Removal of chromium and copper ions by using pumpkin seeds as adsorbent

This study aimed to prepare adsorbent by using pumpkin seeds and to investigate the effectiveness between calcined and uncalcined pumpkin seeds that were physically and chemically treated to remove chromium and copper ions in aqueous solution. The uncalcined pumpkin seeds were prepared by physical (P-UC) and chemical (C-UC) treatments. In chemical treatment, the pumpkin seeds were impregnated with local vinegar to activate its active site. In both treatments, part of the pumpkin seeds was calcined at temperature 350oC (PC-350, CC-350), 450oC (PC-450, CC-450) and 550oC (PC550, CC-550). The adsorbents were characterized by using Fourier Transform Infrared (FT-IR). Batch adsorption experiments were carried out in order to determine the effectiveness of the adsorbents in removing chromium and copper ions. The effect of adsorbent dosage, contact time and initial concentration on the adsorption process were evaluated. The final concentration of the chromium and copper ions was determined by using Atomic Absorption Spectrophotometer (AAS). The most effective pumpkin seeds as adsorbent in removing chromium ions was discovered to be C-UC at optimum condition such as 1.5g adsorbent dosage, 50mL of 50ppm initial chromium ions concentration, 700rpm speed with 30 minutes contact time since the result showed that it can remove the maximum amount of chromium ions, 68.12% compared to other types of adsorbents. Meanwhile, the most effective pumpkin seeds as adsorbent in adsorbing copper ions were revealed to be PC-550 at an optimum condition such as 1.5g dose of adsorbent, 50mL of 50ppm initial copper ions concentration, stirred for 30 minutes at 700rpm speed to remove 85.95% copper ions. The changes in FT-IR spectra of uncalcined to calcine adsorbent treatment suggested that the sorption of chromium and copper ions was consistent with the findings.