal, indicating the presence of both film and jet droplets which had a volume
distribution mode of 3-5 mm and over 10 mm,
respectively. Moreover, the film droplets
and the jet droplets were found to have a
separating diameter of about 7 mm.
In general, the droplet volume
concentration appeared to have a maximum
in the studied concentration range of bulk
electrolyte solutions and increased linearly
with increasing gas flow rate. However, an
increase in bubble rise distance led to a
reduction in droplet volume concentration.
The Cr(VI) concentration ratio between the
droplets and the bulk solution decreased
exponentially with increasing CrO3
concentration in the bulk solution. The
liquid surface tension was an important factor
governing the Cr(VI) fractionation by droplet
generation.
Subjects
chromium droplets
bubble bursting
chromium electroplating/anodizing
surface tension
Publisher
臺北市：國立臺灣大學公共衛生學院公共衛生學系
Type
report
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