Electrochemical regeneration of glyphosate-saturated carbon as an alternative for activated carbon reutilization

One of the challenges in removing contaminants of emerging concern is the reduced efficiency due to their low concentrations in the natural environment. To overcome this, a pre-concentration step can be applied, followed by the degradation of the contaminant. In this sense, adsorption on activated carbon (AC) can be used in the first step, while anodic oxidation is suitable for eliminating the pollutant and regenerating the carbon. This work applies, for the first time, this principle to treating synthetic wastewater contaminated with glyphosate (GLY). First, the adsorption of GLY onto the AC is studied at different pHs, observing a more intense adsorption in acid pH, whereas the adsorption weakens in neutral and alkaline pH. Furthermore, the addition of NaCl reduces the GLY adsorption on AC. The subsequent electrochemical regeneration (ER) is applied to the saturated AC under different currents for five consecutive cycles in a batch reactor equipped with a boron-doped diamond anode. The results demonstrate that the ER is effective in recovering carbon adsorption capacity with levels above 80% compared to the initial capacity after the five consecutive cycles if a current of 0.3 A is applied. Thus, this work intends to demonstrate that the ER can play a critical role in the AC circular economy, making its reutilization possible when applied, as in this case, to the GLY removal.

Automated summary

One challenge in removing emerging contaminants is the low concentrations in the environment, which reduces efficiency. To overcome this, a pre-concentration step and contaminant degradation can be applied. This study demonstrates the use of activated carbon adsorption and anodic oxidation for the treatment of GLY-contaminated wastewater.