OPTIMASI PRESIPITASI SPENT CATALYST LANTHANUM MENGGUNAKAN ASAM OKSALAT DENGAN METODE:RESPONSE SURFACE METHODOLOGY

FELLICIA KARTIKA S, Himawan Tri Bayu Murti Petrus, S.T., M.Eng., D.Eng. ; Dr.Eng. Widi Astuti, S.T., M.T.

2021 | Tesis | MAGISTER TEKNIK KIMIA

Logam Tanah Jarang (LTJ) memiliki peranan penting yang strategis karena pemanfaa-tannya pada aplikasi di berbagai sektor ekonomi global. Saat ini, LTJ dikategorikan sebagai mineral kritis dimana cadangan sedimen bawah tanah hanya sedikit dan terjadi dalam konsentrasi kecil di banyak lokasi. Selain sumber dari cadangan primer (bijih tambang), LTJ dapat ditemukan pada sumber sekunder berupa limbah industri salah satunya berupa katalis bekas. Penelitian ini menjadi dasar untuk mempelajari pengen-dapan salah satu mineral LTJ (yaitu lantanum) dari katalis bekas menggunakan asam oksalat pada berbagai temperatur dan pH. Diawali dengan proses pelindian 125 gram katalis lantanum bekas menggunakan 500 mL asam sitrat 1 M, dilanjutkan dengan pengendapan menggunakan asam oksalat 0.5 M dengan memvariasikan suhu (60oC; 80oC; 90oC) dan pH (1.0; 1.5; 2.0). Berdasarkan hasil yang dianalisis menggunakan Response Surface Methodology (RSM), untuk mengetahui nilai optimal dari beberapa variabel bebas yang mempengaruhi variabel respon terhadap karakteristik presipitasi. Persamaan polinomial orde dua digunakan untuk mengkorelasikan respon dan variabel independen. Koefisien determinasi (R2) menunjukkan hasil yang memuaskan sebesar 70.27% dan plot probabilitas normal memastikan kecukupan model. Kondisi optimum %recovery terjadi pada pH 1, suhu 90oC, 120 menit didapatkan hasil 98,87%.

Rare earth elements (REEs) have a strategic importance because of their use in applications in various sectors of the global economy.Currently, REEs is categorized as a critical mineral where there are few underground sediment reserves and occurs in small concentrations in many locations. The increasing use of REEs globally has a vital function in the high technology industry to produce superior products. Indirectly unwanted by-products are also produced as a waste of spent catalysts. Interestingly, the use of spent catalysts as secondary resources is mostly done for extracting valuable minerals using reagents. This research is the basis for the study of the precipitation of one of the REE minerals (i.e. lanthanum) from spent catalysts using oxalic acid at various temperatures and pH. Begins with a leaching process of 125 grams of used lanthanum catalyst using 500 mL of 1 M citric acid, followed by precipitation using 0.5 M oxalic acid by varying the temperature (60oC; 80oC; 90oC) and pH (1.0; 1.5; 2.0). Based on the results that are analyzed using the response surface method (RSM), to find the optimal value of several independent variables that affect a response variable on precipitation characteristics. A second order polynomial equation was used to correlate response and independent variables. The coefficient of determination (R2) shows a satisfactory result of 70.27% and the normal probability plot ensure the models adequacy. Optimum conditions occurred at pH 1, temperature 90oC and time 120 minutes obtained 98.87% % recovery on lanthanum oxide.

Kata Kunci : lanthanum, oxalic acid, precipitation, REE, RSM (Response Surface Methodology), spent catalyst