Effect Of Quaternization And Iron-loaded Composite And Modified Reed On Phosphorus Adsorption

Straw is an important agricultural by-product.As a large agricultural country,China's annual straw output exceeds 900 million tons,and the comprehensive utilization rate is only about 30%,which causes a large amount of waste of resources and easily causes environmental pollution problems.At the same time,excessive phosphorus is discharged into the water,causing an excessive amount of plant nutrients in the water body,resulting in eutrophication of the water body.Adsorption has significant advantages in removing phosphorus from water.At present,ion exchange resins with good adsorption effect on the market are expensive and difficult to be widely used.Therefore,it is of practical significance to use cheap and readily available agricultural waste to prepare anionic adsorbents.In this paper,quaternary amine groups with positively charged properties were introduced into reed straw through ammonium reaction.At the same time,the strong ligand adsorption of phosphorus on iron is used.The composite adsorption materials were prepared by Fe³⁺and quaternary amine groups.The single-factor test and the response surface method based on Box-Behnken design were used to investigate the effects of four single-factor variables on the removal rate of PO₄^3-and their interactions.;Using scanning electron microscopy and other testing methods to characterize the morphological characteristics and physicochemical properties of modified reed rods;investigate the phosphorus adsorption characteristics of modified reed straw adsorbents under different influencing factors,and combine the Langmuir and Freundlich adsorption isothermal models to study phosphorus According to the adsorption kinetics and diffusion model,the kinetic characteristics of phosphorus removal by modified reed straw were analyzed.The adsorption mechanism was discussed based on the above research.The desorption of modified reed straw adsorbent was studied,and the toxicological analysis of materials was carried out to explore the practical application significance and the possibility of popularization of the modified method.The optimal conditions predicted by the model are a sodium hydroxide concentration of 7.7%,a crosslinking temperature of 81?,an ammonium tempe rature of 80?,and an iron salt concentration of 24%.When the pH is 8.5 and the dosage is 4g/L,the two modified reed straws have relatively good adsorpt ion effect.Because of the chemical reaction between Fe³⁺and PO₄^3-and the ad sorption of Fe-O and PO₄^3-polar molecules in iron-supported aminated reed straw,the removal effect of PO₄^3-is better.At the same time,it is less affected under extreme pH conditions and maintains a high stability,which confirms that the modified reed straw material after iron loading is far superior to the quat ernized modified reed straw;Grade kinetic model can better describe the adsorption kinetics of PO₄^3-on two modified materials.At a phosphorus solution concentration of 2mg·L^-1 and a temperature of 303K,the equilibrium adsorption amount of iron-loaded aminated reed is 0.31 mg·g^-1,which is 2.21 times the adsorption amount of aminated reed.The Langmiur equation can better fit the adsorption isotherms of the two adsorbents,and also has a larger adsorption capacity at a lower concentration.Modified reed straw material after saturated adsorption.The better desorption conditions are to use NaOH as the desorbent,the concentration is 2.0 mol/L,desorption temperature at 30?,desorption time at 30 min,and the maximum to tal phosphorus recovery is about 78.6%.