No abstract

It is essential to solve the problem of phosphorus pollution in urban landscape water and reduce the degree of eutrophication. In this paper, lanthanum-modified bentonite (La-B) was prepared by high-temperature calcination and liquid-phase precipitation. Then La-B was modified with chitosan to prepare a low-cost environment-friendly functional material: Lanthanum/Chitosan Co-Modified Bentonite (La-BC). It can reach the adsorption equilibrium within 30 min, and the maximum adsorption capacity is 15.5 mg/g (initial phosphate concentration 50 mg/L); when the target concentration is 2 mg/L, the removal rate can reach 98.5%. La-BC has a stronger anti-interference ability to common coexisting anions SO42−, HCO3−, NO3− and Cl− in the urban landscape water body. La-BC has excellent performance in weakly acidic to neutral water, and its pH applicable range has been improved, making it possible to apply in practical water. The fitting results show that the adsorption behavior conforms to the pseudo-second-order kinetic model and the Freundlich model. After 5 regenerations, the removal efficiency remained around 80%. In the actual water test results, the phosphate concentration can be controlled below 0.1 mg/L and the removal rate is above 75%. Due to its low cost and reusability, it has great potential in the practical application of phosphate removal from landscape water.

In this work, uniform polydopamine (PDA) layers by self-polymerization of dopamine were successfully coated around titanate nanotubes (TNTs) to enhance its adsorption ability. The polydopamine-functionalized titanate nanotubes (PDA-TNTs) exhibited outstanding U(VI) adsorption capacity (247.53 mg/g) and rapid adsorption efficiency. The nitrogenous groups and phenolic hydroxyl groups of PDA coordinating with UO22+ was dominant, while ion exchange between Na+/H+ and U(VI) was of secondary importance. Besides, the introduction of PDA significantly alleviated the competitive adsorption between U(VI) and coexisting metal ions, making it possible for PDA-TNTs to be an effective sorbent to remove U(VI) in radioactive wastewater.

Titanate nanotubes was rapidly synthetized by nano anatase with mild hydrothermal method, and its protonation was carried by Nitric acid to prepare TNTs and TNTs-H with different H+/Na+ for further application of uranium removal in the wastewater. It was characterized by XRD, TEM and FT-IR. The results showed that at 298 K and pH 7, the adsorption rates of TNTs and TNTs-H to 10 mg/L U(VI) were 77.90% and 97.78% respectively, and the maximum adsorption capacity of U(VI) were 41.494 mg/g and 49.505 mg/g respectively. The adsorption processes all followed a pseudo second-order kinetic model and were in accordance with isotherm adsorption models like Langmuir model.