Recovery Ion Hg2+ dari Limbah Cair Industri Penambangan Emas Rakyat dengan Metode Presipitasi Sulfida dan Hidroksida

https://doi.org/10.22146/jrekpros.34496

Ilma Fadlilah(1*), Agus Prasetya(2), Panut Mulyono(3)

(1) Departemen Teknik Kimia, Fakultas Teknik, Universitas Gadjah Mada, Jl. Grafika No.2 Kampus UGM, Yogyakarta, 55281
(2) Departemen Teknik Kimia, Fakultas Teknik, Universitas Gadjah Mada, Jl. Grafika No.2 Kampus UGM, Yogyakarta, 55281
(3) Departemen Teknik Kimia, Fakultas Teknik, Universitas Gadjah Mada, Jl. Grafika No.2 Kampus UGM, Yogyakarta, 55281
(*) Corresponding Author

Abstract


Unlicensed gold mining activities using mercury (Hg) as a gold element binder is called the amalgamation process. Mercury is a heavy metal and categorized as toxic material. The use of mercury can potentially cause a pollution in environment, especially the aquatic system. For overcoming the heavy metals of mercury in liquid waste, it needs an alternative wastewater treatment method e.g. chemical precipitation. This study is aimed to recover Hg2+ ions from liquid wastes by using sulphide precipitation and hydroxide methods. This research studied the effect of pH on Hg2+ ions which is deposited in the precipitation process and evaluated the rate of Hg2+ precipitation formation. Precipitation was carried out by using sodium sulphide (Na2S) 0.3 M and Ca(OH)2 0.004 M as a precipitation agent with a rapid mixing speed for about 200 rpm for 3 minutes and continued with slow mixing for about 40 rpm for 30 minutes. Then, the liquid sample was left for 24 hours to precipitate. The results showed that precipitation method by using Na2S solution can decrease the content of Hg in HgCl2 synthetic waste. Optimum mass of HgS precipitate of 0.046 g was achieved at pH 9 with a removal efficiency percentage up to 99.81%. The rate of formation of HgS precipitate is 0.4mg/ hour. While, hydroxide precipitation method can decrease mercury level up to 90.11% at pH 12 and mass of Hg (OH)2 precipitate obtained is 0.28 g. However, the result of EDX analysis of the precipitate of Hg (OH)2 showed that the content of Hg precipitate is still low at 0.28 wt.%.

 

A B S T R A K

Kegiatan penambangan emas rakyat tanpa izin (PETI) dengan menggunakan merkuri (Hg) sebagai pengikat unsur emas disebut proses amalgamasi. Merkuri merupakan logam berat yang bersifat racun. Penggunaan merkuri ini berpotensi menimbulkan pencemaran di lingkungan sekitar, terutama lingkungan perairan. Untuk penanganan logam berat merkuri dalam limbah cair ini, maka diperlukan sebuah metode pengolahan limbah alternatif, yaitu metode presipitasi kimia. Penelitian ini bertujuan untuk me-recovery ion Hg2+ dari limbah cair dengan metode presipitasi sulfida dan hidroksida. Selain itu mempelajari pengaruh pH terhadap ion Hg2+ yang terendapkan dalam proses presipitasi dan mengetahui laju pembentukan endapan Hg. Presipitasi dilakukan dengan menggunakan natrium sulfida (Na2S) 0,3 M dan Ca(OH)2 0,004 M sebagai agen presipitan dengan pengadukan cepat 200 rpm selama 3 menit dan dilanjutkan dengan pengadukan lambat 40 rpm selama 30 menit. Larutan sampel didiamkan selama 24 jam untuk mengendapkan presipitat yang terbentuk. Hasil penelitian menunjukkan bahwa metode presipitasi menggunakan larutan Na2S dapat menurunkan kadar Hg pada limbah sintetik HgCl2. Massa endapan HgS optimum sebesar 0,046 g larutan dicapai pada pH 9 dengan persentase efisiensi penyisihan hingga 99,81 %. Laju pembentukan endapan HgS diperoleh sebesar 0,4 mg/jam. Sedangkan metode presipitasi hidroksida dapat menurunkan kadar merkuri hingga 90,11% pada pH 12 dengan massa endapan Hg(OH)2 yang diperoleh adalah 0,28 g. Akan tetapi hasil analisis EDX endapan Hg(OH)2 memperlihatkan bahwa kandungan Hg dalam endapan tersebut masih sangat kecil yaitu sebesar 0,28%.


Keywords


mercury; pH; precipitation; natrium sulphide; calcium hydroxide

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DOI: https://doi.org/10.22146/jrekpros.34496

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