Evaluation of a novel sorbent for recovery of radio-nuclides –a comparison of batch and column operation

8/3/2019 Evaluation of a novel sorbent for recovery of radio-nuclides a comparison of batch and column operation

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actual effluents are in the neutral range therefore in each case the studies has been conducted at

pH 7 to avoid any conflicts. The research presented here concerned the usefulness of the

polymeric chelator for targeting uranium from a very low (ppb) concentration with respect to the

presence of higher concentration of manganese. Our investigations carried out in terms of batch

and column operation of the effluent. Batch experiment has been carried out in both actual and

synthetic solution where as column has been operated with synthetic solution. This synthetic

solution has been prepared targeting the inlet of a uranium mine effluent treatment plant.

Experimental

1. Resin Preparation of the resin has been described by initial solution polymerization method

and later on by conversion of the functional moieties as described in our previous paper (S.

Mishra et al, 2008). Prior to the experiment, the resin was washed with 0.1(N) HCl to eradicate

un-reacted materials and to see the compatibility of the resin in that condition and after that

thoroughly rinsed with de-ionized water.

2. Feed solution- The feed solutions were prepared to stimulate the same quantity of uranium

and manganese present in the actual effluent. The pH of the solutions was adjusted with HCl and

NaOH.

3. Eluent - 25 ml of 1(N) HCl solution was used for elution of 1 gm of sorbent.

4. Sample Collection and procedures for the batch experiment:- For the application of this

polymer in field conditions, the effluent treatment plant inlet sample and uranium tailings

samples disposed in tailings pond were collected from Jaduguda. These samples were containing

high concentration of Mn, U as well as other radionuclides and stable elements. Uptake studies

were carried out by adding 0.5 gm of dried polymer in about 25 ml of treated effluent and

tailings leachate sample in neutral pH, and also with the synthetic solution of uranium and

potassium permanganate, whereas elution of the loaded sorbent completed with 1 (N) HCl.

5. Immobilisation factor - Metal ion Immobilisation of a resin is the act of limiting

movement or making incapable of movement of the metal ions by trapping or rather

chelating it with the functional groups of resin, can be caluclated as

immobilisation factor = (1- Elution factor)


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6. Uranium loading - Resin (0.5 gm) was packed in a glass column of 1 inch ID, resulting in a

bed height of 28 ml after equilibration with the desired synthetic solution. The spiked solution

was adjusted to neutral pH. The spiked solution of uranium (60 ng/ml) and manganese (60

ug/ml) down flowed at the rate of 4 ml/min at 40 ml effluent intervals and U and Mn

concentration in the effluent was analyzed to determine break through point.

7. Instrumentation and sample analysis- The estimation of manganese and uranium in the

original feed sample ( i.e., before the sorption experiment), the filtrate and eluent obtained after

the experiments were carried out by flame atomic absorption spectrophotometry using GBC-

Avanta atomic absorption spectro-photometer and differential pulse adsorptive strripping

voltammeter, respectively.

Results and Discussion

The capacity of the resin for the actual effluent has been presented in Table 1. Uranium and

manganese in initial feed solution has been determined. The experiments have been conducted in

duplicate and in static condition with actual (A) and synthetic solution (B) to achieve a

comparative study.

From the tabulated results (Table -1 and Table -2) it has been seen that initial uranium

concentration is in ppb level for both the solutions (A) and (B), whereas manganese is present in

ppm level. Sorption study was carried out contacting 25 ml of solution with 0.5 gm of resin in

duplicate. The respective filtrates were tested. The filtrate containing negligible amount of

uranium (Table -1) compared to manganese indicates the inlet of ETP after treating with sorbent

can be disposed safely, as seawater having 3ppb level of uranium complex content on average.

Table 2 also indicates a good percentage of sorption preferably uranium in the actual effluent,

having a high distribution factor of 1450 ml/gm for uranium compared to manganese (Kd = 111.64

ml/gm). Even synthetic solution treatment showed a 6 times greater value of uranium distribution factor

compared to manganese. The elution results (Table -2) show efficient recovery for both (A) and

(B) solution. It is indicative of the fact that not only it can be entrapped but all trapped uranium

can be recovered, therefore a possibility of efficient reuse of the sorbent for scale up. When we

have contacted the sorbent in column mode a good separation has been found, which supports

the above fact, the sorbent in column rapidly chelated with uranium, still manganese remained

that indicates time efficiency.


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Conclusions

The experimental studies revealed that the sorbent is useful for the uptake of uranium from the

inlet of uranium mine effluent treatment plant very selectively and although present in very low

concentration compared to manganese but still has the ability to form the chelates and can be

recovered efficiently for uranium recovery and out let effluent of the treated sorbent can be

safely disposed. Similarly we have experimented in column mode and have found 2 hrs are

approximately sufficient to reach the desired pick up, although a thorough investigation is

required to set up in pilot scale.

Acknowledgement

For procurement and preparation of resin material, help from Mr. Chunu Soren (DD) and for

analytical sample preparation and analysis Mr. Dilip Kumar Chaudhary (EAD) is acknowledged.

References

1. S. Mishra, Sangita Pal, G. G.Pandit, P. K.Tewari and V. D. Puranik, 2008. Use of

Polymeric Sorbent for the Uptake of Heavy Metals and Radionuclides from DifferentEffluents. Proceedings of the Sixteenth National Symposium on Environment on

Groundwater Resources: Conservation and Management. pp 161-165.

2. Sangita Pal, S. Mishra, G.G.Pandit, K.L. Thalor, P. K.Tewari and V. D. Puranik, 2008.

Potentiality of polymeric sorbent for immobilization and recovery aspect of contaminants

from nuclear efluents. In Chemcon-2008, under Safety and Hazards Control, Index no ST35, page. 355

Table 1 Uptake and elution characteristics of uranium and manganese in the inlet of

Effluent treatment plant (ETP) and synthetic ETP effluent during batch

experiment


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Table 2 The characteristic factors of uranium and manganese in the inlet of effluent

treatment plant (ETP) and synthetic ETP effluent during batch experiments

Time

(min)

Mn

(ppm)

U

(ppb)10 16.4 12.1

20 10.7 6.3

30 9.6 4.1

40 7.5 1.6

50 6.4 0.5

60 3.83 0.08

70 2 0.08

80 1.415 0.08

90 1.37 0.08

100 0.0798 0.08

110 0.829 0.24

120 0.828 0.56

130 0.912 1.2

140 1.04 1.6

150 1.33 1.8160 1.45 2.5

Sample Element Initial

conc.(C0)

Amount of

total uranium

present (g) in

25 ml solution

Metal content in

the filtrate

(g)

Amount of metal

ion in the elute

(g)

ETP inlet

Actualsolution

(A)

U 97.22 6.2

(ng/ml)

2.43 0.15 g 0.081 0.008

(almost same for

i. and ii.)

i. 2.18 0.1 g

ii. 2.39 0.09 g

Mn 54.96

(g/ml)

1374 g i. 425 g

ii. 413 g

i. 899 g

ii. 919.5 g

ETP inlet

Synthetic

solution

(B)

U 60 (ng/ml) 1.5 g NIL i. 1.33 0.1 g

ii. 1.06 0.07 g

Mn 60 (g/ml) 1500 g i. 7.05 g

ii. 5.19 g

i. 1150 g

ii. 1088.5 g

Sample Element Absorption %

(Co-Ce)/Co . 100

Kd

(Co-Ce)/Ce . V/m

Elution % Immobilization

factor

ETP inlet Actual

solution (A)U 96.67 1450 92.8 0.072

Mn 69.07 111.64 94.7 0.053

ETP inlet synthetic

solution (B)

U 99.93 74950 88.725 0.113

Mn 99.53 10588.3 77.03 0.23


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30

40

50

60

70

10 30 50 70 90 110

130

150

170

190

210

230

250

Time in minutes

ncentration

Mn (ppm)

170 7.8 8.8

180 15.6 21.2

190 20.6 24.7200 35.3 36.5

210 42.3 39.8

220 48.5 45.5

230 57.8 55.3

240 58.2 57.9

250 58.6 58.6

260 59.1 59.5

Figure 1 Column study of the sorbent with synthetic effluents

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Evaluation of a novel sorbent for recovery of radio-nuclides –a comparison of batch and column operation