Study On Phosphorus Removal Effect Of Iron-Based Composites And Its Modified Quartz Sand

Eutrophication of water has become a global environmental problem in recent years.In 2018,29%of China's lakes are still in a state of mild and moderate eutrophication.Phosphorus as a nutrient element has an important impact on the organisms in the waters,especially the algae in the water environment has a wider range,and it is one of the main elements leading to eutrophication of water.In order to reduce the occurrence of eutrophication and reduce the harm of phosphorus to water,advanced treatment of phosphorus-containing wastewater is necessary.In this paper,different methods are used to prepare iron-based composites?iron-based adsorbents?and iron-based composite-modified quartz sands,and the phosphorus removal efficiency is studied.The influence of p H,interfering ions and other factors on the adsorption efficiency,and its adsorption mechanism was analyzed through characterization.The experimental results show that:?1?The iron-based adsorbent prepared by the heating method has a good phosphorus removal effect.The main removal mechanism is the exchange of phosphate ions with-OH on the iron-based adsorbent.The reaction process is an anion replacement reaction,which belongs to chemical adsorption.And the adsorption reaction is easier to proceed.The influence of p H value on iron-based adsorbent is obvious.When the H⁺concentration in the solution is increased,the adsorption reaction will be promoted,and the adsorption and removal rate of phosphorus by the iron-based adsorbent will be increased.Interfering ion adsorption experiments show that when Cl^-,NO3^-,SO4^2-is present in the phosphorus-containing solution,the iron-based adsorbent will have an effect on the removal of phosphorus,and the order of influence is SO4^2->NO3^->Cl^-.Characterization and analysis of iron-based adsorbents,it was found that the iron-based adsorbent did not form a stable crystal form;the phosphorus element apparently appeared after adsorption,indicating that the iron-based adsorbent has adsorbed phosphorus;The distribution of phosphorus adsorption sites on iron-based adsorbents is relatively uniform.?2?Phosphorus removal experiment results of iron-based composite-modified quartz sand prepared by various methods such as dipping method,heating method,shaking method,shaking dipping method,and alkaline deposition show that iron-based compounds prepared at 60?The composite modified quartz sand has a good adsorption effect on phosphorus,with a saturated adsorption capacity of 20.94?g/g.The limiting factors when using iron-based composite-modified quartz sand as a filter material to remove phosphorus are the thickness of the filter material layer and the filtration speed.It shows that the higher thickness of the filter material layer and the slower the filtration speed,the longer the phosphorus sand retention time and the reaction time of the quartz sand,and the phosphorus removal effect is more obvious.Characterization analysis showed that the iron-based composite was evenly distributed on the surface of the quartz sand.After the adsorption reaction,phosphorus was obviously adsorbed on the surface of the quartz sand,and a small amount of phosphorus was still adsorbed at the position of the iron-free composite.Physical and chemical adsorption coexist.