INTRODUCTION:

Cationic surfactants can be used to modify the sorption capacity of different sorbents for anionic pollutants[1-3].The hydrophobic groups of the surfactants were attached to the adsorbents and hydrophilic groups were exposed to the aqueous phase and there by changing the adsorption behavior of the adsorbents [4].Considering the fact, the present study was intended to evaluate the effect of some cationic surfactants on As(III) biosorption by an As(III) resistant strain Aspergillus niger X₃₀₀ from aqueous solution. All these surfactants tested showed positive impact on As(III) biosorption.

MATERIALS AND METHODS:

Microorganism: An experimentally developed As(III) resistant fungal strain Aspergillus niger X₃₀₀ was used throughout the study [5].

Growth medium medium used: The fungal growth medium composed of: glucose, 10%; urea, 0.8%; MgSO₄.7H₂O, 0.03%; KH₂PO₄, 0.1%; K₂HPO₄, 0.1% and CaCl₂,0.3% [6].

Physical conditions for the fungal growth: The following Physical cultural conditions was adopted for maximum growth of the fungus: pH,4.5; temperature, 30⁰C; spore density, 7x108 spores or cells/ml; shaker speed, 200rpm; volume of medium,100ml in 250 ml Erlenmeyer conical flask; age of inoculum,7days and period of inoculums,7 days [6].

Composition of Synthetic medium: The synthetic medium was composed of glucose,12%; (NH₄)SO₄, 0.8%; K₂HPO₄, 0.01%; MgSO₄.7H₂O, 0.03µg/ml; MnSO₄.4H₂O, 0.02 µg/ml; FeSO₄.7H₂O, 0.02 µg/ml and Thiamine-HCl, 0.02 µg/ml[7].

Addition of surfactants in the synthetic medium: Surfactants were added as 50% alcoholic solution in the broth.

Estimation of As(III): Arsenic concentration was estimated in the broth by the method as proposed by Cernansky et al.(2007) [8].

Estimation of Dry cell /spore weight: Fungal spores/cells were filtered using Whatman No1 filter paper and heated at 70⁰C until it becomes dry and its weight was estimated by electronic weighing machine (Ecelon MS -2690)[5].

Statistical analysis: All data were expressed as Mean ±SEM, where n=6. Data were analyzed by One Way ANOVA followed by Dunett’s post hoc multiple comparison test considering p<0.05 as significant and p<0.01 as highly significant (using Prism 4.0).

RESULTS AND DISCUSSION:

The effect of different cationic surfactants on As(III) biosorption by Aspergillus niger X₃₀₀ were depicted in Table 1 .All these surfactants showed positive impacts on the biosorption.

Table 1:Effect of cationic surface active agents on As(III) biosorption

Surfactants	Concentration (%)	As(III) concentration(mg/ml)		Dry cell weight (gm/L)
Surfactants	Concentration (%)	Initial	Final	Dry cell weight (gm/L)
Benzalkonium chloride	0.0(Control)	1500	89.3±3.213	15.1±1.867
	5.0	1500	*82.1±3.123	15.1±1.119
	10.0	1500	**78.1±6.213	15.1±0.993
	●15.0	1500	**66.3±2.991	15.1±1.119
	20.0	1500	**66.3±7.143	15.1±2.162
Lauryl methyl gluceth-10 hydroxypropyl dimonium chloride	0.0(Control)	1500	89.3±6.161	15.1±0.993
	5.0	1500	*80.0±6.668	15.1±1.913
	10.0	1500	**71.1±4.213	15.1±1.836
	●15.0	1500	**67.2±3.661	15.1±2.613
	20.0	1500	**67.2±4.161	15.1±0.996
Dimethyl dicatadecylammonium chloride	0.0(Control)	1500	89.3±5.162	15.1±1.725
	5.0	1500	*84.1±6.832	15.1±0.991
	●10.0	1500	*81.1±6.661	15.1±1.913
	15.0	1500	*81.1±3.918	15.1±1.683
	20.0	1500	*81.1±7.556	15.1±1.913
Tetramethyl ammonium hydroxide	0.0(Control)	1500	89.3±6.613	15.1±1.668
	5.0	1500	85.2±5.321	15.1±2.342
	10.0	1500	**76.2±8.193	15.1±1.113
	●15.0	1500	**61.1±6.538	15.1±1.187
	20.0	1500	**61.1±6.432	15.1±0.936
Centrimonium Chloride	0.0(Control)	1500	89.3±6.613	15.1±1.824
	5.0	1500	86.1±8.186	15.1±2.786
	10.0	1500	*81.3±5.331	15.1±1.248
	●15.0	1500	**78.2±6.132	15.1±0.913
	20.0	1500	**78.2±6.884	15.1±0.991
Bromidox	0.0(Control)	1500	89.3±4.162	15.1±0.552
	●5.0	1500	*84.1±8.112	15.1±0.681
	10.0	1500	*84.1±7.645	15.1±2.915
	20.0	1500	*84.1±8.813	15.1±1.113
	15.0	1500	*84.1±6.116	15.1±0.916
	20.0	1500	*84.1±8.112	15.1±1.663

(Values were expressed as mean± SEM, where n=6. *p<0.05, **p<0.01 when compared to control.

●Stands for maximum biosorption.)

REFERENCES:

1. Choi HD., Shin MC., Kim DH., Jeon CS., and Baek K., Removal characteristics of reactive black 5 using surfactant-modified activated carbon. Desalination, 223, 2008: 290-298 .

2. Choi H D., Cho JM., Baek K., Yang JS., and Lee J Y., Influence of cationic surfactant on adsorption of Cr(VI) onto activated carbon. Journal of Hazardous Materials, 161, 2009:1565-1568.

3. Choi HD., Jung WS., Cho JM., Ryu BG., Yang JS., and Baek K., Adsorption of Cr(VI) onto cationic surfactant-modified activated carbon. Journal of Hazardous Materials, 166,2009: 642-646 .

4. ChmIelewsk EA , Adsorption of Arsenate and Chromate from Waters on Hydrophobized Zeolitic Media. Turkish Journal of Chemistry, 27, 2003: 639 - 648.

5. Ganguly S , Selection of suitable fungus, development of arsenic resistant strain and kinetic analysis for As(III) Biosorption. Indian Journal of Applied Research, 3(3), 2013: 9-10.

6. Ganguly S, Optimization of Physical Conditions for As(III) Biosorption by Aspergillus niger X_300.International Journal of Pharma Medicine and Biological Sciences, 2(2), 2013:1-5.

7. Ganguly S, Selection of suitable synthetic medium for As(III) Biosorption by Aspergillus niger X_300.Asian Journal of Research in Chemistry.6(4), 2013:301-304.

8. Cernansky S, Urik M and Khan M, Biosorption and Biovoltalization of Arsenic by heat resistant fungus, Environmental Science and Pollution Research. 14, 2007: 31-35.

Received on 19.05.2013 Accepted on 05.07.2013

Asian J. Pharm. Res. 3(3): July-Sept. 2013; Page 132-133