(399v) Fluoride Removal from Antarctic Krill (Euphausia superba) By Donnan Dialysis

Fluoride
removal from Antarctic Krill (Euphausia superba) by Donnan Dialysis

Guojia Yan^1,2, Yan Bao¹,
Xiaolan Lu², Ming Tan^1*, Yang Zhang^1* 

¹Qingdao
Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences,
189 Songling Road, Laoshan District, Qingdao 266101, PR China

²Key
Laboratory of Marine Chemistry Theory and Technology, Ministry of Education,
College of Chemistry and Chemical Engineering, Ocean University of China,
Qingdao 266100, PR China

*Corresponding
author: tanming@qibebt.ac.cn (Ming Tan); zhangyang@qibebt.ac.cn
(Yang Zhang)

Abstract:

Antarctic krill
(Euphausia superba) has abundant species in the Southern Ocean which makes
krill an alternative protein source for humans as well as rich fishery resource
[1].
However, a high fluorine levels in Antarctic krill have attracted attention
which is the reason why krill has not been widely used commercially. The total
fluoride concentration in the exoskeleton of krill is 3828-4278 mg kg⁻¹
dry weight (DW), 178-285 mg kg⁻¹DW in muscle, and 1102-1432 mg kg⁻¹DW
in whole krill [2].
Thus, fluoride should be removed and those expenses adversely affected the
economics of krill exploitation. [3]

Donnan dialysis (DD) is
a potentially attractive membrane-based equilibrium process for removing
undesirable ions from solution [4].
Compared to other popular methods, a low purity of treated water is a serious
problem by absorption [5].
Electrodialysis [6]
may have high kinetics compared to DD, it has some disadvantages which is great
strength of DD, i.e. economical, energy saving and need simple technology, etc.
[4]

The
effect of NaCl concentration (0.1, 0.5,1 and 2mol/L) on receiver cell,
experiment stage (1^st, 2^nd and 3^rd) and flow velocity
(0.01 and 0.03cm/s) were investigated by synthetic solution (43mg/L NaF and
4.15g/L NaCl) firstly. The results show that fluoride was removed 65% at first
stage which is the most removal rate when receiver concentration was 1 mol/L. Higher
receiver concentration provided higher driven force for chloride to pass
through anion exchange membrane which is good for defluorine. However, higher
receiver concentration also increased the percentage of other ion, such as
sodium which may explain 1mol/L result is better than 2mol/L. Furthermore, flow
velocity 0.01 cm/s offered high removal efficiency than 0.03cm/s at 65% and 62%
respectively. More time for fluoride to be exchanged into receiver chamber at
0.01cm/s. When concentration and flow velocity were both optimized, three
stages were investigated at 1 mol/L. The results were 65%, 85% and 93.6% at 1^st
, 2^nd and 3^rd stage separately as displayed by Fig. 1.

After
that, krill solution was operated by optimum parameters, leakage of protein and
amino acids were investigated at the same time. Due to complex impurity
characteristic of krill solution, the absence of other ion leakage cut down the
removal rate. Nevertheless, fluoride removal by DD maintained more protein than
absorption as well as higher purity of treated water.

Figure:

Fig.1 The effect
of experimental stage at 1 mol/L receiver concentration.

References:

[1].   Xie, C.L., et al., Organic Acid
Extraction of Fluoride from Antarctic Krill Euphausia superba. Fisheries and
aquatic sciences, 2012. 15(3): p. 203-207.

[2].   Adelung, D., et al., Fluoride
in tissues of krill Euphausia superba Dana and Meganyctiphanes norvegica M.
Sars in relation to the moult cycle. Polar Biol 7:43-50. Polar Biology, 1986.
7(1): p. 43-50.

[3].   Schmidt, K. and A. Atkinson,
Feeding and Food Processing in Antarctic Krill ( Euphausia superba  Dana).
2016: Springer International Publishing.

[4].   Ktari, T., C. Larchet and B.
Auclair, Mass transfer characterization in Donnan dialysis. Journal of Membrane
Science, 1993. 84(1-2): p. 53-60.

[5].   Engelo Lu, Y., E. K R and M.
Ers Z, Removal of fluoride from aqueous solution by using red mud. Separation
and Purification Technology, 2002. 28(1): p. 81-86.

[6].   Arahman,
N., et al., The removal of fluoride from water based on applied current and
membrane types in electrodialyis. Journal of Fluorine Chemistry, 2016. 191: p.
97-102.