Korosi dapat menyebabkan kerusakan lingkungan, sehingga perlu adanya proses pencegahan menggunakan inhibitor  korosi. Inhibitor korosi merupakan suatu zat yang ditambahkan terhadap suatu logam untuk penurunan laju korosi. Inhibitor korosi berasal dari senyawa organik dan anorganik. Inhibitor organik dalam penurunan laju korosi telah banyak diteliti karena ramah lingkungan dibandingkan dengan inhibitor  anorganik. Tujuan dalam penelitian ini untuk mengetahui konsentrasi dan efisiensi inhibisi korosi dari ekstrak metanol tumbuhan paku perak (P. calomelanos) terhadap baja ASTM A36 dalam larutan 3% NaCl.  Proses ekstraksi dilakukan dengan metode maserasi. Ekstrak metanol tumbuhan paku perak telah dilakukan pengujian fitokimia untuk mengetahui adanya kandungan senyawa fenolik, flavonoid, alkaloid, tanin, dan saponin. Metode yang digunakan adalah metode kehilangan berat (weight loss) dengan waktu perendaman selama 6 hari. Data konsentrasi ekstrak dan laju korosi dianalisis secara statistika varian satu arah (ANOVA) untuk menentukan signifikansi pengaruh ekstrak metanol terhadap laju korosi baja. Hasil uji fitokimia menunjukkan bahwa ekstrak metanol tumbuhan paku perak menghasilkan senyawa fenolik, flavonoid, alkaloid, tannin, dan saponin. Hasil penelitian menunjukkan bahwa  efisiensi inhibisi mencapai 57,27% pada konsentrasi 2500 ppm. Peristiwa adsorpsi isotermal yang terjadi termasuk dalam jenis adsorpsi isotermal Langmuir. Dengan demikian ekstrak metanol tumbuhan paku perak berpotensi sebagai inhibitor korosi.

Kata-kata kunci: Pityrogramma calomelanos, ekstrak metanol,  uji fitokimia, pengendalian organik, metode kehilangan berat (weight loss), baja ASTM A36.

Corrosion can cause environmental damage, so there is a need to prevent the use of corrosion inhibitors. Corrosion inhibitors are substances that are added to metals to decrease the rate of corrosion. Corrosion inhibitors of organic and inorganic compounds. Organic inhibitors in decreasing corrosion rates have been widely investigated because they are environmentally friendly compared to inorganic inhibitors. The purpose of this study was to determine the concentration and efficiency of corrosion inhibition of methanol extract of silver ferns (P. calomelanos) on ASTM A36 steel in a 3% NaCl solution. The extraction process was carried by maceration method. The methanolic extract of silver ferns was tested by phytochemical testing to know the existence of phenolic, flavonoid, alkaloid, tannin, and saponin compounds. The corrosion rate was determined by weight loss method immersion time for 6 days. Data of corrosion rate were analyzed statistically using one-way ANOVA to determine the significance of the effect of methanol extract on steel corrosion rate. The results showed that the methanol extract of silver ferns contained phenolic, flavonoid, alkaloid, tannin, and saponin compounds. The inhibition efficiency reached 57.27% at a concentration of 2500 ppm. The isothermal adsorption events that occur was included in the Langmuir isothermal adsorption type. Thus the methanol extract of silver ferns had the potential as a corrosion inhibitor agent.

Keywords: Pityrogramma calomelanos, methanol extract,  phytochemical test, organic control, weight loss method, ASTM A36 steel.