Green synthesis of silver nanoparticles using Calotropis gigantea and its characterization using UV-Vis Spectroscopy

The use of Calotropis gigantea from Ie Seu-Um, Aceh Besar geothermal area for silver nanoparticles (AgNPs) synthesized has been reported. The process of synthesis AgNPs can be carried out with chemical methods, physical methods, and green synthesis methods, but in this study, the process is focused on the green synthesis method using C. gigantea flowers and leaves extract from Ie Seu-Um geothermal area, Aceh Besar. Phytochemical analysis showed that C. gigantea leaves contain alkaloids, steroids, tannins, phenolics, and saponins, while the flowers of C. gigantea contain alkaloids, terpenoids, steroids, flavonoids, tannins, phenolics, and saponins. The reaction of the AgNPs formation was observed by colour change formed. AgNPs-C. gigantea flower extract dan AgNPs-C. gigantea leaves extract showed the reddish-brown and brownish-yellow solution respectively after 48 h incubation in dark condition at room temperature. The result of the reaction characterized using UV-Vis Spectrophotometry showed that the phenomenon of Surface plasmone resonance (SPR) occurs in the mixture of nanoparticles formed. The concentration of AgNO3 as a reagent affected the SPR phenomenon. The result showed that particles formed are the same size and shape.

Dyeing mechanism and photodegradation kinetics of gardenia yellow natural colorant

In this study, gardenia yellow solution is used to dye 100% cotton fabric. The dyeing rate curve and adsorption isotherms were recorded to explore the thermodynamic model and to calculate the corresponding parameters. A definite concentration of gardenia yellow solution was placed under the xenon arc lamp for irradiation to test its photodegradability. Absorbance of the solution was measured at different degradation times and the corresponding varying curve of the absorbance was drawn to explore the photodegradation reaction order of the natural colorant and consistent parameters were calculated. The experimental results proved that the dyeing of cotton fabric with gardenia yellow colorant followed the pseudo second order kinetic model whereas adsorption isotherm followed the Langmuir model and the photodegradation process followed the second order kinetic model. Values of different parameters were calculated: reaction rate constant k = 2.26 × 10–3 (mg · L−1)1−m h−1, the correlation coefficient R2 = 0.994, and half decay time t1/2 = 5.82 h.

Colorimetric Sensor Based on β-Cyclodextrin-Functionalized Silver Nanoparticles for Zidovudine Sensitive Determination

Zidovudine (ZDV) is an antiviral drug against HIV that was approved by the FDA on March, 1987. It is a reverse transcriptase inhibitor. This type of drug stops the reproduction of DNA and decreases the amount of the virus in the patients’ blood. Due to the ability of forming various molecular bonds, silver nanoparticles (AgNPs) are widely used for the detection of large range of agents, including drugs. In this study, we synthesized AgNP-modified β-cyclodextrin (β-CD) using green synthesis for the sensitive and selective zidovudine (ZDV) determination. Characterization of nanoparticles was done using different methods including infrared (IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and also, X-ray diffraction (XRD) patterns. The AgNP λ-max peak was at approximately 405 nm. In the presence of ZDV, yellow solution was turned to red color, and surface plasmon absorption band was dramatically centered at 560 nm. ZDV was determined in the range of 50–500 μM, and the detection limit value was obtained as 42 μM. The sensor was used to determine ZDV in tablets with good recovery.

A Dual Sensor Probe for the Sequential Detection of Copper(II) and Lactic Acid

<p>Herein, we report<b> </b>a novel fluorescent probe for the sequential detection of Copper II (Cu²⁺) and lactic acid. The probe based on acyl-thiourea derivative, N-((6-methoxypyridin-2-yl)carbamothioyl)benzamide (<b>1</b>) was synthesized, and its application as dual sensor for Cu²⁺ and lactic acid is reported. The dual detection by the probe is possible since <b>1 </b>formed complex with Cu²⁺and yielded yellow solution which disappeared after the addition of lactic acid. The probe exhibits yellow fluorescence with Cu²⁺and LOD of Cu²⁺ with fluorescence is as low as 0.1ppm. The fluorescence is quenched after the addition of lactic acid and LOD of fluorescence quenching by lactate is as low as 1 ppm. Further, structural modification in the probe <b>1</b> suggest crucial role of both pyridine and acyl-thiourea moiety in the binding of Cu²⁺. Interestingly, <b>1</b> also assembles to fluorescent fibers which show tunable emission properties. These fibers are broken in the presence of Cu²⁺ and regenerated in the presence of lactic acid. Hence, disaggregation at molecular level might play a crucial role in causing yellow fluorescence in the presence of Cu²⁺. To, the best of our knowledge, this is the first report wherein a dual sensor for Cu²⁺ and lactate ion is synthesized and it may in all possibilities pave the way for diagnosis of Cu²⁺ associated disorders like Wilson’s disease and in the detection of elevated lactate levels which are associated with wide range of pathologies like mitochondrial diseases, cerebral ischemia and cancer.<b></b></p>

Kinetika Fotodegradasi Remazol Yellow Menggunakan Fotokatalis ZnO dan ZnO-Ag

Telah dilakukan penelitian tentang kinetika fotodegradasi remazol yellow dengan menggunakan ZnO dan ZnO yang disisipi 1%, 3%, 5%, 7%, dan 9% Ag yang disintesis dengan metode kopresipitasi. Eksperimen kinetika dilakukan melalui penentuan konsentrasi remazol yellow yang tersisa setelah interaksi ZnO dan ZnO-Ag dengan larutan remazol yellow yang disinari UV selama 0, 20, 40, 60, 80, 100, 120 dan 140 menit. Selanjutnya data dianalisis mengikuti model kinetika reaksi orde pertama. Hasil penelitian menunjukkan bahwa laju reaksi fotodegradasi oleh ZnO meningkat dengan penambahan konsentrasi dopan AgA research on photodegradation kinetics of remazol yellow using ZnO and Ag-doped ZnO (1, 3, 5, 7 and 9 wt% Ag) synthesized by co-precipitation method had been studied. Kinetics experiment was performed by determining the concentration of remazol yellow remained after interaction of ZnO and ZnO-Ag with remazol yellow solution that were irradiated by UV-light at 0, 20, 40, 60, 80, 100, 120 and 140 minutes. Data obtained was analyzed using firs-order kinetics model. The results showed that photodegradation rate was increased with the increasing Ag concentration.

Kinetika Fotodegradasi Remazol Yellow Menggunakan Zeolit A Terimpregnasi TiO2

Telah dilakukan penelitian tentang kinetika fotodegradasi remazol yellow dengan menggunakan zeolit A terimpregnasi TiO2. Jumlah TiO2 divariasikan dalam perbandingan berat zeolit A : TiO2 sebesar 1:0.4, 1:0.6, 1:0.8, 1:1, 1:1.2, dan 1:1,4 g/g. Eksperimen kinetika dilakukan melalui penentuan konsentrasi remazol yellow yang tersisa setelah interaksi zeolit A : TiO2 dengan larutan remazol yellow yang disinari UV pada waktu 10, 20, 30, 40, 50, 60, dan 90 menit. Selanjutnya data dianalisis mengikuti model kinetika reaksi orde-1. Hasil penelitian menunjukan bahwa semakin tinggi jumlah TiO2 dalam material zeolit A : TiO2 maka semakin kecil laju fotodegradasi. Perbandingan berat 1:0,4 menghasilkan laju fotodegradasi paling besar dengan konstanta laju sebesar 0,0184 menit-1.A research on photodegradation kinetics of remazol yellow using TiO2-impregnated A-type zeolite has been done. The amount of TiO2 was varied in weight ratio of zeolite A : TiO2 which were 1:0.4, 1:0.6, 1:0.8, 1:1, 1:1.2, and 1:1.4 g/g. Kinetics experiment was performed by determining the concentration of remazol yellow remained after the interaction of zeolite A : TiO2 with remazol yellow solution that is illuminated by UV-light at 10, 20, 30, 40, 50, 60 and 90 minutes. Data obtained was analyzed using first-order reaction kinetics model. The results showed that the higher the amount of TiO2 in the mixture of zeolite A : TiO2 material, the smaller the rate of photodegradation. The weight ratio of 1:0.4 produced the greatest rate of photodegradation with rate constant of 0.0184 min­­­­-1.

Development of a Novel and Bi-Functional Quantum Dots as FRET Energy Donor

A novel CdTe/Ni QDs which combined both magnetism and fluorescence was successfully synthesized and its optical properties were investigated. Ni magnetic nanoparticles (MNPs) were synthesized and used as magnetic core, CdTe quantum dots (QDs) were applied as fluorescent shell material, the qualified magnetic CdTe/Ni quantum dots (mQDs) were achieved via layer-by-layer process using 1,6-hexylenediamime as linker, surface charge types of MNPs and mQDs were confirmed with a delsa nano beckman coulter. Morphology of the prepared Ni MNPs and CdTe/Ni mQDs was characterized by transmission electron microscopy (TEM), and optical properties were investigated with fluorescence spectrum (FS). Qualified CdTe/Ni mQDs with high fluorescence and narrow maximum emission peak width were obtained under the optimum conditions. Surface zeta-potential of CdTe QDs and Ni MNPs were estimated to be -36.2 and 27.97mV, respectively. TEM data indicated that ca 20nm of Ni MNPs and ca 25nm of CdTe/Ni mQDs were prepared, respectively; the size-increasing indicated the formation of CdTe shell on the Ni MNPs core. Narrow half peak width of emission peak was detected and calculated to be about 50nm via FS. High fluorescence intensity of CdTe/Ni mQDs was determined and brilliant yellow solution was observed when excited under UV360nm. The synthesized CdTe/Ni mQDs showed excellent magnetic property, and can be magnetically concentrated with a common magnet. The obtained data indicated that the prepared bi-functional CdTe/Ni mQDs possess excellent magnetic and fluorescent properties, and it can be used as a energy donor in DNA sensing based on fluorescence resonance energy transfer (FRET).

MEASUREMENT OF DISSOLVED INORGANIC NUTRIENT IN EUPHOTIC ZONE THE BANTEN BAY

At a few this last years, measurement concentration of dissolved inorganic nutrient is has rapidlyed grow by using various methods. But method anything applied must based on at formation of indicator end of measurement amonia, nitrite, nitrate, orthophosphate and silicate. At measurement of amonia its indicator is formation of blue indophenol, nitrite formation of pink azo, nitrate formation of yellow colored solution, orthophosphate formation of blue molybdenum, and silicate based on formation of yellows silicomolibdate. The intensity of color that is highly dependent on the concentration of each element. Measurement of amonia blue indophenol intensity perfected concentration in the range 0.206-0.396 mg/L. Measurement nitrite the formation of a pink azo easy imperfect because its low concentration. Intensity measurements nitrate solution yellow perfect concentration in the range 0.128-0.989 mg/L. Measurement of imperfect blue molybdenum intensity orthophosphate because its low concentration. While measuring the formation silicate of yellow silicomolibdate perfect concentration on the range 10.573-26.470 mg/L. As a whole from result of measurement is obtained chemical composition of dissolved inorganic nutrient in euphotic zone the Banten bay is more predominated by silicate 97.27%, nitrate 1.84%, amonia 0.49%, orthophosphate 0.20%, and nitrite 0.18%. Keywords: blue indophenol, pink azo, yellow solution, blue molybdenum, yellow silicomolibdate

H2O2-assisted photolysis of reactive dye BES golden yellow simulated wastewater

Reactive dye BES golden yellow simulated wastewater was treated with H2O2-assisted photolysis method. Influences of factors such as reaction time, initial pH and H2O2 dosage were investigated, and the reaction kinetics of the process were explored. Results showed that, the degradation of 200 mg/L BES golden yellow solution happened only in the presence of both conditions: UV irradiation and H2O2 addition. Initial pH and H2O2 dosage had remarkable influence on the removal efficiency of the dye. Through several groups of univariate experiments, the optimum pH and H2O2 dosage of the photolysis process were found to be 6–7 and 0.0375 mL 30% H2O2 per milligram of BES golden yellow, respectively. The photolysis process was approximately in accordance with the second-order kinetic equation.

The Generation of a Carbon Nanotube- Cyclodextrin Complex

ABSTRACTIn this study the intermolecular interactions of small diameter (∼0.7nm) carbon nanotubes and γ-cyclodextrin were examined. Four samples of γ cyclodextrin and HiPco carbon nanotubes were prepared. The first, by grinding the tubes and the cyclodextrin (1:30 ratio) together in a dry mixture, the second was prepared in a similar fashion but was ground in the presence of water (1ml). Finally an aqueous solution of γ-cyclodextrin (0.3M) and HiPco carbon nanotubes (5mg) was prepared by refluxing for ∼100 hours, forming a pale yellow solution from which a number of crystals were produced, both the solution and the recrystallised material were analysed. The samples were analysed using UV-Vis-NIR and Raman spectroscopy. The results presented are the first spectroscopic evidence of an intermolecular interaction between γ-cyclodextrin and single wall nanotubes.