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Effect of iron oxide coating on sand filtration

1994; Wiley; Volume: 86; Issue: 8 Linguagem: Inglês

10.1002/j.1551-8833.1994.tb06236.x

1551-8833

V. Susie Stenkamp, Mark M. Benjamin,

Urban Stormwater Management Solutions

Although the difference in their efficiencies was frequently small, iron‐oxide‐coated sand outperformed uncoated sand as a filter medium in almost all cases. Plain sand was compared with iron‐oxide‐coated sand as a medium for filtration. The coated sand has a positive surface charge at neutral pH, whereas uncoated sand is negatively charged under similar conditions. The influent to the filters contained either latex particles, which were negatively charged in all solutions investigated, or ferrihydrite particles, which were negatively charged at pH > 5 but positively charged at lower pH values. The coated medium outperformed the uncoated one in most experiments, a result that is consistent with expected electrostatic interactions.