Research On Preparation Of ZSFB Composite Fiber And Performance Of Phosphate Remover From Aqueous Solution

At present,various kinds of environmental issues in the world are taking place frequently and have become the obstacles that constrain the sustainable development of the social economy.Among them,water pollution is the most serious environmental problem in China only next to atmospheric pollution.With the increase of population,the advancement of urbanization,and the development of industry and agriculture,a large amount of waste water is discharged into natural water,causing the deterioration of water quality and the frequent occurrence of eutrophication.Usually,phosphorus is the minimum limiting factor for the eutrophication in fresh water bodies,and phosphorus removal is the key to preventing the eutrophication.Therefore,the development of economically efficient and widely applicable phosphorus removal materials is an important research direction for reducing phosphorus emissions and controlling the eutrophication.Based on this thesis,natural zeolite and two kinds of industrial waste slag（steel slag and fly ash）are selected as the adsorption substrate,and the characteristics of phosphorus removal are studied.At the same time,in order to improve the phosphorus removal capacity,four methods are used to carry out the modification research.For the sake of solving the issue of solid-liquid separation of granular adsorbents used in water treatment,cellulose acetate is used as a molding material,and basalt fiber is used as a reinforcing material.The modified zeolite,steel slag,fly ash and basalt fibers are fixed in cellulose acetate.ZSFB composite fiber materials are prepared by wet spinning and the phosphorus removal characteristics of composite fibers are studied.The main research content is as follows:（1）The phosphorus removal characteristics of zeolite,steel slag,and fly ash are studied.The results show that the adsorption process of three adsorption substrates are all combined with the Langmuir isotherm adsorption model.The maximum saturated adsorption capacity is calculated to be 0.235 mg/g,respectively 92.947mg/g,7.943mg/g;kinetic experiments show that the process of phosphorus removal by zeolite and fly ash is more in line with the pseudo-first-order kinetics model,and the process of phosphorus removal by steel slag is more consistent with the pseudo-second-order kinetic model.The zeolites,steel slags and fly ash are modified by four methods:high temperature modification,HCl modification,NaOH modification and FeCl₃ modification.The results show that the best modification method of zeolite is FeCl₃ modification.The concentration of FeCl₃ solution is 0.5mol/L;the best modification method of steel slag is NaOH modification,NaOH solution concentration is1.5mol/L;the best modification method of fly ash is FeCl₃ modification,and the concentration of FeCl₃ solution is 0.3mol/L.（2）400 mesh modified zeolite,steel slag,and fly ash are used as the adsorbent substrate,cellulose acetate is the forming substrate,basalt fiber is the reinforcing substrate,and acetone solution is used as the solvent.Continuous and uniform ZSFB composite fiber materials are prepared by wet spinning technology to obtain the best process parameters for preparing ZSFB composite fiber,namely cellulose acetate:zeolite:steel slag:fly ash:the mass ratio of basalt fiber is 100:5:15:10:0.8,and the spinning fluid injection rate is 8.57 mL/h,the coagulation bath temperature is 20³0°C,and the stretching speed is 1.10m/min.The ZSFB composite fiber is characterized:the maximum tensile force that the single fiber can withstand is 0.2188N;the fiber diameter is between 0.5⁰.6mm;the specific area of fiber is26.194m²/g,the total pore volume is 0.145cm³/g,the mean pore size is 43.014nm;the hydraulic stability of the fiber is good.There is no hydration phenomenon in the hydraulic experiment fiber,and the number of fracture root is relatively less.The microstructure of fiber is observed by scanning electron microscopy,and the surface of ZSFB composite fiber is coarser than that of cellulose acetate,the interior is honeycomb structure,the ore powders are evenly distributed.（3）Adsorption thermodynamics and adsorption kinetics of ZSFB composite fibers are studied by static adsorption phosphorus removal experiments.The results show that the maximum saturated adsorption capacity of phosphorus for composite fibers is 3.745,3.905,and 4.177mg/g at 15,25,and 35°C,respectively.Mg/g,the adsorption process conforms to the Langmuir isotherm model;ΔG⁰<0 indicates that the adsorption of phosphorus by the composite fiber proceeds spontaneously;ΔH⁰=44.721kJ/mol,it’s a positive value,indicating that the adsorption of phosphorus on the composite fiber is an endothermic process and chemical adsorption;the selected temperature and At different initial concentrations,the pseudo-first-order kinetics model and the pseudo-second-order kinetics model can better reflect the adsorption kinetics of phosphorus on the composite fibers.However,from the correlation coefficient,the pseudo-second-order kinetic model is more accurate.（4）The effects of temperature,initial phosphorus concentration,adsorption time,fiber dosage,pH,ammonia nitrogen and anion on the phosphorus removal efficiency of ZSFB composite fiber are studied.Also,the adsorption stability of the composite fiber is studied.The results show the following:adsorption amount is positively correlated with temperature,initial phosphorus concentration,and adsorption time.The removal rate of phosphorus from the composite fiber is positively correlated with the dosage.When the simulated phosphorus-containing wastewater concentration is 10 mg/L,the optimal dosage is 3.5 g/L.100mL;both acidic and alkaline conditions are beneficial to increase the removal rate of phosphorus from composite fiber;ammonia nitrogen has a certain role in promoting the removal of phosphorus from composite fibers.The higher the ammonia nitrogen concentration,the higher the phosphorus removal rate.SO₄^2-,Cl^-,NO₃^-anions have almost no effect on phosphorus removal efficiency of ZSFB composite fibers,CO₃^2-anion has inhibitory effect on the removal of phosphorus from composite fibers,and composite fibers have good adsorption stability for phosphorus,in clean water and hot water.The resolution is very low;in the sulfuric acid solution,phosphorus is easily desorbed from the composite fiber,and the desorption rate is positively correlated with the concentration of sulfuric acid.（5）Dynamic adsorption experiments of ZSFB composite fibers are carried out using a fixed bed dynamic adsorption device.The relationship between influent flow rate,filler quality,influent concentration and adsorption column penetration are studied.The results show that:under the same working condition,the larger the water inflow,the shorter the absorption column is,but the amount of water processed by the adsorption column will increase first and then decrease with the increase of the influent flow,and the water volume is the most in the flow rate of 1.5ml/min.The larger the packing mass,the longer the absorption column is,the more water is processed.The higher the water inlet concentration,the shorter the penetration time of the adsorption column and the less water processed.