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Biosorption Properties of Cu(Ⅱ) Ions from Aqueous from Solutions Using Biosorbent of Modified Pine Bark

Author: ZouZuo
Tutor: SunYaBing
School: Nanjing University
Course: Environmental Engineering
Keywords: Pine bark Saponification Optimum adsorption conditions Adsorption thermodynamics Adsorption kinetics Adsorption mechanism
CLC: X703
Type: Master's thesis
Year: 2011
Downloads: 49
Quote: 0
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Abstract

The toxic heavy metal contaminants caused by the discharge of untreated effluents containing heavy metal ions into water bodies have been one of the most important environmental issues. Copper is one of the major contaminants emanating from electroplating, mining, smelting and metal finishing industries. Pine bark as a raw material used in this paper, by a modification to prepare its high adsorption efficiency of the target product, and the modified pine bark as an adsorbent for the adsorption performance of aqueous solution of Cu2+.First of all, the best method of modification was researched. The maximum adsorption capacity was measured under different concentrations by the original pine bark as adsorbent, the highest removal efficiency of Cu2+ was only 57%, the pine bark needed to be modified to improve its adsorption capacity. Nine modification approach were used to treat the original pine bark powder to get different products which were used as adsorbent respectively. Under the same experimental conditions Cu2+ was adsorbed, the adsorption capacity was determined, then the best modification can be got. The saponification was a good way to improve the adsorption performance, the adsorption capacity of pine bark reduced through acidification. When organic solvents with weak acid as a modifier, the adsorption properties of pine bark changed little.Again, the thermodynamic and kinetics of the adsorption process were analyzed. The single factor experiment was made to investigate the effect of initial pH, adsorbent particle size, temperature, biosorbent does, contact time and initial concentration respectively by the Adsorption of Cu2+ onto product of saponification of modified pine bark as adsorbent. Then the best adsorption conditions could be drawn.For different concentrations of Cu2+ solutions, when pH value was 5, the adsorbent particle size was 0.05mm, temperature was 20℃, the adsorption equilibrium time was 120min, the best adsorption process appeared. But the best biosorbent does changed with the initial concentrations of Cu2+ varing. When the proportion of the quality of Cu2+ and biosorbent was in the range of 80-100 mg/g, the maximum removal rate and the most economical does were got.Once again, carry out thermodynamics and kinetics analysis of the biosorption process. On the basis of the above conditions further thermodynamic and kinetic experiments were done, using the Langmuir, Freundlich and Temkin adsorption isotherm were used to fit the experimental data. By comparing the calculated linear correlation coefficients and the maximum adsorption capacity calculated, the adsorption Process best consistent of the Langmuir adsorption model. The pseudo-first-order order model, the pseudo-second-order model, the Elovich model, the intraparticle diffusion model were used to fit experimental adsorption data of time and different concentrations. By comparing the linear correlation coefficients and the model parameters, The conclusion that adsorption process was in line with of the pseudo-second-order model was obtained.Finally, the adsorption mechanism was discussed through characterization of biosorbent. By scanning electron microscopy analysis, to understand the morphology and their characteristics of original pine bark, modified pine bark and modified pine bark after adsorption on the surface. By infrared spectroscopy active functional groups of species of biosorbent surface playing an important role during the process were known. Based on this analysis, the adsorption mechanism is mainly considered to ion exchange reaction that plays a dominant role.

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