STUDI ADSORPSI KOMPETITIF KADMIUM(II) DAN SENG(II) DENGAN GREEN ADSORBEN – ASAM HUMAT TINJA SAPI; COMPETITIVE ADSORPTION STUDY OF CADMIUM(II) AND ZINC(II) BY GREEN ADSORBENT – COW DUNG HUMIC ACID

Amelia Handayani Burhan, Bambang Rusdiarso

2014 | Disertasi | PROGRAM STUDI S-2 KIMIA

Cow dung shows their ability as a green source of humic acid, because it’s a renewable source and it doesn’t potentially damage environment. Cow dung humic acid extraction was performed by slightly modification of alkaline extraction methods. Cow dung humic acid purification is exactly the same with peat humic acid purification. This used 0.1M HF/ 0.3M HCl (1:1). Cow dung humic acid was then used as adsorbent to study adsorption of Cd(II) and Zn(II), as well as competitive adsorption between Cd(II) and Zn(II). The adsorption aspects studied were adsorbent weight effect, optimum pH, rate, pattern, energy, and capacity of adsorption. Six types of cow dung humic acid were produced. Based on the determination results of functional groups, adsorption capacity, and green chemistry aspects, it was found that cow dung humic acid without heating and purification process showed the best result. Adsorption of Cd(II) and Zn(II) using cow dung humic acid followed Langmuir Isotherm, with adsorption energy of 20.92 and 22.32 kJ/mol, respectively. Zn(II) adsorption rate was higher than that of Cd(II), i.e. 1,06x10-4 g/mg min for Zn(II) and 4,12x10-5 /mg min for Cd(II). Cd(II) and Zn(II) adsorption capacity were 8.85x10-4 and 8.18 mol/g, respectively. The competitive study between Cd(II) and Zn(II) on cow dung humic acid showed that the concentration of Cd(II) adsorbed by cow dung humic acid was greater than that of Zn(II). This was due to higher polarity binding between Zn(II) and cow dung humic acid active sites, resulting in its solubility increased, thus the concentration of Zn(II) adsorbed by cow dung humic acid was smaller than that Cd(II).

Kata Kunci : asam humat; tinja sapi; adsorpsi; adsorpsi kompetitif; kinetika; isoterm; kadmium; seng