Evaluation of a New Arsenic Adsorbing Resin (WASP)
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Evaluation of a New Arsenic Adsorbing Resin (WASP) Dr. Robert Stanforth, Ng Aik Teng and Woo Su-Fang National University of Singapore July 2002
description
Evaluation of a New Arsenic Adsorbing Resin (WASP). Dr. Robert Stanforth, Ng Aik Teng and Woo Su-Fang National University of Singapore July 2002. Introduction. A Singapore Company (OSES) has developed a new arsenic adsorbing resin (WASP) Tested to determine properties and effectiveness - PowerPoint PPT Presentation
Transcript of Evaluation of a New Arsenic Adsorbing Resin (WASP)
Evaluation of a New Arsenic Adsorbing Resin (WASP)
Dr. Robert Stanforth, Ng Aik Teng and Woo Su-Fang
National University of Singapore
July 2002
Introduction• A Singapore Company (OSES) has developed a new arsenic adsorbing resin (WASP)•Tested to determine properties and effectiveness•Both column and batch studies used
Column Studies• 1000 mg/L Arsenate solution
• Column 1.2 m, 2.85 L, 35 ml/min flow
• Parameters tested– pH– Ionic Strength– Residence time
• As concentration reduced from 1000 mg/L to 0.001 mg/L using two columns
Graph of Total Arsenic Removed (g) vs. Total Arsenic Added (g)
0
5
10
15
20
25
30
35
40
0 5 10 15 20 25 30 35
Total Arsenic Added (g)
Tota
l Ars
enic
Rem
oved
(g)
100% Removal
pH 7
pH 10
pH 7 with NaCl
Graph of Concentration (ppm) vs. Time (min) at pH 10
0
100
200
300
400
500
600
700
800
900
0 30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 480 510 540 570 600 630 660
Time (min)
Conc
entra
tion
(ppm
)
12 days lag1 day lag
6 days lag
Batch Studies•0.5 g resin/100 mL, 1 hr, 18 RPM shaker•Parameters tested
•Arsenic speciation•Arsenic concentration•pH•Ionic strength (higher ionic strength enhanced adsorption)•Reaction time (reaction almost complete within 1 hour)
Arsenate and Arsenite Adsorption (%) at Various pH Levels (Initial [As] = 50 mg/L
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12
pH
Arse
nic
Adsr
optio
n (%
)
Arsenate
Arsenite
Adsorption Isotherms at pH 7
0
5
10
15
20
25
30
35
0 100 200 300 400 500 600 700 800 900
Equilibrium Concentration (mg/L)
Arse
nic
Adso
rbed
(mg/
g of
Dry
Res
in)
Arsenate Desorption using Different Regenerants at Different Surface Coverage
0
10
20
30
40
50
60
5.32 9 14.6
Amount As Absorbed (mg/g Dry Resin)
Arse
nic
Deso
rptio
n (%
)
NaOH
D.I.
HNO3
Conclusions
• Resin very effective under optimal conditions• pH-adsorption profiles similar to metal oxides• Capacity of 35 – 50 g As/kg• Difficult to regenerate resin• Ionic strength effects mixed – needs further
study• Resin has good potential
