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In the recent years, LiFePO4 has been widely developed as a cathode for lithium ion batteries because it has high theoretical capacity (170 mAh/g), good stability and is also environmentally friendly. However, the poor electronic conductivity (~10-9 S/cm) and low diffusion coefficient of lithium ion (~10-15-10-14 cm2/s) are limiting its application. Some solutions to overcome this problem are carbon coating and doping metal ions. This study aims to determine the effect of Gd3+ ion doping on the electronic conductivity of LiFePO4/C. The synthesis method was used is carbothermal reduction with Fe2O3, Gd2O3, LiH2PO4 and carbon black reagents. The synthesized LiFe1-xGdxPO4/C was characterized using XRD, SEM-EDS, and four point probes. The results obtained showed that gadolinium ion doping increased the conductivity of LiFePO4/C from 1.8952 x10-6 to 8.69x10-6 Scm-1 using 0.07 mol ion Gd3+.

Monitoring the quality of the river is essentially to know the status of the periodic quality of the river. Good assessment of river water quality should use a combination of physical, chemical and biological parameters. One way that can be done to describe water quality in an area is the primary productivity in the water. Primary productivity is the amount of organic material produced by autotrophic organisms with the help of sunlight. Perifiton as a river microorganism, will provide dissolved oxygen (DO) through photosynthesis to maintain most of the life of the surrounding water, then Periphyton can respond quickly to environmental changes, this is an indicator of changing conditions (Gaiser 2008 and Lakewatch, 2000) in Brown and Wright (2016) Chemical reactions that occur in the aquatic environment also involve interactions between ions and other phases. Some important interactions in the waters are the occurrence of photosynthesis by algae and the exchange of dissolved solids with dissolved gases in water. The same exchange occurs when bacteria degrade organic matter (often in the form of particles) in water. Some important elements move around in aquatic systems as colloidal chemical compounds or are absorbed into soil particles. The equilibrium of physical chemical reactions in waters involves sediment, gas, and water. Sediment is a layer of material or material that covers the bottom of small rivers, lakes, reservoirs, bays, and oceans. Sediments contain fine mixtures and subtle minerals, including clay, silt, and sand, which mix with organic materials. These materials may experience changes in composition from pure mineral ingredients to main organic ingredients. Sediments contain biological ingredients, chemicals, and pollutants in water. Keywords: Primary Productivity; citarum river ; sediment; water test parameter

ABSTRAKKadmium Cd(II) merupakan salah satu logam berat berbahaya yang mencemari lingkungan khususnya di perairan. Bioadsorben merupakan salah satu cara pengolahan limbah cair logam berat. Bioadsorben yang digunakan dalam penelitian ini adalah kulit pisang tanduk (Musa)"horn", sabut kelapa dan ijuk enau untuk dapat mengadsorpsi logam berat kadmium.Kulit pisang tanduk (Musa)"horn" mengandung senyawa pektin sedangkan sabut kelapa dan Ijuk mengandung selulosa dan lignin untuk mengikat unsur logam. Penelitian ini bertujuan untuk mengetahui konsentrasi optimal kulit pisang tanduk (Musa)"horn", sabut kelapa dan ijuk enau dalam mengadsorpsi logam berat Cd(II) dalam limbah cair buatan. Penelitian ini diawali dengan analisa kualitatif dan kuantitatif. Serbuk kulit pisang tanduk sebanyak 1 gram dimasukkan ke dalam 200 mL limbah Cd(II) 5 ppm buatan dengan koagulasi dan flokulasi pada 120 Rpm, 20 Rpm dan 0 Rpm selama 24 jam. Kemudian dilanjutkan penyaringan pada kolom berisi serbuk sabut kelapa dan ijuk enau. Sampel diukur kandungan logam Cd(II) dengan menggunakan alat Spektofotometer Serapan Atom (SSA). Dari hasil penelitian didapat Persentase (%) maksimum kemampuan adsorpsi kulit pisang tanduk (Musa Horn) terhadap logam berat Cd (II) pada limbah cair buatan sebesar 61,63 % dengan ukuran partikel (-60+80) mesh, dan Penurunan kadar Cd(II) pada limbah buatan dengan serbuk kulit pisang tanduk dan penyaringan oleh serbuk sabut kelapa dan ijuk dengan kondisi optimal perbandingan konsentrasi sabut kelapa dan enau ijuk sebesar 2:1 menghasilkan persentase penurunan konsentrasi kadmium Cd(II) sebesar 97,32% dan nilai kekeruhan sebesar 6,54.Kata kunci: SSA, Kadmium, Kulit pisang tanduk, bioadsorben, adsorpsi, sabut kelapa, ijuk enau ABSTRACT Cadmium Cd(II) is one of the hazardous heavy metals in the environment, especially in the waters. Bioadsorben is one of wastewater treatment. The Bioadsorben be used in this study is a tanduk banana's peel (musa)"horn", coconut fiber and enau ijuk fiber . Tanduk banana's peel (musa)"horn" compounds containing pectin while coconut fiber and enau ijuk fiber contain cellulose and lignin to bind the metal element. Studies conducted to obtain the optimal concentration of tanduk banana's peel (musa)"horn", coconut fiber and enau ijuk in adsorbing heavy