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Red - aqueous systems Cr (Ⅵ) Adsorption Characteristics of

Author: LuPeng
Tutor: WuXiaoZuo；HuYueLi
School: Central South University of Forestry Science and Technology
Course: Environmental Science
Keywords: Wastewater treatment Liquid / solid overcast Pirates ion adsorption system Adsorbent concentration effect Strength due to Consisting of adsorption Adsorption kinetics Cr (VI) Red
CLC: X703
Type: Master's thesis
Year: 2007
Downloads: 57
Quote: 1
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Abstract

With electroplating, printing and dyeing industry, the rapid development of wastewater contaminated with Cr increasingly serious situation, serious impact on human health and survival. Artificial wetland treatment containing heavy metal ions from wastewater is an emerging technology, its low energy consumption, low operating cost advantages to attract the attention of many researchers. Artificial wetlands adsorbent adsorption of pollutants is an important element of treatment processes. Therefore, the choice of filling, quantitative and heavy metal ion adsorption behavior of artificial wetlands in Wastewater Treatment of great significance. Classic isotherms Adsorption equilibrium theory will be defined as the equilibrium density qe liquid ion concentration C unary function, and all the classic kinetic equation gives only the adsorption density and adsorption contact time t q relationship. In practice, there is the classical adsorption equation and the equation adsorbent concentration effect parameters instability problems. Limited by the basic function of the classical equation can not be directly used to calculate the initial concentration of known concentration C0 and the adsorbent of the adsorption W0 system. Therefore, to improve and perfect the liquid / solid adsorption theory, establish a more scientific and practical quantitative model ion adsorption adsorption become one of the key areas of research is the theoretical basis of this study ion adsorption four-component model. Model assumes that the adsorption system should be composed of four essential factors, which are as follows: liquid ion C, the solid phase ion Q, adsorption sites unoccupied Wu, and the ions occupy adsorption sites Wc. And the classic theory of adsorption isotherms are different, four-component theory that a balanced ion adsorption density qe (ion adsorption and adsorbent amount Wo Qe ratio) is C0/W0 (initial liquid ion concentration C0 and W0 adsorbent concentration ratio) and Ce/W0 (equilibrium liquid ion concentration ratio of Ce and W0) unary function. Based on this principle can be drawn with ce qe basic relationship: k = Ce (qm-qe) / qe2 Ce = Ce/W0 and qe and c0 basic relationship (ie, equilibrium sorption prediction model): qe = {co qm - [[(c0 qm) 2-4c0qm (Ik] 1/2} / [2 (1-k)] co = C0/W0 purpose of this study is to investigate the three ions through / adsorbent ratio, qe, ce and c0 to examine the relationship between the four-component model is suitable for describing the solid / liquid adsorption system anion adsorption process; and four components to create a new theory on the basis of the adsorption kinetics equations used to predict different time point t ion adsorption capacity. solve the above problems, this study selected red as an adsorbent, in the initial ion concentration 5-375 mg / L and the adsorbent concentration of 50-250 g / L range of Cr (Ⅵ) adsorption isotherm test and dynamic adsorption tests results are as follows: (a) red wide variety of sources, cheap and easy to get rich in iron, aluminum oxide gel, with a strong adsorption of Cr (Ⅵ) ability as an artificial wetland fillers, can be efficiently remove wastewater Cr (Ⅵ). (2) Cr (Ⅵ) adsorption rate is high during the initial two hours, about 10 hours towards the adsorption equilibrium in the adsorption equilibration time and initial concentration C0 and adsorption concentration Wo related to the underlying trend is increasing with C0 prolonged increases with Wo shortened. (3) the application of classical equations there are two main problems: First, the adsorbent concentration effect, the performance of the adsorption isotherm (ie qe-Ce curve) decreases with increasing concentration of adsorbent; Second, the equation is a constant parameter is not constant, with the adsorbent concentration changes, indicating that the liquid phase adsorption equilibrium density qe than one yuan of Ce ion concentration function (4) follow The only function of the system state by the state to determine the difference between the principles of thermodynamics, equilibrium solid-phase ion / adsorbent ratio (Qe/W0) single by starting phase ion / adsorbent ratio (C0/W0) and fluid balance phase ion / adsorbent ratio (Ce/W0) to determine the differences, and ionic adsorbent volume concentration and adsorption reaction process has nothing to do, which means that the liquid / solid adsorption system ion intensity factor is not the volume concentration of ions, and the ion volume and the ratio of the amount of adsorbent, which determines the direction and rate of adsorption of ionic adsorption reached equilibrium condition is the chemical potential of the ions with the adsorbent, and the difference between the liquid phase is zero. (5) Ion / Adsorption agent ratio test and volume affect the test results show that, given c0, qe and ce values ??remained constant, indicating qe ce or c0 is a function of one yuan. qe and Ce ce rather than having one function relationship, so classic isotherms (ie, q,-Ce curve) exist adsorbent concentration effect is a natural phenomenon. (6) repeated tests showed that equilibrium sorption model predictions are in good agreement with the experimental data with high prediction accuracy. New defined qe-ce and qe-c0 isotherms basically eliminating the adsorbent concentration effect. (7) Based on qe-c0 relations, the establishment of new ion adsorption kinetics equation: q = qe {1 - [b / (bt) ] a}, a = 1/2, b = qe / (c0qm) 1/2 test results that the new equation parameters and initial concentration C0 and the adsorbent has a relatively stable concentration W0 function, may be given as an C0, Wo condition red - aqueous systems Cr (Ⅵ) adsorption kinetics of predictive models. Experimental results show that the four-component adsorption model suitable to describe anion adsorption process.

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