2. Materials-palygorskite, tetracycline 1.
Goal 2.
Outline
Result and discussion 3.
Batch
study IC
XRD TG
FT-IR
Kinetic adsorption
Isotherm adsorption
Desorbed cation
pH edge adsorption effect
Ionic strength effect
Temperature effect

3. Materials 1
一. Materials
1.clay:playgorskite
2.tetracycline

4. Materials-clay Palygorskite1
Palygorskite
Palygorskite is a special type of clay made of periodic reversal of the building block
so that the interlayer space is made of one dimensional channel, thus limiting its
expandability. Even though, it is still a good adsorbent for a variety of compounds.
SEM:short fiber﹛~0.1μm wide and 1-2μm long﹜

5. Materials-antibiotic1
Materials-antibiotic
D C B A
NHMe2 OH
pKa2 = 7.7
pKa3 = 9.7
pKa1 = 3.3 +
Tetracycline (TC)
Properties~
pKa1=3.3
0.0
0.2
0.4
0.6
0.8
1.0 2 4 6 8 10 12 pH
Fraction
TCH3 +
TCH2 
TCH - TC 2-
pKa2=7.7
pKa3=9.7
+00
+-0
+--
0--
Fig. 1. Molecular structure
of TC on an planar view A(a)
and speciation under different
pH (b).
3.3
7.7
9.7

6. 二. Goal Rectorite Illite TC SYn-1 SAz-1 SHCa-1 SWy-2 palygorskite7 2 TC
The goal of this research is to study the adsorption of
TC on palygorskite under different physical and chemical
conditions in conjunction with X-Ray diffraction (XRD)
and Fourier transform infrared (FTIR), in order to access
the feasibility and applicability of using palygorskite as
a potential adsorbent to treat wastewater containing
higher amounts of TCs.
SYn-1
SAz-1 6 3
SHCa-1
a synthetic mica- montmorillonite
SWy-2
a high charge Ca- montmorillonite 4 5
a Li- bearing trioctahedral smectite
a low charge Na- montmorillonite

7. Result and discussion-kinetic adsorption3
Ci:200ppm
Amount TC Sorbed (mg/g)
Equilibrium Time (h) 6 12 18 24 30 5 10 15 20 25
y = x
r2=
0.0
0.2
0.4
0.6
0.8
1.0
t/qt (h-g/mg) 2
equilibrium 24
Fig. 1. Sorption kinetics of TC on palygorskite. The solid line is pseudo-second
order fit to the observed data.

8. Result and discussion- Langmuir sorption isotherm3
Result and discussion- Langmuir sorption isotherm 20 40 60 80
100
200
300
400
500
600
700
pH=8.7
pH=1.5
pH=6
pH=11
Amount TC Sorbed (mg/g)
Equilibrium TC Concentration (mg/L)
TCH-
TCH3+
At pH 8.7, although the TC is in its anionic form TCH-, its sorption reached a
Maximum of 210 mmol/kg. Due to the presence of positively charged functional
group of dimethylammonium, cation exchange may still play a role.
TCH20
TC2-
Fig. 2. Sorption isotherm of TC on palygorskite at pH1 (), 4-5 (), 8.7 (), and 11 ().The lines are Langmuir fit to the observed data.

9. Result and discussion- IC data: pH=63
Result and discussion- IC data: pH=6
50ppm ppm ppm ppm 600ppm
800ppm
The extra Ca2+ desorption associated with TC sorption could be attributed to the
Replacement of H+ for Ca2+ as the TC used is in HCl form.
Fig. 3. Amount of Na (), K (), Mg () Ca (), and total cation ( )
desorbed as affected by TC sorption on palygorskite.

10. Result and discussion- effect of pH on TC sorption edge3
Result and discussion- effect of pH on TC sorption edge
Ci:200ppm 8
9.5
The trend in TC sorption as effected by pH agrees well with the TC sorption isotherm
study.
Fig. 4. Sorption of TC on palygorskite as affected by solution pH.

11. Result and discussion- effect of ionic strength on TC sorption3
Result and discussion- effect of ionic strength on TC sorption
Amount TC Sorbed (mg/g)
Log (Ionic strength as NaCl, log(mol/L)
y = -5.2x + 18
r2=0.95 20 25 30 35 -3 -2 -1
50.0
62.5
75.0
87.5
Percentage of TC Sorbed
82% of the input TC was
removed from water
56% of the input TC was
removed from water
0.01M
0.001M
0.1M
Fig. 5. Sorption of TC on palygorskite as affected by solution ionic strength.
The line is just a linear fit on a semi-log scale showing reverse relationship
between TC sorbed and solution ionic strength.
The competing of present ion against TC for sorption sites shows that part of the TC
sorption was due to ion exchange mechanism, same as that observed for TC sorption
on rectorite and montmorillionite.

12. Result and discussion- effect of temperature on TC sorption3
Result and discussion- effect of temperature on TC sorption
55℃
40℃
25℃ 11
Ci:200ppm
pH=1.5 10
pH=6
y = x 9 R 2 =
y = x 8 2
pH=8.7 R
= 0.937
Ln Kd (L/kg) 7
y = x
pH=11 2 6 R =
The small positive S indicates that the sorption is spontaneous due to an
increase in system randomness as TC molecules remove themselves
from water onto solid surfaces. 5
y = x R 2 = 4
0.0030
0.0031
0.0032
0.0033
0.0034
1/T (1/K)
Fig. 6. Influence of temperature on TC sorption on palygorskite.
Positive:
Endothermic process
Negative:spontaneous

13. Result and discussion- XRD analyses3
Result and discussion- XRD analyses
700
1400
2100
2800
3500
4200 2 6 10 14 18 22 26 30
2θ (º)
Intensity (cps)
pH 11
pH 8.7
pH 6
pH 1.5
Raw PFl-1
d110=10.53 Å
8.4
Fig. 7. X-Ray diffraction patterns of palygorskite after treated with TC at an initial concentration of 800 mg/L at different pH conditions.

14. Result and discussion- XRD analyses3
Result and discussion- XRD analyses
These results are completely different from those of TC sorption on montmorillionite
(Porubcan et al. 1978; Kulshrestha et al. 2004), on soils (Pils and Laird, 2007),
and on rectorite(Chang et al. 2008).
700
1400
2100
2800
3500
4200 2 6 10 14 18 22 26 30
800 mg/L
600 mg/L
400 mg/L
200 mg/L
100 mg/L
50 mg/L
Raw PFl-1
The invariability of d-spacing after adsorbing different amounts of TC at different pH
conditions suggest that the uptake of TC by palygorskite is on the external surface.
Intensity (cps)
2θ (º)
Fig. 8. X-Ray diffraction patterns of palygorskite after treated with TC at different initial concentrations at neutral pH.

15. Derivative of mass (g/min)
result 3
Result and discussion-Derivative of thermogravimetric (DTG) analyses
350
If the Tpeak at 205 ℃ is thought as a composite peak made of 214 ℃ for the removal
of zeolitic water and the decomposition of TC at a slightly lower temperature, the
thermal stability of the TC sorbed on PFL-1 is less stable compared to crystalline TC.
300
Dehydration temperature
Dehydroxylation temperature
250
83℃
420℃
200
220℃
Derivative of mass (g/min)
150
Raw PFL-1
pH1.5
pH6
pH8.7
Crystalline TC
600℃, mass loss is 56%
100
214℃ 50
205℃ 20
120
220
320
420
520
620
decomposition temperature (Tpeak) :230℃。Mass loss is 25% T℃
Fig. 9. Derivative of thermogravimetric analysis of raw PFL-1, and PFL-1 with
TC adsorbed at an initial concentration of 800 mg/L and pH 1.5, pH 6, and pH 8.7.
Also drawn is the DTG of crystalline TC, whose vertical scale is reduced by 50%.

16. Result and discussion-FT-IR3 20 40 60 80
100
400
800
1200
1600
2000
2400
2800
3200
3600
4000
pH 11
pH8.7
pH6
pH1.5
PFl-1
Wave number (cm–1)
Transmittance (%) TC
The TC vibrations were much weaker compared to that sorbed to
montomorillonite (Kulshrestha et al. 2004) and rectorite (Chang et al. 2008),
→ indicating that less amount of TC was adsorbed on PFL-1.
Figure 8. FTIR spectra of palygorskite after equilibrated with TC at an initial concentration of 800 mg/L at different pH.

17. Result and discussion-FTIR3
Result and discussion-FTIR 20 40 60 80
100
1250
1300
1350
1400
1450
1500
1550
1600
1650
1700
1750
pH 11
pH8.7
pH6
pH1.5
PFl-1 TC
Wave number (cm–1)
Transmittance (%)
The most characteristic peaks are those in 1250–1750 cm–1.
At a solution pH of 1.5, the bands at 1311, 1356, 1456, 1524, 1579
and 1616cm−1 all shifted about 10–15 cm−1 to higher frequencies.
A shift to higher frequencies resulted from strong interaction between
palygorskite surface and the intercalated TC molecules.
Figure. FTIR spectra of palygorskite after equilibrated with TC at an initial
concentration of 800 mg/L at different pH in the range of 1250–1750 cm–1.

18. Conclusions
1. Sorption of TC on palygorskite followed a pseudo-second-order kinetics.
Sorption equilibrium could be reached in 2 h.
2. Sorption of TC on palygorskite followed a Langmuir sorption isotherm with
the sorption maximum reached to 99mg/g, or 210 mmol/kg at pH 8.7.
3. Solution pH and ionic strength had strong effects on TC uptake by palygorskite.
4. Sorption of TC on palygorskite is an endothermic reaction, and thus, increasing
temperature will enhance the uptake of TC by palygorskite. The moderate negative
G indicates that physisorption or surface complexation may be the dominant
mechanism. The small positive S suggests that the sorbed TC molecules adopted
a random arrangement on palygorskite surfaces.
5. XRD analyses showed no d-spacing changes at different pH values or different
sorption amounts, further suggesting that the sorption is on the external surfaces.