Preparation and application of modified activated carbon for effective removal of phosphorus from glyphosate by-product salt

Glyphosate is a non-selective, residue-free insecticidal herbicide, and its byproduct salts obtained through evaporation and concentration have high phosphorus content, thus preventing resource utilization. In this paper, cerium- aluminum- modified activated carbon (Ce/Al- AC) adsorbent was synthesized by loading cerium-aluminum into the interior and surface of activated carbon using the oil bath method with activated carbon as the raw material. Phosphorus removal using activated carbon composite adsorbent and the influences of pH, initial waste salt concentration, modified activated carbon addition, and adsorption time on the phosphorus extraction effectiveness of modified activated carbon were investigated in a controlled variable manner. As part of the characterization of the adsorbent, scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy were performed. The experimental results show that under the conditions of 10 g/L glyphosate waste salt solution, the initial phosphorus concentration of 32.67 mg/ L, the amount of adsorbent addition of 10 g/L, pH 7, and the adsorption time of 180 min, the phosphorus removal rate of unmodified activated carbon is 36.2%. In contrast, the rate of modified activated carbon can reach more than 99%. With the modified activated carbon adsorbent, a pH range of 3-11 was effective for adsorption, with the best adsorption performance observed at neuter pH. Phosphorus removal followed Langmuir (R-2 = 0.921) models. The theoretical adsorption capacity reached 8.13 mg/ g. The total phosphorus content was decreased to below 0.5 mg/L. This study demonstrates that modified activated carbon has potential value in the treatment of glyphosate byproduct salt and high-salinity wastewater.