Sintesis Ca-Al-Fosfat Hidrotalsit dan aplikasinya sebagai adsorben logam timbal (Pb2+) dalam limbah cair

KARYANI, Muhammad Said, Dr. Roto, M.Eng

2007 | Tesis | S2 Ilmu Kimia

Telah dilakukan kajian sintesis Ca-Al-Fosfat hidrotalsit dan aplikasinya pada adsorpsi logam timbale (Pb 2+ ) dalam larutan. Preparasi Ca-Al-Fosfat hidrotalsit dilakukan dengan menggunakan CaCl 2 , AlCl 3 dan Na 2 HPO4 /NaOH. Kajian sintesis Ca-Al-Fosfat hidrotalsit meliputi rasio molar kation Ca 2+ dengan Al 3+ sama dengan 3, pH sintesis, karakterisasi padatan hasil sintesis dengan difraksi sinar X dan Spektroskopi FTIR, dan SEM, komposisi kimiawi Ca-Al- Fosfat hidrotalsit menggunakan AAS, UV-Vis dan metode gravimetric. Kajian adsorpsi Pb 2+ oleh Ca-Al-Fosfat hidrotalsit meliputi pengaruh pH adsorpsi, kinetika reaksi, kapasitas adsorpsi, energi adsorpsi, perubahan struktur Ca-Al- Fosfat hidrotalsit setelah adsorpsi dan mekanisme reaksinya. Adsorpsi Pb 2+ oleh Ca-Al-Fosfat hidrotalsit dikerjakan dengan menggunakan system bacth dengan mencampurkan larutan Pb 2+ dan padatan hidrotalsit. Pb 2+ dalam filtrate dianalisa menggunakan AAS setelah dipisahkan dengan sentrifug. Hasil penelitian menunjukkan bahwa Ca-Al-Fosfat hidrotalsit dapat disintesis melalui metode kopresipitasi pada pH 4,6 dan diikuti dengan perlakuan hidrotermal di dalam botol poli propilen pada temperature 90 o C selama 18 jam. Rasio molar Ca/Al dalam produk adalah 2,6 dan kristalinitasnya dapat ditingkatkan melalui peningkatan konsentrasi reaktan. Selama adsorpsi, setelah keseimbangan dicapai pH dari campuran terukur menjadi 7. Ca-Al-Fosfat hidrotalsit dapat mengadsorpsi Pb 2+ dimana kondisi optimum dicapai pada pH antara 4 sampai dengan 6 sedangkan kinetika adsorpsi Pb 2+ oleh Ca-Al-Fosfat hidrotalsit berlangsung cepat melinatkan reaksi elektrostatik. Struktur Ca-Al- Fosfat hidrotalsit mengalami perubahan setelah menyerap ion Pb 2+ yang ditandai dengan pembentukan timbale fosfat. Ca-Al-Fosfat hidrotalsit merupakan adsorben yang baik bagi ion Pb 2+ . Jumlah Pb 2+ yang teradsorpsi dapat mencapaim 600 mg/g Ca-Al-Fosfat hidrotalsit atau melalui model Langmuir diperoleh kapasitas adsorpsi sebesar 3,9 x 10 −3 mol/gram Ca-Al-Fosfat hidrotalsit dan energi adsorpsi sebesar 28,77 kJ/mol. Pembentukan timbale fosfat dalam interlayer hidrotalsit dipercaya sebagai penyebab kapasitas adsorpsi yang tinggi.

Study of Ca-Al-Phospate Hydrotalcite synthesis and its application for adsorbent of aqueous Pb 2+ solution. Preparation of Ca-Al-Phospate Hydrotalcite was performed using CaCl 2 , AlCl 3 and Na 2 HPO4 by co-precipitation method at various pH and followed by hydrothermal treatment inpoly propylene bottle at 90 o C for 18 hours. The solid product was confirmed by X-ray diffraction, FTIR. Morphology of the Ca-Al-Phospate Hydrotalcite was determinet using SEM and elemental analysis using atomic absorption (AA) and UV-Vis spectrometry. The adsorption study was conducted by investigating the influence adsorption pH, kinetics, capacity and energy of adsorption of aqueous Pb 2+ solution on Ca-Al- Phospate Hydrotalcite. Adsorption of Pb 2+ by the Ca-Al-Phospate Hydrotalcite was done using batch experiment by mixing the Pb 2+ solution and Ca-Al-Phospate Hydrotalcite solid. After equilibrium was reached, the pH of the mixture was measured to be 7. The remaining Pb 2+ in the solution was analyzed using AAS after being separated using a centrifuge. Result showed that Ca-Al-Phospate Hydrotalcite could be synthesized at pH 4.6. molar ratio of Ca/Al in product was found to be 2.6 and increasing crystalinities can be achieved by increasing concentration of reactans. During the adsorption, after equilibrium was reached, the pH of the mixture was measured to be 7. Ca-Al-Phospate Hydrotalcite could to adsorp Pb 2+where optimum condition reached at pH between 4 up to 6. kinetics of adsorption of aqueous Pb 2+ by Ca- Al-Phospate Hydrotalcite take place quickly entangle electrostatic reaction. Structure Ca-Al-Phospate Hydrotalcite experience of change after adsorption Pb 2+marked by formed is phosphate lead. The amount of Pb 2+ adsorbed by Ca- Al-Phospate Hydrotalcite was approximately 600 mg/g adsorbent or with Langmuir isotherm model, the adsorption capacity was 807 mg/g absorbent and adsorption energy was 29 kJ/mol. The adsorption capacity is very high. The formation insoluble lead phosphate in the interlayer space of hydrotalcite is believed to be the cause of this high adsorption capacity.

Kata Kunci : Adsorpsi Logam Pb,Pengolahan Limbah,Penyerapan Logam Pb, Ca-Al-Phospate Hydrotalcite, layered double hydroxide, aqueous lead removal