Graduate school

A novel modified glassy carbon electrode with platinum (Pt)-electrodecorated and nitrogen-containing functional groups was prepared by stepwise electrolysis. The prepared electrode exhibited electrocatalytic activity towards sulfite oxidation that was better than that of a bare glassy carbon electrode. The electrocatalytic activity of sulfite oxidation has been applied to an amperometric sulfite sensor. A favorable linear relationship between the current response (ΔI) and the sulfite concentration up to 500 μM was exhibited. The detection limit was estimated to be 3 μM based on the criterion of a signal-to-noise (S/N) ratio of 3 under optimized conditions. In regards to the reproducibility, the RSD (n = 10) was 8.9% for 80 μM sulfite.

Electrodeposltlon of Pt micropartlcles at microgram levels In three types of M y (4-vlnylpyrldine) (PVP) films on glassy carbon (gc) electrodes Is described. The PVP films were formed by (1) electrochemical polymerization, (2) spln-coaUng linear PVP on the gc surface, and (3) crob&linWng the

In this study, we report the development of an absolute determination method based on potential-controlled coulometric analysis using carbon-felt-electrode-introduced nitrogencontaining functional groups fabricated by the electrode oxidation of ammonium carbamate solution for measuring nitrite. The potential-controlled coulometric cell was constructed by using a working electrode consisting of a carbon felt electrode that was electro-oxidized at +1.1 V (vs Ag/AgCl) in 0.1 M ammonium carbamate solution. When the applied potential of the sensor cell was +0.75 V, the oxidized current of nitrite was immediately observed by adding 10 µL of 1 mM nitrite. In addition, the electron number of the electrode reaction was two electron paths from the estimation of the electrical charge of nitrite detection. This finding indicates that the proposed determination method resulted in the absolute quantity analysis of nitrite. The current vs time curves indicate that the determination of nitrite was finished completely in a relatively short time (~30 s). The relative standard deviation (RSD) for ten successive measurements of 1 mM nitrite was 2.2%. This indicates that our coulometric method can be used for the absolute determination of the nitrite concentration in practical applications.

This study reports a novel electrochemical sensing technique based on electro-deposited Pt particles on glassy carbon electrodes modified with nitrogen atoms containing functional groups (PtNF-GC) electrode for detecting sulfite in aqueous solution. PtNF-GC electrodes have a favorable electrocatalytic activity of sulfite oxidation, which moves the oxidation peak potential to the negative direction of potential unlike Pt disk, a bare glassy carbon electrode and electro-deposited Pt particles on glassy carbon (Pt-GC) electrode. The linear relationship between the oxidation current peak and sulfite concentration is over the range up to 10 mM with a detection limit of 100 µM. Our prepared PtNF-GC electrode was applied for the sulfite detection in sample solution with favorite recovery of sulfite. Additionally, a possible reaction mechanism of sulfite was discussed.

Voltammetric properties of chlorine dioxide (ClO 2) obtained by using a glassy carbon (GC) electrode fabricated by electrolyzing in ammonium carbamate aqueous solution were first reported. GC electrode surface was covalently modified with nitrogen atoms containing functional groups, which were introduced onto GC surfaces by electrochemical oxidation process in ammonium carbamate aqueous solution. The introduction of nitrogen into the GC surface structure enhanced the electrocatalytic activities of GC electrode towards the electro-oxidation of ClO 2 in an acidic medium more than a bare GC electrode does. A favorable linearity for the peak current signals in cyclic voltammograms was exhibited in the concentration range from 2.0 to 100 ppm.

Hairy fruit (Nephelium sp) is fruit of horticultural belong in family Sapindacaeae. Membrane is a thin layer separates two phases which allow the displacement of specific components and hold other components that do not being needed. Ultrafiltration is a filtration process using membranes that filter out particles with a size of 20 to 1000 Angstrom. Results of ultrafiltration has high purity (0.4 to 0.6 NTU turbidity) than results from conventional manner (1.5-3 NTU turbidity). Yield gained was 5-8% higher than that gained from conventional. Dependent variable used is kind of hairy fruits (crops and cans). The independent variable is the pressure 2 kg/cm 2 , 3 kg/cm 2 , 0.4 kg/cm 2 , 0.5 kg/cm 2 , 0.6 kg/cm 2 and the type of membrane (PES and hydrosart). The result of the study showed that greater operation pressure resulted in greater turbidity, and greater flux. The greater flux resulted smaller selectivity and pass the requirement of Environmental Protection Agency, USA. Key word...

Hairy fruit (Nephelium sp) is fruit of horticultural belong in family Sapindacaeae. Membrane is a thin layer separates two phases which allow the displacement of specific components and hold other components that do not being needed. Ultrafiltration is a filtration process using membranes that filter out particles with a size of 20 to 1000 Angstrom. Results of ultrafiltration has high purity (0.4 to 0.6 NTU turbidity) than results from conventional manner (1.5-3 NTU turbidity). Yield gained was 5-8% higher than that gained from conventional. Dependent variable used is kind of hairy fruits (crops and cans). The independent variable is the pressure 2 kg/cm 2 , 3 kg/cm 2 , 0.4 kg/cm 2 , 0.5 kg/cm 2 , 0.6 kg/cm 2 and the type of membrane (PES and hydrosart). The result of the study showed that greater operation pressure resulted in greater turbidity, and greater flux. The greater flux resulted smaller selectivity and pass the requirement of Environmental Protection Agency, USA. Key word...

Nowadays, the lack of renewable energy such as hydrogen, and other environmental issues are problems that must be resolved. 2,4,6-Trichlorophenol (2,4,6-TCP) is classified as a recalcitrant pollutant due to its carcinogenic properties, high toxicity, and dangers to the environment therefore it needs to be eliminated. Hydrogen production using organic pollutant (2,4,6-TCP solution) as a hole scavenger on CdS-TiO2 nanotube arrays photocatalyst (TNTA-CdS) has been investigated at various CdS loading on TNTA and the initial concentration of 2,4,6-TCP. The TNTA sample was prepared by anodization and followed by an electrodeposition method to decorate CdS on TNTA. The H2 which was generated by reduction H+ and the 2,4,6-TCP removal was performed simultaneously by photocatalysis with TNTA-CdS as photocatalyst. The mole ratio of CdCl2:CH3CSNH2 as precursors of CdS deposited on TNTA (CdS loading) were 0.1:0.06, 0.2:0.12, and 0.4:0.24 and the initial concentration of 2,4,6-TCP were 10, 20 and...

Food industry is one of the most crucial and rapidly growing economic sectors in Indonesia. One of the examples is the food jam industry. This industry was located in Tangerang, Indonesia. The majority of the food jam industry uses its own source of water, so this part is also important to water producers in Indonesia. Water used in the food jam industry should meet the requirements of at least drinking water quality, so the factories need to treat the water. Good quality water is water that requires good physical, chemical, and bacteriology properties. Hard water is a term known for water that contains a high concentration of minerals such as Calcium (Ca) and Mag-nesium (Mg). Moreover, water with very high degrees of hardness is harmful to health. In this study, we want to evaluate and determine the pH, total hardness, and total dissolved solids (TDS) at three different times namely morning, midday, and afternoon. The results obtained in the range of pH analysis are 6.98 to 7.99 wi...

Durian peel waste (Durio zibethinus Murray) is not effectively exploited and even left to become rubbish, which pollutes the environment. The cellulose from durian peel can be used to generate absorbent activated carbon. This study improves the durian peel adsorbent for the purification of used cooking oil. Carbon activation expands the pores of activated carbon, increasing its surface area and adsorption capacities for purifying spent cooking oil. The best conditions for producing adsorbents from durian peel were identified by adjusting the carbonization period between 300, 400, and 500 °C, activating the 1.25 m mesh size with HCl and KOH activators at concentrations of 3 M and 4 M, and soaking the material for 24 hours. Using 4 M HCl activator, 24 hours at 400 °C, and SNI 06-3730-1995 criteria, the ideal conditions for activating durian peel activated carbon in the purification of wasted cooking oil were achieved. SEM at 1000-fold magnification (1.357 m) confirmed an even surface and successful absorption. Durian peel adsorption in the purification of wasted cooking oil reduced peroxides (30.26%), free fatty acids (57.14%), and water content (45%), clarifying the color of leftover cooking oil.

Using the electrochemical dissolution phenomenon of platinum counter electrode, we investigated the surface functionalization and characterization of platinum nanoparticles that had been electrodeposited onto aminated carbon electrodes. The electrodeposited platinum functions with nitrogen-atom-containing functional groups introduced by electrolysis in ammonium carbamate solution. The groups can include aromatic amine groups such as aniline. Together, they function as active sites of specific electrocatalytic current, as found from SEM and XPS observations and electrochemical properties.

A novel immobilized biocatalyst with invertase (b-D-fructofuranosidase, E.C.3.2.1.26) activity was prepared by immobilizing Saccharomyces cerevisiae cells into gelatin by using chromium salts. The effect of chromium salts on cell growth of free and immobilized cells was investigated, and optimum concentrations for chromium acetate and chromium sulfate were found to be 0.016 M and 0.008 M, respectively. Since a medium feeding strategy was applied, higher enzymatic activities were obtained with developed biocatalyst compared to free S. cerevisiae cells. Immobilized samples could be used 10 times in a 30-day period with negligible activity loss. After storing it at 25 C for 28 days, our biocatalyst was used 15 times with 2-day intervals with only a slight amount of activity decrease. As a result we managed to produce a very stable biocatalyst with high invertase activity using an inexpensive methodology.

In this study, AuNPs were reduced using ortho-hydroxybenzoic acid (o-HBA) and various stabilizing agents (α-CDs and β-CDs). The stability, shape, size, and sensitivity of the Fe 3+ detection of AuNPs α-CDs and AuNP β-CDs are compared. Both nanomaterials were characterized using ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopes (TEM). After the addition of Fe 3+ , the absorption rate of surface plasma resonance (SPR) increased to 524 nm, and the color of AuNPs α-CDs and AuNPs β-CDs was changed from pink to red and purple, respectively. AuNPs α-CDs are more uniform in shape and size than AuNPs β-CDs with a size of 23.34 nm. Further, AuNPs α-CDs are more stable, and the absorption rate at 524 nm wavelength decreases by 17.76%. AuNPs α-CDs have a good linear relationship with a linear regression coefficient of 0.996. The sensitivity of AuNPs α-CDs was good with LoD and LoQ both with 1.21 and 4.02 ppm, respectively. These results show that the sensor is superior in determining Fe 3+. In addition, AuNPs α-CDs were used to detect Fe 3+ in the tap water in South Tangerang,