Chemical Engineering

In this study, activated carbon was prepared from moringa seed husk by chemical activation method using of potassium hydroxide (KOH) impregnation. The activated carbon produced was characterized and tested for the removal of two different dyes from wastewater. The Activity tests were carried out for five different masses of activated carbon and three contact times in order to investigate the effect of mass of activated carbon and contact time respectively. The experimental results showed that an increase in the mass of the activated carbon produced leads to a higher percentage removal of dye from wastewater.

The possibility of using a three phase pipe separator to separate a mixture of air-water oil was investigated. A 30 ID laboratory based pipe separator was designed, fabricated and installed to study the separation efficiency of air-water-oil mixture. A mixture of air-water-oil flow run through the pipe separator and the separation efficiency calculated in term of the percentage of clean water by volume at the water-rich outlet calculated. The results obtained showed that a clean water stream at the water-rich outlet of the pipe separator is achievable at high water volume fractions and low oil content. This confirmed the possibility that the three phase pipe separator can function as a free water knock-out device.

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.

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.

In this article, we studied the effects of variable viscosity and thermal conductivity on an unsteady two-dimensional laminar flow of a viscous incompressible electrically conducting fluid past a semi-infinite vertical plate taking into account the mass transfer. The fluid viscosity is assumed to vary as a linear function of temperature. The governing equations for the flow are transformed into a system of non-linear ordinary differential equations are solved by a closed analytical form. The effects of the various parameters on the velocity, temperature, concentration and skin-friction profiles are presented graphically.

Increased environmental awareness and strictness in emissions regulations have led to development of Warm Mix Asphalt (WMA). The potential of WMA in reducing the energy consumption as compared to Hot Mix Asphalt (HMA) is becoming more and more attractive nowadays. The goals for the WMA are to lower the mixing and compacting temperatures by reducing the viscosity of the binder, and using the same HMA plants to produce mixes that still meet specifications. The benefits of WMA include reduced emissions, decreased energy (fuel) consumption, reduced asphalt oxidation and early traffic opening. Several technologies of WMA are available today such as Aspha-min, Sasobit, Evotherm, WMA-Foam and Asphaltan B. Viscosity of the binder is used to determine its mixing, laying and compaction temperatures.In the present study Brookfield Viscometer is used for determination of the viscosity of bituminous binders with different combinations of additives at different temperatures ranging from 90ºC to 160ºC. Two binders VG 30 and CRMB 55, and two additives Sasobit and Evotherm are used. The results shows that the viscosity of the bituminous binders varies exponentially with the temperature and linearly with respect to the dose of Warm Mix additives and the mixing temperature can be reduced by 20ºC to 25ºC while laying and compaction temperature can be reduced by 10ºC to 15ºC by using these additives.

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).

The importance of controlling water pollution has increasing in recent years. Dyes are visible in nature, despite it constitutes only a small portion of water pollution to the environment. Color delivery onto the textile fibres in the form of dyes is not an efficient process. As a result, most of the textile industry wastewater is coloured. The treatment to remove this color was not considered until the usage of synthetic dyes. Due to the effects caused by the synthetic dyes to the environment. Government is forcing textile industries to treat their waste effluent to an increasingly high standard before releasing it to the environment due to the recalcitrant nature of modern synthetic dyes. Several strategies have been investigated cost-effective process to remove the colour from wastewater produced by the textile industry. This article reviews the current available technologies and suggests an effective, cheaper alternative for dye removal and decolourisation applicable on large scale.

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 values of 0.9981, 0.9262, 0.9667 and 0.9215, respectively, although, generally decreases with increasing carbonization temperature. 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 high potency of being used as activated carbon for the removal of acenaphthene from wastewater.

Soil that was artificially polluted with Escravos light crude oil was degraded with hydrocarbon degrading micro-organisms isolated from crude oil contaminated soil in Niger Delta area. The micro-organisms isolated and applied included Enterobacter aerogenes, Serratia marcescens and Proteus myxofaciens immobilized in coconut fibre as a carrier. The results of the laboratory analysis showed that the immobilized micro-organisms bacteria had good self-life with micro-organisms load of 5.43 x 108 cfu/ml and 2.52 x 1019 cfu/ml on the first and 28 days respectively. The results gotten from immobilized micro-organisms system are good for the biodegradation of hydrocarbons. At the expiration of 28 days of applying the immobilized micro-organisms system in the laboratory scale degrading of Escravos light crude oil, the remaining concentration of total hydrocarbon decreased to 14.36 % for one of the samples compared to the remaining concentration of total hydrocarbon of 85.31 % in the control sample. Therefore, the immobilized micro-organisms system using coconut fibre as a carrier can serve as an effective and fast biodegradation tool for cleaning up petroleum hydrocarbon polluted soil at low cost.