Chemical Engineering

Sliver nano colloids have been synthesized by chemical reduction of sliver salt solution, characterized by SEM usage of nano particles. Sliver nano colloids are treated with wool fibres and dyed wool fibres (direct and acid dyes). The physical properties colour strength, fastness properties have been studied for dyed wool fibres and ordinary wool fibres. It is observed that the fibres with nano treated fibres have better strength than untreated wool fibres. It is also observed that there is considerable improvement in colour strength and colour fastness of silver nano colloids treated wool fibres (dyed).

DMFC has tremendous potential in serving as a source of clean and renewable energy. Different catalyst combinations are prepared and characterized in DMFC at various operating conditions. The characteristic curves are plotted. Effect of prepared catalyst in DMFC performance is analyzed at load and no load conditions. Demerits of Platinum catalyst is minimized to a great extent by the specially designed catalyst combinations. Based on the DMFC performance, the best catalyst combination (Pt-Ru/C) is identified and analysed in different operating conditions.

The moisture diffusion coefficient and energy activation of two Iranian apricot varieties was determined at five drying air temperatures and at a constant air velocity of 1.5 m/s. The initial moisture content (d.b.), modulus of elasticity, surface area, half of pomace thickness of halved apricot, and total soluble solids of both varieties were determined. The results showed that there were significant differences (p<0.01) in the modulus of elasticity and total soluble solids between two varieties, but no significant differences (p>0.01) were observed for other parameters. The water effective diffusion coefficient ranged from 1.34×10^-10 to 4.15×10^-10 m²/s, and from 2.03×10^-10 to 5.95 ×10^-10 m²/s, for Ghavami and Nasiry, respectively. Energy activation was 27.1 and 25.34 kJ/mol for Ghavami and Nasiry varieties, respectively. The results showed that modulus of elasticity and total soluble solids play a major role in moisture diffusion by limiting water movement within the material subjected to drying.

Rice husk, agricultural waste material of environmental  impact,  was carbonized at temperatures of 300 - 600⁰C in an oven for 2h, after which its adsorption capacities was investigated for the adsorption of acenaphthene in synthetic aqueous solution, at increasing concentrations (50–150mg/L). The yields of carbon obtained from the raw rice husk ranged from 20 - 40 % (w/w), while the adsorption capacities of rice husk increased with increasing carbonization temperature and increasing initial concentration of acenaphthene. The removal efficiencies of the rice husk increased from 71.37 - 80.56% as the carbonization temperature increased from 300-600⁰C, but decreased with increasing initial concentration of acenaphthene. The adsorption equilibrium data obtained, fitted well to the Freundlich, Langmuir, Temkin and Dubnin-Radushkevich isotherms with minimum correlation coefficient (R²) of 0.9981, 0.9262, 0.9667 and 0.9215, respectively. The error analysis showed the order of suitability of the isotherm models selected to be Temkin > Freundlich > Dubnin-Radushkevich > Langmuir. This study shows that carbons rice husk possesses favourable potency of being used as activated carbon for the removal of acenaphthene from wastewater.

The Falcon SB-40 concentrator is an enhanced-gravity separator used in mineral beneficiation, as their superior gravity field enables them to separate particles within narrow classes of density and size. The process of cutting and finishing garnet mineral produces industrial waste as a fine powder mixture of garnet with a few percent of titanium carbide which is derived from titanium blades. This study aims to shed light on the Falcon concentrator’s ability to separate particles within density ranges lower than usual. Specific gravity of the fractions is 3.7 and 4.9 gm/cm3. Various operating conditions such as bowl speed (G force), water pressure, pulp solid ratio and pulp feed rate were investigated. It was shown that under optimized conditions the Falcon SB-40 concentrator can produce an excellent titanium concentrate with titanium carbide of 92.2 % from a feed waste of about 5% titanium carbide with total recovery of 97%.

Osmotic dehydration of mango fruits (Mangifer indica L.) is directed towards reduction of its seasonal losses at glut. Effects of sucrose concentrations; 40 to 65°Brix; temperatures; 30 to 50 ºC and time of immersion between 0 to 180 min were studied using samples of diced mango cubes of 2 cm3 dimensions. The measured response variables of water loss, solute gain and performance ratio were subjected to statistical analysis. The results were modelled and optimised on the premise of maximum WL and minimum SG and maximum PR as constraints using the modified distance approach of the response surface methodology (Design Expert 6.08). Optimal osmotic dehydration evaluated were 59.19oBx, 32.06oC and 156.min. of 53.03°Bx sucrose concentration yielded 42.32% WL, 3.41% SG and PR of 10.69 with a desirability of about 89.73%. The results showed that all the input process variables had a significant effect at 5% level of significance (P < 0.05). Optimal process conditions adopted in a semi-continuous pilot plant yielded about 47 (%) water loss and 7.1 (%) solute gain of the initial sample content. The system proved efficient in the treatment of mango with performance ratio in the range of 3 – 7 and could be used in the food industry for the preservation of fruits. More so, the model could be used to predict operational conditions for the OD of other similar fruits. Running title: Optimal osmotic dehydration of mango cubes

Dye stuff industries produces a bulk quantity of waste which is disposed off into lakes and streams without any prior treatment  and which has a significant negative impact on human being and aquatic habitat . Researchers were employing various treatment methodologies for the removal of the organic and inorganic waste. Research is going on to develop a low cost adsorbent which could be used for removing different sorts of dyes stuff which is discharged from the industrial effluent outlet. In this study, removal of Alizarin Red S Dye by using Ca(OH)₂ treated fly ash powder as an  adsorbent. Operating parameters employed in this study such as adsorbent dosage, pH, and agitation speed. Langmuir Isotherm fits well with the experimental data and Pseudo-Second Order Kinetics is obeyed in this study.

The freeze drying behaviour of local cheese was modeled using conservation laws of mass and energy balances such as Fick’s law of mass transfer, Fourier’s law of heat conduction and the Ideal gas equation. The three models developed and simulated are the drying rate, the moisture content and the energy balance models. Three different samples of cheese labeled A, B and C obtained from Bida, Suleja and Kontagora respectively all in Niger State of Nigeria were used to investigate the drying characteristics of local cheese. The analysis of the moisture contents showed that the moisture contents decreased with drying time and that the final moisture content at any time depends on the initial moisture content. Sample A with initial moisture content of 0.0124 kg has a final moisture content of 0.00097kg after 5 hours of drying, while samples B and C with initial moisture contents of 0.009kg and 0.0104kghave their final moisture contents of 0.00001kg and 0.00010kg respectively at the end of 5 hours. When the effect of temperature on moisture loss was studied, it was observed that the moisture loss increased as the freeze drying temperature was increased from 278 to 298K. Results also revealed that moisture loss depends on the initial moisture contents of samples. For this investigation, Samples A, Band C with initial moisture contents of 0.0124kg, 0.0138kg and 0.0104kg have moisture losses of 0.00420kg, 0.00440kg and 0.00363kg respectively at the highest freeze drying temperature of 298K. When the drying rates of samples was investigated, it was found that the drying rates decreased as the moisture contents decreased and which is also a function of the initial moisture contents of samples. The validation of the model was done by carrying out statistical precision analysis which compared the experimental results with those of the output of the models. From the results, the drying rate model showed 75 % agreement with the experimental results (i.e R2 value of 0.75), with a standard error of 3.27X10-5 and a variance of 5.37X10-8, the moisture content model interprets about 98.44 % of the experimental results with a standard error of 7.04X10-4 and the variance of 2.79X10-6, while the energy balance model showed about 99.0 % agreement with the experimental results with a standard error of 2.16X10-5 and a variance of 3.32X10-7.

The removing dye from wastewaters is a main concern in textile industries letter, press and other commercial manufacturing systems in this decade. This process can make our environment polluted and endanger human being health as they are poisonous and have negative effects on human body. This review paper firstly recognizes synthetic pollution, its characterization and poisonous particles; then, it presents several improvements regarding optimum methods for treating and removing dye from wastewater and finally it suggests some adsorbents that are bio-based and money-saving. A comprehensive category of adsorbents including agricultural waste, bio and natural materials and industrial waste were reported. This paper suggests adsorption method using bio-waste adsorbent as an acceptable method in order to remove dye from waste water. However, further studies are needed to scrutinize the precise results of this approach in industry.

With an aim to study the hydrodynamic characteristics of a cocurrent solid-liquid-gas phase fluidized bed, experiments were conducted using 3 different sizes of gypsum particles, water and air as three respective phases. The characteristics studied were pressure drop and solid, liquid, gas holdups, which were observed to be influenced by three factors namely particle size and superficial velocities of gas and liquid. The Response surface Methodology was applied to investigate the individual and combined effect of the three factors on hydrodynamics characteristics. An attempt has been made to develop quadratic models for pressure drop and phase holdups. The predicted values were compared with experimental values which gave a satisfactory fit with R2 values around and above 0.95, indicating that the values predicted by the models were in good agreement with the experimental values.