A novel approach to epoxy coating removal from Waste Printed Circuit Boards by solvent stripping using NaOH under autoclaving condition

Abstract

The Printed Circuit Board (PCB) was an insulating material as a whole, but having conductive lines printed over it or etched from it and found virtually in all sorts of Electrical and Electronic Equipment (EEE). To process the PCB in an environmentally sound manner, various techniques were under research to reduce the toxicity in the treatment process. Toxicity can be reduced by removing the epoxy coating from the PCB. In our present investigation, solvent stripping combined with autoclave treatment at 121 °C temperature under a pressure of 1.1 kg/cm2 results in 100% epoxy removal efficiency for concentration varying from 0.25 N to 4 N of Sodium hydroxide. Epoxy was completely peeled off from WPCB at a treatment time of 1 h at 0.25 N of Sodium hydroxide prior to recycling WPCB for its metals. Sodium hydroxide was regenerated by filtering the solution through Whatman No.1 filter paper of 125 mm diameter circles having a pore size of 11 μm using vacuum filtration. Sodium hydroxide regeneration was analyzed with the help of Fourier Transform Infra-Red spectroscopy analysis and the metals like copper and lead were leached from WPCB during the pre-treatment process in the NaOH solution was analyzed using Atomic Absorption Spectroscopy.

Keywords

• Solvent stripping
• Auto-clave treatment
• WPCB
• Electronic waste
• Epoxy coating removal
• Pre-treatment