Red mud is a byproduct generated during the production of alumina in the aluminium industry that causes significant environmental and health problems. Red mud's powerful alkalinity has a significant impact on both its potential for use in composite reinforcement and its wide range of other applications. For the neutralisation of red mud, the method using natural waste lemon biomass and no chemical addition was suggested. Lemon juice was used to neutralise red muck, and the stirring process was studied. GC–MS can detect the presence of organic acids in lemon juice. Under experimental conditions, red mud's alkalinity can be effectively lowered by adding lemon juice, which also lowers the material's pH from 10.4 to 7.56. Numerous characterisations, including XRD, FTIR and TGA analyses, were conducted to study the neutralisation mechanism. The findings indicate that red mud undergoes minimal changes post-neutralisation, suggesting that small-molecule organic acids primarily eliminate free alkali without significantly altering the red mud itself without changing the chemical composition. In order to improve corrosion resistance, neutralised red mud was employed as a reinforcement in metal matrix composites.