STUDI DESORPSI UREA PADA HUMIN SINTETIS STUDY OF UREA DESORPTION ON THE SINTETIC HUMIN
IKA AMBARSARI, Dr. Agus Kuncaka, DEA
2014 | Skripsi | KIMIATelah dilakukan penelitian tentang penentuan laju desorpsi urea dari humin sintetis. Humin sintetis berasal dari pupuk SROP (Slow Release Organic Paramagnetic)/humus sintetis, diperoleh residu dari ekstrak humus sintetis dengan larutan NaOH 0,1 M, fraksi yang tidak larut dikeringkan dan diayak dengan ukuran 100 mesh. Humin sintetis dikarakterisasi dengan menggunakan spektroskopi infra merah (FTIR). Uji variasi konsentrasi urea untuk menentukan aktivitas (konsentrasi) kesetimbangan desorpsi adsorpsi dan variasi waktu kontak untuk penentuan konsentrasi terlepas dan kinetika desorpsi urea. Pengukuran konsentrasi urea dilakukan dengan mengomplekskan larutan urea dengan p-dimetilamino benzaldehid (PDAB) dan HCl 0,1 M dan dianalisis dengan spektrofotometer UV-Vis. Karakterisasi IR humin sintetis residu hasil ektraksi menunjukkan bilangan gelombang spesifik pada 3426 cm -1 (vibrasi tekuk gugus hidroksi dari fenol dan vibrasi ulur N-H amina), 2932 cm -1 (vibrasi ulur dari gugus C-H sp 3 ), 1705 cm -1 (vibrasi ulur dari gugus C=O), 1582 cm -1 (vibrasi ulur gugus C=C aromatik), 1096 cm -1 (vibrasi ulur gugus C-O) dan 471 cm -1 (vibrasi tekuk gugus Si-O-Si). Harga pH tidak berpengaruh terhadap laju pelepasan konsentrasi urea. Aktivitas kesetimbangan desopsi-adsorpsi urea adalah 124,45 mg/L. Kinetika desorpsi urea pada humin sintetis mengikuti model kinetika desorpsi orde satu dengan nilai R 2 yaitu 0,9957 dan nilai konstanta laju desorpsi urea (k) adalah 4,5 x 10 -6 per detik.
Study on the determination of urea desorption kinetic on the synthetic humin has been carried out. The synthetic humin was obtained as the residue of extraction of synthetic humus with NaOH 0.5 M. The Fourier Transform Infra Red (FT-IR) spectroscopy was used to characterize its functional groups. The activity of urea on the synthetic humin was determined by varying urea concentration on the adsorbate solution until the equilibrium of urea adsorption and desorption was achieved. The urea desorption kinetic determined by evaluating of urea being unreleased from synthetic humin as a function of time, the dependence of pH on the urea desorption kinetic also was evaluated. Urea was analyzed using spectrophotometer UV-Visible. The p-dimethylamino benzaldehide (PDAB) and HCl 0.1 M were used as reagents. Characterization result using FT-IR showed that the synthetic humin from extract residue had absorption bands at 3426 cm -1 (bending vibration of hydroxyl group of phenol and N-H stretching of amine group), 2932 cm -1 (stretching vibration of C-H sp 3 group), 1705 cm -1 (stretching vibration of C=O), 1582 cm -1 (bending vibration of C=C aromatic group), 1096 cm -1 (stretching vibration of C-O) and 470 cm -1 (bending vibration of Si-O-Si group). The kinetic of urea desorption was independent with the pH. The urea activity at the equilibrium of urea adsorption and desorption was 124.45 mg/L. The model of kinetic urea desorption showed that the urea released from humin synthetic followed first order with R 2 was 0.9957 and the constant of kinetic desorption (k) was 4.5 x 10 -6 per second.
Kata Kunci : humin sintetis, urea, desorpsi, humus sintetis, SROP
