Low efficiency of conventional fertilizer (quick release fertilizer) application in agricultural sectors has caused environmental pollution and health problems. A method to overcome the drawback of the conventional fertilizer is by controlled release fertilizer (CRF) preparation. CRF is expected to be able to fulfil the nutrient demand of targeted plants. The objective of this research is to prepare CRF by coating NPK fertilizer with multilayer chitosan-polyanion using alginate, pectin, and sodium tripolyphosphate (TPP). In addition, the effect of the layer arrangement modification of material on the rate of nitrogen release was also studied. The mechanical strength of coated fertilizer was analysed by compressive stress test and the properties of the fertilizer coating was observed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The nitrogen release study shows that multilayer of chitosan-alginate (CA)5, chitosan-pectin (CP)5, and chitosan-TPP (CT)5 as coating material was able to increase the compressive stress and decrease the nitrogen release of coated fertilizer. These results are supported by the FTIR analysis which exhibits the formation of ionic interaction between amine group of chitosan and carboxyl group of alginate in chitosan-alginate (CA)5 layer, carboxyl group of pectin in chitosan-pectin (CP)5 layer, and phosphate of TPP in chitosan-TPP (CT)5 layer. On the other hand, the modification of the arrangement of chitosan-alginate layers showed that the fertilizer with the alternating layer arrangement (CA)5 was able to optimally increase the compressive strength. The mathematical model for the nitrogen release of coated fertilizer is also prepared and simulated with the MATLAB software. The simulation results showed that the nitrogen release of coated fertilizer followed the proposed diffusion mechanism. The obtained diffusivity coefficient value in the layer of chitosan-alginate (CA)5 is 2.0933 × 10−6 cm2/s, 2.5606 × 10−6 cm2/s in chitosan-TPP (CT)5 layer, and 3.7256 × 10−6 cm2/s in chitosan-pectin (CP)5 layer.
Methylene blue merupakan zat warna organik yang banyak digunakan pada industri tekstil, memiliki sifat mudah larut dalam air dan berbahaya bagi kesehatan manusia. Pada penelitian ini, adsorbsi zat warna metilen blue dilakukan dengan menggunakan adsorben karbon aktif dari tongkol jagung yang terimpregnasi Fe2O3. Proses adsorbsi dijalankan pada sebuah reaktor batch selama 120 menit dengan menggunakan adsorben KAJ/Fe2O3 sebanyak 0,025 gram dan kecepatan pengadukan 150 rpm. Tujuan penelitian ini adalah untuk mempelajari pengaruh suhu (30 0C, 40 0C, 50 0C) serta variasi penambahan reagen fenton H2O2 dan tanpa penambahan H2O2 pada proses adsorbsi zat warna metilen blue. Hasil penelitian diperoleh bahwa penambahan reagen fenton (H2O2) dapat meningkatkan kapasitas adsorbsi sebesar 25,98%. Suhu optimum proses adsorbsi terjadi pada suhu 30 0C dengan kapasitas penjerapan rata-rata sebesar 71,93%. Model kesetimbangan adsorbsi yang sesuai pada penelitian ini ada isotherm Langmuir dengan nilai konstanta Langmuir (b) dan kapasitas penjerapan maksimum (qm) yang diperoleh masing-masing sebesar 0,49 dan 15,38 mg/L.
Expansion of the size of the weight of bioplastics often occurs in daily use. This phenomenon happens because the material from bioplastics can absorb significant amounts of water. This process can lead to accumulation of swelling degree. Therefore, a mathematical model is needed to quantify this mechanism to predict the dynamics of changes in the weight of bioplastics with respet to time while contact with water to help practitioners during application design for the use of bioplastics. This study aims to build a mathematical model derived from the mass sense validated by experimental data through curve fitting. The experiment was conducted by observing the rate of change in the mass of bioplastic made from starch and chitosan by measuring the change in mass concerning time immersed in water under atmospheric conditions. The immersion time was varied between 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40,50, and 60 minutes. As a result, it can be concluded that starch-chitosan-based biofilms can absorb water up to ±10.9174 gr-water/gr-bioplastic, and also this phenomenon can be quantified by a mathematical equation that derived from mass balance with an average percent error of 1.13% and R-squared coefficient of 0.9981.
Metilen biru (MB) merupakan salah satu pewarna sintetis yang sering digunakan pada industri tekstil dan senyawa ini mempunyai gugus benzene sehingga sulit terdegradasi secara alami. Penelitian ini bertujuan untuk mempelajari pengaruh penambahan aktivator kalium hidroksida dan suhu (30, 40 dan 50°C) terhadap proses adsorbsi zat warna metilen biru menggunakan adsorben karbon aktif dari limbah bunga jantan kelapa sawit paska anthesis (BJKSPA). Hasil penelitian menunjukkan bahwa penambahan aktivator KOH dapat meningkatkan kapasitas penjerapan metilen biru sebesar 25,64%. Suhu optimum yang sesuai untuk proses adsorbsi metilen biru dengan karbon aktif limbah BJKSPA yang terkativasi KOH pada suhu 30 0C dengan kapasitas penjerapan sebesar 58,4793% . Mekanisme kesetimbangan adsorpsi dipelajari dengan menggunakan dua jenis isoterm, yaitu isoterm Langmuir dan Freundlich. Fenomena adsorpsi metilen biru dengan karbon aktif limbah bunga jantan kelapa sawit paska anthesis yang teraktivasi kalium hidroksida sesuai dengan jenis isotherm Freundlich adsorpsi yang memiliki nilai koefisien korelasinya (R 2 ) sebesar 0,9557.
Salah satu upaya untuk mengatasi penggunaan plastik yang tidak dapat terurai di alam adalah dengan bioplastik yang terbuat dari biodegradable film. Pada penelitian ini dilakukan karakterisasi biodegradable film berbahan dasar pati garut yang dibuat dengan metode casting. Gliserol ditambahkan sebagai plastisicizer dan asam sitrat sebagai crosslinker. Dari hasil penelitian yang telah dilakukan menunjukkan bahwa biodegradable film yang dihasilkan memiliki warna putih bening dimana semakin banyak pati maka warna akan semakin keruh. Hasil uji kuat tarik pun menunjukkan bahwa semakin banyak pati yang digunakan maka kuat tarik dari biodegradable film akan semakin kuat namun % elongation at breaknya akan semakin kecil atau sifat nya menjadi kurang elastis. Sebaliknya, penambahan asam sitrat menunjukkan bahwa kuat tariknya menjadi semakin lemah yang dikarenakan adanya hidrolisis ikatan glikosida pada pati. Kata Kunci: pati; garut; gliserol; asam sitrat; biodegradable film; bioplastik ABSTRACT: The biodegradable film is an attempt to reduce the use of plastics that cannot be decomposed by nature. This study described biodegradable films produced from arrowroot starch using the casting method. As a plasticizer and crosslinker, glycerol and citric acid are added. The investigation results indicate that the biodegradable film has a clear white color; the greater the amount of starch, the more opaque the color. The tensile strength test results also indicate that the biodegradable film's tensile strength will be greater the more starch is used, but its percent elongation at break will decrease, or its characteristics will become less elastic. In contrast, adding citric acid demonstrates that the tensile strength decreases due to the hydrolysis of glycosidic linkages in starch.
The application of conventional fertilizer, especially for inorganic fertilizer, has low efficiency due to the fast release of its nutrients into the environment. Also, it has a high operating cost caused by multiple fertilization processes in one of the planting periods. One of the possibilities to overcome this limitation is applying organic fertilizer as a slow-release fertilizer (SRF). The objective of this research is to prepare SRF by modifying the formulation of local organic fertilizer with chitosan as a binder. The rate of the nitrogen release was studied and simulated with MATLAB. The result shows that the nitrogen loss by water leaching decreased up to 85% in chitosan/organic fertilizer rather than the fertilizer without chitosan. By MATLAB simulation, the release of nitrogen has followed the proposed mathematical model in which the mass transfer occurred dominated by diffusion mechanism with the diffusivity coefficient of 1.61x10-5 cm2/s.Keywords: chitosan; organic fertilizer; slow-release fertilizer A B S T R A KPenggunaan pupuk anorganik masih memiliki efisiensi rendah yang disebabkan oleh cepatnya pelepasan nutrisi pupuk ke lingkungan sehingga nutrisi tersebut tidak dapat terserap baik oleh tanaman. Selain itu, aplikasi pupuk anorganik yang berulang dalam satu periode tanam berdampak pada peningkatan biaya operasional. Salah satu metode untuk mengatasi permasalahan tersebut adalah dengan menggunakan pupuk lepas lambat (slow-release fertilizer) atau dengan menggunakan pupuk organik. Tujuan pada penelitian ini adalah dengan mengombinasikan dua metode tersebut yaitu dengan memodifikasi formulasi dari pupuk organik lokal dengan penambahan kitosan sehingga dapat diperoleh pupuk organik yang memiliki sifat lepas lambat. Laju pelepasan nitrogen dari pupuk yang dihasilkan kemudian dianalisis dan disimulasikan dengan software MATLAB. Hasil penelitian menunjukkan bahwa nitrogen yang hilang pada komposit pupuk organik-kitosan melalui water leaching menurun hingga 85% jika dibandingkan dengan komposit pupuk organik tanpa kitosan. Hasil simulasi MATLAB juga menunjukkan bahwa laju pelepasan nitrogen pada pupuk mengikuti model matematika yang diusulkan yaitu dengan mekanisme difusi, nilai koefisien difusivitas yang diperoleh adalah sebesar 1,61×10-5 cm2/s.Kata kunci: kitosan; pupuk lepas lambat; pupuk organik
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