Research On Removal Of Phosphate By Modified Carbon-based Nanomaterials

With the development of industrialization,phosphorus pollution is becoming more and more serious.The carbon-based material used to remove phosphorus from wastewater dueing to simply operation and low cost.However,the removal rates of phosphate using carbon materials is low.In this thesis,multi amino carbon nanospheres（CNS）,lanthanum doped aminated carbon nanospheres（CN-L）and iron lanthanum bimetallic modified carbon nanospheres（CFL）were prepared by a simple one-step method using waste syrup wastewater as carbon source.The SEM,TEM,FT-IR,XPS,XRD were used to characterize the materials.The factors including different synthesis conditions,p H of solution,initial phosphorus concentration,reaction time,temperature and interference ions were studied.The phosphate adsorption mechanisms were analyzed by intra-particle diffusion,adsorption isotherm and thermodynamics models.Using waste syrup wastewater as carbon source,ammonia solution as ammoniating agent and triethylenediamine as crosslinking agent,CNS material was prepared.The adsorption quantity on CNS material was 43.97 mg/g when the reaction time was 40 min,p H=4.0,the opitimal temperature of 25℃and the dosage was 0.4g/L through surface deposition and electrostatic attraction.The saturated adsorption capacity for CNS were 71.07 mg/g.The CN-L material was prepared using syrup wastewater,ammonia nitrate and lanthanum.Under the optimal condition including 0.4 g/L CN-L5,p H=4.0,the reaction time of 60 min,the adsorption capacity of KH₂PO₄（100 mg/L）achieved78.47 mg/g.The saturated adsorption capacity was 113.73 mg/g.The FT-IR,XRD,intramolecular diffusion and kinetic analysis showed that the mechanism of the adsorption process was surface deposition,electrostic interaction and inner sphere complexation.The carbon nanomaterial was fabricated using syrup wastewater as carbon resource,iron nitrate and lanthanum nitrate as doping agent.The adsorption capacity for phosphate was 500.66 mg/g under the following condition:p H=4.0-10.0,800mg/L of KH₂PO₄,20 mg CFL-5/2,and reaction temperature of 25℃.The saturated adsorption capacity for CFL-5/2 was 693.04 mg/g.The adsorption process was mainly dominated by surface deposition,electrostatic interaction and inner ball complexation.Phosphate removal by CFL-5/2 was highly selective in the presence of other co-existing anions,while fluorine ions inhibited the adsorption prosess.The removal rates of phosphate maintain on 80%after 3 times of regeneration.Phosphate can be adsorbed by the means of ion exchange,electrostatic interaction,inner complex and surface deposition.Amino group-functionalized sorbents can adsorb phosphate via ion exchange and electrostatic interaction.It can further increase the adsorption capacity of phosphate by replacing the-OH group of the lanthanum hydroxide to form an inner complex and surface deposition.Fe-La mixed oxides can possess the synergistic effects which can enhance their sorption performance by the synergistic flocculation of hydroxyl iron and iron hydroxide.