Mirta Stupak

Non-toxic alternative compounds for marine antifouling paints

Abstract In order to search for alternative non-pollutant substances as antifouling compounds, the effects of sodium benzoate and different tannins (from chestnut, mimosa and quebracho) were studied. Balanus amphitrite (Cirripedia, Balanidae) nauplii were used in the laboratory for the bioassays. The results showed that both benzoates and tannins have a narcotic effect on these larvae, this effect was faster as the concentration of these compounds was increased. Larvae rapidly recovered when they were transferred to fresh, non-toxic, artificial sea water. Field trials in Mar del Plata harbor confirmed that soluble matrix paints, formulated with sodium benzoate or tannins as antifouling agents, were successful in preventing barnacle attachment. These results indicate the potential bioactivity of these compounds on fouling organisms.

A non-toxic antifouling compound for marine paints

SummariesLaboratory tests with the common barnadeBalanus amphitrite showed narcotic effect on nauplii, cyprids and odults of a solution of sodium benzoate in artificial sea water. This effect was faster as the concentration of sodium benzoate was increased. Field trials confirmed it was successfull in preventing barnade deposition on soluble matrix paints formulated with sodium benzoate as the antifouling agent. These results indicate the potential bio-activity of sodium benzoate on fouling organisms.ZusammenfassungLaborversuche mit dem gewöhnlichen Raubenfüsskrebs,Balamus amphitrite, zeigteten die narkotische Wirkung einer Lösung von Natriumbenzoat in kunstlichen Seewasser auf Nouplien, Kypride und Ausgewachsene. Diese Wirkung wurde schneller als die Konzentration Natriumbenzoats vermehrt war. Feldversuche bestättigteten, daß es erfolgreich bei Verhinder ung der Roubehfüsskrebsablagerung auf Farben formuliert mit einer löslichen Matrix auf Natriumbenzoat als Antifoulingmittel wurde. Diese Resultaten zeigen die potentieilen Bioaktivität des Natriumbenzoats auf die Organismen die Bewuchs verursachen.RésuméLes essais au laboratoire sur la bernache ordinaire,Balatus amphitrite, mettent en évidence l’effet narcotique d’une solution du benzoate de sodium en eau de mer artificielle sur nouplii, cyprides et adultes. Cet effet se produisait plus rapidement au fur et a mesure que la concentration de benzoate de sodium se augmentait. Des essais pratiques ont confirmé que ce compose était efficace en empêchant le dépõt des bernaches sur les peintures formulées avec benzoate a sodium en tant qu’agent antifouling au sein du soluble. Ces résultats démontrait la bioactivité potentielle de benzoate de sodium contre des organismes capables d’engendrer les salissures.

Tannin and tannate from the quebracho tree: an eco-friendly alternative for controlling marine biofouling.

Abstract Current antifouling coatings are based on toxic compounds that can be harmful to the natural environment. A promising alternative to these compounds is the use of natural products that are non-toxic, but have antifouling properties. Tannins are natural, water-soluble, complex polyphenolic substances, which precipitate proteins and have anticorrosive and antimicrobial properties. In this study, the effect of quebracho tannin as a probable antifouling pigment in both laboratory and field trials is evaluated. As tannins have high solubility in aqueous media and consequently would leach rapidly, they were precipitated as aluminium tannate, which has an adequate solubility for use as a component in marine paints. In vitro exposure of Balanus amphitrite and Polydora ligni larvae to low concentrations of both quebracho tannin and saturated aluminium tannate solutions produced complete appendage immobilisation. In 28-d field trials of test gels, a significant decrease in micro- and macrofouling density and diversity in relation to the control gel was detected (p < 0.05). This study suggests that natural tannins could be employed as bioactive pigment for new antifouling technologies.

Solubility and toxic effect of the cuprous thiocyanate antifouling pigment on barnacle larvae

Cuprous oxide is one of the most commonly employed antifouling pigments. However, its red color limits further pigmentation of the paint. On the other hand, cuprous thiocyanate is a white pigment that can be employed when film pigmentation in other colors is required. The purpose of this paper is to study the chemical and biocidal properties of cuprous thiocyanate, in comparison with those of cuprous oxide, with a view of its utilization in paint elaboration.The solubility, oxidability, particle size distribution, and oil absorption of the pigment were determined along with two methods for its preparation. A solubilization mechanism for cuprous thiocyanate is also outlined.Biological tests were carried out in the laboratory in order to evaluate the biocidal properties of cuprous thiocyanate. Lt50 and Lt100 were determined for Balanus amphitrite nauplii and cyprids.White cuprous thiocyanate has, in many ways, similar properties to those of cuprous oxide, although it is less oxidizable and has a greater lethal action than cuprous oxide.

Benzoates: a new approach to non‐toxic marine fouling control

Owing to present and expected future regulations on the use of polluting antifouling compounds, there is a growing need for alternative methods for the prevention of biofouling. Some experiments on the effect of iron benzoate, as a possible biocide agent, on nauplii of Balanus amphitrite were carried out. This pigment was used because it is rapidly hydrolysed and consequently it produces a pH decrease. Although anion benzoate has an intense narcotic effect on nauplii, the results clearly demonstrated that the combined action of this compound and a pH decrease (generated by iron benzoate hydrolysis) produce a pronounced antifouling activity, i.e. the synergic effect is greater than separate effects.

Core-shell pigments in antifouling paints

SummariesMarine fouling is the result of the settling and subsequent growth of organisms on surfaces immersed in seawater. Fouling of ships’ hulls has been traditionally controlled through the use of toxic antifouling paints, but increased ecological awareness and the strict regulations of biocides used in such paints have led to the development of low toxic content or non-toxic coatings to control fouling.Results of investigations on the performance of five antifouling formulations in exposure trials carried out at Mar del Plata harbour (Argentina) are presented. The tests have revealed that these paints, which were formulated with a combination of a thin layer or shell of toxic pigment (cuprous thiocyanate) surrounding a core particle of non-toxic pigment (herein termed core-shell pigments), prevented the settlement of foulers, reducing costs and marine pollution.RésuméLa salissure provient du dépôt des organismes et de leur croissance subséquente sur des surfaces immergée dans l’eau de mer. Traditionnellement, on a contrôlé la salissure des coques de navires en utilisant des peintures antisalissure toxiques. mais la sensibilisation intensififée aux considérations écologiques et la stricte règlementation des biocides utilisées dans de telles peintures a mené au développement de revêtements non-toxiques ou à faible toxicité, pour contrôler la salissure.Les résultats de l’examen de la performance de cinq formulations antisalissure au cours des essais d’exposition au port de Mar del Plata (Argentine) sont présentés. Les essais ont révélé que ces peintures, qui sont formulées avec la combinaison d’une fine couche ou “shell” de pigment toxique (thiocyanate de cuivre) qui recouvre une particule centrale de pigment non-toxique (dénommée “core/shell pigments” dans cet article), ont empêché le dépôt de la salissure, réduisant ainsi la pollution marine et les frais.ZusammenfassungOberflächen die in Meereswasser ausgesetzt sind werden gerne von Algen und anderen Meeresbewohnern besiedelt. Dieser Vorgang wurde in der Vergangenheit hautsächlich durch die Verwendung von Anti-Fouling-Anstrichen verhindert, aber mit vermehrter Rücksicht auf das Ökosystem und strengere Richtlinien für die Verwendung von Bioziden in Anstrichen hat dazu geführt, daß neue, ungiftige or nur leicht giftigen Anstriche für Schiffe entwickelt wurden.Wir führten Tests an fünt Anti-Fouling-Formulierungen im Mar del Plata Hafen von Argentinien durch, und stellen die Ergebnisse hier vor Unsere Tests ergaben, daß diese Anstriche, die aus einer Kobination von einer dünnen Lage eines giftigen Pigmentes ([cuprous] Thiocyanat) auf einem ungiftigen Pigmentkern bestanden, die Ansiedlung von Meerespflanzen und-tieren verhinderten, und damit die Kosten und die Meeresverschmutzung verminderten.

Reversible effect of potassium sorbate on Balanus amphitrite larvae. Potential use as antifoulant

Marine biofouling constitutes a major worldwide technical and economic problem. International regulations concerning the protection of both the environment and industrial workers have prompted paint manufacturers and end users to look for suitable replacements for traditional antifouling (AF) pigments. For this reason, the potential AF activity of potassium sorbate (KS) on nauplii and cyprids of Balanus amphitrite was tested in laboratory and field trials. Larval bioassays demonstrated a marked inhibitory and reversible effect. The values obtained for EC50 and LC50 were 9.91 mM and 36.73 mM, respectively, and the therapeutic ratio was 3.71, indicating that KS acts via a non-toxic mechanism. After 60 days in the sea, a varnish coating incorporating KS showed a substantial decrease in micro- and macrofouling density and diversity. This investigation indicated that KS is a promising AF agent for replacing the traditional toxic compounds.

Transitioning to nontoxic antifouling paints

Purpose – The purpose of this paper is to reduce the amount of copper in antifouling paints by using eugenol as an additive. Biofouling leads to deterioration of any submerged material. The most widespread method for control is the application of cuprous oxide antifouling paints which are toxic. First of all, the paper describes the effect of eugenol on larvae of Balanus amphitrite (fouling organism) under laboratory conditions and then the preparation, application and performance of different types of antifouling paints in field trials. Design/methodology/approach – Three types of soluble matrix antifouling paints were prepared with different pigments. The first one containing 16 per cent v/v copper, the second with 1.6 per cent copper and the third with 1.6 per cent copper + 2 per cent eugenol. Findings – After 12 months of immersion in Mar del Plata harbour paints containing 1.6 per cent copper + eugenol and 16 per cent copper were the most effective. Although these formulations showed a similar perfor...

Hacia una reducción del contenido decobre en pinturas antiincrustantes

Biofouling leads to deterioration of any submerged material. The most widespread method for control is the application of cuprous oxide antifouling paints which are toxic. For this reason non-toxic natural products could be combined with small amounts of copper to diminish its contribution to the environment.Thymol is isolated from essential oils of several plants (thyme, oregano, basil) and it is well known for its antimicrobial properties. The hypothesis proposed in this study is this compound would inhibit initial steps in fouling sequence and consequently would also inhibit settlement of later species.The aim of this work was to reduce the amount of copper in antifouling paints employing thymol as an additive. Two antifouling paints were prepared, one containing 16% v/v copper and another with 1.6% copper + 2% thymol. Paints were applied on acrylic panels and were submerged in Mar del Plata harbor.After 6 months of immersion in Mar del Plata harbor fouling cover percentage on panels was estimated under stereomicroscope and optic microscope. Estimation of fouling cover by species was carried out using a 25 random point grid. Also, control paints and unpainted acrylic tiles were simultaneously submerged. All tests were performed in triplicate.Paints containing 1.6% copper + thymol and 16% copper were effective. No significance differences were registered in cover percentage between copper-based paints and copper+thymol based paints (p>0.05). Although these formulations showed a similar performance, copper+thymol based paint contains 90% lesser copper than a traditional copper based formulation. Then, the aim of this work was reached.