Harnessing Unripe Banana Peel Derived‐Pectin for Efficient Divalent Metal Biosorption

ABSTRACT This study investigates the extraction of pectin from unripe banana peel using citric acid (CA) and hydrochloric acid (HCl) under varying conditions of temperature, pH and solvent type. Optimal pectin extraction was achieved at 90°C, using CA and HCl with pH 1.8 and ethanol as precipitating agent. Under these extraction conditions, CA produced a higher pectin yield (27%) compared to HCl (22%). The extracted pectin was evaluated on the basis of parameters, such as equivalent weight, methoxyl content, degree of esterification (DE), anhydrouronic acid content, ash, moisture and overall yield. The structural integrity of the extracted pectin was confirmed using FT‐IR and 1 H NMR. Pectin extracted using CA shows promising adsorption properties for divalent metal ions, such as Zn(II), Pb(II), Ca(II), Fe(II) and Ni(II) in synthetic wastewater treatment. Pectin(CA) achieved adsorption capacities of 192.31 mg/g for Pb(II) and 91.74 mg/g for Ni(II), superior to the values obtained with pectin(HCl), which were 76.33 mg/g for Pb(II) and 56.49 mg/g for Ni(II). The enhanced performance of pectin(CA) is attributed to its lower DE, which provides more active binding sites and makes it a highly efficient and sustainable biosorbent. Kinetic modeling revealed that Pb adsorption onto both pectin(CA) and pectin(HCl) is best described by a pseudo‐second order model, indicating chemisorption as the dominant mechanism.