Danny C.K. Ko

Optimised correlations for the fixed-bed adsorption of metal ions on bone char

The sorption of two divalent metal ions, namely, copper and cadmium ions, has been studied due to their toxicity in nature and extensive use in industry. Fixed-bed column experiments with different feed concentrations, flowrates and adsorbent particle sizes have been carried out, evaluating sorption of these two metal ions on bone char. Pilot-plant experimental studies have been performed and two simplified design models, namely, the BDST model and EBRT analysis, have been used to analyse the data. New correlations, incorporating a time-dependent term, have been developed to compensate for the time required for the bed to achieve equilibrium sorption capacity. Finally, predictions of the operating lines on the EBRT plot have been correlated using the two metal ion sorption systems.

Municipal Solid Waste Utilization for Integrated Cement Processing with Waste Minimization: A Pilot Scale Proposal

A novel design of an integrated process for cement production incorporating municipal solid waste (MSW) separation and combustion has been developed. The novel design offers significant opportunities for waste minimization. The MSW combustion system design incorporates the use of supplementary fuel from waste marine oil. Very high temperature, 1200C, high turbulence and high residence time, >4 s, are achieved. This results in very high burnout of MSW, resulting in negligible particulate organic matter to form dioxin by de-novo synthesis. The energy produced is used for the cement process calcination of limestone and residual heat is converted into energy to drive the cement plant. The calcination process itself is used as a large scrubber to remove SO x and HCl, the latter minimizing the chance of dioxin formation further. A front end materials recovery and recycling facility, MRRF, is used to remove valuable recyclable components, chlorine-based plastics and metal-containing materials, such as batteries. The combustion of the MSW achieves a 85–90% volume reduction and the MSW ash is used as a feedstock for the production of the cement clinker.

Fixed Bed Studies for the Sorption of Metal Ions onto Peat

In this study, peat has been used as an adsorbent for the removal of heavy metals in a fixed bed system. Experiments have been performed to investigate the effect of flowrate and bed depth on the peat–metal ion system. A film-pore diffusion model has been used to predict the breakthrough behaviour. The three major parameters in the mathematical model are the external mass transfer coefficient, k , the effective pore diffusivity D eff , and the solid-phase loading capacity, q e . One of the main problems in this type of modelling is the prediction of q e , particularly for sorbent–solute systems which take a long time to achieve equilibrium saturation. Some researchers have used the equilibrium isotherm capacity, some utilize a fixed fraction of the isotherm capacity and other workers perform the numerical or graphical mass balances at the breakthrough curves, which is time-consuming and tedious. The present method incorporates a novel empirical solution for q e which is correlated with the service time. Good agreement between the predicted theoretical breakthrough curves and the experimental results is observed.

A branched pore model analysis for the adsorption of acid dyes on activated carbon

A new branched-pore adsorption model has been developed using an external mass transfer coefficient, Kf, an effective diffusivity, Deff, a lumped micropore diffusion rate parameter, Kb, and the fraction of macropores, f, to describe sorption kinetic data from initial adsorbent-adsorbate contact to the long-term adsorption phase. This model has been applied to an environmental pollution problem—the removal of two dyes, Acid Blue 80 (AB80) and Acid Red 114 (AR114), by sorption on activated carbon. A computer program has been used to generate theoretical concentration-time curves and the four mass transfer kinetic parameters adjusted so that the model achieves a close fit to the experimental data. The best fit values of the parameters have been determined for different initial dye concentrations and carbon masses. Since the model is specifically applicable to fixed constant values of these four parameters, a further and key application of this project is to see if single constant values of these parameters can be used to describe all the experimental concentration-time decay curves for one dye-carbon system.The error analysis and best fit approach to modeling the decay curves for both dye systems show that the correlation between experimental and theoretical data is good for the fixed values of the four fitted parameters. A significantly better fit of the model predictions is obtained when Kf, Kb and f are maintained constant but Deff is varied. This indicates that the surface diffusivity may vary as a function of surface coverage.

Effect of Concentration-Dependent Surface Diffusivity on Simulation of Fixed Bed Sorption Systems

The sorption of cadmium and copper ions onto bone char has been studied. The equilibrium data have been analysed using the Langmuir and the Sips isotherm equations. A series of fixed bed sorption studies have been undertaken for the two single component systems to study the effects of various system parameters, including initial metal ion concentration, solution flowrate and bone char particle size. A new mass transfer model has been developed based on external mass transfer and surface diffusion. This model has been tested using both isotherms and incorporating a variable surface coverage. Both metal ion systems have been correlated using this diffusion model and the experimental breakthrough curves with good agreement.