Thermodynamics and adsorption studies of blended guava and mango leaves extract as inhibitors for 7075 aluminium

Abstract

The petroleum industry has been very concerned about corrosion challenges. The thermodynamic and adsorption and studies on Aluminium grade 7075 using blended extract in hydrochloric acid was carried out using weight loss measurement and polarization techniques with optimization approach. The Box Behnken Design (BBD) of four variables namely; acid concentration, inhibition ratio, time of immersion and temperature were used to study the interaction of the variables. A phytochemical analysis of PGLE, MILE, and blended extract revealed that the blended extract contained more phytochemicals that prevent corrosion. The best process level observed from experimental design was at 30 °C, 80 % − 20 % inhibition volume ratio, 1.0 M acid concentration, and 9 days with 98.28 % inhibition efficiency. The result of polarization revealed that extract functioned as mixed type inhibitor. The adsorption of blended extract on Aluminium surface fitted more into Langmuir adsorption model. The result of ΔGads was from –16.73 to –22.73 kJ/mol, which indicated Spontaneity, Ea showed physisorption, −△H showed exothermic process and △S showed high disorderliness and randomness. The results of FTIR and SEM demonstrated that more effective protective film was formed on MS surface. it can be concluded that the blended extract could serve as good substitute to industrial inhibitor.