Kapok-Based Agricultural Biomass Inhibitor for Steel Corrosion Control in H₂SO₄: Kinetic and Thermodynamic Study

Inhibitor Biomassa Pertanian Berbahan Dasar Kapuk Untuk Pengendalian Korosi Baja Dalam H₂So₄: Studi Kinetika Dan Termodinamika

Abstract

Steel corrosion in acidic environments is a critical issue affecting material durability and service life. This study aims to analyze the effect of kapok peel extract inhibitor concentration on the corrosion rate of steel in sulfuric acid media and to determine kinetic and thermodynamic parameters using Arrhenius plots and transition state theory. The weight loss method was employed with inhibitor concentrations (blank, 1000, 2000, and 3000 ppm) and temperatures (27, 35, and 45°C). Results indicate that corrosion rate significantly decreases with increasing inhibitor concentration, achieving a maximum inhibition efficiency of 74.06% at 3000 ppm and 27°C. Conversely, higher temperatures increase the corrosion rate. Kinetic analysis shows linear relationships in ln(CR) vs 1/T and ln(CR/T) vs 1/T plots. Activation energy increased from 15.82 to 26.75 kJ/mol, while ΔH° increased and ΔS° was negative. These findings suggest an adsorption-controlled inhibition mechanism forming a protective layer on the steel surface, indicating that kapok peel extract is a promising eco-friendly corrosion inhibitor.