Phosphorus adsorption from aqueous solutions using different types of cement: kinetics, isotherms, and mechanisms

Xingyu Yu; Yongqiang Yang; Hanxiao Zhang; Shijun Wu; Fanrong Chen; Runliang Zhu

doi:10.1039/d4ra01929f

Phosphorus adsorption from aqueous solutions using different types of cement: kinetics, isotherms, and mechanisms

RSC Adv. 2024 May 14;14(22):15637-15646. doi: 10.1039/d4ra01929f. eCollection 2024 May 10.

Authors

Xingyu Yu^{1

2

3}, Yongqiang Yang^{1

2}, Hanxiao Zhang^{1

2

3}, Shijun Wu^{1

2}, Fanrong Chen^{1

2}, Runliang Zhu^{1

2}

Affiliations

¹ CAS Key Laboratory of Mineralogy and Metallogeny, Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences 511 Kehua Street 510640 Guangzhou China yqyang@gig.ac.cn.
² CAS Center for Excellence in Deep Earth Science 511 Kehua Street 510640 Guangzhou China.
³ University of Chinese Academy of Sciences 19 Yuquan Road 100049 Beijing China.

Abstract

Exploring low-cost and high-performance phosphorus (P) adsorbents is key to controlling P contamination in water. This study evaluated the P adsorption performance of three types of cement: Ordinary Portland cement (OPC), Portland slag cement (PSC), and Portland pozzolana cement (PPC). Furthermore, SEM-EDS, XRD, XPS, and FTIR were employed to reveal the adsorption mechanism. The results showed that the pseudo-second-order model exhibited higher regression coefficients than the pseudo-first-order model, indicating that chemisorption dominated the adsorption process. The Langmuir equation fitted the P adsorption data well, with maximum P adsorption capacities of 245.8, 226.1, and 210.0 mg g^-1 for OPC, PSC, and PPC at 25 °C, respectively. P adsorption capacities decreased gradually with increasing initial pH and reached their maximum values at pH 3. The anions of F^-, CO₃^2-, and SO₄^2- negatively affected P adsorption due to the competitive adsorption with Ca²⁺. The results of XPS, XRD, and FTIR confirmed that Ca-P precipitates (i.e., hydroxyapatite) were the main removal mechanism. A real domestic sewage experiment showed that 0.6 g L^-1 OPC effectively reduced the P concentration from 2.4 to below 0.2 mg L^-1, with a dosage cost of 0.034 $ per ton. This study indicated that cement, as a low-cost and efficient P adsorbent, has great potential for application in removing P from acidic and neutral wastewater.