Irwana Nainggolan

Role of Metals Content in Spinach in Enhancing the Conductivity and Optical Band Gap of Chitosan Films

Blend of chitosan and spinach extract has been successfully prepared using acetic acid as a solvent medium to produce chitosan-spinach films. The conductivity measurements showed that chitosan-spinach films for all ratios of 95 : 5, 90 : 10, 85 : 15, and 80 : 20 had better conductivity than the chitosan film. The optical band gap reduced with the addition of the spinach extract into chitosan. Chitosan-spinach film with the ratio of 85 : 15 gave the best electrical properties in this work with the conductivity of 3.41 × 10−6 S/m and optical band gap of 2.839 eV. SEM-EDX spectra showed the existence of potassium, phosphorus, sulphur, iron, and oxygen in chitosan-spinach films. AFM image showed that the surface morphology of the films became rougher as the spinach incorporated into chitosan. The minerals which exist in spinach extract play a role in enhancing electrical properties of chitosan film.

Ammonia Gas Sensor Based on Chitosan Biopolymer

Ammonia classified as one of the hazardous chemical to environment and human. Therefore, monitoring the ammonia in air is vital. Chitosan film was selected as a sensing material for ammonia detection in this study. Chitosan powder was dissolved in 2% of acetic acid to form chitosan solution gel. It was subsequently deposited on patterned electrode by using electrochemical deposition technique. The response of the chitosan sensor towards ammonia was tested via electrical testing by exposing different ammonia concentration ranging from 20 ppm, 100 ppm, 200 ppm, and 300 ppm using air exposure technique. The response of the chitosan sensor towards ammonia was recorded as output voltage. Sensor properties which include sensitivity, stability, recovery, and repeatability were studied. The electrical result showed that the response of chitosan sensor increases as the ammonia concentration increases. All the sensing properties were achieved. Finally, the structure characterization of the chitosan was studied using Fourier Transform Infrared Spectroscopy (FTIR). The appearance of N-H and O-H groups in FTIR spectrum of chitosan film provides evidence that the domain functional group exist in chitosan after it was processed into film.

Chloroform Gas Sensor Based on Chitosan Biopolymer

Chloroform classified as one of the hazardous chemical to human. Therefore, monitoring the chloroform concentration in air is vital. In this study, chitosan powder was dissolved in 2% of acetic acid to form chitosan solution gel. It was subsequently deposited on printed circuit board (PCB) by using electrochemical deposition technique. The response of the chitosan sensor towards chloroform was tested via electrical testing by exposing different chloroform concentration ranging from 10 ppm, 20 ppm, 30 ppm, 40 ppm, and 50 ppm using air exposure technique. The response of the chitosan sensor towards chloroform was recorded as output voltage. Sensing properties of the chitosan sensor which include sensitivity, stability, recovery, and repeatability were studied. The electrical result showed that output voltage increases as the concentration of chloroform increases. All the sensing properties were achieved. The structure characterization of the chitosan was studied using Fourier Transform Infrared Spectroscopy (FTIR). The appearance of N-H and O-H groups in FTIR spectrum of chitosan film provides evidence that the domain functional group exist in chitosan after it was processed into film.

Hexanal Gas Detection Using Chitosan Biopolymer as Sensing Material at Room Temperature

Hexanal was identified as one of the major volatile gases which are produced in degraded dairy products and wood industries. Therefore, preliminary study on hexanal gas detection with the laboratory scale was carried out in this paper. Electrical testing with chitosan as a sensing material to sense hexanal gas in low concentration was carried out at room temperature. Chitosan sensor was fabricated by using electrochemical deposition technique to form active sensing layer. The response of the chitosan film sensor (CFS) towards hexanal was tested via electrical testing by exposing different hexanal concentrations ranging between 20 ppm, 100 ppm, 200 ppm, and 300 ppm using air as a carrier gas. Sensing properties of the CFS toward hexanal exposure including responsibility, recovery, repeatability, stability, and selectively were studied. Overall, our result suggested that hexanal sensor based on chitosan was able to perform well at room temperature demonstrated by good response, good recovery, good repeatability, good stability, and good selectively. This simple and low cost sensor has high potential to be utilized in early quality degradation detection in dairy products and can be used to monitor the level of hexanal exposure in wood industries.

New Application of Chitosan Film as a Water Vapor Cell

This study is aimed at finding a new application of chitosan film in energy conversion material. A water vapor cell in a single chip form which consists of chitosan film on the top layer, patterned gold layer in the middle and isolator substrate in the bottom layer was manufactured and used to convert water vapor into electrical power by direct chemical interaction. When the water vapor was exposed onto chitosan film surface, the chitosan film resistance changed and as a consequence, the output voltage and current could be measured. The electrical power was significantly increased by combining several cells, namely twenty cells in series, twenty cells in parallel, twenty cells in series-parallel and twenty cells in parallel-series. It was found that twenty cells in series have the highest electrical power. Furthermore, the lifetime of a water vapor cell under water vapor exposure maintained until eight months. Therefore, chitosan film has evidenced a huge potential as energy conversion material to produce a water vapor panel in future.

The Effects of Branched-Tail Structure of Surfactant on the Phase Behaviour of Alkylglucoside/Water/n-Octane Ternary System

Two glycolipids were synthesized to study the lyotropic behavior of these glycolipids in alkylglucoside/water/n-octane ternary system. These glycolipids have been distinguished based on the structure of alkyl chain (branched-alkyl chain and straight alkyl chain). 2-octyl-β-D-glucopyranoside (2-OG) and 2-ethylhexyl-β-D-glucopyranoside (2-EHG) were used as surfactants to perform two types of phase diagram. Phase behaviours investigated were phase behaviours of 2-OG/n-octane/water ternary system and 2-EHG/n-octane/water ternary system. Small angle x-ray (SAXS) and optical polarizing microscope were used as the instruments to study the lyotropic phase behaviour of these two surfactans in ternary phase diagram. Study the effect of branched-tail structure on the phase behaviour of glycolipids in ternary system is one of strategy to derive the structure-property relationship. For this purpose, 2-OG and 2-EHG were used as surfactants in the same ternary system. The phase diagram of 2-OG/water/n-octane ternary system showed rectangular ribbon phase and lamellar phase. The phase diagram of 2-EHG/water/n-octane ternary system showed wide region of lamellar lyotropic liquid crystalline in different ratio of weight composition. In 2-OG/water/n-octane ternary system, as more surfactant was added to the system, the interlayer spacing, d1 and scattering angle, a value increased, whereas in 2-EHG/water/n-octane ternary system, the d1 and a value decreased.

The Influence of Sintering Temperature and Mn-Ti Doped BaFe12O19 on the Microwave Absorbing Properties

The effect of sintering temperature and Mn-Ti (x = 0.1 and 0.5 % mol) doped in Barium hexaferrite (BaFe12O19) on the microwave absorption properties have been investigated. The BaFe(12-2x)MnxTixO19 samples were prepared by using a solid state reaction method from technical grade materials of BaCO3, Fe2O3, MnO2, and TiO2. The permagraph and vector network analyzer (VNA) measurement with frequency of 4 – 10 GHz were used to determine the magnetic properties and microwave absorbing properties, respectively. The magnetic induction and magnetizing force (B-H) curve analysis of BaFe(12-2x)MnxTixO19 revealed that by increasing the Mn-Ti dopant concentrations, the remanence (Br) and BH(max) increases, meanwhile, the HCB value decreases for both 1100 and 1150oC. The frequency dependence of reflection loss (RL) measurement given anoptimum value of-26.15 dB at frequency of 9.18 GHz which obtained by x = 0.1% mol Mn-Ti (1100oC). The maximum absorption peak was achieved for 0.5 % mol Mn-Ti sample with ~98.3 % at 9.18 GHz. By controlling the sintering temperature and Mn-Ti dopant concentration, the RL and absorption behavior can be modified to desirable values and also indicates that higher Mn-Ti dopant concentration (0.5% mol) possess better absorbing characteristics. Furthermore, it was found that complex permitivitty and permeability values of BaFe12O19 can be modified by controlling the Mn-Ti dopant concentration.

Manufacture of Water Vapour Filter Based on Natural Pahae Zeolite Used for Hydrogen Fueled Motor Cycle

Province of North Sumatera has been well known as a territory having multi kind of industrial minerals which have not been used and maintained properly and optimally. One of which is a natural Pahae zeolite derived from Tarutung, Tapanuli Utara-Indonesia. The objective of this research is to exploit Pahae zeolite to absorb water molecules flowing into the combustion chamber of a hydrogen fueled motorcycle. The generation of water molecules was as a result of water splitting process in water to hydrogen converter of the motorcycle. The grain size of Pahae zeolite was lessened up to 60 and 200 meshes which were then chemically activated by soaking with 30% KOH solution and calcination at a temperature of 300°C for 2 hours. The test results conducted on the intake pipe of combustion chamber showed that the particle size of 200 meshes had more absorption than that of 60 meshes. It was also found that type of Pahae zeolite had better absorption compared with Cikalong zeolite.

Spinach Ferredoxin (Fdx) as an Organic Material to Improve Optical Band Gap of Chitosan (Cs) Biofilm

In this study, the effect of spinach-ferredoxin addition in chitosan matrix towards optical band gap was investigated. 5 distinct solutions were prepared by blending chitosan and spinach-ferredoxin (Cs-Fdx) with the volume to volume ratios of 100:0, 95:5, 90:10, 85:15 and 80:20 respectively. The solutions were cast into film via spin coating technique. The optical properties in terms of absorbance for these films were investigated using UV-Vis Spectrometer. UV-Vis result showed that the absorbance increased as the spinach-ferredoxin content increases. Finally, the optical band gaps of the films were determined by extrapolating a straight line of (αhν) 2 vs. hν curves. Band gap value of 3.48 eV, 3.25 eV, 3.2 eV, 3.0 eV, and 2.8 eV were observed for (Cs-Fdx) films with 100:0, 95:5, 90:10, 85:15 and 80:20 respectively.

Roselle Blend Film Sensor (RBFS) for Detecting Fertilizer Concentration of Grape Tree

A Roselle blend chitosan film sensor (RBFS) with different concentration of roselle has been developed. Electrochemical deposition has been chosen as an efficient technique for the fabrication of RBFS. RBFS with the concentration of 20cc of roselle has a stable value to detect the different concentration of fertilizer ranging from 0 ppm until 60 ppm. The type of fertilizer used in this testing was magnesium sulphate. The electrical laboratory testing result of the RBFS exposed to de-ionised water (DIW) showed the highest response with the value ~94%. The highest response value of RBFS exposed to magnesium sulphate with the concentration of 10 ppm was ~66%. The lowest response value of RBFS exposed to magnesium sulphate with the concentration of 60 ppm was ~30%. The results have been proven that RBFS is able to differentiate the concentration of fertilizer. The RBFS fulfils all the reliable sensing properties which include excellent response time, stability, repeatability, recovery, and selectivity. The morphological surfaces of RBFS were observed with SEM and chemical interactions between roselle blend chitosan were explained using FTIR spectra results. SEM image of RBFS showed the film surface was compact and the roselle was well distributed within the chitosan.