title: [Removal of Phosphate by Calcite in Open-System].
abstract: Batch methods were deployed to study the removal of phosphate by calcite in an open-system. Results showed that: (1) The pre-equilibrium process of calcite in open system could be achieved within 24 hours (2) The kinetic results showed that, at initial concentration of 0.5 mg · L⁻¹, the phosphate removal was almost completed within 10 hours of the first phase. The observation may be attributed to surface adsorption. At initial concentration of 2.5 mg · L⁻¹, the phosphate removal was mainly carried out by the precipitation of phosphate at later stage of the process; (3) At initial concentration of ≤ 2.5 mg · L⁻¹ setting 10 h as reaction time, the phosphate removal process was described well by the Langmuir model. It is hypothesized that surface adsorption was the principal removal way of phosphate; (4) With the addition of phthalate, at initial concentration of < 2.5 mg · L⁻¹, the phosphate removal rate experienced a small decrease. That was because phosphate was mainly removed by surface adsorption, and thus, phthalate was a competitor to phosphate for the same adsorption site. The phosphate removal rate increased a little at initial concentration of > 2.5 mg · L⁻¹, this was because the phosphate precipitation was reinforced by the increase of calcium concentration, which was caused by phthalate addition.
authors.forename: Zhen-xuan
authors.initials: ZX
authors.lastname: Li
authors.forename: Jia-yong
authors.initials: JY
authors.lastname: Diao
authors.forename: Li-dong
authors.initials: LD
authors.lastname: Huang
authors.forename: Yan-fan
authors.initials: YF
authors.lastname: Chen
authors.forename: Da-gang
authors.initials: DG
authors.lastname: Liu
authors.forename: Zheng-wen
authors.initials: ZW
authors.lastname: Xu
mesh_terms: D000327:Adsorption; D002119:Calcium Carbonate / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D010795:Phthalic Acids
chemical_list: D010710:Phosphates; D010795:Phthalic Acids; C032279:phthalic acid; D002119:Calcium Carbonate