제주도 해양 갈조류를 이용한 Cu 및 Zn의 생물흡착

감상규·이민규*·이동환**

제주대학교 해양환경공학과, *부경대학교 화학공학과,

**동의대학교 화학과

Biosorption of copper and zinc by biomass of marine brown algae in Cheju

Sang-Kyu Kam·Min-Gyu Lee*·Dong-Hwan Lee**

Dept. of Marine Environ. Eng., Cheju National University

*Dept. of Chemical Engineering, Pukyong National University

**Dept. of Chemistry, Dongeui University

1. Introduction

Copper is one of the most common in the industrial metals. Also zinc is used very extensively in galvanizing and in manufacturing brass and other alloys.  There are numerous industrial activities involving these two very common metals and as a result there are correspondingly numerous sources of industrial effluents discharging both copper and zinc into the environment. Interest has primarily focused on heavy metals due to their known toxicity as they are discharged in small quantities into the environment, where they tend to accumulate, being concentrated throughout the food chain. This aspect coupled with their persistence results in a serious health hazard threatening water supplies and populations depending on them.

The potential of some fresh water algal biomass for heavy metal binding has been recognized earlier, leading to the focus on technological aspects of removal and recovery of heavy metals[1,2].  While toxicological studies with heavy metals in marine algae prevail, passive biosorption of heavy metals by seaweed materials have been studied only recently, revealing the interesting potential of these abundant natural materials[3,4].  Greene et al.[5] revealed that algal biomass was a useful material for heavy metal recovery from industrial wastewaters. The prospects of algal biomass are not only in the exploitation of polysaccharides(e.g., alginates and carrageenans) in the food industry, but also in their potential to bind and remove heavy metals from industrial solutions and wastewaters.

In this study, the biomass of nonliving, dried marine brown algae U. pinnatifida, H. fusiforme and S. fulvelum harvested in the sea near Cheju, were used in order to investigate the sorption performance of copper and zinc as a preliminary step to apply to the treatment of industrial wastewaters practically.

2. Materials and Methods

The marine brown algae(Phaeophyta) Undaria pinnatifida, Hizikia fusiforme, and  Sargassum fulvelum harvested in the sea near Cheju were used.  These materials were washed with water, stored in a refrigerator for three days, and then stored in the freezing dryer for 2 days.  Biomass of brown algae which water was removed by these procedures was ground, sieved(70, 100mesh), and stored in the desicator.

Analytical grades of Cu(NO3)2□3H2O, Zn(NO3)2□6H2O(Aldrich Chem. Co., USA), Na2CO3(Hayashi Pure Chem. Co., Japan), HNO3(Hori Pharm. Co., Japan), and NaOH (Yakuri Pure Chem. Co., Japan) were used and the solutions were prepared with deionized distilled water.  The concentrations of copper and zinc in solution were determined  by an atomic absorption spectrophometer(GBC 904AA) at 324.7nm and 213.9nm, respectively.

3. Results and Discussion

The copper removal by the biosorbent materials was investigated.  As shown in Fig. 1 and 2, the copper removal increased as added amount of biomass increased and The copper uptake increased with increasing copper concentration.  Among the biosorbents materials the decreasing order was as follows: U.pinnatifida> H. fusiforme> S.fulvelum.

The copper uptake by biosorbent materials in the solution containing 10mg Cu/L, was performed with time at different pH values. The starting pH of copper solution with no pH adjustments was 5.3 and changed little as biomass was added.  The copper uptake at different Ci was applied to the Langmuir sorption isotherm.  The values of q10, q100, qmax, and b for biomass sorption systems are summarized in Table 1.  The copper biosorbent uptake in the solution with no pH adjustments, decreased in the following sequence: U. pinnatifida > H. fusiforme > S. fulvelum. The similarity between the experimental values for q100 and Langmuir calculated values for qmax indicates that the maximum copper uptake is obtained near q100.

Table 1. Experimental and calculated copper uptake by biosorbent materials

Biosorbent materials	Experimentala				Calculateda									Differenceb
	q10 (mg/g)	q100 (mg/g)			q10 (mg/g)		q100 (mg/g)	qmax (mg/g)		b (×10)					q10 (mg/g)	q100 (mg/g)	r2
U.pinnatifida pH 3.0 pH 4.0 Nonadjusted pHc	24 32 42	49 72 84		28 39 48		48 66 79		52 71 85	1.16 1.22 1.32				-14.3 -21.9 -12.5			2.1 9.1 7.1	0.939 0.953 0.971
H.fusiforme (Nonadjusted pHc)	38	79		48		74		79	1.55				-20.8			8.2	0.966
S.fulvelum (Nonadjusted pHc)	10	39		12		39		69	0.13				-16.7			0	0.963

a: q10 and q100 represent the metal uptake at the residual concentrations of 10 and 100 mg/L, respectively.

b: (qexp-qcal) × 100/qcal

c: The starting pH of the solution with no pH adjustments was in the range of 5.3-4.8 and the final pH of those was in the range of 5.3-4.4, 5.3-4.4, and 5.3-4.6 for U. pinnatifida, H. fusiforme, and S. fulvelum, respectively.

As shown in Fig. 3 and 4, the zinc removal increased as added amount of biomass increased and the zinc uptake increased with increasing zinc concentration.  Among the biosorbent materials the decreasing order was as follows: U. pinnatifida > H. fusiforme > S. fulvelum.

As shown in Table 2, the zinc uptake by H. fusiforme increased with increasing pH like in the copper uptake. The zinc uptake in the solution with no pH adjustments, decreased in the following sequence: U. pinnatifida > H. fusiforme > S. fulvelum. The similarity between the experimental and Langmuir calculated values for q10 and q100 indicates that the zinc uptake by biosorbent materials follows Langmuir isotherm equation.

Table 2. Experimental and calculated zinc uptake by biosorbent materials

Biosorbent materials	Experimentala				Calculateda									Differenceb
	q10 (mg/g)	q100 (mg/g)			q10 (mg/g)		q100 (mg/g)	qmax (mg/g)	b (×103)			q10 (mg/g)			q100 (mg/g)	r2
H.fusiforme pH 3.0 pH 4.0 Nonadjusted pHc	13 28 30	46 66 74		14 31 33		43 62 70		55 70 80		3.6 7.9 7.1			-7.1 -9.6 -9.1		7.0 6.5 5.7	0.997 0.958 0.984
U.pinnatifida (Nonadjusted pHc)	34	82		34		75		87		6.4			0		9.3	0.986
S.fulvelum (Nonadjusted pHc)	12	44		12		40		54		2.8			0		10	0.996

a: q10 and q100 represent the metal uptake at the residual concentrations of 10 and 100 mg/L, respectively.

b: (qexp-qcal) × 100/qcal

c: The starting and final pH of the solution with no pH adjustments was in the range of 5.7-5.4.

There was a little difference among the biosorbent uptake of copper and zinc. Several factors may be responsible for this difference. These metal sorption follows the general rule that metal sorption increases with increasing valence and atomic weight. The higher sorption of copper in comparison to zinc can be related to the fact the former has much higher selectivity coefficients for alginates than the latter, which features the highest one reflected in the highest values of alginate gel shrinkage[6].

References

1. Greene, H. and Darnall, D.W.:Biorecovery, 1, 27(1988).

2. Darnall, D.W.: "Removal and recovery of heavy metals from wastewaters using a new biosorbent alga SORB□, Innovative Hazard Waste Treatment Technol., Ser. Bio. Proc. 3, 65(1991).

3. Holan, Z.R., Volesky, B. and Prasetyo, I.:Biotechnol. Bioeng., 41, 819(1993).

4. Percival, E. and McDowell, R.H.:□Chemistry and enzymology of marine algal poly- saccharides□, Academic, London(1967).

5. Greene, B., Darnall, D.W., Henzel, M.T., Hosea, J.M., Hosea, J.M., McPherson, R.A., Sneddon, J. and Alexander, M.D.:Environ. Sci. Technol., 20, 764(1986).

6. Volesky, B.:□Biosorption byfungal biomass□, In: Volesky, B.(ed.), `□BIosorption of heavy metals□, CRC Press, Boca Raton, FL.(1990).