Immobilization of phosphorus from water and sediment using zirconium-modified zeolites

Abstract

Adding sorbents to sediments has been suggested as an effective technology for contaminated sediment remediation. In this study, a zirconium-modified zeolite (ZrMZ) was prepared, characterized, and used as a sediment amendment to control phosphorus (P) release from eutrophic lake sediments. The efficiency of ZrMZ in immobilizing P from water and sediments was investigated through a series of experiments. The phosphate adsorption capacity for ZrMZ decreased with increasing water pH. The adsorption of phosphate on ZrMZ followed a pseudo-second-order kinetic model. The equilibrium adsorption data of phosphate on ZrMZ could be well described by the Langmuir isotherm model with a maximum monolayer adsorption capacity of 10.2 mg P/g at pH 7 and 25 °C. Sequential extraction of P from the phosphate-adsorbed ZrMZ suggested that most of P bound by ZrMZ existed as the NaOH extractable P (NaOH-P) and residual P (Res-P) and was unlikely to be released under natural pH and reducing conditions. The addition of ZrMZ into sediments reduced the inorganic P activity in the sediments by transforming bicarbonate-dithionite extractable P (BD-P) to NaOH-P and Res-P. The contents of bioavailable P such as water-soluble P (WS-P), NaHCO3 extractable P (Olsen-P), and algal available P (AAP) in sediments reduced after the sediments were mixed with ZrMZ, making P in the sediments more stable. The addition of ZrMZ into sediments significantly reduced the releasing flux of P from the sediments to the water column under different conditions. Results of this study indicate that the ZrMZ is a promising sediment amendment for controlling the internal P loading of lake sediments.

Adsorption of phosphate in water using one-step synthesized zirconium-loaded reduced graphene oxide

“…Beside, RGO was successfully obtained from GO in pure water without using any reductant or surfactant, and ZrO 2 was tightly integrated on the RGO surface during the hydrothermal treatment. Furthermore, RGO-Zr could easily be applied for small-scale treatment facilities or wastewater with relatively low phosphate concentrations, while some reported phosphate adsorbents in the literatures2741 have higher equilibrium concentrations of phosphate after treatment.…”

“…However, at higher initial phosphate concentrations of 1.00, 3.00 and 5.00 mg/L, the adsorption reached equilibrium within 40, 250 and 375 min, respectively. The pseudo-first-order and pseudo-second-order equations were further used to model the kinetics data using a linear fitting, with the models expressed in equations (7) to (8) 2:…”

“…The constant k 2 is used to calculate the initial adsorption rate h (mg/(g h)) at t → 0 according to equation (9) 2:…”

“…Water eutrophication could lead to several harmful effects, including the destruction of the aquatic life, deterioration of water quality, and even have a hazardous influence on humans12. As a result, removal of excessive phosphorus is important for controlling water eutrophication.…”

Applicability of drinking water treatment residue for lake restoration in relation to metal/metalloid risk assessment

“…Satisfactory results have thus far been achieved by using various commercial materials, such as aluminum (Al) salts5, iron (Fe) salts6, and La-modified bentonite clay (Phoslock ® )7. However, to obtain environmental benefits and attain economic viability, low-cost industrial byproducts8 and naturally occurring or modified mineral complexes910 have also been tested for eutrophication control.…”