Modified attapulgite for phosphorus removal from glyphosate by-product salt solution

Glyphosate is an organophosphorus herbicide, and has been widely used in agriculture. The glyphosate by-product salt is an intermediate product of glyphosate. The total phosphorus and total organic carbon contents of the by-product are high. Thus, achieved resource utilization is difficult. Attapulgite is often used as an adsorbent because of its large specific surface area and low price. In this study, a new strategy of phosphorus removal for glyphosate by-product salt utilization was developed by using attapulgite modified phosphorus removal agent. Three types of attapulgite, grey white–palygorskite clay (ATP1), opal–palygorskite clay (ATP2) and dolo- mitic–palygorskite clay (ATP3) were used for phosphorus removal by adsorption. The effects of attapulgite types, calcination temperature, chemical modification on the phosphorus removal from glyphosate by-product salt solution were studied. The modified attapulgite was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and Fourier- transform infrared spectroscopy. The ATP3 was calcined at 700°C, and the total phosphorus removal rate can reach 96.96%. The phosphorus removal rate of Al and Fe loaded the third of attapulg- ite composite (Al/Fe-TATPIII) can reach 99.97%. The adsorption isotherm is consistent with the Langmuir model. The theoretical adsorption capacity reaches 14.59 mg g –1 , which conforms to the pseudo-second-order adsorption kinetic model.