Chemical Engineering

In this work, the adsorption of chromium(VI) was studied on activated carbon prepared from Tamarind wood with zinc chloride activation. Adsorption studies were conducted in the range of 10–50mg/l initial chromium(VI) concentration and at temperature in the range of 10–50°C. The experimental data were analyzed by the Freundlich isotherm and the Langmuir isotherm. Equilibrium data fitted well with the Langmuir

This study evaluated the effectiveness of grape seed extracts (GSE) on lipid oxidation of corn chips stored for 90 days in comparison to tert-butylhydroxytoluene (BHT). Proximate chemical analysis results showed that corn chips contained low moisture contents (less than 2%) and also that no significant differences were found in the dry matter values in ash, fat, protein, and fiber. Antioxidant activity

ABSTRACT.

The study was an assessment of productive skill competency levels of secondary school chemistry students for entrepreneurship. Ten research questions and ten null hypotheses guided the study. A descriptive survey design was employed for the study. From the population of 6121 chemistry students, 1132 was sampled by balloting and used in the study.
The study was carried out in all the secondary schools in the six education zones in Anambra state. Instrument for data collection was
Test of Acquisition of science process skills (TASPS).  Mean scores were used  in answering the ten research questions, while the ten hypotheses were tested using t-test. From the analysis, the researcher found that: SS3 chemistry students possessed science process skills. There was no significant difference between the level of competence of the male and female SS3 chemistry students. The study has shown that at the end of three years of senior secondary school, the chemistry students possessed science process skills which if properly channeled will enhance their entrepreneurial abilities. Based on the findings and discussions, some recommendations were made: the State Ministry of Education should encourage exhibition of students’ products from time to time as this will encourage both teachers and students to improve  their productive skills. The examination bodies WAEC and NECO should encourage the productive skills of the students by emphasizing on questions that will require them to produce articles like soap, cream, salt, charging of battery etc so as to give those avenues to apply the Science Process Skills  (SPS) learnt in other practical aspects. Limitations of the study were stated and suggestions for further study proffered.

 Abstract-Aeronautical Data Chain is a conceptual representation of the path that a set or element of aeronautical data takes from its origination up to end-use. There are classical databases such as navigation or terrain database and configuration files for modularity and portability purposes. These databases can be used to activate or deactivate software items, adapt the software computation to the aircraft configuration, or provide computation data. The RTCA DO-200B establishes three Data Process Assurance Level (DPAL) as the level of rigor, representing the amount of verification and validation tasks performed, during data processing to assure data quality. This paper presents four different and complementary validation techniques to ensure correctness for Aeronautical Databases. This work aims to cover the existing gap in the available standards, presenting and exemplifying some proposed techniques. It also presents some techniques and provides different comparisons and specific intentions. At the end, some relevant needs of qualified tools are discussed to ensure that the use of techniques can be automated, and credits can be sought using tools.

Phosphogypsum disposal from Dinh Vu DAP company was used to separate phosphate and make gypsum by (NH¬4)2SO4. The reaction time was 120 min. The percentage of P2O5 after removal was 0.72 % and met the Vietnam Standard 11833:2017 issued by Institute of Building Materials. The components in phosphogypsum could be applied to manufacture cement. The final product was mixed by PG120 : clinker : fly ash with ratio 5:80:15% (w/w), respectively to manufacture cement. The cement was tested compressive strength. The strength was 55 N/mm2 after 28 days. Index Terms-Phosphate gypsum (PG), CaHPO4.2H2O, CaSO4.2H2O, P2O5, cement, diammonium phosphate (DAP).

— In digital communication system, digital information can be sent on a carrier through changes in its fundamental characteristics such as phase, frequency and amplitude. The use of a filter plays an important part in a communication channel because it is effective at eliminating spectral leakage, reducing channel width, and eliminating interference from adjacent symbols (Inter Symbol Interference) ISI. It describe the developed and dynamic method of designing finite impulse response filter with automatic rapid and less error by an efficient genetic and neural approach. GA and Neural are powerful global optimization algorithm introduced in combinational optimization problems. Here, FIR filter is designed using Genetic, Neural approach by efficient coding schemes. We need to design these filters with some constraints imposed by requirements of the communication system in which we are going to use them. The use of optimization techniques have been proved to be quite useful towards the design of those digital filters with certain specifications. This paper reviews about the uses of optimization systems in digital filter design.

 Abstract— Data Leakage can be referred as the unauthorized transfer of classified information from a computer or data centre to the outside world. Big data is an evolving term that describes any voluminous amount of structured, semi-structured and unstructured data that has the potential to be mined for information. The data loss in such huge massive data sets may cause critical vulnerabilities. In this paper we proposed a novel model in Hadoop master/slave architecture for data leakage prevention with LRA algorithm. The LRA algorithm evaluates the Least Reliable Agent and sends it to the DLA (Data Leakage Avoider). DLA prevents the NameNode from allocating data to these agents.

Enhanced output power from a ZnO nanorod (NR) based piezoelectric nanogenerator (PNG) is demonstrated by forming a hetero-junction with Si micro-pillar (MP) array. The length of the SiMP array, which was fabricated by electrochemical etching, was increased systematically from 5 to 20 ?m by controlling the etching time. Our structural and optical investigations showed that the ZnO NRs were grown hierarchically on the SiMPs, and their crystalline quality was similar regardless of the length of the underlying SiMPs. The peak output voltage from the ZnO NR-based PNG was greatly increased about 5.7 times, from 0.7 to 4.0 V, as the length of the SiMP arrays increased from 0 (flat substrate) to 20 ?m. The enhancement mechanism was explained based on the series connection of the ZnO NRs regarded as a single source of piezoelectric potential by creating a hetero-junction onto the SiMP arrays.

The effects of sulphuric acid modification on the structural and bleaching performance of Ukpor clay were investigated. The clay samples from Ukpor were mined; washed; sun-dried; sized to 0.075mm particle size and reacted with different concentrations of sulphuric acid ranging from 1M to 6M. The raw and acid modified samples were characterized using X-ray Fluorescence and Fourier Transform Infrared Spectroscopy (FTIR) to investigate the effects of acid leaching. The adsorptive performance of the modified samples was investigated by using the samples to remove colour pigments from palm oil. The analyses showed that sulphuric acid leaching caused an exchange of Al 3+ , Fe 3+ , and Mg 2+ with H + ions which led to the modification of the clay crystalline structure and the surface area of the modified samples was observed to increase to more than three times that of the raw sample. The adsorption results showed that the adsorptive performance of the modified samples was improved over that of the raw sample with the sample modified with 4M H 2 SO 4 given the best result. The adsorptive capacity increased from 28.4% (using the raw clay sample) to 79.5% (using the 4M H 2 SO 4 modified sample). The equilibrium result showed that the colour pigment adsorption onto acid modified Ukpor clay occurred in multi-layer in agreement with Freundlich adsorption isotherm model. Conclusively, this study has shown that sulphuric acid modified Ukpor clay is a good adsorbent for palm oil bleaching and that acid concentration is an important factor in the modification step.

Past research with high temperature molten carbonate electrochemical cells has shown that carbon dioxide can be separated from flue gas streams produced by pulverized coal combustion for power generation. However, the presence of trace contaminants, i.e., sulfur dioxide and nitric oxides, will impact the electrolyte within the cell. If a lower temperature cell could be devised that would utilize the benefits of commercially-available, upstream desulfurization and denitrification in the power plant, then this CO2 separation technique can approach more viability in the carbon sequestration area. Recent work has led to the assembly and successful operation of a low temperature electrochemical cell. In the proof-of-concept testing with this cell, an anion exchange membrane was sandwiched between gas-diffusion electrodes consisting of nickel-based anode electrocatalysts on carbon paper. When a potential was applied across the cell and a mixture of oxygen and carbon dioxide was flowed over the wetted electrolyte on the cathode side, a stream of CO2 to O2 was produced on the anode side, suggesting that carbonate/bicarbonate ions are the CO2 carrier in the membrane. Since a mixture of CO2 and O2 is produced, the possibility exists to use this stream in oxy-firing of additional fuel.From this research, a novel concept for efficiently producing a carbon dioxide rich effluent from combustion of a fossil fuel was proposed. Carbon dioxide and oxygen are captured from the flue gas of a fossil-fuel combustor by one or more electrochemical cells or cell stacks. The separated stream is then transferred to an oxy-fired combustor which uses the gas stream for ancillary combustion, ultimately resulting in an effluent rich in carbon dioxide. A portion of the resulting flow produced by the oxy-fired combustor may be continuously recycled back into the oxy-fired combustor for temperature control and an optimal carbon dioxide rich effluent.

The authors have evaluated the emulsification of oil of varying viscosities for concentrated o/w emulsions (>60%). Rushton type impellers and baffled mixing vessels were used. The emulsions were prepared in the transition regime (80 < Re < 200). It was found that, when the oil content increases, it is the emulsion viscosity that controls droplet size, regardless of the dispersed phase viscosity and hydrodynamics. The authors have followed an experimental procedure that allows for the scale-up of the results.

Fermented food composts, to be recycled into fertilizer and animal feed, require sodium chloride concentrations to be less than 1 wt% due to several toxicities. Electrochemical methods are used to remove sodium ions from fermented food composts. By washing the compost with tap water (with no electric current applied), 48% of the initial sodium ion is removed. With an electric current density of 3 mA/cm2 (the distance between the electrodes is 16 cm), the removal efficiency increases to 96% for a 36 h operation. Major factors influencing the efficiency are the treatment time and the electric current density. Removal efficiency increases with energy demand to yield 96% removal at 60 Kwh/m2. Due to the difference in relative ionic mobility, less than 9% of calcium is removed, during the same operation time, which supports the feasibility of this method.

Novel electronic materials play an ever-increasing role in technological applications. They cover a rather broad spectrum of materials that exhibit exotic transport and magnetic properties. These include superconductors, narrow band gap semiconductors, electronically active polymers, colossal magneto resistive systems, nanoscale electronic materials, and Fullerenes, to name a few. Understanding the interplay between strong electronic correlations and structural properties of these materials is important. In this communication, we report the growth and preliminary characterization of single crystal Cerium based intermetallic compounds that are known to show superconductivity at Tc = 2.3K.

Annona squamosa and Catunaregam nilotica seeds and oils were characterized for their approximate analysis and physico-chemical properties. The oil and protein contents were 26.8, 17.5 and 40.0, 22.2%, in A. squamosa and C. nilotica seeds, respectively. The oils were extracted using cold extraction (CE) and Soxhlet extraction (SE) methods. Fatty acids and tocopherols were determined by GC–MS and HPLC, respectively. Generally the physico-chemical properties and fatty acids were not significantly (P ≤ 0.05) affected by the extraction methods. The major fatty acids of A. squamosa oil extracted by CE and SE were oleic 49.2 and 50.5%, linoleic 22.3 and 22.7%, palmitic 15.6 and 15.2%, and stearic 10.6 and 9.3%, respectively. While the major fatty acids in C. nilotica oil extracted by CE and SE were oleic 10.5, and 10.4%, linoleic 63.1 and 63.4%, palmitic 9.7 and 9.8% and stearic 5.1 and 5.4%, respectively. The tocopherol content of CE and SE extracted oils from A. squamosa amounted to 16.6 and 15.5 and from C. nilotica amounted to 110.5 and 107.7 mg/100 g oil, respectively, with delta-tocopherol as the predominant tocopherol in A. squamosa oil, and beta-tocopherol in C. nilotica oil. The total amount of amino acids was found to be 7.266 and 14.202 g/100 g protein, in seeds of A. squamosa and C. nilotica, respectively.

Although water is a cheap and effective medium for thermal energy storage, other options are currently being studied, to increase the storage density or to reduce the cost of the storage. The authors have been developing a system which combines the advantages of stratified sensible heat storage and latent, phase change heat storage; i.e. a hot water storage tank with stratification where a phase change material (PCM) is included into a spiral tube installed in the top of the tank. The PCM used was a granular PCM–graphite compound of about 90 vol.% of sodium acetate trihydrate and 10 vol.% graphite. This paper presents the results of an experimental investigation of the performance of the new storage concept, and of a conventional hot water storage tank for comparison. The data are further analysed with respect to the energetic and exergetic performance of the two systems. Copyright © 2007 John Wiley & Sons, Ltd.