KESETIMBANGAN DAN KINETIKA PENYISIHAN ORTHOFOSFAT DARI DALAM AIR DENGAN METODE ADSORPSI-DESORPSI
Abstract
Abstrak: Ion fosfat sering dikaitkan dengan terjadinya algae blooming dan masalah estetika pada badan air permukaan. Fosfat ini perlu diolah dan dimanfaatkan lebih lanjut. Salah satu metode yang dapat digunakan untuk mengolah orthofosfat adalah metode adsorpsi. Tujuan dari penelitian ini adalah mengadsorpsi ion fosfat ke dalam adsorben yang murah. Tanah (tanah Dago dan tanah Arcamanik) dan bebatuan lokal seperti dolomite hadir sebagai media adsorben yang murah dan mudah diperoleh. Dilakukan percobaan pengaruh pH larutan terhadap proses adsorpsi. Hasil penelitian menunjukkan bahwa efisiensi penyisihan orthofosfat tertinggi saat pH asam (pH 2). Efisiensi penysihan orthofosfat oleh tanah Dago, tanah Arcamanik, dan dolomite berurutan adalah 65,641%-99,334%, 55,540%-99,12%, dan 50,240%-91,489%. Kemampuan desorpsi dari tanah Dago, tanah Arcamanik, dan dolomite berurutan adalah 0,32%-2,46%, 1,02%-5,337%, and 4,36%-15,703%. Adsorpsi orthofosfat oleh kedua jenis tanah mengikuti model isoterm Temkin dan dolomite mengikuti model isoterm Freundlich. Semua adsorben mengikuti model laju kinetika pseudo-second order. Hasil penelitian juga menunjukkan bahwa mekanisme penyisihan orthofosfat di dalam air oleh tanah Dago dan tanah Arcamanik adalah adsorpsi secara kimia melalui ligand exchange, sedangkan penyisihan oleh dolomite adalah adsorpsi secara fisik dan presipitasi permukaan.
Kata kunci: adsorpsi, desorpsi, isoterm, kinetika, orthofosfat
Abstract: Phosphate ions are usually considered as the responsible for the algal bloom in receiving water bodies and aesthetic problems in water. From the environmental point of view, management of such contaminant and valuable resource is very important. One method that can be used to remove orthophosphate is the adsorption method. An experimental study on the adsorption or phosphate onto cost effective adsorbents is presented. Cost effective adsorbents named Dago soil, Arcamanik soil, and dolomite. The effect of pH solution was examined. As a result, it was found that the highest efficiency of phosphate removal is at acidic pH (pH 2). The orthophosphate removal efficiency by Dago soil, Arcamanik soil, and dolomite respectively are 65.641%-99.334%, 55.540%-99.12%, and 50.240%-91.489%. The desorption ability of Dago soil, Arcamanik soil, and dolomite respectively are 0.32%-2.46%, 1.02%-5.337%, and 4.36%-15.703%. Adsorptions of orthophosphate by both soils occur according to the Temkin isotherm model, and for dolomite, the Freundlich isotherm depicted the equilibrium data most accurately. For all adsorbents were well fitted with pseudo-second order kinetics model. The Experimental data further indicated that the removal of orthophosphate by Dago and Arcamanik soil occur by chemisorptions mechanism, while adsorption orthophosphate by dolomite occur by physicsorption mechanism and surface precipitation.
Keywords: adsorption, desorption, isotherm, kinetic, orthophosphate
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