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Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 8 Number 08 (2019) Journal homepage: http://www.ijcmas.com Original Research Article https://doi.org/10.20546/ijcmas.2019.807.361 Impact of Nanocoating on Micro and Macro Foulers in FRP, Steel and Wooden Materials S. Archana1*, B. Sundaramoorthy1, N. Neethiselvan1 and R. Jeyashakila2 1 Department of Fisheries Technology and Fisheries Engineering, Fisheries College and Research Institute, Tamilnadu Fisheries University, Thoothukudi-628008, India 2 Department of Fish Quality Assurances and Management, Fisheries College and Research Institute, Tamilnadu Fisheries University, Thoothukudi-628008, India *Corresponding author ABSTRACT Keywords Antifouling, Nanocoating, Boat building materials, Macrofouling and microfouling Article Info Accepted: 26 July 2019 Available Online: 10 August 2019 The field experimental study with test panels was carried out in the jetty of CECRI, Regional centre, located inside the V.O.C. Port at Thoothukudi. Test panels were made from selected boat building materials viz., wood, steel and FRP with a size of (15 cm h x 8 cm b and 12 mm thickness were tied in an iron frame with the dimension of 106.5 cm x 106.5 cm were allowed to hang at a depth of 1.5 m. Periodical samplings were carried out to study the pattern of microfoulers (diatoms) followed by macrofouling communities. Under microfouling communities, 11 species of diatom identified on the test panels, Nitzchia spp. was found to be most hardy species recorded irrespective of the types of panel and treatments. Steel material showed very poor resistance to serpulid worms despite different treatments. Another important macrofouling community namely barnacles showed progressive increment in terms of numbers during soaking period. Two species of barnacles namely Balanus amphitrite and B. variegates were identified on the test panels, and of these B. amphitrite was found to be the dominant barnacles species. FRP panels showed very poor resistance to foulingby barnacles. Both antifouling treatments viz. (i) nanocoating with copper and (ii) antifouling paint application showed significant effect in controlling mussel and oyster settlement. Two species of mussels namely Perna indica and Anomia spp and two species of oysters viz. Crossesstrea madressensis and Pinctada fucata were recorded on control panels during the study period. However, their settlement was arrested when the plates were given treatment. The commercial grade antifouling paint showed better effect in controlling fouling by ascidians than by copper nanocoating treatment. Introduction Biofouling is the deposition and growth of micro and macro organisms on submerged surfaces. Fouling of ship hulls, navigational buoys, underwater equipment, seawater piping systems, industrial or municipal intakes, beach well structures, oil rigs and allied structures has often been reported. In the past few decades, the list of affected structures has expanded. Ships show a 10% higher fuel consumption caused by increased drag and frictional resistance resulting from hull and propeller fouling. Many marine organisms themselves face the constant problem of being colonized and overgrown by fouling organisms. Immobile plants and animals are generally exposed to biofouling and 2908 Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 consequent loss of species and community assemblages. Biofouling also promotes corrosion of materials. It is estimated that the marine industry incurs an expenditure of 10 billion sterling pounds a year to combat the situations arising from biofouling worldwide (9). Biofouling control is a worldwide problem in marine system. One of the earliest methods of solving the problem is to scrape the hulls of ships. When cleaning or scraping becomes time consuming or ineffective, industries turn to perhaps the most of controlling and preventing biofouling namely antifouling coatings. The best method to control the formation of biofouling on submerged surfaces has been found to be the use of anticoating. From the dawn of maritime history, the growth of marine organisms on man-made surfaces, the first attempt to control biofouling goes back to the Greek and Roman civilizations, 700 BC, when copper or lead sheathing was used to protect wooden boats (2) . Around 1860, ships were built of steel; however copper sheathing could not be used because electrolyte action accelerated the corrosion of the hull (2).This gave the need for alternative methods to protect ships and the dawn of modern paints systems. A variety of paints was developed mid 1800s based on the idea of dispersing a toxicant in a polymeric vehicle. Copper-oxide, arsenic, and mercury oxide were popular antifoulants. Recently nanotechnology has been evolved as a tool for the formation of antifouling coating. It has promising future in maritime industries including shipping in controlling the biofouling. Nanocoating has been found to control properties that are responsible for „non-stick‟ nature of the surface, such as surface energy, charge, conductivity, porosity, roughness, wettability, friction, physical and chemical reactivity. A European Union research project entitled “Advanced nano structured Surfaces for the Control of Biofouling” has investigated how to prevent the build-up of organisms on surfaces under marine conditions to avoid biofouling. Nanocoating of the metals with antifouling properties have shown positive results for the effective control of fouling in shipping industry in different parts of the world. With this background, an attempt was made to study the effect of copper nano-coating on different boat building materials Materials and Methods Study area The study was carried out in the jetty of Central Electro Chemical Research Institute (CECRI), Regional Research Centre, located within the Tuticorin New Port area was chosen for testing the experimental panels. This site has no chance for the mix of freshwater to dilute the seawater so that salinity is reasonably stable except during the monsoon season. Test panels The test panels were made up of Aini wood (Artocarpus hirsutus), Fiber Reinforced Plastic (FRP) and mild steel of width size 15 cm height, 8 cm breadth and 12mm thickness. The weight of each panel of wood, FRP and steel were 200gm, 240gm, and 1kg, respectively. These test panels were mounted with the help of 4mm polypropylene rope in an iron frame having a dimension of 106.5cm length, and 106.5cm width. Ten panels were mounted in each frame; i.e. five control panels and five coated panels. With the help of a loop provided on the top of the frame, each frame was tied with a 12mm polypropylene rope and suspended in the CECRI jetty, inside the Thoothukudi harbour area. All the frames were suspended from the platform at a depth of 1.5m. 2909 Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 Sampling schedule Results and Discussion After immersion in seawater, the study panels were sampled periodically formicro and macrofoulers attachment studies. Diatom species recorded on various test panels For the study of macrofoulers, samplings were carried out after 1st, 2nd, 3rd and 4th month from the date of immersion. Spray coating The nano coating was done for wood, steel and FRP panels by spray method. The synthesized copper nano powder was mixed at the rate of 0.4µg/ L with enamel paint using magnetic stirrer at 600C for 6 h. Then, the paint was spray coated at 2-4 bar / 30 psi pressure and dried for 24 h under room temperature. Antifouling coating For comparative studies, all three selected boat-building materials were painted with commercially available antifouling paint (Brand name: NOAH Marine Paints, Cochin). Identification of Micro and Macro foulers Micro and macro foulers like protozoa, diatoms, were observed under laser microscopy method and barnacles, bivalves, crabs, etc. were identified using the guideline of Fouling Organisms and Instruction Regarding the Docking Report (1942), Instructions Regarding the Docking Report and Guide to Fouling Organisms (1944) and Fouling of Ships' Bottoms: Identification of Marine Growths (1944). The total numbers of macro-foulers were calculated and tabulated on each sampling. Among the three types of panels tested, the wooden control panel harbor more number of diatom species during the 90th day of inspection. The control wooden panel, control steel panel and control FRP panel had 7, 5 and 2 settlers respectively. Regarding antifouling coated panels; there was a domination by single species irrespective of the type of panel. However, Vorticella spp dominated on antifouling coated wooden panel while Nitzchia spp dominated over antifouling coated steel panel and antifouling coated FRP panel. In the case of nanocoated panels, on 90thday of observation, clear-cut impact was noticeable on nanocoated FRP panel, as it was dominated only by single species. However, it was not significant on nanocoated wooden and nanocoated steel panels as 3 and 4 species were recorded. As the soaking duration increases from 90th to 150th day, a clear-cut reduction in species diversity was noticed with respect to wooden control panel and steel control panel. However, a reverse phenomenon was observed with respect to FRP control panel. In the case of control wooden panel, the number of species reduced from 7 to 2 from 90th day of observation to 150th day of observation. It was from 5 to 1 in the case of control steel panel. Regarding control FRP panel, an increase was noticed from 2 genera to 5 genera (Table 1). Regarding species succession due to antifouling painting test panels on various effect was found to be highly pronounced on steel panel as it allowed single genus namely, Nitzchia spp alone from 90th day to 150th day. However, when antifouling paint was coated over wooden and FRP panels, it could retain single genus distribution over the panel surface up to 120th day and thereafter the number of species increased to 4 with same 2910 Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 composition both in wood and FRP panel on 150th day of observation. Nano-coating was found to have noticeable impact with respect to FRP panel up to 90 days thereafter the species diversity increased with the representation of 4 genera on 150th day of observation. Regarding nano-coating over wooden and steel panel no visible impact could be seen as evidenced through the contribution of same number of genera throughout the study period during different intervals of sampling. The study clearly indicated that the genus Nitzchia as the most hardy genus of diatom both in antifouling paint and nanocoated with copper. (Table 2). Serpulid worm recorded on various test panels Among the three types of panel tested, wooden panels both treated and control did not show any occurrence of serpulid worm throughout the study period. In the case of FRP panel, occurrence of serpulid worms was arrested throughout the study period by antifouling painting and nano coating of copper. However, control FRP panel showed the highest occurrence of five numbers per panel throughout the study period. It was evident that soaking duration did not have any impact and abundance of serpulid worm on different panels, which showed its occurrence (control steel panel, anti-fouling painted steel panel, nano coated steel panel). Among the materials tested, steel was prone to infestation by serpulid worm was noticed both on control and treated panels. Both antifouling painting and nano coating of copper gave negative impacts as evidenced through higher abundance of this worm over antifouling painted and nano coated panels compared to control panels (Table 3). Barnacle species recorded on various test panels The details on various barnacle species recorded on various test panels during different study period are given in (Table 4). From the result of the analysis of barnacle settlement over different test panels, following inferences could be arrived. There was progressive increment in the number of barnacle with the duration of soaking. Balanus amphitrite was found to be the hardiest species as its distribution could be noted in all the panels irrespective of the type and antifouling treatment Balanus variegates also showed occurrence in all the types of panels tested. However, after 120th day of observation in the case of nano coated FRP, nano coated wood, nano coated steel panels. Further, this species showed about 25 percent contribution in terms of number whenever it co-occurred with the Balanus amphitrite. Among the control panels, the barnacle settlement was higher over FRP panel. With respect to steel control panel there was a sudden increment after the second sampling. Regarding control panels, the barnacle settlement was lower in wooden panels in relation to FRP and steel panels. Irrespective the types of panels anti-fouling painting could arrest the settlement of Balanus variegates upto 90th day of soaking. Though anti-fouling painting could have notable impact on the settlement of fouler over different types of material studied, the effect was lower in FRP followed by steel and wood. Nano coating could prolonged the nonsettlement period of Balanus variegates on the three types of panel tested upto 120th day while it was 90th day by anti-fouling painting. 2911 Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 Nano coating was found to be more effective on steel compared to wood and FRP (Table 4). Mussel species recorded on various test panels The fouling of Perna indica and Anomia spp observed only on control panels irrespective of its type. Infestation both by Perna indica and Anomia spp could be observed over control wooden and control FRP panel. Further, the mussel infestation could be observed in over control wooden and FRP panel during the second sampling. There was a progressive increase of the two mussel species over control FRP panel, while the number remains same in the case of control wooden panel. There was a infestation by Perna indica over control steel panel starting from the first sampling however with no change in population density over the panel (Table 5). Oyster species recorded on various test panels Fouling by the edible oyster Crossastrea madrasensis and Pinctada fucata could be observed only on control steel panel and control FRP Panel. In these two types of panels progressive increase with the duration of soaking could be observed on control FRP Panel. In the case of control steel panel increment in number of edible oyster and pearl oyster could be observed only after 120th day (Table 6). Ascidians species recorded on various test panels Among the three types of test panels studied, the attachment of ascidians was found to be higher over FRP control panels. Its number got reduced when treated with nano coating with copper. However, anti-fouling painting did not show any significant impact on FRP panel. Similar impact was observed with respect to wooden test panel. Steel panel were found to be resistant to infestation by ascidians. Ascidians did not show any significant increase with duration of soaking with respect to different types of panel studied (Table 7). Diatom species recorded on various test panels As far as diatom settlement is concerned, there were clear-cut differences noticed between the control and treated test panels irrespective of materials. Among the controls, wooden panels were more attracted by diatoms. Among the treated, antifouling paint coated panels showed less number of diatom settlements than that of copper nanocoated. Among the species settled, Nitzchia spp was found to be dominant and found in majority of panels studied. (3) studied the fouling diatom from offshore waters of Bombay and he recorded 58 species of fouling diatoms on aluminium panels. Also he recorded Navicula, Coscinodiscus, Rhizosolenia and Chetoceros dominated in the biodiversity of fouling diatoms. In the west coast of India, another study was carried out by (6) using mild steel, aluminium FRP and glass panels and he recorded 92 species from Waghotana estuary. (5) investigated the diatoms of Goa Coast and found that Navicula, Synedra and Nitzchia species were dominated the samples. As most of these works were carried out in the west Coast of India, the species composition and population are showing great deviation from the present work. The present study reveals that the genus Nitzchia is most hardly genus of diatom for both antifouling painted and copper nanocoated panels. The nanocoated wooden, steel panels showed no visible impact on controlling the diatoms, but the nanocoated FRP showed some impact in the early phase of study and subsequently with more number of genera of diatoms. 2912 Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 Table.1 Diatom species recorded on various test panels S. No Panel type First sampling (90th day) Second sampling (120th day) Third sampling (150th day) 1) a. Wood control 1. 2. 3. 4. 5. 6. 7. 1. 1. 2. 3. 4. Bacilaria spp. Chlorella spp. Synedra spp. Vorticella spp. 1. 2. Nitzchia spp. Synedra spp. 1. Nitzchia spp. 1. 2. 3. Chlorella spp. Navicula spp Nitzchia spp. Synedra spp. b.Woodantifoulin g paint coated Chlorella spp. Coscinodiscus spp. Fragilaria spp Navicula spp. Nitzchia spp. Stentor spp Vorticella spp. Vorticella spp. 4. c.Wood nanocoated 2) a.Steel control 1. 2. 3. 1. 2. 3. 4. 5. 1. b.Steel antifouling paint coated c.Steel nanocoated 1. 2. 3. 4. Chlorella spp. Netrium spp. Nitzchia spp. 1. 2. 3. Navicula spp. Nitzchia spp. Synedra spp. 1. 2. 3. 4. Bacillaria spp. Navicula spp. Nitzchia spp. Synedra spp. Bacillaria spp. Chlorella spp. Fragilaria spp. Netrium spp. Sphaeroma spp. 1. 2. 3. spp. Fragilaria spp. Navicula spp. Sphaeroma 1. Synedra spp. Nitzchia spp. 1. Nitzchia spp. 1. Nitzchia spp. Chlorella spp. Fragilaria spp. Netrium spp. Nitzchia spp. 1. 2. Nitzchia spp. Synedra spp. 1. 2. Navicula spp. Nitzchia spp. Synedra spp. 3. 2913 Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 3) 1. 2. Navicula spp. Nitzchia spp. 1. 2. 3. 4. 5. Bacillaria spp. Chlorella spp. Netrium spp. Nitzchia spp. Synedra spp. 1. 2. 3. 4. 5. Bacillaria spp. Navicula spp. Netrium spp. Nitzchia spp. Synedra spp. b.FRP antifouling 1. paint coated Nitzchia spp. 1. Nitzchia spp. 1. 2. 3. 4. Chlorella spp Navicula spp. Nitzchia spp. Synedra spp. 1. Nitzchia spp. 1. 2. 3. Navicula spp. Nitzchia spp. Synedra spp. 1. 2. 3. 4. Bacillaria spp. Navicula spp. Nitzchia spp. Synedra spp. a.FRP control c.FRP nanocoated Table.2 Analysis of variance of diatom species recorded on various test panels Source Variation Between Controls of Sum Square of Degree of Mean F- value Freedom Sum of Square 73.33333 24 3.055556 0.339394 P-value (P<0.05) 0.715565 Between treatments 2.074074 2 1.037037 -- -- Error 9.804239 8 1.22553 _ _ Total 55.2028 17 _ _ _ 2914 Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 Table.3 Serpulid worm and their abundance on various test panel S. No 1) 2) 3) Panel type First sampling Second sampling Third sampling Species wise number per panel Total number per panel Species wise number per panel Total number per panel Species wise number per panel Total number per panel a. Wood control NIL NIL NIL NIL NIL NIL b. Wood antifouling paint coated c.Wood nanocoated NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL a.Steel control Serpulid worm 2 Serpulid worm 2 Serpulid worm 2 b. Steel antifouling paint coated Serpulid worm 4 Serpulid worm 4 Serpulid worm 4 c.Steel nanocoated Serpulid worm 3 Serpulid worm 3 Serpulid worm 3 a.FRP control Serpulid worm 5 Serpulid worm 5 Serpulid worm 5 NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL NIL b. FRP antifouling paint coated c. FRP nanocoated 2915 Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 Table.4 Barnacle species and their abundance on various test panels S. No 1) Panel type a. Wood control b.Wood antifouling paint coated c.Wood nano-coated 2) a.Steel control b.Steel antifouling paint coated c.Steel nano-coated 3) a.FRP control b.FRP antifouling paint coated c.FRP nanocoatedpanel First sampling Species wise number % per panel Balanus amphitrite-18 75 Balanus variegates-6 25 Balanus amphitrite-12 100 Balanus amphitrite-16 100 Balanus amphitrite-3 75 Balanus variegates-1 25 Balanus Amphitrite—6 100 Balanus amphitrite-12 100 Balanus amphitrite-34 75 Balanus variegates-12 25 Balanus amphitrite-29 100 Balanus amphitrite-15 100 Total number per panel 24 12 16 4 6 12 46 29 15 Second sampling Species wise % Total number per panel number per panel Balanus amphitrite76 78 60 Balanus variegates24 18 Balanus amphitrite74 19 14 Balanus variegates-5 26 Balanus amphitrite108 100 Balanus amphitrite18 Balanus variegatecs6 Balanus amphitrite23 Balanus variegates-6 75 Balanus amphitrite12 100 24 25 76 29 24 Balanus amphitrite64 Balanus variegates21 75 Balanus amphitrite29 Balanus variegates-9 76 Balanus amphitrite111 100 2916 108 12 85 25 38 24 111 Third sampling Species wise % Total number number per panel per panel Balanus amphitrite99 Balanus variegates31 Balanus amphitrite24 Balanus variegates-8 76 Balanus amphitrite108 75 Balanus variegates36 Balanus amphitrite139 Balanus variegates46 Balanus amphitrite45 Balanus variegates16 Balanus amphitrite55 Balanus variegates19 Balanus amphitrite120 Balanus variegates40 25 Balanus amphitrite101 Balanus variegates34 Balanus amphitrite121 Balanus variegates41 75 130 24 75 32 25 75 144 185 25 74 61 26 74 74 26 75 160 25 135 25 75 25 162 Int.J.Curr.Microbiol.App.Sci (2019) 8(8): 2908-2922 Table.5 Mussel species and their abundance on various test panels First sampling S. No 1) 2) 3) Panel type a.Wood control Species wise number per panel NIL Second sampling Total number per panel NIL Species wise number per panel Perna indica-1 Anomia spp-1 Total number per panel 2 Third sampling Species wise number per panel Perna indica-1 Anomia spp-1 Total number per panel 2 b. Wood antifouling paint coated NIL NIL NIL NIL NIL NIL c. Wood nano-coated NIL NIL NIL NIL NIL NIL Perna indica-2 2 Perna indica-2 2 Perna indica-2 2 b. Steel antifouling paint coated NIL NIL NIL NIL NIL NIL c. Steel nano-coated NIL NIL NIL NIL NIL NIL a. FRP control NIL NIL Perna indica-2 Anomia spp-2 4 Perna indica-6 Anomia spp-4 10 a. Steel control b.FRP antifouling paint coated NIL NIL NIL NIL NIL NIL c. FRP nanocoated panel NIL NIL NIL NIL NIL NIL 2917