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Hai-Hua Li ¹, Wei-Feng Yan ¹, Rui-Jing Meng ¹, Liang Qian ¹, Ya-Ting Liu ¹

Affiliations
1 North China University of Water Resources and Electric Power, Zhengzhou, 450011, CN

Abstract

To understand the influencing factors of the sediment adsorption of As³⁺, prototype sand of the Yellow River was taken as the material. The effects of sediment adsorption saturation time and adsorption regularities were investigated when coexisting ions Fe³⁺ and Mn²⁺ existed. The results show that: (1) when there was only As³⁺ existing alone, the saturation time was 60 min; when Fe³⁺ and Mn²⁺ were added, the saturation time was 90 min; (2) when Fe³⁺ existed, the sediment adsorption laws of As³⁺ were as follows: during the initial period, with the increasing concentration of Fe³⁺, the adsorption decreased; when the concentration of Fe³⁺ was more than 0.4mg/L, the adsorption capacity increased with the increasing concentration of Fe³⁺; when there was Mn²⁺ existing, the regulation also showed that it initially decreased slightly and then increased, i.e., when Mn²⁺ was less than 1.0mg/L, the adsorption capacity decreased with the increasing concentration of Mn²⁺; when Mn²⁺ was higher than 1.0mg/L, the adsorption capacity increased with the increasing concentration of Mn²⁺; when Fe³⁺ and Mn²⁺ coexisted, the sediment adsorption of As³⁺ increased with the increasing concentration of the coexisting ions; (3) when the coexisting ion concentration was 0.2-0.4mg/L, the removal rate of Fe³⁺ was less than that of Mn²⁺, and also less than that of the coexistence of Fe³⁺ and Mn²⁺. When the concentration of coexistent ions is less than 0.2 or more than 0.4 mg/L, the removal rate of Mn²⁺ was less than Fe³⁺, and also less than that of the coexistence of Fe³⁺ and Mn²⁺.

Keywords

As(III), Sediment Sorption, Coexisting Ions, Fe, Mn.

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Hai-Hua Li ¹, Rui-Jing Meng ², Qiang Huang ¹, Lin Qiu ²

Affiliations
1 Key Laboratory of Northwest Water Resources and Environment Ecology of MOE at Xi’an University of Technology, Xi’an 710048, CN
2 Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450011, CN

Abstract

The present study deals with sediment sorption of arsenic onto sediments from the middle Yellow River and major affecting factors (such as temperate, pH, particle size and sediment dose have been studied by isothermal sorption and single factor experiments. The results showed that sorption equilibrium time of each dose and particle size sediment was 5-10 min. expect 1kg/m³. When the sediment dose was 1kg/m³, the sorption equilibrium time was about 180min. The retention rate of As(III) increased with respect to sediment dose while the retention quality of per sediment decreased. As the sediment concentrations are the same, the smaller the particle size, the more the retention quality. The order for sorption As(III) was fine sediment>medium sediment>coarse sediment. When pH>7, the percentage of As (III) removal was higher compared to pH 7. A general increase was there in sorption with respect to pH above 7.0 for both the fractions of the sediment. It is evident that the pH for minimum uptake of As (III) is 7.0, and for maximum uptake is 9.0. At the same time, temperate as the main factor for sorption was also studied. The temperate experiments showed that the temperature is of significance to sorption. When temperatures between 10-15°C, the higher the temperature, the lower the removal rate. When temperatures between 15-20°C, the higher the temperature, the bigger the removal rate. After temperature greater than 20°C, temperature change effects on arsenic sorption rates do not remain obvious.

Keywords

Arsenic (III), River Sediment, Sorption, pH, Temperature.

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Hai-Hua Li ¹, Wei-feng Yan ¹, Qian Liang ¹, E. Zheng-Yang ¹, Kang-Jia Ge ¹

Affiliations
1 Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450011, CN

Abstract

Aiming at exploring the effect of initial arsenic concentration on sediment adsorption, at first, an orthogonal experiment of four factors and four levels was carried out to determine the optimal experimental conditions. Based on orthogonal experiments, the single factor experiments of different sampling times under the optimal experimental conditions were conducted to explore the influence of the initial arsenic concentration on adsorption of sediment of different concentrations. To confirm the arsenic’s adsorption equilibrium time, the experiments with different sediment concentrations were conducted under the optimal experimental conditions, when sampling times respectively, were 5, 10, 15, 30, 45, 60, 90 and 120 mins. The results showed that (1) the optimal conditions for the sediment adsorption of arsenic: temperature is 40°C, vibration velocity is 250 r·min^-1, pH is 9, and sediment diameter ranges from 0.15 to 0.3 mm; (2) when the sampling time and the sediment concentration are constant, with the increase of initial arsenic concentration, the amount of the unit sediment adsorption increases gradually; when the concentration of the initial arsenic and sediment is constant, adsorption capacity of per unit mass of the sediment increases with time; (3) the time of arsenic adsorption equilibrium from sediment is 60 mins.

Keywords

Arsenic, Sediment, Adsorption, Optimal Conditions, Adsorption Equilibrium.

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