## 2 Materials and Methods
### Research Method
#### 2.3.4 Experimental Setup and Methods for Static Adsorption Phosphorus Removal Tests  
* Isothermal Adsorption Experiments  
Nine portions of 1 g Zr-EPRC particles were meticulously weighed and placed into 250 mL conical flasks. Subsequently, 0.5 mg/L, 5 mg/L, 10 mg/L, 30 mg/L, 60 mg/L, 100 mg/L, 150 mg/L, 200 mg/L, and 300 mg/L of \"KH2 PO4\" solution were separately added to these flasks. These solutions were subjected to an adsorption test within a constant temperature water bath shaker operating at 25 \(\pm\) 1 \({}^{\circ}\)C and 150 rpm. After reaching adsorption equilibrium, the supernatant of each solution was aspirated to determine the remaining phosphorus concentration in the adsorbed liquid.
* Adsorption Kinetics Experiments  
Different Initial Concentrations: Four portions, each containing 3 g of Zr-EPRC particles, were weighed and placed into separate 250 mL conical flasks. Next, 250 mL of \"KH2 PO4\" solution with concentrations of 5 mg/L, 10 mg/L, 15 mg/L, and 20 mg/L were added to the respective conical flasks. These flasks were then placed within a constant temperature water bath shaker at 25 \(\pm\) 1 \({}^{\circ}\)C and 150 rpm. At intervals of 1 h, 3 h, 6 h, 9 h, 12 h, 18 h, 24 h, 36 h, and 48 h, the supernatant of each solution was aspirated, and the residual phosphorus concentration in the adsorbed liquid was determined.  
Different Initial Temperatures: Three portions, each containing 3 g of Zr-EPRC particles, were weighed and placed into separate 250 mL conical flasks. In these flasks, 250 mL of 20 mg/L \"KH2 PO4\" solution was added. The conical flasks were then positioned within a thermostatic water bath shaker (150 rpm) set at temperatures of 15 \({}^{\circ}\)C, 25 \({}^{\circ}\)C, and 35 \({}^{\circ}\)C. The adsorption time was maintained at 1 h, 3 h, 6 h, 9 h, 12 h, 18 h, 24 h, 36 h, and 48 h, and the supernatant of each solution was aspirated at these intervals to determine the residual phosphorus concentration in the adsorbed liquid.  
* One-way Adsorption Experiments  
Dosage Experiment: Various quantities (ranging from 0.5 g to 4.0 g) of Zr-EPRC particles were weighed into 250 mL conical flasks. To each flask, 250 mL of 5 mg/L \"KH2 PO4\" solution was added. The adsorption was allowed to proceed for 48 h within a constant temperature water bath shaker (25 \(\pm\) 1 \({}^{\circ}\)C, 150 rpm). The supernatant of the adsorbent was then extracted, and the phosphorus concentration in the adsorbent was determined using ammonium molybdate spectrophotometry. Subsequently, the adsorbed amount of phosphorus and the phosphorus removal rate were calculated.  
pH: Five portions of 5 g Zr-EPRC adsorbent material were immersed in a phosphorus solution with an initial concentration of 10 mg/L. The pH levels of these solutions were adjusted to 3, 5, 7, 10, and 12 using 1 mol/L NaOH and 1 mol/L hydrochloric acid solutions. Static adsorption was carried out at a constant temperature of 25 \({}^{\circ}\)C. At intervals of 3 h, 6 h, 9 h, 12 h, 24 h, 36 h, and 48 h, the phosphorus concentration in the solution was determined.  
Co-existing Anions: Solutions with a phosphorus concentration of 10 mg/L were prepared by introducing various anions such as \"NaHCOs\", \"NaCl\", \"Na2 SO4\", and \"NaNO\({}_{3}\)\" into the phosphorus-containing solution. This was carried out to achieve ratios of phosphate to anion of 1:1 and 1:5 in the solution. A solution containing only phosphate served as a blank control. In each solution, 1 g of Zr-EPRC particles was added, and static adsorption experiments were conducted to assess changes in the adsorption capacity of Zr-EPRC materials.