Parameters Of Adsorption Process Research Articles

The isoxazolidines: the effects of steric factor and hydrophobic chain length on the corrosion inhibition of mild steel in acidic medium

Several new isoxazolidines having varying degree of steric environment and hydrophobic chain length, prepared efficiently using single-step nitrone cycloaddition reactions, are tested for corrosion inhibition of mild steel in 1 M and 5 M HCl at 50–70 °C range by gravimetric and electrochemical methods. All compounds have shown very good corrosion inhibition efficiency (IE%) in acidic solution. Steric crowding around the nitrogen centres and hydrophobic chain lengths as well as increase in temperature (in the presence of the inhibitor in the higher concentration range 100–400 ppm) are found to increase the inhibition efficiency of the isoxazolidines. Thermodynamic parameters ( Δ G ° ads , Δ H ° ads , Δ S ° ads ) for the adsorption process and kinetic parameters for the metal dissolution (or hydrogen evolution) reaction in the presence of one of the isoxazolidines were determined. Experimental results agree with the Temkin adsorption isotherm. The inhibition of corrosion in 1 M HCl, influenced by both physi- and chemi-sorption, was found to be under mixed control, but predominantly under cathodic control.

Removal and recovery of malachite green from wastewater using an agricultural waste material, de-oiled soya

De-oiled soya is a waste product obtained during the processing of soyabean in soya oil extraction mills. Attempts have been made to exploit this wonder crop for different purposes to mitigate many of our problems. This laboratory utilized de-oiled soya as waste material and low cost adsorbent for the removal of toxic textile dye ‘malachite green’. The characterization of the adsorbent was done through IR and DTA curves and preliminary investigations were carried out by batch adsorption technique, which includes effect of pH, adsorbate concentration, sieve size, adsorbent dosage, contact time, temperature, etc. Tenable mechanism of the ongoing adsorption process and thermodynamic parameters were also obtained from Langmuir and Freundlich adsorption isotherm models. The kinetic measurements helped in determining the specific rate constant confirming the applicability of the first-order rate expression. To identify whether the on-going process is particle diffusion or film diffusion, the treatment given by Boyd and Reichenberg was employed. To assess the practical utility of the adsorbent a fixed bed column was designed and necessary parameters were calculated by applying mass transfer kinetic approach. Experiments were also performed for recovery of loaded dye through chemical regeneration of spent column and an estimate of the operational cost was also calculated.

Optimisation of Process Parameters for Adsorption of Metal Ions on Straw Carbon by using Response Surface Methodology

Optimisation of process parameters for adsorption of metal ions viz., Cu2+, Cd2+ and Ni2+ ions on Straw Carbon (SC) was carried out by using Box-Behnken statistics and analysis of variance methods. Response surface methodology with three levels of initial pH (4, 5, 6), dose (8, 10, 12 gl-1) and particle size (0.075, 0.090, 0.106m micron) were used in the identification of significance of the effects and interactions in adsorption studies. Response surface methodology requires no assumption and identifies the principal experimental variables and their interactions which have the greatest effect on adsorption. The optimum process parameters for maximum adsorption of Ni2+, Cu2+ and Cd2+ were obtained by this procedure.

Adsorption kinetics and column operations for the removal and recovery of malachite green from wastewater using bottom ash

The thermal power plant waste material, ‘bottom ash’ was utilized as a potential adsorbent for the toxic textile dye ‘malachite green’. Preliminary information was gathered by batch adsorption studies, which include effect of pH, adsorbent dose, contact time, adsorbate concentration and temperature. Plausible mechanism of the on-going adsorption process and thermodynamic parameters involved were obtained by carrying out kinetic measurements. The data obtained was successfully used to equate Langmuir and Freundlich adsorption isotherm models. A fixed-bed column was designed and necessary parameters were calculated by applying mass transfer kinetic approach. Attempts were also made to recover dye and regenerate the column.

Adsorption of (4-amino-2-methyl-5-pyrimidinyl methylthio) acetic acid on mild steel from hydrochloric acid solution (HCl)—Part 1

The adsorption of (4-amino-2-methyl-5-pyrimidinyl methylthio) acetic acid (AMMPTA) on mild steel from hydrochloric acid solution was studied using the weight loss and hydrogen evolution techniques. The corrosion rates of mild steel in hydrochloric acid solution containing AMMPTA are measured as a function of AMMPTA concentration. The degree of surface covered is used to calculate the free energy of adsorption, Δ G ad of AMMPTA. The variation of negative free energy of adsorption, Δ G ad with surface coverage, θ is interpreted in terms of change in mechanism of inhibitor action of AMMPTA with concentration. Phenomenon of physical adsorption is proposed. The effect of AMMPTA is discussed from the viewpoint of adsorption model. The thermodynamic parameters of adsorption process were obtained from experimental data using Bockris–Swinkels adsorption isotherm.

Determination of the Kinetic and Thermodynamic Parameters of Adsorption Processes by a Volume Step Thermal Method

A volume step method measuring the pressure and the adsorbent temperature of an adsorbent-adsorbate system has been developped. It is shown that this method allows the determination of all the relevant parameters of an adsorption process, kinetic as well as thermodynamic in case of Linear Driving Force mass transfer. The method for determining the parameters can be extended to the case of diffusive mass transfer if the mass transfer kinetics is faster than the heat transfer kinetics. An example is given, showing the determination of the diffusion coefficient of carbon dioxide in NaX zeolite pellets and the change of the diffusion coefficient and of the isosteric heat of adsorption when the adsorbent is not fully dehydrated.

Investigation of the effect of adsorption process parameters on the removal of oxygen from argon

Investigation of the effect of adsorption process parameters on the removal of oxygen from argon