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Surface modification of adsorbents plays a crucial role in its adsorption performance. Furthermore, the most important step in modification is to design the modification groups based on target pollutants. In this study, the phosphate adsorption performance of zirconium hydroxide was enhanced by different ammonium modification as a result of increasing utilization efficiency of adsorption site. The maximum capacity is 155.04 mg/g from the zirconium hydroxide modified by dimethylamine. In comparison with undecorated zirconium hydroxide, the selectivity factors for Cl − , SO 4 2− , and NO 3 − are all raised by almost 2 times by dimethylamine modification. The mass transfer rate K 2 also increase 6 times using N-methylaniline and N-ethylmethylamine. Results from zeta-potential and FT-IR revealed that the enhanced adsorption capacity for phosphate were directly related to the inner-sphere complex and electrostatic interactions (quaternary ammonium groups and phosphate) and ligand exchange (the hydroxyl groups of zirconium hydroxide and phosphate). Moreover, the utilization ratios of hydroxyl groups on adsorbents were improved from 22.9% to 33.9% by dimethylamine modification, which is proved by XPS. At last, the modified zirconium hydroxide presents excellent performances of anti-interference in real wastewater. Overall, modified zirconium hydroxide is considered to have great potential for engineering application, and then the method of increased utilization of the adsorption site gives a new route for other adsorption systems.

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N-(Phosphonomethyl)glycine (glyphosate, PMG) is an effective broad-spectrum organic phosphoric herbicide. The mass production and wide use of PMG presents a potential environmental hazard. This study evaluated the feasibility of using montmorillonite (MT) as an adsorbent to remove PMG from wastewater in the presence of Fe(III) ions. The results showed that the PMG adsorption process is dependent on the Fe(III) concentration. Adsorption was fast, and the adsorption kinetics were best described by a pseudo-second-order model. Adsorption of PMG was most effective over the pH range from 1.9 to 4.1. Ionic strength was found to have little effect on PMG removal at pH < 4.1 but to enhance PMG removal at pH > 4.1. Competing ions reduced the PMG removal at low pH (pH < 5.9) but increased the PMG removal at pH > 5.9. The adsorption capacity was found to be greater than 210 mg/g. The mechanism of this removal process is discussed in detail in terms of XRD and species calculations.