New calcareous soil–alginate composites for efficient uptake of Fe(III), Mn(II) and As(V) from water

In the present study, various grades of sodium alginates were extracted from different brown macro-algae and their characteristics were investigated using FTIR, UV–vis and EA. The alginates were used in combination with different proportions of calcareous soil to develop new composite microparticles as potential sorbents for efficient uptake of Fe(III), Mn(II) and As(V) from water. Under the investigated conditions (1 g of composite equilibrated in 100 ml of standard metal ion solution), the composites have removed almost 100% of Fe(III) in the concentration range of 0.5–16.0 mg l−1. Soil, alginate and composites exhibited the highest removal (about 89%) of Mn(II) at 0.5 mg l−1. Reasonable removal efficiency (50–60%) was recorded at 0.5 mg l−1 of As(V) whereas, increasing the initial As(V) concentration resulted in marked decrease in removal efficiency. The collected equilibrium data were also fitted to both Langmuir and Freundlich isotherms for all the developed composites.