Continuous Adsorption Simulation And Optimization Calculation Based On Intermittent Experimental Date

The long experimental period of continuous adsorption experiments makes it very difficult to study the effects of various factors on the breakthrough curves,while the shorter experimental period of intermittent adsorption experiments makes it convenient to study.In this paper,the method of intermittent adsorption model used for continuous adsorption model and the analysis of influencing factors are investigated by using activated alumina adsorption for fluoride removal as an example.Firstly,two intermittent models,the Langmuir-Freundlich isotherm equation considering the effect of p H and the kinetic equation of variable mass transfer coefficient considering the effect of particle size,were established through mechanistic analysis and experimental data validation.Through this study,it was found that as the p H value increases,the adsorption amount of activated alumina increases and then decreases at the same fluorine ion concentration.The smaller the particle size of activated alumina,the larger the adsorption capacity per unit mass.Then,the established intermittent adsorption model was brought into the material balance equation and the continuous adsorption model with fixed bed breakthrough curve was developed by Matlab program writing.The experimental data were brought in for validation,and the model was found to be good simulation results at lower influent fluoride ion concentrations and space velocity,while the effects of influent p H and activated alumina particle size on the breakthrough curve could be quantitatively analyzed.With the increase of fluorine concentration,space velocity and particle size of activated alumina,the slope of breakthrough curve becomes larger and the breakthrough time shortens.As the p H of the feed water decreases,the slope of the breakthrough curve gradually decreases and the breakthrough time gradually becomes larger.However,when the p H value decreases to a certain value,the slope of the curve begins to increase and the breakthrough time decreases.A costing program for fluoride removal by single-column adsorption was developed in Matlab,and the fixed-bed breakthrough time under different operating conditions was simulated using the constructed continuous adsorption model as one of the input parameters of the program.With the determined simulated influent water quality,adsorption system and treatment volume,the costs of each of the fluoride ion concentrations in the range of 2～7mg/L,space velocity in the range of 1～5 h^-1and p H in the range of 5.5～7.8were compared and optimized in terms of both space velocity and p H.When the influent fluoride ion concentration is 5 mg/L and the influent p H is 7.8,the cost is lowest at an influent space velocity of 2.2 h^-1.When the feed water fluoride ion concentration was at 5 mg/L and the feed water space velocity was 2 h^-1,the cost of p H adjustment using sulfuric acid and hydrochloric acid was compared,and it was found that the cost was lowest when the feed water p H was adjusted to 7 using sulfuric acid.