Synthesis of eco-friendly liquid detergent from waste cooking oil and ZnO nanoparticles

The environmentally friendly anionic surfactant methyl ester sulfonate (MES) was synthesized from waste cooking oil (WCO), a low cost raw material. MES was combined with ZnO nanoparticles, producing nanofluidic detergent. Free fatty acid (FFA) in WCO was reduced by adding NaOH solution, while other impurities, such as food residues, were removed by means of filtration. Bleaching was also performed using activated carbon at various concentrations of 5%;10%;15%;20%wt. The purified cooking oil then underwent transesterification with oil-methanol molar ratio of 1:9. The as-produced methyl ester and WCO were analyzed using GC-MS to confirm their composition. Sulfonation was then performed by adding sodium bisulfite (NaHSO ₃ ) to produce MES surfactant. The product was then purified using methanol of various concentrations of 10%;20%;30%;40%v. Finally, NaOH solution was added to neutralize the synthesized MES, and FTIR analysis was subsequently performed to scrutinize its chemical bonding properties. Combined with ZnO nanoparticles, nanofluidic detergent was produced at various MES concentrations of 10%;12.5%;15%wt. In this work, we established the optimum condition for bleaching process being in the use of 20% activated carbon, causing WCO color to alter from dark brown to light yellow while promoting significant reduction of FFA as high as 31.17%. We also found that purification of MES using 40%v methanol results in surfactant with adequately low surface tension of 33.6 dyne/cm. Liquid detergent comprising of 15% MES concentration and 0.1% ZnO nanoparticles exhibit notable stability of 88.22%, while retaining 64.97% stain removal as well as 82.36% stain degradation.