BUAH API-API PUTIH (Avicennia alba Blume) TERMODIFIKASI ASAM MERKAPTOASETAT (AMA) SEBAGAI ADSORBEN ION Pb(II) DAN Cd(II); API-API PUTIH FRUIT (Avicennia alba Blume) MODIFIED BY MERKAPTOACETIC ACID (MAA) AS ADSORBENT OF Pb(II) AND Cd(II) IONS

Dwijayanti, endah, Nurul Hidayat Aprilita

2015 | Disertasi | FMIPA UGM

Avicennia alba Blume) unmodified and modified by mercaptoasetic acid (MAA) to adsorb Pb(II) and Cd(II) ions. Modification was conducted through reacting api-api putih fruit which had been activated by NaOH dan HNO3 with 5.0 M mercaptoacetic acid at 30 °C and pH 7.1. Modification was aimed to increase the effectivity and capacity of adsorption. Characterization of unmodified adsorbent (UMA) and modified adsorbent (MA) was carried out by using spectrophotometer infrared (FT-IR), Scanning Electron Microscope (SEM-EDS) and Gas Sorption Analyzer (GSA). Adsorption study included optimization of adsorbent mass, pH solution, contact time, initial concentration of heavy metal ion and temperature. The result of MA characterization using spectrophotometer FT-IR showed C-S bond at 694 cm-1 and the presence of sulphur (S) element on EDS spectrum of 5.22 % mass as the result of modification with mercaptan (-SH). The results of GSA at MA indicated an increasing surface area from 2,79 m2 g-1 to 39,24 m2 g-1 and pore volume from 0,0037 cm3 g-1 to 0,0368 cm3 g-1. Optimum condition of MA to adsorption 50 mg L-1 of Pb(II) and Cd(II) ions was occured at each adsorbent mass 0.1 g at pH 4 and 1.25 g at pH 6 within the same optimum time, 90 minutes. Adsorption kinetic of UMA and MA showed that Pb(II) and Cd(II) ions followed pseudo second orde and isotherm Langmuir model. Maximum capacity adsorption (qmax) UMA and MA of Pb(II) ion at 50 °C were 32.26 mg g-1 and 45.45 mg g-1. At the adsorption of Cd(II) ion, each of qmax UMA and MA value was 23.81 mg g-1 and 27.03 mg g-1 at 30 °C. Adsorption Pb(II) and Cd(II) ions showed that UMA and MA were chemisorption process with spontaneous and exothermic adsorption reaction. The result of this study showed that api-api putih fruit (Avicennia alba Blume) modified by merkaptoacetic acid has good adsorption affinity toward Pb(II) and Cd(II) ions with increasing adsorption capacity compared than unmodified.

Kata Kunci : Avicennia alba Blume; mercaptoacetic acid; Pb(II); Cd(II)