Oil palm empty fruit bunch extract and powder as an eco-friendly corrosion inhibitor for mild steel: A comparison study

A comparison study in terms of inhibition performance between oil palm empty fruit bunch (OPEFB) extract and OPEFB powder against mild steel corrosion in 1 M hydrochloric acid was evaluated using weight loss technique and adsorption isotherms. OPEFB extract and powder were prepared at various concentrations of 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% (v/v) and dosages of 0.2, 0.4, 0.6, 0.8, and 1.0 g, respectively. The results showed that OPEFB extract achieved higher inhibition efficiency (IE) at high concentration and short immersion time compared to OPEFB powder. Despite having lower IE, OPEFB powder seemed to have better behavior; 6.6% IE increment at longer immersion time, gradual release of active compounds and stronger adsorption capacity. Fourier transform infrared (FTIR) and energy-dispersive X-ray studies confirmed the presence of active compounds in OPEFB extract and powder that is responsible for inhibition. Thermodynamic study revealed that both OPEFB extract and powder obeyed Langmuir isotherm and worked through physical adsorption. Overall, OPEFB powder is concluded to have better performance as corrosion inhibitor compared with OPEFB extract.