No abstract

No abstract

Studies on the removal of lead(II) ions by adsorption onto indigenously prepared bamboo dust carbon (BDC) and commercial activated carbon (CAC) have been carried out with an aim to obtain data for treating effluents from metal processing and metal finishing industries. Effect of various process parameters has been investigated by following the batch adsorption technique at 30±1°C. Percentage removal of lead(II) ions increased with the decrease in initial concentration and increased with increase in contact time and dose of adsorbent. Amount of lead(II) ions adsorbed increases with the decrease in particle size of the adsorbent. As initial pH of the slurry increased, the percentage removal increased, reached a maximum and the final solution pH after adsorption decreases. Adsorption data were modeled with the Freundlich and Langmuir isotherms, the first order kinetic equations proposed by Natarajan – Khalaf, Lagergren and Bhattacharya and Venkobachar and intra- particle diffusion model and the models were found to be applicable. Kinetics of adsorption is observed to be first order with intra-particle diffusion as one of the rate determining steps. Removal of lead(II) ions by bamboo dust carbon (BDC) is found to be favourable and hence BDC could be employed as an alternative adsorbent to commercial activated carbon (CAC) for effluent treatment, especially for the removal of lead(II) ions

No abstract

No abstract

Studies on the removal of cadmium(II) ions from aqueous solutions by adsorption on various activated carbons [commercial activated carbon (CAC) and chemically prepared activated carbons (CPACs) from raw materials such as straw, saw dust and datesnut] have been carried out with an aim to obtain information on treating effluents containing Cd(II) ions. Factors influencing the adsorption of Cd(II) ions from aqueous solution by ACs have been investigated by following a batch adsorption technique at 30 ± 1 • C. The percentage removal increased with decrease in initial concentration and particle size of CPACs and an increase in contact time, dose and initial pH of the solution. Adsorption process was inhibited by the added electrolytes. The adsorption data were fitted with the Langmuir, Dubinim-Radushkevich and Freundlich isotherms and first-order kinetic equations viz., first-order, Lagergren and Bhattacharya-Venkobachar equations and intra-particle diffusion model. The kinetics of adsorption is first order with intra-particle diffusion as one of the rate determining steps. Thermodynamic parameters were obtained from equilibrium constants measured at 30, 35 and 40 • C (Error = ±1 • C). Results of the studies on adsorption of Cd 2+ ions from simulated wastewater were compared with that of CAC and Tulsion CXO-9(H), a commercial ion exchange resin/cationic resin (CR). Straw carbon showed the maximum adsorption capacity towards Cd 2+ ions and a high value of rate constant of adsorption. Straw carbon is an alternative low-cost adsorbent to CAC.

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.

The present study envisages a method to remove phenol from the phenolic effluents by the electrooxidation under alkaline conditons. Synthetic effluent containing phenol (100 ppm) is subjected to electrolysis under various experimental conditions inorder to find out the optimum conditions for the removal of phenol. An electrolysis cell was designed with graphite electrodes and electrolysis was carried out under galvanostatic conditions keeping the total quantity of current at 0.75 A h. The reduction in concentration of phenol was analysed in terms of COD. Continuous electrolysis was also carried out at optimum conditions (current density: 4 A dm 2 , phenol: 100 ppm and supporting electrolyte: 1M NaOH) to find out the maximum removal of phenol. The removal of phenol from phenolic effluents is found to be highly efficient to the extent of 98.55%. The electrooxidation of phenol at anode leads to the formation of carbon di-oxide and water. The study reveals that, the phenol can 2186 KANNAN ET AL. be almost completely oxidised at the graphite anode with a maximum current efficiency of 17%. It is concluded that, the phenol can be removed from phenolic effluents effectively by electrooxidation method.