Comparative performance evaluation of anodic materials for electro-kinetic removal of Lead (II) from contaminated clay soil

ABSTRACT

A comparative cost-effectiveness performance evaluation of graphite, glassy carbon, irrudium coated titanium and titanium anodes during electro-kinetic removal (EKR) of Pb(II) ions from contaminated clay soil was investigated. The influences of catholyte concentration (0.2-1N), spacing between electrodes (15-25 cm), treatment time (1-3 weeks) and distance from anode(5-15 cm) on Pb (II) residual concentration were evaluated and optimized using Response Surface Methodology. The relative contribution of the operating conditions follows the order; treatment time > distance from anode > electrode spacing > catholyte concentration. All the anodes yielded high Pb(II) removal with graphite exhibiting slower performance. The electro-osmotic volumes collected at the catholyte compartments suggest electro-osmosis as dominant removal mechanism while Ir-coated titanium exerted the highest electroosmotic mobility coefficients of 0.0054 cm³s^-1, 4.98 x 10^-5 cm²V^-1s^-1 and 0.00208 cm²A^-1s^-1. The least energy expenditure of $46.21per kWh, $0.13 per kWhm^-3and $49.74 per kWh.m^-3mg^-1was attributed to graphite, followed by titanium and then Ir-coated titanium. The most exorbitant glassy carbon considerably exhibited the least performance with $2134.64 per kWh, $6.15 per kWhm^-3 and $2094.8 per kWh.m^-3mg^-1. This study underscores the relevance of taking anodic materials cost into considerations for better evaluation of EKR effectiveness for remediation of heavy metals contaminated-soils.

KEYWORDS:

• Remediation of heavy metal contaminated soils
• cost-effectiveness evaluation
• specific energy expenditure
• titanium
• graphite
• glassy carbon and iridium-coated titanium anodes
• electro-osmotic flow parameters

Acknowledgments

The authors acknowledge the finanacial support provided by King Abdul-Aziz City for Science and Technology (KACST)through NSTIP Project No. 12-Env2229-46 at Imam Abdulrahaman Bin Faisal University, Dammam Saudi Arabia.

Additional information

Funding

The authors acknowledge the support provided by King Abdul-Aziz City for Science and Technology (KACST) under NSTIP through Project No. 12-Env2229-46 at Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.