Cadmium is one of the most hazardous metals in the environment, even when present at very low concentrations. This study reports the systematic development of Kenaf fiber biochar as an adsorbent for the removal of cadmium (Cd) (II) ions from water. The adsorbent development was aided by an optimization tool. Activated biochar was prepared using the physicochemical activation method, consisting of pre-impregnation with NaOH and nitrogen (N2) pyrolysis. The influence of the preparation parameters—namely, chemical impregnation (NaOH: KF), pyrolysis temperature, and pyrolysis time on biochar yield, removal rate, and the adsorption capacity of Cd (II) ions—was investigated. From the experimental data, some quadratic correlation models were developed according to the central composite design. All models demonstrated a good fit with the experimental data. The experimental results revealed that the pyrolysis temperature and heating time were the main factors that affected the yield of biochar and had a positive effect on the Cd (II) ions’ removal rate and adsorption capacity. The impregnation ratio also showed a positive effect on the specific surface area of the biochar, removal rate, and adsorption capacity of cadmium, with a negligible effect on the biochar yield. The optimal biochar-based adsorbent was obtained under the following conditions: 550 °C of pyrolysis temperature, 180 min of heating time, and a 1:1 NaOH impregnation ratio. The optimum adsorbent showed 28.60% biochar yield, 69.82% Cd (II) ions removal, 23.48 mg/g of adsorption capacity, and 160.44 m2/g of biochar-specific area.
This development aims to determine the characteristics and feasibility of the oNature of Science (NOS) oriented module On the Chemical Bonds andMolecular Forms subject material through the 4D stage (Define, design,develop and disseminate). This research and development is carried out up tothe stage of development (development) with adjustments based ondevelopment needs. The module prototype was validated by 2 expertvalidator, 1 practitioner validator and 10 students as limited test respondents.Quantitative data were analyzed by percentage formulas and category.Qualitative data in the form of responses and suggestions are used asconsiderations for revisions. The results of expert validation showed anaverage percentage of 92.67% with very good categories of material experts,83.34% with very good categories from product design experts and 76% withgood categories from teacher practitioners. The average response of studentsto the modul prototype is 85.1% with a very good category. This shows thatthe module that developed is feasible to proceed to a large-scale trial phase.
Development of student understanding of nature of science, conceptual understanding, and scientific literacy on learning must be supported by proper learning process. An offline and online environment on mobile learning oriented with Nature of Science oriented learning can be considered to commit. Mobile-Nature of Science (Mobile-NOS) is suitable model of learning for this purpose. Evaluating the influence of Mobile-NOS model of learning application towards Students' understanding of nature of science, chemistry concept understanding, and scientific literacy on general chemistry learning are focus of this study. This study was carried out by posttest only control group design, in form of quasi experimental. There are 44 sample determined by saturated sampling technique of general chemistry students as population. Sample divided into two group equally, the experimental and control group. Data were collected by understanding nature of science questionnaire, scientific literacy test, and chemistry conceptual understanding test. Data was analyzed by independence sample t test. The result of the study showed that the application mobile-NOS model of learning make students better on understanding of nature of science, conceptual understanding, and scientific literacy
Pembelajaran IPA banyak menyajikan masalah-masalah yang ada dikehidupan sehari-hari misalkan peristiwa pencemaran lingkungan. Setiap orang membutuhkan keterampilan berpikir tingkat tinggi untuk menghadapi setiap masalah dengan baik. Salah satu bentuk keterampilan berpikir tingkat tinggi adalah keterampilan berpikir kritis. Model yang dapat melatih keterampilan berpikir kritis adalah model discovery learning. Tujuan penelitian ini untuk mengetahui pengaruh model discovery learning terhadap keterampilan berpikir kritis siswa SMP pada materi pencemaran lingkungan. Jenis penelitian ini adalah quasi experimental dengan desain Posttest-only Nonequivalent Control Group Design. Populasi penelitian ini adalah semua kelas VII SMPN 4 Praya Tengah Tahun Pelajaran 2014/2015 yang terdiri atas 2 kelas. Sampel diambil dengan tekhnik sampling jenuh sehingga semua populasi dijadikan sampel. Data hasil penelitian dianalisis menggunakan uji-t pada taraf signifikansi 5 % dengan bantuan SPSS 16.0 For Windows. Hasil analisis diperoleh nilai signifikan data keterampilan berpikir kritis sebesar 0,034. Hal ini menunjukkan bahwa ada pengaruh model discovery learning terhadap keterampilan berpikir kritis siswa pada materi pencemaran lingkungan.
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