Chiang Mai Journal of Science

     Carbofuran is a carbamate pesticide commonly used to control insects on various field crops. The pesticide residues on fruits and vegetables are potentially toxic to humans. Calcium chloride (CaCl₂) is a potential chemical for rinsing pesticide residues from the surface of fruits and vegetables. Eggshell waste, rich in calcium carbonate, is a possible resource for calcium for the low-cost producti on of CaCl₂. This research aimed to extract calcium from chicken eggshells with a 10% (w/v) hydrochloric acid (HCl) solution and investigate the removal efficiency of carbofuran residues from the surface of cucumber (Cucumis sativus Linn.) using the indirect spectrophotometric detection of methylamine at an absorbance of 530 nm. The maximum yield of 80.28% (w/w) eggshell extract and 81.74% (w/w) anhydrous CaCl₂ was obtained. The carbofuran concentration was 11.20 ± 1.49, 114.56 ± 24.56, and 169.68 ± 29.04 mg/L after being soaked in 1%, 2%, and 3% (w/v) of the eggshell extract solution for 10 minutes. No carbofuran residue was detected in the distilled water (control). CaCl₂ tablets were formed by compression of dried CaCl₂ extract. The increase in the compression forces from 0.5 to 1, 1.5, and 2 tons/cm² decreased the thickness of the pellets from 7.01 ± 0.07 to 6.03 ± 0.12 mm, and increased the tablet hardness from 5.27 to 11.43 kg/cm², the percentage of fracture (weight loss) from 2.18 ± 0.90 to 12.44 ± 2.45%, and the dissolution time from 4.76 to 6.72 min.