15.계면현상 - Physical Pharmacy Laboratory
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Transcript 15.계면현상 - Physical Pharmacy Laboratory
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Liquid Interface
Adsorption at Liquid Interfaces
Adsorption at Solid Interfaces
Applications of Surface Active Agents
Electric Properties of Interfaces
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Interface
The boundary between two phases (faces)
Surface
Ether a gas-solid or a gas-liquid interface
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Fig. 15-1
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Surface tension
A force pulls the molecules of the interface together
Unit : dyne/cm
Interfacial tension
The force per unit length existing at the interface between
two immiscible liquid phases
Unit : dyne/cm
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
= f / 2L
Fig. 15-3
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
W = A
W : The work done or surface free energy (ergs)
: surface tension (dyne/cm)
A : The increase in area (cm)
dw
force dis tan ce
dw
f ds 2 L ds dA
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Capillary rise method
DuNoüy ring method
Drop weight ….
Temperature Surface tension
Critical Temperature Surface Tension = 0
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
2r = r2hg
= 1/2 rhg
Fig. 15-5
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
dial reading in dynes
correction,β
2 ring circumference
Fig. 15-6
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Wa = L + S - LS
Fig. 15-7
w A
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Wc = 2L
Fig. 15-8
w A
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
S = Wa - Wc = (L + S - LS) - 2L
S = S - (L + LS)
s : 기질액체의
표면장력
L : 퍼지는 액체의 표면장력
ㅣㄴ : 두 액체 사이의 계면장력
S > 0 : spreading
S < 0 : form globules or a floating lens
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Surface free energy
The work that must be done to increase the surface by unit
area
Adsorption
A phenomenon, where the added molecules are
partitioned in favor of the interface
Absorption
The liquid or gas being absorbed penetrates into the
capillary spaces of the absorbing medium
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Surface-active agent (= surfactant, amphiphile)
Molecule and ion that are adsorbed at interfaces
The molecule or ion has a certain affinity for both polar
and nonpolar solvent
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
An arbitrary scale of
values to serve as a
measure of the
hydrophilic-lipophilic
balance of surface-active
agents
Fig. 15-11
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Nonionic surfactant
HLB = E/5
E : Percent by weight of nonionic surfactant
Polyhydric alcohol fatty acid esters
S
HLB 20 1 -
A
S : The saponification number of the ester
A : The acid number of the fatty acid
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
The specific HLB that the oil phase of an oil-inwater(O/W) emulsion required
6 s
Qs
4Q 1000
10 0.5 RHLB
s : The density of the surfactant mixture
: The density of the dispersed phase
Q : The percent of the dispersant of the
emulsion
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Adsorbent : The material used to adsorb the gas
Adsorbate : The substance being adsorbed
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Physical adsorption
Van der Waals forces
Reversible
Temperature, pressure
desorption (the removal of the adsorbate from
the adsorbent)
Chemisorption
Chemical bond
Irreversible
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
The relationship between the amount of gas
physically adsorbed on a solid and the equilibrium
pressure or concentration at constant temperature
Fig. 15-18
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
x
1n
y
kp
m
y : the mass of gas x adsorbed per unit mass m of
adsorbent
k, n : constants
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
ymbp
y
1 bp
p
1
p
y
bym
ym
y : the mass of gas adsorbed per gram of adsorbent
at pressure p and at constant temperature
ym : the mass of gas that 1 gram of the adsorbent can
adsorb when the monolayer is complete
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Fig. 15-20
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
p
1 b 1 p
y p0 p y m y m b p0
P : the pressure of the adsorbate in mmHg at which
the mass y of vapor per gram of adsorbent is
adsorbed
p0 : the vapor pressure when the adsorbent is
saturated with adsorbate vapor
ym : the quantity of vapor adsorbed per unit mass of
adsorbent when the surface is covered with a
monomolecular layer
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Langmuir equation
c
1
c
y
by m
ym
c : the equilibrium conc. In milligrams of
alkaloidal base per 100mL solution
y : the amount of alkaloidal base x in milligrams
adsorbed per gram m of clay
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Wetting agent
: A surfactant that, when dissolved in water, lowers
the advancing contact angle
Fig. 15-24
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
s = SL + L cos
S = L ( cos -1 )
Wa = WSL = L ( 1- cos )
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Surface tension
at cos = 1
(c)
Fig. 15-25
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Emulsifying agents
Detergents
Wetting agents
Solubilizing agents
Antibacterial agents
Protective agents
Aids to absorption of drug
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Fig. 15-28
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Nernst potential (E)
: aa’
Zeta potential ()
: bb’
Fig. 15-29
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실
Concentration of electrolyte
Screening effect of the counterion
Potential falls off more rapidly with
distance
SKKU Physical Pharmacy Laboratory
성균관대학교 물리약학연구실