Magnetic binary oxide particles (MBOP): A promising adsorbent for removal of As (III) in water

Magnetic binary oxide particles (MBOP) synthesized using chitosan template has been investigated for uptake capacity of arsenic (III). Batch experiments were performed to determine the rate of adsorption and equilibrium isotherm and also effect of various rate limiting factors including adsorbent dose, pH, optimum contact time, initial adsorbate concentration and influence of presence cations and anions. It was observed that uptake of arsenic (III) was independent of pH of the solution. Maximum adsorption of arsenic (III) was ∼99% at pH 7.0 with dose of adsorbent 1 g/L and initial As (III) concentration of 1.0 mg/L at optimal contact time of 14 h. The adsorption equilibrium data fitted well to Langmuir and Freundlich isotherm. The maximum adsorption capacity of adsorbent was 16.94 mg/g. With increase in concentration of Ca2+, Mg2+ from 50 mg/L to 600 mg/L, adsorption of As (III) was significantly reduced while for Fe3+ the adsorption of arsenic (III) was increased with increase in concentration. Temperature study was carried out at 293 K, 303 K and 313 K reveals that the adsorption process is exothermic nature. A distinct advantage of this adsorbent is that adsorbent can readily be isolated from sample solutions by application of an external magnetic field. Saturation magnetization is a key factor for successful magnetic separation was observed to be 18.78 emu/g which is sufficient for separation by conventional magnate.

MBOP is attracted by the magnetic retriever and conventional magnet confirming magnetic property.Figure optionsDownload high-quality image (69 K)Download as PowerPoint slideHighlights
► MBOP synthesized has magnetic property and exhibited typical super-paramagnetic behaviour.
► magnetic saturation value of 16.3 emu/g which is sufficient for magnetic separation with a conventional magnet.
► MBOP has high surface are and highly porous in nature which makes it suitable for adsorption.
► MBOP removes more than 90% arsenic at wide range of pH 3–9 which is a limitation in most of the adsorbents.
► MBOP was regenerated upto 90% using 1% NaOH and MBOP retained the adsorption capacity after desorption.