Penelitian ini mengkaji tentang adsorpsi tunggal dan kompetitif logam Ag(I) dan Cu(II) menggunakan adsorben asam humat yang diperoleh dari tanah gambut Kota Pontianak, Propinsi Kalimantan Barat. Kajian meliputi isolasi asam humat, pengaruh keasaman, waktu dan konsentrasi terhadap adsorpsi logam dan bagaimana kompetisinya pada kondisi optimum masing-masing logam. Asam humat diekstrak dengan basa dan diendapkan dengan asam. Asam humat hasil isolasi dikarakterisasi menggunakan spektrofotometri Fourier-Transform Infrared (FTIR) dan UV-Vis. Hasil karakterisasi asam humat dengan spektrofotometer FTIR menunjukkan adanya gugus O-H, C-H alifatik, C=O asam karboksilat dan C=C aromatik. Berdasarkan spektrofotometer UV-Vis tidak terdapat puncak yang tajam dan terjadi kelandaian pada panjang gelombang 260-280 nm. Berdasarkan pengaruh keasaman terhadap adsorpsi logam menunjukkan bahwa Ag(I) teradsorpsi maksimum pada pH 8 dan Cu(II) pada pH 4. Berdasarkan percobaan pengaruh waktu kontak diketahui bahwa Ag(I) mencapai kesetimbangan pada menit ke-120 dan Cu(II) pada menit ke-60. Adsorpsi Ag(I) mencapai kesetimbangan pada konsentrasi 40 ppm dan Cu(II) pada konsentrasi 150 ppm. Adsorpsi Ag(I) mengikuti kinetika orde 1 sedangkan Cu(II) mengikuti kinetika orde 2. Isoterm adsorpsi Ag(I) dan Cu(II) mengikuti persamaan isoterm Langmuir. Kompetisi logam Ag(I)

This research was carried out to investigate the ability of humic acid to adsorp Ag(I) and Cu(II) as a single and multiple metal ion. For this purpose, humic acid was isolated from peat soil that was taken from Pontianak, West Kalimantan. This study included: the isolation of humic acid; the influence of acidity, time, and concentration to metals adsorption; and the competition of metals in their optimum condition. Humic acid was extracted using base and was precipitated using acid. Then, the isolate of humic acid was characterized by means of infra red (FTIR) and UV-Vis. Characterization of humic acid by means of FTIR spectrofotometry showed the bands of OH, C-H aliphatic, C=O carboxylic acid, and C=C aromatic. Based on UV-Vis spectrophotometry, there was no any sharp peak. Only a slightly peak that seen at 260-280 nm. Base on influence of acidity to metals adsorption showed that Ag(I) was maximum adsorbed at pH 8 and Cu(II) at pH 4. Base on influence of time showed that Ag(I) reached the equilibrium at the 120th minute and Cu(II) at the 60th minute. Adsorption of ion Ag(I) reached equilibrium at 40 ppm and Cu(II) at 150 ppm. Adsorption of Ag(I) followed the first-order kinetic, meanwhile Cu(II) followed the second-order kinetic. Isotherm adsorption of Ag(I) and Cu(II) followed the equation of Langmuir. Metals competition of Ag(I) and Cu(II) showed competition of two metals, Ag(I) was maximum adsorbed however the acidity conditions.

Kata Kunci : Asam humat, adsorpsi, Ag(I), Cu(II)