Preparation Of Sodium Carboxymethyl Cellulose/Chitosan Composites And Research On Phosphorus Removal Performance

Recently,with the development of society and economy,problems such as the arbitrary discharge of phosphorus-containing sewage in industry and the abuse of phosphate fertilizer in agriculture have become increasingly serious.However,Phosphorus(P)is considered to be a key element leading to eutrophication of water bodies.This continuous phenomenon seriously pollutes water sources and directly or indirectly affects human health.Therefore,it is urgent to find an effective measure to remove the phosphorus in the water source.The adsorption method has been widely studied by domestic and foreign scholars due to its many advantages such as easy operation,low cost,no secondary pollution and high efficiency.Sodium carboxymethyl cellulose(CMC)and chitosan(CS)are biological polysaccharides that are widely found in nature.They have inexpensive and easy,have a large number of active functional groups,etc.,and both have good gel properties and can be used in sewage treatment.However,problems such as poor mechanical properties of gel beads made of pure CMC or CS hinder their application in actual environments.Based on the above reasons,this paper uses the unique properties of CMC,AlCl₃and LaCl₃as crosslinking agents,and then uses the interaction between CMC and CS to prepare CMC/CS composite gel materials.In view of its poor mechanical properties and other problems,fly ash(FA),which is cheap and easy to obtain and UiO-66 metal-organic framework materials with super large specific surface area are introduced into CMC/CS.This will improve its mechanical properties.The specific research content and results are shown as follows:By mixing fly ash and CMC solution and introducing it into CMC/CS,a FA/CMC/CS composite gel bead adsorbent with high mechanical strength and large specific surface area was successfully prepared.Taking the phosphorus removal efficiency as the standard,the ratio of each component was optimized,and the samples were characterized and analyzed by XRD,SEM,BET and finally the phosphorus removal performance was evaluated.Phosphorus adsorption experiment results show that:at room temperature,the p H of the solution system is 3,the initial phosphorus concentration is 50 mg/L,and the amount of adsorbent is 4 g/L and the adsorption equilibrium is reached at 180 min.The adsorption efficiency is 69.8%,and the adsorption capacity is 8.72 mg/g.After four cycles,the phosphorus removal efficiency dropped to 36.58%.The entire adsorption process follows the pseudo-second-order kinetics and Langmuir isotherm model.The adsorption process is an endothermic reaction.Through the exploration of the adsorption mechanism,it is found that FA/CMC/CS removal phosphorus by electrostatic attraction and coordination exchange.(2)Firstly,UiO-66 metal organic framework material was prepared by solvothermal method.Then mix UiO-66 with CMC solution and then introduce it into CMC/CS.Finally,UiO-66/CMC/CS composite gel bead adsorbent was successfully prepared.The ratio of each component was optimized,and the material was characterized by XRD,FT-IR,TGA and its phosphorus removal performance was evaluated.The results of the phosphorus adsorption experiment are as follows:at room temperature,the p H of the solution system is7,the initial phosphorus concentration is 50 mg/L,and the amount of adsorbent is 1.5 g/L and the adsorption equilibrium is reached at 90 min.The adsorption efficiency is 95.44%,and the adsorption capacity is 31.81 mg/g.After five cycles,the phosphorus removal efficiency is still above 50%.The entire adsorption process follows the pseudo-second-order kinetics and Langmuir isotherm model.The adsorption process is an endothermic reaction.UiO-66/CMC/CS remove phosphorus by electrostatic attraction and coordination exchange.