Iron [Fe(0)]-rich substrate based on iron-carbon micro-electrolysis for phosphorus adsorption in aqueous solutions
Shihai Deng1, Desheng Li1, Xue Yang1
1School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, PR China; Beijing Key Laboratory of Aqueous Typical Pollutants Control and Water Quality Safeguard, Beijing, 100044, PR China.
Abstract:
The phosphorus (P) adsorption properties of an iron [Fe(0)]-rich substrate (IRS) composed of iron scraps and activated carbon were investigated based on iron-carbon micro-electrolysis (IC-ME) and compared to the substrates commonly used in constructed wetlands (CWs) to provide an initial characterization of the [Fe(0)]-rich substrate. The results showed that P was precipitated by Fe(III) dissolved from the galvanic cell reactions in the IRS and the reaction was suppressed by the pH and stopped when the pH exceeded 8.90 ± 0.09. The adsorption capacity of the IRS decreased by only 4.6% in the second round of adsorption due to Fe(0) consumption in the first round. Substrates with high Ca- and Mg-oxide contents and high Fe- and Al-oxide contents had higher P adsorption capacities at high and low pH values, respectively. Substrates containing high Fe and Al concentrations and low Ca concentrations were more resistant to decreases in the P adsorption capacity resulting from organic matter (OM) accumulation. The IRS with an iron scrap to activated carbon volume ratio of 3:2 resulted in the highest P adsorption capacity (9.34 ± 0.14 g P kg-1), with minimal pH change and strong adaptability to OM accumulation. The Fe(0)-rich substrate has the considerable potential for being used as a CW substrate.
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