A green desorption process and an effective electrochemical treatment of desorbed highly polluted solution.

Abstract

This invention aims to find out a sustainable and cost-effective option for the management of dyes-rich effluent produced by textile industries. It consists on the following steps: i) preparation of an alkaline-modified lignocellulosic biomass by stirring orange tree sawdust into a 0.14 M NaOH solution at ambient temperature and 1 h of contact time, ii) the effective adsorption of dyes from effluents by this adsorbent in column mode, iii) the desorption of the loaded alkaline-modified adsorbent in column mode by using a filtered seawater solution though a paper filter having a porosity of 0.45 µm, iv) the recovery of the dye as a solid phase from the highly-concentrated desorbing solution by decantation at 4 °C. This solid phase can be used again in others similar dyeing processes, v) the degradation of the residual dye in the desorbing solution through electrochemical treatment under galvanostatic mode by using a boron-doped diamond layer (BDD) as anode / cathode with 1 mm gap between at T= 25°C. The generated active radicals (HCIO and CIO) from the Cl ions existing in the seawater ensure a high discoloration and total organic carbons degradation with a remarkably low consumed energy. The treated wastewater may be reused again by the company inside or outside their dyeing process.