Study On The Removal Of Oxic Acid From Water By Lanthanum Modified Biomass Carbon And Its Mechanism

As a big developing country,China has been plagued by environmental problems while enjoying rapid economic development.Since the critical battle of pollution prevention and control was carried out in the 13 th Five-Year Plan,China’s ecological environment and water resource quality have been improved to some extent,but the harm of oxygen-containing acid in water environment is still serious,especially the chromate phosphate.Due to the relatively low ability of removing anions,original biochar(BC)is often modified to enhance the adsorption capacity of oxygen-containing acid groups.However,rare earth metal oxides represented by lanthanum oxide have strong complexing ability to anions,so lanthanum modified biochar can effectively adsorb oxygen-containing acid roots in wastewater.In this paper,two kinds of algae polysaccharides were extracted.Lanthanum-loaded biochar adsorbent was prepared by sodium alginate and kappa-carrageenan as raw materials,and its removal mechanism of excessive hexavalent chromium and phosphate in water was studied.Using sodium alginate as raw material and lanthanum chloride as coagulating bath,sodium alginate fiber loaded with lanthanum was prepared by wet spinning technology and pyrolysis to prepare biomass based carbon fiber(La-BC),which was used to study its adsorption behavior and mechanism of hexavalent chromium.A series of characterization of La-BC and adsorption experiments proved that La-BC has excellent adsorption capacity for chromate,has the advantages of large adsorption capacity,fast adsorption rate and strong recoverability.The data showed that the adsorption process of Cr(VI)by La-BC was in good agreement with the Langmuir and Freundlich adsorption isotherm model,indicating the existence of both monolayer and multi-layer adsorption.In addition,the coexistence ion experiment showed that phosphate had a greater impact on the adsorption of hexavalent chromium,that is,there was a competitive adsorption between hexavalent chromium and phosphate.The adsorption mechanism of La-BC for hexavalent chromium includes electrostatic interaction and complexation of oxygen-containing functional groups by ion exchange,etc.The outstanding performance of La-BC in the treatment of chromium containing wastewater has proved its environmental protection and economic benefits.The above adsorbents La-BC were used in phosphate adsorption experiments to study the influence of experimental parameters such as carbonization temperature,adsorption time,adsorption temperature and p H on the phosphate adsorption effect.The data show that La-BC has a high selectivity for phosphate adsorption,and the removal rate can generally reach more than 80%.The high adsorption capacity of phosphates by La-BC may be attributed to its tubular fiber structure,large specific surface and abundant adsorption sites,which are conducive to capturing phosphates.The adsorption of phosphate by La-BC conforms to the Langmuir isotherm model,and the variation of the adsorption amount with time follows the pseudo-second-order adsorption kinetics,indicating that the reaction process is dominated by monolayer chemisorption.The relationship between the adsorption amount and the adsorption temperature indicated that the adsorption process of La-BC for phosphate was spontaneous endothermic.At room temperature and neutral conditions,the saturated adsorption amount of La-BC(900℃)for phosphate reached 163.9 mg/g.In addition,the recycling experiment shows that La-BC has a high recycling efficiency,which proves that La-BC has a broad application prospect in the field of sewage treatment.Based on the favorable treatment effect of La-BC on phosphate,the κ-carrageenan biochar(κ-LC)supported on lanthanum was generated by pyrolysis of another Marine biomass to investigate whether lanthanum has specific adsorption on phosphate and its adsorption mechanism.The results showed that the adsorption capacity of κ-LC for phosphate in water was 157.6 mg/g at room temperature and neutral conditions.The mechanism of removal of phosphate from water by κ-LC was mainly composed of precipitation,electrostatic interaction,ion exchange and inner sphere complexation.The above two groups of experiments also proved that lanthanum-containing materials showed a high selectivity and stability for the adsorption of phosphate.In summary,sodium alginate and carrageenan were used as precursors in this paper to prepare two kinds of lanthanum-modified biomass-based carbon materials.Synthetic load of lanthanum carbon materials can not only realize the efficient removal of hexavalent chromium in water and phosphoric acid root,can also be recycled for many times,and after the adsorption of phosphorus biological carbon can also be used as phosphate fertilizer,follow-up in sewage treatment field on oxygen acid radical in waste water adsorption study provides reference,realize the unity of the economic and environmental benefits and social significance.