STUDI ADSORPSI DESORPSI UREA PADA HUMUS SINTETIS DALAM KONDISI LINGKUNGAN ASAM; ADSORPTION DESORPTION STUDY OF UREAIN SYNTHETIC HUMUS UNDER ACIDIC ENVIRONMENT

Gunawan, Alineo, Agus Harjoko

2015 | Skripsi | FMIPA

Study of urea adsorption desorption in synthetic humus under acidic environment has been conducted. The purposes of this research are to evaluate urea adsorption and desorption by synthetic humus and determine its effect in acidic environment. The research was started with isolation of synthetic humus in acidic solution and characterization using IR spectroscopy (FTIR). Determination of synthetic humus effect for solution pH value was done by varying the amount of synthetic humus at pH 4 of solution. The time variation test was conducted to determine the adsorption and desorption kinetics of urea in synthetic humus. The adsorption isotherms and activity equilibrium of urea in synthetic humus were deteminated by varying the concentration of urea. Urea was measured by using spectrophotometer UV-Visible. The p-dimethylamino benzaldehide (PDAB) and HCl 0.1 M were used as reagents. Characterization using IR spectroscopy shows humin fraction is the most stable component of synthetic humus in acidic environment. Synthetic humus is proven in increasing solution pH through H+ ion bonding by –OH and also metal oxide (MxO) hydrolysis in synthetic humus. Urea adsorption by synthetic humus follows pseudo-second kinetic order with value of k 3.80×10-4min-1. It is suitable with isotherm Langmuir model with parameters value Kl 8.94×10-2L mg-1. The activity at equilibrium of urea in synthetic humus is 131.64 mg L-1. Urea desorption is slow released system from synthethic humus and follows pseudo-second kinetic with constant of desorption kinetic (k) value at6.91×10-4 min-1.

Kata Kunci : synthetic humus; acidic environment; adsorption; desorption, urea