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Nelius Harefa
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Agriculture, Biological Sciences & Forestry Chemistry Education Mathematics Physics

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Journal : Edumatsains

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Sensitivitas Ligan Ditizon terhadap Absorbsi Logam Zink dengan Teknik Emulsi Membran Cair Nelius Harefa
EduMatSains : Jurnal Pendidikan, Matematika dan Sains Vol 3 No 1 (2018): Juli
Publisher : Fakultas Keguruan dan Ilmu Pendidikan, Universitas Kristen Indonesia

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Abstract

Contamination by zink metal can cause death in humans, animals, and plants. one of the uniqueness of this metal is that it can accumulate. consuming it at a low concentration does not cause death but if it happens continuously it will accumulate into high concentrate which can cause death. Ligand ditizon is one of the ligands which can absorb zink metal at low concentration, to be more efficient then used the liquid membrane emulsion technique which enables separation without going through the process of precipitation. Variations of concentration used is 1:3 v/v, 1:1 v/v and 3:1 v/v. Optimum absorption occurs at concentrations 1:3 v/v are 90.77%. Variations of liquid membrane emulsion duration used is 5 minute, 10 minute and 15 minute. Optimum absorption at duration 5 minute are 50.22%. Optimum absorption on the interaction between concentration and liquid membrane emulsion duration are 43.73% obtained F (392.76) > Ftable (14.80). Keywords: ditizon, absorption, emulsion liquid membrane
Efektivitas Tawas Hasil Olahan Limbah Aluminium Terhadap Penyerapan Logam Alkali Tanah dengan Metode Gravimetri Nelius Harefa; Gayus Sadarman Tafonao; Desy Lisdawaty Sinaga
EduMatSains : Jurnal Pendidikan, Matematika dan Sains Vol 4 No 1 (2019): Juli
Publisher : Fakultas Keguruan dan Ilmu Pendidikan, Universitas Kristen Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33541/edumatsains.v4i1.1045

Abstract

Waste is one of the major problems in Indonesia. Waste continues to increase every year. The two major contributors of waste are plastic and metal processed waste. The two kinds of waste are undegradable. Therefore, the most appropriate solution in handling these kinds of waste is to recycling or converting. One of the efforts that can be made to waste aluminum is beverage packaging, namely by turning it into alum. Alum is commonly used as a water purifier, especially water containing calcium and magnesium metals which are often called hard water. The method used is gravimetric methods. Based on research data, alum can absorb calcium metal with an effectiveness level of 42.25% and magnesium metal with an effectiveness level of 64.12%. Keywords: alum, calcium metal, magnesium metal, gravimetric methods
Pengaruh Kandungan Oksigen Udara Sekolah Terhadap Konsentrasi Belajar Siswa Leony Sanga Lamsari Purba; Nelius Harefa
EduMatSains : Jurnal Pendidikan, Matematika dan Sains Vol 4 No 2 (2020): Januari
Publisher : Fakultas Keguruan dan Ilmu Pendidikan, Universitas Kristen Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33541/edumatsains.v4i2.1381

Abstract

Oxygen content in the surrounding air affects the oxygen intake of the human brain. In learning, the adequacy of brain oxygen affects students' readiness to begin learning, which can be observed through the concentration of student learning. Through this research, information on the effect of school air oxygen content on student concentration will be obtained. The study population was East Jakarta State High School, with a sample of SMA Negeri 9 Jakarta, SMA Negeri 91 Jakarta, SMA 61 Jakarta, SMA 71 Jakarta, SMA Negeri 14 Jakarta. The sampling technique is Purpose Sampling. To obtain information about the oxygen content of school air, measurements were carried out using a Disolved Oxsigen Meter (DO Meter) with an average result of 25.98 school air oxygen levels. validated. Data analysis was performed using exlel. The average concentration of student learning is 1.85 from a scale of 4. The results of hypothesis testing using SPSS 24 obtained tcount of 83.754> ttable of 2.776, with a significance level <0.05 ie 0.00. Furthermore, the results of the linear regression correlation test obtained r = 0.948, air oxygen levels around the school with the concentration of student learning at a sig level of 0.14 (sig 0.05). Both of the results of this analysis indicate that this shows that there is an influence of the oxygen content of the school air on the concentration of student learning with a positive correlation. Keywords : Air, Oxygen, Brain, Concentration, Learning
Co-Authors Desy Lisdawaty Sinaga Gayus Sadarman Tafonao Leony Sanga Lamsari Purba