PEMISAHAN ION KROM(III) DAN KROM(IV) DALAM LARUTAN DENGAN MENGGUNAKAN BIOMASSA ALGA HIJAU SPIROGYRA SUBSALSA SEBAGAI BIOSORBEN

Abstract

Karakteristik pemisahan ion Cr³⁺ dan Cr⁶⁺ dalam larutan melalui proses biosorpsi menggunakan biomassa alga hijau Spirogyra subsalsa dengan sistem batch telah diteliti. Dalam pelaksanaannya diawali dengan melakukan analisis kualitatif gugus fungsi dalam biomassa menggunakan instrumen FTIR, kemudian dipelajari karakteristik pengaruh variabel pH awal larutan, ukuran partikel biosorben, kecepatan pengadukan, pengaruh pemanasan biosorben, laju penyerapan, pengaruh konsentrasi larutan ion logam terhadap kapasitas serapan biomassa alga. Berdasarkan spektra spektroskopi FTIR dapat disimpulkan bahwa  biomassa alga hijau S. Subsalsa mengandung gugus-gugus karboksilat, amina, amida, amino, karbonil dan hidroksil, disamping adanya senyawa silikon, belerang dan fosfor. Hasil penelitian yang diperoleh  memperlihatkan bahwa kapasitas biosorpsi sangat dipengaruhi oleh pH larutan, waktu kontak dan konsentrasi awal larutan. Biosorpsi optimum kation Cr³⁺ terjadi pada pH 4,0 sedangkan ion Cr⁶⁺ terjadi pada pH 2,0 kemudian berkurang dejalan dengan naiknya pH larutan. Perhitungan dengan persamaan Isoterm Langmuir diperoleh data kapasitas serapan maksimum biomassa alga S. subsalsa untuk masing-masing ion Cr³⁺ dan Cr⁶⁺ adalah 1,82 mg (0,035 mmol) dan 1,51 mg (0,029 mmol) per gram biomassa kering. Kinetika biosorpsi berlangsung relatif cepat, dimana selama selang waktu 30 menit, masing-masing ion terserap sekitar 95,7%; dan 86,5%. Daya serap biomassa juga dipengaruhi kecepatan pengadukan, sedangkan faktor ukuran partikel dan pemanasan biosorben kurang mempengaruhi daya serap biomassa.

Key Word : biosorpsi, spirogyra subsalsa, krom(III), krom(VI), sistem batch

Abstract

Separation of Ion Chromium(III) and Chromium(IV) In Solution Using Green Algae Biomass Spirogyra subsalsa as Biosorbent. The characteristics of Cr³⁺andCr⁶⁺ ion separation in solution through biosorption process using green algal biomass Spirogyrasubsalsa with batch systems have been investigated. The study began with aqualitative analysis of functional groups in biomass using FTIR instrument, then followed by a study of the characteristics of influences by several variables, such as: the initial pH of the solution,the size of biosorben particles, stirring speed, the effect of heating the biosorben, the rate of absorption, and the effect of metal ion concentration in solution on the absorption capacity of algal biomass. Based on FTIR spectroscopy spectra gave a conclusion that biomass of green algae S.subsalsa contains carboxylate groups, amine, amide, amino, carbonyl and hydroxyl, in addition to silicon, sulfur, and phosphorus compounds. The results showed that the biosorption capacity was strongly influenced by pH, contact time, and initial concentration ofthe solution. The optimum biosorption of Cr³⁺cation occurred at pH 4.0 while that of Cr⁶⁺ions occurred at pH 2.0 and then decreased with the increasing pH of solution. The calculation of Langmuir isotherm equation showed that the maximum absorption capacity of algal biomass S.subsalsa for Cr³⁺and Cr⁶⁺ ion respectively was 1.82mg (0.035 mmol) and 1.51 mg (0.029 mmol) pergram of dry biomass. The kinetics of biosorption took place relatively quick, in which during the 30minutes time interval, each ion was absorbed approximately 95.7%; and 86.5%. The absorptive capacity of biomass was also influenced by stirring speed, while the size of particles and heating biosorben gave lessinfluence to the absorption of biomass.