Percentage Of Hydrogen Research Articles

Computer simulation study of ion-water and water-water hydrogen bonds in sulfuric acid solutions at low temperatures

Molecular dynamics simulations of sulfuric acid solutions at several temperatures (230, 250, 273 and 298 K) and concentrations (10, 20, 30 and 40 wt%) have been carried out. The dissociation of the acid has been explicitly considered, in accordance with the available experimental measurements. So, the simulated systems are made up of the following molecular constituent species: water molecules, hydronium cations, bisulfate anions and sulfate dianions. Calculations have been conducted using a reliable force field, which allows us to determine density and viscosity values, which are in a reasonably good agreement with the available experimental data in the temperature and concentration ranges considered in this work. Simulations have also been employed to determine the radial distribution functions, which involve water molecules, and the diffusion coefficients of the constituent species. Moreover, a hydrogen bond analysis, involving only water molecules, has also been fulfilled. To this end, the mean number of hydrogen bonds between water molecules and between ions and water molecules, the percentages of molecular species hydrogen bonded with a given number of water molecules, and the continuous and interrupted lifetimes have been calculated. We observe that most properties are mainly sensitive to the concentration. We also notice that water molecules bonded to the anions are more labile than those bonded to other water molecules or to hydronium ions, the labilities increasing when the temperature rises. Moreover, the characteristic tetrahedral structure of water vanishes when the concentration or the temperatures increases. In the first case because water molecules tend to bond to a larger number of ions. In the second because the mean number of hydrogen bonds between water molecules and their lifetimes decrease. Finally, we also estimate the activation energies from the interrupted lifetimes, the viscosity and the diffusion coefficients. We note that these energies are very similar and they increase when the concentration rises.

Operation Analysis of Selected Domestic Appliances Supplied with Mixture of Nitrogen-Rich Natural Gas with Hydrogen

This article presents the results of the testing of the addition of a hydrogen-to-nitrogen-rich natural gas of the Lw group and its influence on the operation of selected gas-fired domestic appliances. The tests were performed on appliances used for the preparation of meals and hot water production for hygienic and heating purposes. The characteristics of the tested gas appliances are also presented. The burners and their controllers, with which the tested appliances were equipped, were adapted for the combustion of Lw natural gas. The tested appliances reflected the most popular designs for domestic gas appliances in their group, used both in Poland and in other European countries. The tested appliances were supplied with nitrogen-rich natural gas of the Lw group, and a mixture of this gas with hydrogen at 13.2% content. The article presents the approximate percentage compositions of the gases used during the tests and their energy parameters. The research was focused on checking the following operating parameters and the safety of the tested appliances: the rated heat input, thermal efficiency, combustion quality, ignition, flame stability, and transfer. The article contains an analysis of the test results, referring, in detail, to the issue of decreasing the heat input of the appliances by lowering the energy parameters of the nitrogen-rich natural gas of the Lw group mixture with a hydrogen addition, and how it influenced the thermal efficiency achieved by the appliances. The conclusions contain an explanation regarding, among other things, how the design of an appliance influences the thermal efficiency achieved by it in relation to the heat input decrease. In the conclusions, on the basis of the research results, answers have been provided to the following questions: (1) Whether the hydrogen addition to the nitrogen-rich natural gas of the Lw group will influence the safe and proper operation of domestic gas appliances; (2) What hydrogen percentage can be added to the nitrogen-rich natural gas of the Lw group in order for the appliances adapted for combusting it to operate safely and effectively, without the need for modifying them?

Application of robust machine learning methods to modeling hydrogen solubility in hydrocarbon fuels

Having accurate information about the hydrogen solubility in hydrocarbon fuels and feedstocks is very important in petroleum refineries and coal processing plants. In the present work, extreme gradient boosting (XGBoost), multi-layer perceptron (MLP) trained with Levenberg–Marquardt (LM) algorithm, adaptive boosting support vector regression (AdaBoost−SVR), and a memory-efficient gradient boosting tree system on adaptive compact distributions (LiteMORT) as four novel machine learning methods were used for estimating the hydrogen solubility in hydrocarbon fuels. To achieve this goal, a database containing 445 experimental data of hydrogen solubilities in 17 various hydrocarbon fuels/feedstocks was collected in wide-spread ranges of operating pressures and temperatures. These hydrocarbon fuels include petroleum fractions, refinery products, coal liquids, bitumen, and shale oil. Input parameters of the models are temperature and pressure along with density at 20 °C, molecular weight, and weight percentage of carbon (C) and hydrogen (H) of hydrocarbon fuels. XGBoost showed the highest accuracy compared to the other models with an overall mean absolute percent relative error of 1.41% and coefficient of determination (R2) of 0.9998. Also, seven equations of state (EOSs) were used to predict hydrogen solubilities in hydrocarbon fuels. The 2- and 3-parameter Soave-Redlich-Kwong EOS rendered the best estimates for hydrogen solubilities among the EOSs. Moreover, sensitivity analysis indicated that pressure owns the highest influence on hydrogen solubilities in hydrocarbon fuels and then temperature and hydrogen weight percent of the hydrocarbon fuels are ranked, respectively. Finally, Leverage approach results exhibited that the XGBoost model could be well trusted to estimate the hydrogen solubility in hydrocarbon fuels.

STUDY OF THE PYROLYSIS KINETICS AND ENERGY CONTENT OF ACID WASHED RICE HUSK SAMPLE USING ISOCONVERSIONAL METHODS

The rice husk was characterized by proximate and ultimate analysis. The proximate analysis was determined by moisture, volatile and ash content as 15.48%, 57.28% and 15.35% respectively. Ultimate analysis was determined using the data obtained from proximate analysis to calculate carbon, hydrogen, nitrogen and oxygen percentage as 43.67%, 4.64%, 0.956% and 35.78% respectively. The rice husk pyrolysis was studied by TGA/DTG analysis in a nitrogen atmosphere at flow rate of 60mL/minute, heating from 20.00 oC to 1000.00 oC at three different heating rates: 10, 15 and 20 oC/minute. The devolatilization and decomposition pattern portray by TGA curve for all the samples were almost the same, however, different peak temperatures were shown by DTG curve differently for all the samples at different heating rates. The sample RHC ran at three different heating rates: 10, 15 and 20 oC/minute with peak temperatures of 260.85 oC, 318.14 oC and 358.57 oC respectively. While the acid modified samples RHL and RAA at the same heating rates of 10, 15 and 20 oC/minute with peak temperatures of 402.05 oC, 343.91 oC and 280.76 oC respectively for sample RHL. And 399.34 oC, 325.59 oC and 282.61 oC respectively for sample RAA. Three kinetic models were used in this research, which are known as model fit methods for kinetics. The models are Flynn Wall Ozawa (FWO), Kissinger Akahira Sunose (KAS) and Coats Redfern methods. The KAS and FWO methods were used for the determination of activation energy and C-R method for the reaction mechanisms

Isolation And Characterization Of Biosurfactant Producing Bacteria From Different Environmental Soil Samples

Isolation And Characterization Of Biosurfactant Producing Bacteria From Different Environmental Soil Samples

Numerical modeling of plasma gasification process of polychlorinated biphenyl wastes

The plasma gasification process is one of the most innovative and efficient methods for the disposal of various wastes and energy production. But it is still an extremely complicated process; therefore, to optimize it, modeling could be used as an invaluable asset. The aim of this study is to develop a computational model to evaluate the plasma gasification process of polychlorinated biphenyl wastes. The model was created in Aspen Plus® commercial software. It is based on the principle of Gibbs free energy minimization. The results acquired in this research were validated by the data in the literature. It has to be noted that satisfactory results have been obtained. Also, air, steam, and carbon dioxide were considered as oxidizers and the effects of various parameters such as temperature, equivalence ratio (ER), steam-to-waste (S/W) ratio, and carbon dioxide-to-waste (CO2/W) ratio on the production of syngas components were investigated. The results show that processing this hazardous waste leads to the production of a large percentage of acidic gases, which demands a gas cleaning unit in such treatment facilities. The results also show that PCBs with lower chlorine atoms are favorable to the production of higher-quality syngas. The increase of the gasifier temperature turns the waste into purer syngas. However, after the temperature of 1200 ºC the results showed that the major constituents of syngas reach almost a constant molar fraction. A steam-to-waste ratio of 0.5 can be used to produce syngas with greater percentage of hydrogen and fewer pollutants. The use of CO2 as gasifying agent led to the production of large amounts of CO. Conclusion could be drawn that this process can be considered safe and very effective while processing the aforementioned hazardous wastes and in the production of high-quality syngas.

The influence of nitrogen and hydrogen addition/dilution on soot formation in coflow ethylene/air diffusion flames

Harmful emissions from combustion, such as soot, have severe adverse effects on the environment and human health. One way to mitigate these emissions and their dangerous influence is through fuel dilution. In the present study, the effects of adding different percentages of hydrogen and nitrogen to the fuel in a set of laminar coflow ethylene/air diffusion flames are investigated numerically by employing an in-house algorithm, the CoFlame code. The various influences of hydrogen, including dilution, density, transport, thermal, and chemical effects on soot formation and flame characteristics, are evaluated by introducing different fictitious species into the chemical mechanism. The numerical calculations of temperature, soot volume fraction, and average primary particle diameter of soot are in agreement with experimental measurements from the literature. Results show that blending hydrogen and nitrogen into the fuel decreases soot volume fraction and radiation. The hydrogen abstraction C2H2 addition (HACA) surface growth and polycyclic aromatic hydrocarbon (PAH) condensation rate reductions are responsible for the decrease in soot volume fraction. It is found that the soot formation/oxidation reaction rates are decreased under the dilution effect while increased under the transport and chemical effects. Among the various effects of hydrogen addition, the dilution effect has the most significant influence on soot formation/oxidation reaction rates. It is seen that the density and thermal effects have a negligible effect on soot volume fraction.

Dynamical Characterization of Thermoacoustic Oscillations in a Hydrogen-Enriched Partially Premixed Swirl-Stabilized Methane/Air Combustor

Abstract In this study, we systematically analyze the effects of hydrogen enrichment in the well-known PRECCINSTA burner, a partially premixed swirl-stabilized methane/air combustor. Keeping the equivalence ratio and thermal power constant, we vary the hydrogen percentage in the fuel. Successive increments in hydrogen fuel fraction increase the adiabatic flame temperature and also shift the dominant frequencies of acoustic pressure fluctuations to higher values. Under hydrogen enrichment, we observe the emergence of periodicity in the combustor resulting from the interaction between acoustic modes. As a result of the interaction between these modes, the combustor exhibits a variety of dynamical states, including period-1 limit cycle oscillations (LCO), period-2 LCO, chaotic oscillations, and intermittency. The flame and flow behavior is found to be significantly different for each dynamical state. Analyzing the coupled behavior of the acoustic pressure and the heat release rate oscillations during the states of thermoacoustic instability, we report the occurrence of 2:1 frequency-locking during period-2 LCO, where two cycles of acoustic pressure lock with one cycle of the heat release rate. During period-1 LCO, we notice 1:1 frequency-locking, where both acoustic pressure and heat release rate repeat their behavior in every cycle.

Spatial Evaluation of Groundwater Quality Using GIS and WQI in Gadilam River Basin, Tamil Nadu, India


 
 
 The aims of the current research are to assess the drinking water quality of the groundwater in the Gadilam River Basin, which is located in the northern part of Tamil Nadu, by identifying the groundwater quality index and examine its suitability for drinking. The current work determines the levels of groundwater quality parameters based on 120 groundwater samples; 50 samples from Archaean formation, 34 samples from Quaternary formation, 35 samples from Tertiary formation and the remaining sample from Cretaceous formation. Additionally, this research compares the determined levels with the various standards for drinking. Furthermore, the variability of parameters of the groundwater quality is explored in this paper by using the spatial interpolation method. The conclusion of this research reveals that the groundwater quality parameters such as Calcium (Ca2+), Magnesium (Mg2+), Nitrate (NO32-), Fluoride (F-), Sulphate (SO42-), Bi-carbonate (HCO3-) and Percentage of Hydrogen (pH) values are observed to be within the limiting value for WHO 2017 in all the formations during the seasons in which they were taken. The water quality index (WQI) values of the Archaean, Quaternary and Tertiary formations are found to be less than 100 meq/L in all stations in both seasons. In order of WQI, these stations come under the category of “Excellent” and “Good”. The Piper trilinear classification of groundwater samples fall in the field of mixed Ca-Mg-Cl, and No dominance, some of the samples represent Na-K, Cl types of water.
 
 

Hydrogen Addition to Natural Gas in Cogeneration Engines: Optimization of Performances Through Numerical Modeling

A numerical study of the energy conversion process occurring in a lean-charge cogenerative engine, designed to be powered by natural gas, is here conducted to analyze its performances when fueled with mixtures of natural gas and several percentages of hydrogen. The suitability of these blends to ensure engine operations is proven through a zero–one-dimensional engine schematization, where an original combustion model is employed to account for the different laminar propagation speeds deriving from the hydrogen addition. Guidelines for engine recalibration are traced thanks to the achieved numerical results. Increasing hydrogen fractions in the blend speeds up the combustion propagation, achieving the highest brake power when a 20% of hydrogen fraction is considered. Further increase of this last would reduce the volumetric efficiency by virtue of the lower mixture density. The formation of the NOx pollutants also grows exponentially with the hydrogen fraction. Oppositely, the efficiency related to the exploitation of the exhaust gases’ enthalpy reduces with the hydrogen fraction as shorter combustion durations lead to lower temperatures at the exhaust. If the operative conditions are shifted towards leaner air-to-fuel ratios, the in-cylinder flame propagation speed decreases because of the lower amount of fuel trapped in the mixture, reducing the conversion efficiencies and the emitted nitrogen oxides at the exhaust. The link between brake power and spark timing is also highlighted: a maximum is reached at an ignition timing of 21° before top dead center for hydrogen fractions between 10 and 20%. However, the exhaust gases’ temperature also diminishes for retarded spark timings. Lastly, an optimization algorithm is implemented to individuate the optimal condition in which the engine is characterized by the highest power production with the minimum fuel consumption and related environmental impact. As a main result, hydrogen addition up to 15% in volume to natural gas in real cogeneration systems is proven as a viable route only if engine operations are shifted towards leaner air-to-fuel ratios, to avoid rapid pressure rise and excessive production of pollutant emissions.

The Degradation of Austenitic Stainless Steel at High Temperature in Simulated Carbon Monoxide Containing Atmosphere of Biomass-to-Liquid Plants

Biomass fuel is effective renewable energy and being used for replacing fossil fuel energy. It can be produced from synthesis gas containing a high percentage of carbon monoxide (CO) and hydrogen (H2) in biomass-to-liquid plants. Austenitic stainless steel AISI 316L (Cr17% Ni 10% Mo 2%) is used for equipment parts in chemical and petrochemical industries due to good corrosion resistance at various operating conditions. The corrosion resistance of stainless steel may be degraded by the reduction reaction of the passive film and carbide formation from carbon diffusion, which leads to the intergranular corrosion on the steel surface. This research aims to study the degradation of stainless steel AISI 316L in a simulated carbon monoxide containing atmosphere at 15-45%CO and a sensitizing temperature of 800 °C. Before the test, the samples were preoxidized in the air at 800 °C for 6 hours. An electrochemical reactivation (EPR) technique was used to analyze for detecting sensitization. The mass change of AISI 316L slightly increased after the reduction test. Besides, the high carbon diffusion was shown on the steel surfaces as chromium carbides at the high percentage of carbon monoxide.

Effect of hydrogen addition on combustion, performance and emission of stoichiometric compressed natural gas fueled internal combustion engine along with exhaust gas recirculation at low, half and high load conditions

Petrochemicals are the main source of pollution that can be controlled with the implementation of hydrogen fuel in transportation sector due to the property of carbon free structure. In the present study, experiments of gas engine have been conducted under a wide range of hydrogen percentages (0–50% in volume) in CNG fuel, EGR rates (0–26%), spark timings (14-42°CA bTDC) and loads (25%, 50% & 75%) at stoichiometric operating condition. Performance and emissions of compressed natural gas fueled internal combustion engine has been achieved and analyzed at different EGR rates and ignition timings at stoichiometric combustion and half load condition. These parameters have been further studied with the enrichment of hydrogen fractions in CNG fuel, regulation of EGR ratios and spark timings at low, half and high loads. Total ten parameters have been investigated that included: brake thermal efficiency, cyclic variation, in-cylinder pressure, temperature, mass fraction burned, heat released rate, NOx, carbon monoxide, total hydrocarbon, and methane emissions to evaluate the fitness of laboratory-based spark ignition CNG engine. Engine’ emissions have been analyzed with respect to emission mechanisms simulated by GRI Mech3.0.Maximum brake timing advances by 2° to 3°CA with each addition of EGR ratio by 3%, while it retarded by the same angle with each enrichment of 10% hydrogen fraction in compressed natural gas. The smaller H2/EGR ratio (HCNG10 & EGR = 10%) is the best mixture at low load conditions, medium H2/EGR ratio (HCNG50 & EGR = 14%) is suitable for half load conditions and larger H2/EGR ratio (HCNG50 & EGR = 26%) is appropriate charge composition for high load conditions.

Effects of diffused hydrogen atoms on thermomechanical properties and contact behavior of a diamond-like carbon film

Hydrogen atoms are doped to diamond-like carbon (DLC) to improve its thermomechanical properties and tribological performance as a surface protective coating. In this study, molecular dynamics (MD) simulations are performed to investigate the impacts of diffused H atoms on the mechanical stiffness, surface energy, specific heat, and thermomechanical contact behavior of DLC. The hydrogenated DLC (a-C:H) is prepared by adding H atoms to a fixed amount of C atoms (method 1) and by replacing C atoms in DLC with H atoms (method 2). The atomic percentage of hydrogen (at. % H) in DLC is varied from 0 to 8.6%. From the systematic MD simulation results, it is observed that the DLC's mechanical stiffness increases with at. % H due to the increasing density with a higher sp3%, but it shows a decreasing trend for method 2 due to the decreasing density. During the sliding contact with a hemispherical diamond tip, the a-C:H samples show a lower coefficient of friction (COF) than the hydrogen-free DLC (ta-C) sample for method 1 but a higher COF for method 2, which can be attributed to the changes in density and surface energy with respect to hydrogen contents in DLC.

High-quality hydrocarbon fuel production from municipal mixed plastic waste using a locally available low-cost catalyst

Thermal treatment of plastic waste into fuels has gained substantial prominence in the scientific community, but processing of municipal mixed plastic waste (MMPW) has still challenging issues due to the wide variance in plastic composition, size, decomposition behavior, and thermal behavior. Hence, the current study was aimed to address these problems by converting MMPW into high-quality hydrocarbon fuel and compare its behavior with conventional mixed virgin plastics (MVP) via thermochemical pyrolysis technology. A locally available low-cost catalyst i.e., CAT-1 of 10 wt% was employed to enhance the fuel yield. Yield patterns of the process were investigated to identify the optimum operating conditions and the maximum fuel yields of liquid fuel attained with MMPW, and MVP was 74.8 wt% and 86.1 wt%, respectively. Detailed chemical characterization of the fuel fractions revealed the presence of a wide variety of hydrocarbons disbursement i.e., C9 – C18. Non-condensable gas composition revealed the major percentage of ethane and propene along with a minor percentage of hydrogen. Physical characteristics of produced hydrocarbon fuel were found to be comparable with the conventional petroleum fuels i.e., higher heating value of 42.1 MJ kg−1, kinematic viscosity 2.48 cSt, and carbon residue value of 0.15 wt%, which signifies the application of the produced hydrocarbon fuel in automobiles, stationary engines and industrial heating appliances as a promising fuel candidate.

Study on the formation of olefinic-bond-containing asphaltenes during thermal cracking of vacuum residue

In this study, the occurrence of olefinic bonds in asphaltenes separated from vacuum residue (VR) during thermal cracking was explored. Also, the effect of various thermal cracking conditions on the nature of olefinic bonds was discussed. The results showed that olefinic bonds were formed in asphaltenes during VR thermal cracking. The olefinic structure of asphaltenes detected by Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy was mainly in the type of R–CH = CH–R′. An in-depth investigation revealed that increasing the severity of thermal cracking promoted the formation of more olefinic-bond-containing asphaltenes; the percentage of olefinic hydrogen in asphaltenes peaked at cracking under 420 °C for 40 min, was 2.7%. Meanwhile, the olefinic-bond-containing asphaltenes of high concentration consequently became precursors for the formation of coke by increasing the instability of the liquid system. Consequently, further prolongation of the cracking time led to a drastic decline of olefins content accompanying a sharp leap of coke yield. Finally, the hypothetical average molecular structures of the olefinic-bond-containing asphaltenes during VR thermal cracking were proposed based on the modified Brown-Ladner empirical formulas with improvement. They serve as intuitive insights into the existing olefinic bonds in asphaltenes.

BLEACHING WITH 37.5% HYDROGEN PEROXIDE-A CASE REPORT

Today's dentists have a variety of treatment options for restoring a smile with discoloured vital teeth. Treatment options include full crowns, veneers, and direct restorations, as well as minimally invasive procedures such as microabrasion, macroabrasion, and bleaching. Bleaching of teeth is the least invasive and conservative treatment option, so it is gaining popularity. The purpose of this case report is to describe an in-office vital tooth bleaching case in a young patient using POLA OFFICE + (37.5%percent hydrogen peroxide gel). By the end of the second visit, the results were satisfactory, with no side effects.
 Keywords: In office Bleaching, Pola Office +, Discoloration

Integrating flare gas with cogeneration systems: Operational risk assessment

Flare gas utilization in a cogeneration plant is an attractive proposition considering its environmental and economic incentives. Evaluation of the operational risk of integrating flare gas with cogeneration is complex due to the uncertainty in flare gas quality and process conditions. The current study delves into the change in operational risk after modifying the existing cogeneration process with the addition of fuel from flare gas. Based on the process hazards evaluation, the current study identified two critical loss control events (or top events) - boiler gas temperature exceeding operating design temperature and rich fuel mixture in the boiler firebox. The underlying causes that may contribute and lead to these loss control events were identified using fault trees and were updated to the existing cogeneration scenarios. Similarly, different consequential events that may arise from the loss control events were analysed using event trees with existing system safeguards. A Bayesian network model with its explanatory power mapped all the identified dangerous scenarios from the fault trees and event trees to predict integrated systems reliability and diagnose causal factors. Bayesian Network analysis illustrates the dynamic cause-effect relationship and determines the risk escalation due to the changes in the composition of flare gas that is fed to the boiler. The presence of a higher percentage of hydrogen (above 40 mol%) in the flare gas escalates the risk of lean air to fuel ratio in the boiler firebox and increases boiler radiation zone duty. These conditions are detrimental to the boiler firebox operation and can result in critical scenarios such as flame impingement and tube rupture. Additionally, other consequences-a steam explosion and boiler stack explosion were also investigated. However, their probability of occurrence was relatively insignificant with the given frequency of flare gas utilization in the cogeneration system.

Uji Performa Mesin Bensin dengan Sistem Injeksi Berbahan Bakar HCNG

Compressed Natural Gas (CNG) is an alternative renewable fuel gasoline replacement. However, due to the low heating value, the use of CNG in the engine will reduce its performance. The addition of hydrogen gas in CNG namely hydrogen-enriched compressed natural gas is expected to increase the power of the motor. This study aims to analyze the effect of hydrogen concentration on the performance of a CNG gasoline engine. The research was conducted on the engine with an indirect fuel injection system with a volume of 124,9 cc. The parameter of the engine that measured is torque, effective power, specific fuel consumption, and effective thermal efficiency. The results showed that the small percentage of hydrogen in CNG could increase the power of the gasoline engine. Power and efficiency reach a maximum of 10% hydrogen concentration. Increasing the proportion of hydrogen in CNG fuel above 10% will significantly reduce engine torque and power. Engine performance at optimal conditions with 10% hydrogen results in torque of 2.71 Kg.m at 670 rpm, effective power of 3.28 Ps at 1055 rpm, SFCe 0.17 Kg / Ps. Hours at 770 rpm and 33.62% effective thermal efficiency at 770 rpm

Influence of Gasification Operating Parameters on Performance of the Nong Bua Dual Fluidized Bed Gasification System in Thailand

Gasification system performance generally depends on feed moisture content, activity of bed material, gasifier and combustor temperatures, and scrubber media. The tar concentration and gas composition of product gas are two indicators of the gasification system performance. In this research, the effects of gasifier temperature and the activity of bed material on the tar concentration and gas composition of the product gas produced from a dual fluidized bed (DFB) gasification system power plant were investigated. The DFB gasification system power plant is located in Nong Bua district, Nakhon Sawan province, Thailand. Two periods of gasification operation were examined. These two periods were when the olivine was freshy activated and then after a period of operation. The gasifier temperature had several peaks during the operation, which caused the product gas composition to fluctuate. When the olivine had been used for a period, the percentage of hydrogen was approximately 3% higher than when the olivine had been freshly activated, and a lower heating value was observed, which was probably due to lower heating value of hydrogen. The tar concentration was substantially lower when compared with the freshly activated olivine. When the olivine was used for a period, the average tar concentration was 56±22 mg/Nm3 (this is after 95 h continuous operating time) while the average tar concentration of the freshly activate olivine was 872±125 mg/Nm3 (which was after 34.5 h continuous operating time). It was concluded that the average tar concentration and gas composition were influenced by the activity of the bed material and the gasification temperature.

Preparation and characterization of seaweed encapsulated into chitosan beads

Current case in modern agriculture industry has shown that application of agrochemicals has led to high cost of production and serious environmental pollution. In this study, a natural organism known as seaweed, a renewable bio-resources originated from the sea has been chosen to be encapsulated in chitosan hydrogel. The rationale to use seaweed is because it is common in agriculture and horticulture, that the application of seaweed could promote growth, prevent pests and diseases. The seaweed was encapsulated at different concentrations (w/v%) of 5%-20% in chitosan solution using sodium tripolyphosphate as a crosslinker. The encapsulated seaweed in chitosan has been made into beads to suit the application as fertilizer beads. The analysis of FTIR for all beads confirmed the encapsulation took place when both functional groups of the host, chitosan and the guest, seaweed existed together in all the FTIR spectra of the chitosan-seaweed beads. CHNS further confirmed quantitatively that addition of seaweed at various concentrations into the chitosan beads showed increased percentage of carbon, hydrogen, nitrogen, and sulphur content accordingly. The swelling test showed that when seaweed was encapsulated into the chitosan beads, the swelling percentage decreased accordingly with the increase in concentration of seaweed. This is due to the seaweed filling up the voids in the chitosan thus limiting the uptake of water into the system. The morphology study by SEM supported the results of swelling test, agglomeration of large particles surface out accordingly to the concentration of seaweed when the void spaces has been fulfilled. It could be perceived that the encapsulated seaweed chitosan beads is a promising material to the agriculture sector; promoting plant growth which could enhance the income of the farmers and yet safe to the human and environment.