scholarly journals Matriks Pengontrol Pelepasan Urea Berbasis Karagenan: Pengaruh Konsentrasi Glutaraldehid

2020 ◽  
Vol 18 (1) ◽  
pp. 17
Author(s):  
Sperisa Distantina ◽  
Mujtahid Kaavessina ◽  
Fadilah Fadilah
Keyword(s):  
Controlled Release ◽  
Mathematic Model ◽  
Urea Concentration ◽  
Urea Solution ◽  
Chemically Modified ◽  
Urea Content ◽  
Urea Release

Abstrak. Pada penelitian ini, matrik hidrogel berbasis karagenan dibuat dan diaplikasikan untuk mengontrol pelepasan urea. Tujuan penelitian ini adalah mempelajari pengaruh konsentrasi glutaraldehid terhadap kecepatan pelepasan urea dan menyusun model kecepatan pelepasan urea. Film karagenan dimodifikasi secara kimiawi menggunakan ikatan silang atau crosslinking dengan glutaraldehid. Larutan karagenan 7 g/100 mL dicetak menjadi lembaran dan kemudian dikeringkan sehingga diperoleh lapisan film. Film direndam dalam larutan glutaraldehid dengan konsentrasi tertentu selama 2 menit dan dilanjutkan dipanaskan pada suhu 110oC selama 20 menit. Film yang dihasilkan dicuci dengan etanol dan dikeringkan. Pengisian urea ke dalam matrik film menggunakan metode difusi. Film kering direndam dalam larutan urea 0,074 g/mL selama satu jam dan selanjutnya dikeringkan. Kecepatan pelepasan urea dari film ke dalam media air dievaluasi berdasarkan data konsentrasi urea dalam cairan sebagai fungsi waktu. Berdasarkan hasil penelitian didapatkan bahwa semakin besar konsentrasi glutaraldehid (1-5%) menyebabkan urea yang tersimpan di dalam film semakin rendah. Model matematika yang diusulkan dapat mewakili peristiwa pelepasan urea dari film. Film berbasis karagenan yang dihasilkan berpotensi sebagai matrik pengontrol pelepasan urea. Kata kunci: crosslinking, glutaraldehid, hidrogel, karagenan, urea. Abstract. Controlled Release Matrices of Urea from Carrageenan: Effect of Glutaraldehyde Concentration. In this study, carrageenan-based hydrogel matrices were prepared and applied for urea controlled release. The aim of this work was to study the effect of glutaraldehyde concentration on the rate of urea release in water. Carrageenan films were chemically modified by crosslinking with glutaraldehyde. The films were prepared by casting the aqueous carrageenan 7 g/100 mL and then followed by drying. The films obtained were immersed in certain glutaraldehyde concentration for 2 min and then heated in the oven at 110oC for 20 min. The crosslinked films were washed using ethanol and then air-dried until the weight is constant. The dried films were immersed in a urea solution (0.074g/ml) for 1 hr and then dried. The rate of urea release was determined by measuring the urea concentration in water as a function of time of release. Results showed that higher glutaraldehyde concentration (1–5%) produced films with less urea content. The proposed mathematic model of urea release from the film can represent the rate of urea release. The prepared carrageenan-based film has the potential for controlling of urea release. Keywords: carrageenan, crosslinking, glutaraldehyde, hydrogel, urea. Graphical Abstract

Improvement of Hydrophobicity of Urea Modified Tapioca Starch Film with Lignin for Slow Release Fertilizer

2012 ◽  
Vol 626 ◽  
pp. 350-354 ◽  
Author(s):  
Sarwono Ariyanti ◽  
Zakaria Man ◽  
Mohammad Azmi Bustam
Keyword(s):  
Fourier Transform ◽  
Water Uptake ◽  
Slow Release ◽  
Fourier Transform Infrared ◽  
High Potential ◽  
Tapioca Starch ◽  
Chemically Modified ◽  
Slow Release Fertilizer ◽  
Urea Release ◽  
Modified Tapioca Starch

Tapioca starch was chemically modified with urea in the presence of borate as crosslinker and catalyst. Fourier transform infrared (FTIR) and viscosity were performed to measure qualitatively the reactivity of the mixture. To improve the hydrophobicity, 10% of lignin (10%L) was then added into the starch-urea-borate (SUB) system. The incorporation of lignin leads to lower water uptake film. It was found that lignin retards the urea release and the SUB10%L film is stable and stayed intact for one month after immersing in water which shows high potential as a biopolymer for slow release fertilizer.

Study on the Changes of Urea Content during Brewing of Chinese Huangjiu

2013 ◽  
Vol 798-799 ◽  
pp. 1075-1080
Author(s):  
Jian Zhou ◽  
Yan Lin ◽  
Jian Gang Yang ◽  
Ying Ying Ma
Keyword(s):  
Growth Curve ◽  
Colorimetric Method ◽  
Urea Concentration ◽  
Stable Phase ◽  
Yeast Growth ◽  
Culture Temperature ◽  
Urea Level ◽  
Urea Content

The two acetyl monoxime colorimetric method was used to detect urea content. The yeast growth curve shows that a large amount of urea in the extracellular is secreted during the growth processing. And in the stable phase (cultured for 51 hours), urea concentration is up to 38.642 mg / L, but intracellular urea concentration (cultured for 27 hours) is only 6.043 mg / L. At same time, the extracellular urea amount secreted in the medium at initial pH3-4 is less than it at initial pH5 treatment. The urea secretion level is lower when yeast cultured in the medium with 12% of alcohol. The extracellular urea level decrease when the culture temperature increased from 28°C to 32°C.

Controlled-Release Material for Urea Fertilizer from Polylactic Acid

2008 ◽  
Vol 55-57 ◽  
pp. 897-900 ◽  
Author(s):  
J. Papangkorn ◽  
C. Isaraphan ◽  
S. Phinhongthong ◽  
Mantana Opaprakasit ◽  
Pakorn Opaprakasit
Keyword(s):  
Controlled Release ◽  
Polylactic Acid ◽  
Urea Fertilizer ◽  
Technique Effect ◽  
Preparation Conditions ◽  
Micron Size ◽  
Coated Urea ◽  
Urea Release ◽  
Uv Visible ◽  
Controlled Release System

Urea fertilizer is a major source of nitrogen, which is one of the essential nutrients for plant growth. Due to its uncontrollable release, this chemical can be wasted easily by leaching and volatilization that can adversely cause the contamination to the environment. In this work, a controlled-release material for urea fertilizer has been prepared by using degradable polylactic acid. Unlike other conventional controlled-release system, the resulting material is able to provide an efficient supply of urea fertilizer, without causing further contamination to the environment from residue material, as polylactic acid can be degraded in the environment. Micron-size particles of polylactic acid coated urea were prepared by employing atomizing technique. Effect of the preparation conditions; urea/PLA composition, PLA concentration, and pressure of atomizing gun on the particle size of material are investigated. The urea release rate of these samples is then studied by employing UV-Visible spectrophotometer. In addition, the effect of preparation conditions on shape and morphology of sample is determined by using Scanning Electron Microscope (SEM).

The Role of the Colon in Urea Metabolism in Man

1976 ◽  
Vol 50 (1) ◽  
pp. 51-59 ◽  
Author(s):  
J. A. Gibson ◽  
N. J. Park ◽  
G. E. Sladen ◽  
A. M. Dawson
Keyword(s):  
Dietary Protein ◽  
Colonic Mucosa ◽  
Normal Subjects ◽  
Urea Concentration ◽  
Low Protein ◽  
Urea Content ◽  
Colonic Lumen ◽  
Urea Metabolism ◽  
Protein Diets

1. The urea content of ileostomy effluent has been measured by the urease method as an indirect estimate of the urea concentration in the lumen of the normal ileum. 2. The plasma disappearance of intravenously administered [14C]urea was used to study intestinal urea breakdown. Normal subjects on high and low protein diets and patients with either excised (i.e. with ileostomies) or excluded colons were studied. 3. The 24 h intestinal urea breakdown was considerably greater than the quantity of urea estimated to be entering the colon from the ileum and across the colonic mucosa. 4. Intestinal urea breakdown increased with increase in dietary protein and decreased with, but was not abolished by, exclusion or excision of the colon. 5. Our results suggest that the colonic lumen is not the only site of intestinal ureolysis and that significant quantities of urea must be broken down either at a juxtamucosal site or in the ileum.

scholarly journals PCL/PHBV Microparticles as Innovative Carriers for Oral Controlled Release of Manidipine Dihydrochloride

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Fernanda Malaquias Barboza ◽  
Willian Moreira Machado ◽  
Luiz Renato Olchanheski Junior ◽  
Josiane Padilha de Paula ◽  
Sônia Faria Zawadzki ◽  
...  
Keyword(s):  
Controlled Release ◽  
Animal Studies ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Chemically Modified ◽  
Diffraction Patterns

Microparticles of poly(ε-caprolactone) (PCL) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) containing manidipine dihydrochloride (MAN) were successfully prepared by the simple emulsion/solvent evaporation method. All formulations showed loading efficiency rates greater than 80% and average particle size less than 8 μm. Formulations had spherical shape with smooth and porous surface for PCL and PHBV, respectively. According to Fourier-transform infrared spectroscopy, initial components were not chemically modified during microencapsulation. X-ray diffraction patterns and differential scanning calorimetry demonstrated that this process led to drug amorphization.In vitrodissolution studies showed that all microparticles prolonged MAN release, mainly which one obtained using PCL that contained 5% of drug loaded (PCL-M5). Animal studies demonstrated that formulationPCL-M5was able to keep the variation of mean arterial pressure after phenylephrine administration up to 24 hours. These data confirmed the sustained antihypertensive effect of the investigated microparticles. Results provided an experimental basis for using formulationPCL-M5as a feasible carrier for oral controlled release of MAN intended for treating high blood pressure.

scholarly journals Smart-Urea-Controlled-Release-Nitrogen-Fertilizer Menggunakan Plastik Biodegradable Poli Asam Laktat Sebagai Carrier

2017 ◽  
Vol 1 (2) ◽  
Author(s):  
Mujtahid Kaavessina ◽  
Chitra Husnabilqis ◽  
Meylani Tri Hardiyanti
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Controlled Release ◽  
Nitrogen Fertilizer ◽  
Average Molecular Weight ◽  
Urea Concentration ◽  
Poly Lactic Acid ◽  
Heating Process ◽  
Toxic Substances ◽  
The Matrix

<p>Poly lactic acid is a polymer that has been developed as an alternative to substitution of conventional polymers. The properties of this polymer are biodegradable in nature and non-toxic substances. These polymers potentially can be used as a matrix for urea carries. The aim of this research was to synthesize poly lactic acid in a low molecular weight. This product can be used as a matrix that urea release controller during the process of fertilization. The methodology consisted of two stages. The first stage was polycondensation of lactic acid and degradability test. Lactic acid was mixed with SnCl2 catalyst 0.1% and heated to 138oC for 24 hours. The second stage was producing in the form of Smart Urea Controlled Release Nitrogen Fertilizer (CRNF). Urea was dissolved in poly lactic acid through a heating process at 150°C to dissolve urea with variation in urea concentration weight of  0.5%; 0.1%; 0.15%; 0.2%; 0.25%; 0.3% and CRNF granulation processes. Finally, the mixture was granulated in ambient temperature. Chemical analysis was done the molecular weight of poly lactic acid. The relationship between intrinsic viscosity  and  molecular  weight  was  used.  The  IR  spectra  (FTIR)  was  used  to  fine molecular structure. The release testing of urea from the matrix of poly lactic acid uses UV-VIS Spectrophotometer. The results showed that the average molecular weight of poly lactic acid is 1149.49 g /gmol. FTIR spectra of CRNF with variation in urea concentration weight showed the presence of groups owned by poly lactic acid and urea. The peaks are</p><p>1627.03 to 1629.92 cm-1 for the -NH group and 3478.77 to 3498.06 cm-1 for group -OH. The existence of these groups proves the existence of urea in CRNF. The release of urea from poly lactic acid occurs by diffusion. It can be seen, when urea in CRNF form immersed in water, the concentration of urea in water increase as well as the increasing immersed time.</p>

Corrosion behavior of 15CrMo steel for water-wall tubes in thermal power plants in the presence of urea and its byproducts

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Zhiping Zhu ◽  
Xianzhi Song ◽  
Youwei Song ◽  
Pan Zhou ◽  
Mingpeng He
Keyword(s):  
Corrosion Behavior ◽  
Power Plants ◽  
Thermal Power ◽  
Electrochemical Analysis ◽  
Urea Concentration ◽  
Localized Corrosion ◽  
Urea Solution ◽  
X Ray Diffraction ◽  
Water Wall ◽  
Urea Decomposition

AbstractThe corrosion behavior of 15CrMo used for water-wall tubes was studied in various urea-containing solution to determine the corrosion problem of water-wall tubes caused by urea in a coal-fired power plant. Urea decomposition tests, together with corrosion experiments, were carried out. The temperature was 320 °C, and the concentrations of urea were 70, 140, 280, 560 and 840 mg/L. Weight loss experiments and surface analysis indicated that the corrosion of 15CrMo steel is mainly manifested as localized corrosion. The corrosion rate of 15CrMo steel increased with the increase of urea concentration, and the maximum value reached 0.686 mm/y (mm per year) when the urea concentration was 840 mg/L. Electrochemical analysis suggested that the corrosion rates of 15CrMo were enhanced substantially by urea decomposition products. The results of UPLC-ESI-MS, infrared spectroscopy and X-ray diffraction showed that urea solution produced corrosive ions NH2COO− during the decomposition process, which caused the corrosion of 15CrMo. Results provided evidence as relevant explanation for the corrosion behavior of 15CrMo in urea solution.

Preparation of Starch/PS-g-MAH Blends and Effect on Controlled Release of Herbicide

2011 ◽  
Vol 415-417 ◽  
pp. 1231-1234
Author(s):  
Li Min Tai
Keyword(s):  
Electron Microscope ◽  
Composite Materials ◽  
Controlled Release ◽  
Ph Value ◽  
Basic Medium ◽  
Neutral Medium ◽  
Chemically Modified ◽  
Single Screw ◽  
Impact Of Pesticides ◽  
Scanning Electron

PS was chemically modified by grafting with maleic anhydride to obtain PS-g-MAH on a single-screw extrude. The blending of starch and PS-g-MAH was carried out to prepare the degradable composite materials by melt extrusion on the extruder. The fractured surfaces of the blends were observed and discussed with the different incorporation of starch by a scanning electron microscope (SEM). The results exhibited that MAH improved the component compatibility of the blends. Then the starch/PS-g-MAH blends were used as the carrier for preparing bensulfuron-methyl CRFs. The bensulfuron-methyl CRFs’ release performance was investigated in the different pH value media by UV analysis. It was shown that the starch/PS-g-MAH matrix has obvious controlled-release function, and the release rate in a basic medium is much higher than in an acidic or neutral medium. The bensulfuron-methyl CRFs should have the longer validity in acidic soil, and have an important potential in reducing inefficient use and impact of pesticides in the environment.

The eff ect of selected factors on urea concentration in the milk of Polish Holstein-Friesian cows

2016 ◽  
Vol 12 (3) ◽  
pp. 21-32
Author(s):  
Alicja Satoła ◽  
Ewa Ptak
Keyword(s):  
Milk Yield ◽  
Mixed Linear Model ◽  
Urea Concentration ◽  
Protein Percentage ◽  
Stage Of Lactation ◽  
Urea Content ◽  
Holstein Friesian ◽  
Milk Urea ◽  
Percentage Data ◽  
Friesian Cows

The objective of the study was to determine the relationships between milk urea concentration and factors such as lactation number, stage of lactation, month and season of the test day, age at calving, milk yield and protein percentage. Data for the calculations consisted of 7,731 test-day records from 1,078 Polish Holstein-Friesian cows. Test-day milking was performed for first, second and third lactations during the period from December 2010 to December 2011. Calculations were performed using the MIXED procedure in SAS/STAT. A mixed linear model using was applied in which parameters were estimated by the restricted maximum likelihood (REML) method. Least squares means for fixed eff ects in the model were compared by the Tukey-Kramer test. The first lactation diff ered significantly (p<0.05) from the second and third in terms of mean urea concentration, but there were no significant diff erences between the second and third lactations. For primiparous cows the milk urea concentration increased throughout lactation, but for older cows it increased only up to 7–8 months of lactation. Urea concentrations did not diff er significantly in the same stages of consecutive lactations, i.e. the first and second or second and third. Statistically significant diff erences were noted between the first and third lactations only in months 9 and 10 of lactation. Seasonal changes in milk urea content varied depending on the lactation number. In the first lactation the milk urea concentration was lowest in spring and highest in autumn. This tendency was not observed in the second and third lactation. Milk urea concentration was positively associated with both milk yield and protein percentage

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