Research On Phosphate Adsorption Ability Of Treated Waste Rare Earth Polishing Powder

In view of solid waste recycling and development and utilization of high effective phosphorus adsorption material, this research has discussed an effective way of converting waste rare earth polishing powder into MLP (Modified Lanthanide Polishing Powder) phosphorus adsorption material. It promises an approach to advanced phosphorus removal and solid waste recycling.It was found that the raw waste material could be transformed into a feasible phosphate adsorption agent by acid treatment under heating followed by alkaline treatment. The preferential transformation condition was the following: sulfuric acid concentration 2 mol/L, heating temperature 90℃, and drying temperature 80℃, respectively.Adsorption performance of MLP adsorption material was studied by a series of batch adsorption experiments. It was verified that MLP adsorption material could keep rather high adsorption ability at a wide pH range of 4-10, whereas common coexistent anions such as Cl-, SO42-, and NO3- have had little adverse influence.The adsorption rates at low pH and at low initial phosphorus concentrations were faster than that at high pH value and at high concentrations, and were fast enough at the beginning stage in spite of different pH and concentrations. The adsorption reaction was tentatively first-order reaction by fitting Lagergren equation. The reaction could be divided into two stage, the first stage was diffuse controlled reaction and the second was chemisorption controlled one.The adsorption isotherm study concluded that Langmuir adsorption dominated the reaction and Freundlich adsorption also played a role. An adsorption heat of +34.87 kJ/mol was determined based on the Langmuir adsorption isotherm, indicating that the adsorption was endothermic and entropy-driven.Desorption study showed that the appropriate desorption condition of adsorbed MLP adsorption material was 100 mL NaOH of 2 mol/L. Resorption study proved that it was very likely to regenerate adsorbed MLP adsorption material and to reuse it.