relevance between marine biofouling and physical...

Relevance between marine biofouling and physical

properties of porous ceramics coated with oxide powders

Sang-won Lee1, Seung-gu Kang

1

1Dept. of Advanced Materials Engineering, Kyonggi University

Iui-dong, Yeongtong-Gu, Gyeonggi-do 154-42, KOREA

[email protected]

Corresponding Author : [email protected]

Abstract. Recently, the eliminating methods of red tide organisms has been at-

tempted by filtering method using the porous ceramic bodies. The marine bio-

fouling, however, can be developed on the outer surfaces of porous ceramic

body after use for long period of time, decreasing the function of the porous

bodies. In this paper, the effect of ceramic coating to porous ceramic body upon

inhibiting marine bio-fouling has been examined. The ceramic powders tried as

coating materials were Al2O3, TiO2, and ZrO2. In the primary stage about for

one month, the amount of bio-fouling decreased with increased water absorp-

tion rate of specimens. During the early stage, the bio-fouling was caused by

mostly from light-weight organisms such as red algae or microbes. After two

months later, however, the amount of bio-fouling increased with decreased sur-

face roughness of the specimen due to larger fouling organisms such as barna-

cle. The Al2O3 proved as the optimum coating materials among three ceramic

powders to prevent the marine bio-fouling owing to offering lower water ab-

sorption and higher surface roughness to the specimens. It was confirmed that

the amount of bio-fouling could be reduced by controlling the water absorption

and the surface roughness of the porous ceramic through the oxide coating

without using the environmentally hazardous materials.

Keywords: Ceramic porous ceramic, bio fouling, oxide coating

1 Introduction

Recently, the waste water discharged from various industrial and household sites

seriously contaminates river and ocean. As a result, the water-bloom and red tide

occurrence become a serious social problem. Especially the red tide turned out to a

exorbitant damage to fish cage farms during the every summer [1-2]. Several methods

such as dusting ocean with the ocher to reduce the red tide have been tried in Korea,

but perfect and safe method to control red tide has not been yet established. The elim-

inating methods of red tide organisms has been recently attempted by filtering them

using the porous ceramic bodies [3]. The marine bio-fouling, however, can be devel-

oped on the outer surfaces of porous ceramic body after use for long period of time,

and it could decrease the function of the porous bodies. Bio-fouling is often occurred

Advanced Science and Technology Letters Vol.116 (Bioscience and Medical Research 2015), pp.254-260

http://dx.doi.org/10.14257/astl.2015.116.52

ISSN: 2287-1233 ASTL Copyright © 2015 SERSC

at the bottom of a ship, power station turbines or marine structures. At first a light

weight life such as micro-organisms attached to marine structures and consequently a

variety of species being attached to feed them which gradually increase amount of bio-

fouling [4]. Attached large algae accelerates to increase the weight of vessel or marine

structure and cause problems of structural safety [4]. The anti-biofouling paints devel-

oped contain a wide variety of materials such as organic tin compounds. But the or-

ganic tin compound exert a fatal toxicity even with concentration of 1 ppt (part per

trillion, 10-12) to marine organisms, so its use is prohibited now around the world [5].

Accordingly, environmental-friendly methods for inhibiting bio-fouling have been

continuously studied. Most methods are modifying surface character of body to give

hydrophilic or hydrophobic character, the plus or minus charge, and large or slight

roughness. Cho et. al. showed that the aluminum substrate surface with hydrophobic

character had anti-biofouling effect at the initial step [6]. Benbi Bai and Jones

changed the surface charge through the surface modification of polymeric membranes

to show effect of preventing bio-fouling [7]. Kim and Lovitt have reported the results

of controlling bio-fouling by change surface charge and surface roughness for the

filtration membrane [8,9]. The previous research, however, has focused mostly on

anti-biofouling of metal or polymer, so anti-fouling of porous ceramic materials has

not been much studied. In this research, environmentally friendly method for anti-

biofouling on porous ceramic bodies without the use of toxic materials was examined.

The factors tried were the surface charge, the surface roughness and absorption of the

porous ceramic bodies controlled through the various oxides coating.

2 Experimental procedure

Three kinds of oxides of Al2O3, TiO2, and ZrO2 were coated on porous ceramics

whose main constituent is SiO2. The most porous ceramic specimens used were of

spherical shape and the mean diameter is 17.5±2 mm. Oxide powder reagent were

used Al2O3 (High Purity Chemicals, Japan, 99.9%), TiO2 (High Purity Chemicals,

Japan, 99.9%), and ZrO2 (Junsei Chemical Co., Japan, 99.0%), and average particle

size of the oxide powders was 1.8±0.7 ㎛. A method of coating of oxide powder on

the surface of porous ceramic body is as follows. First, soaking the porous ceramic

body for 10 seconds in 1.0 wt% PVA (polyvinyl alcohol) solution giving sticky sur-

face was performed, and then placed the specimens into a vessel rotating for 10

minutes at a speed of 70 rpm to mixed with the oxide powder. The amount of the

oxide coating was from 0.1 to 1.0 wt%. The specimens then was dried for 24 hours at

105 ℃, and heat-treated at 1200 ℃ for 10 minutes to bond completely the oxide pow-

der to the specimen surface. Absorption of the porous ceramic body was measured in

accordance with Korea Industrial Standard as “KS F 2503: test method density and

water absorption of coarse aggregate.” In addition, surface roughness was observed

using a confocal laser microscope (Confocal Laser Scanning Microscope, OLS3000-

300mm autostage, OLYMPUS), and the average roughness value was obtained from

four measurements. Porous ceramic body was attached on acrylic plate of width 15 cm,

and length 21 cm using an organic adhesive. The specimens attached to plate were

Advanced Science and Technology Letters Vol.116 (Bioscience and Medical Research 2015)

Copyright © 2015 SERSC 255

installed in the sea of 1 m depth, located in Geoje-si, Gyeongsangnam-do during from

July to October in 2014. The amount of bio-fouling generated were measured at every

month, and calculated using the following equation (1).

(1)

Where, Wa is a weight of the specimen after one month and Wb is a weight of the

specimen before installation into the sea.

3 Result and discussion

Fig. 1 shows that the water absorption of the porous ceramic bodies used in this study.

The water absorption of the oxide coated porous ceramics has too low values. Com-

paring the absorption value for three type of specimens, the Al2O3-coated sample

showed the lowest value and the ZrO2-coated one had the highest value. In addition,

increasing amount of oxide coating from 0.1 wt% to 1.0 wt%, except for Al2O3, in-

creased slightly the absorption of specimen. The lowered absorption of the coated

specimen is due to filling-up of fine powders into cracks or open pores presented in

the specimen surface.

Fig. 1. The water absorption of porous ceramics coated with various oxide powders.


256 Copyright © 2015 SERSC

Fig. 2 shows that an average roughness value by measuring the four points random-

ly selected from a confocal microscopic images for the porous ceramic body. Rough-

ness of the no-coated specimens showed a value of about 100 ㎛, while the specimen

coated with oxide powders showed increased roughness regardless of the type and the

amount of coating.

Most specimens showed roughness of 120~140 ㎛ which is 20~40% higher com-

pared to the no-coated specimen except the case of 1 wt% of Al2O3. In particular, 1

wt% Al2O3 coated specimen had about 220 ㎛ roughness which is significantly 120%

higher value compared with no-coated specimen.

Fig. 2. Surface roughness of porous ceramics coated with various oxides.

Fig. 3 shows the pictures for appearance of porous ceramic bodies bio-fouled as a

function of time and amount of coating powders and kinds of oxides. The specimens

were first installed in the marine of Geoje-si, Gyeongsangnam-do in July, 2014.

All specimen surface can be seen as light red color which means red algae are

weakly attached. After two months later, biological styela clava seems to attatch and

after three months, the barnacle and shellfish such as mussels was very firmly attached.

Fig. 4 shows the amount of bio-fouling measured at every month during three

months. First, the amount of bio-fouling, regardless of the type of oxide coating on the

specimens, showed a tendency to increase greatly with time. But it was not large

amount of bio-fouling for any specimens with the time elapsed until the first month.

The microbial fouling organisms film usually occurs at the early stage. However,

the amount of fouling organisms began to increase after one month and rapidly in-

creased in all specimens after two months. The increased weight is due to large mus-

sels or barnacles attached to the specimen after two months.



Time

Specimen

As-installed 1 month 2 months 3 months

No-

coated

Al2O3

Fig. 3. Pictures for appearance of bio-fouling with time developed at porous ceramics with

various oxide; (a) no-coated, and (b) 1.0 wt% Al2O3-coated. The specimens were first installed

in the marine of Geoje-si, Gyeongsangnam-do in July, 2014.

Fig. 4. Amount of bio-fouling for porous ceramics coated with 1wt% coated. The specimens

were first installed in the marine of Geoje-si, Gyeongsangnam-do in July, 2014.

The amount of fouling in the specimen after two months was much higher com-

pared to that of first month later. The amount of bio-foulng for ZrO2 and Al2O3 were



lower than that of no-coated specimen, except TiO2 coated specimens showing a high-

er amount of bio-fouling. After three months elapse, overall amount of bio-fouling

was much higher than that of 2 months after. The specimens coated with ZrO2 and

Al2O3 showed a lower amount of fouling than that of no-coated specimen. The speci-

mens with the highest fouling resistance was proved as Al2O3 coated specimen.

When analyzing the amount of bio-fouling after one month (Fig. 4) and water ab-

sorption (Fig. 1) of coated specimen, the lower the water absorption, the lower the

amount of bio-fouling in the specimen can be seen. That means that the coating shows

a lowering effect to suppress biological fouling for 1 month due to lower water ab-

sorption.

When associating amount of bio-fouling and the surface roughness of specimen

(Fig. 2), the larger surface roughness value showed greater controling effect on bio-

fouling during 2 months. Especially, the surface roughness of the 1 wt% Al2O3 coated

specimen had the highest, and consequently had lowest bio-fouling among all speci-

mens. The greater the roughness, the greater inhibitory effect on microbial adhesion in

the seawater for the long term exposure. The bio-fouling starts with attachment of the

microorganisms and then large algaes such as barnacles or prey become to attach to

the specimen. These hard large algae was proven to not grow easily to the specimen

surface of larger roughness value.

4 Conclusion

By coating the oxide powder on porous ceramic bodies to study the anti-fouling effect,

the following results were concluded. The ceramic powders tried as coating materials

were Al2O3, TiO2, and ZrO2. In the initial stage about one month, the amount of bio-

fouling decreased with increased water absorption rate of specimens. In the early stage,

the bio-fouling was mostly caused by light-weight organisms such as red algae or

microbes. After two months later, however, the amount of bio-fouling decreased with

increased surface roughness of the specimen because the fouling at the later stage was

due to by larger fouling organisms such as barnacle. It showed the Al2O3 was the op-

timum coating materials among three ceramic powders to prevent the marine bio-

fouling because it offered lower water absorption and higher surface roughness to the

specimens. It was confirmed that the amount of bio-fouling could be reduced by con-

trolling the water absorption and the surface roughness of the porous ceramic through

the oxide coating. It is expected that, therefore, this result could be applied to future

marine structures without using the environmentally hazardous materials.



Acknowledgment: This work was supported by the National Research

Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No.

NRF-2013R1A2A2A04014978).

References

1. KBS News, 2015. 8. 18, http://news.changwon.kbs.co.kr/4609/

2. Red Tide Information, National Institute of Fisheries Science,

http://www.nfrdi.re.kr/redtide/webpage/operation/ operation_01.jsp].

3. J. H. Shim, and M. S. Jeong, “Development and succession of marine fouling organisms

on artificial substrata”. J. Oceanol. Soc. Korea 22(4) (1987) 257.

4. D. H. Jung, A. R. Kim, D. S. Moon, S. W. Lee, H. J. Kim, and Y. H. Ham, 2009, “Prelim-

inary Experimental Study on Biofouling in Real Sea Environment”, Journal of the Korean

Society for Ocean Engineering, Vol. 23, No. 6 (2009) 39.

5. D. M. Yebra, S. Kiil, and D. J. Kim “Antifouling technology-past, present and future steps

towards efficient and environmentally friendly antifouling coatings” Prog. Org. Coat. 50

(2004) 75.

6. S .H. Cho, S. N. Ryu, W. B. Hwang and B. S. Yoon, “Anti-fouling property of hydropho-

bic in sea water”, J. Korean Society for Marine Environment and Energy 16 (2013) 82.

7. C. X. Liu, D. R. Zhang, Y. He, X. S. Zhao and R. Bai, “Modification of membrane surface

for anti-biofouling performance: Effect of anti-adhesion and anti-bacteria approaches”,

Journal of Membrane Science 346 (2010) 121.

8. H. S. Kim, “Influence of Membrane Material and Structure on Fouling of a Submerged

Membrane Bioreactor”, Journal of Korea Society Environment Engineers 30 (2008) 31.

9. A. Al-Amoudi, P. Williams, S. Mandale, and R. W. Lovitt, “Cleaning results of new and

fouled nanofiltration membrane characterized by zeta potential and permeability”, Separa-

tion and Purification Technology 54 (2007) 234.



relevance between marine biofouling and physical...

Documents