Iron doped phenolic resin based activated carbon micro and nanoparticles by milling: synthesis, characterization and application in arsenic removal

In this study, we have prepared iron-doped activated micro/nano carbon particles as efficient adsorbents for arsenic removal. Starting with phenolic resin monomers, polymeric spherical beads of size ˜0.2-1 mm were first synthesized by suspension polymerization. Iron (Fe) was incorporated in an intermediate step during polymerization. The internal porous structure was developed in the Fe-doped polymeric beads by carbonization followed by physical activation using steam. Subsequent to activation, beads were milled to prepare the micro/nano particles in the size range of 100-500 nm. In an alternate route to preparing the adsorbents, the synthesized polymeric beads were first milled and then carbonized and activated. The absorbent particles thus prepared were applied in the removal of arsenic (III and V) present at low concentration levels (<20 mg/L) in water. The method in which milling was performed first produced a superior adsorbent. For both the ions, the equilibrium loading (˜3-15 mg/g) in the adsorbate were found to be comparable to the adsorbates reported in literature. The simple and up-scalable methodology developed in this study has the potential for the preparation of a wide variety of similar metal impregnated porous (polymeric precursor based) adsorbents/catalysts in other environmental remediation applications

Development of bi-metal doped micro- and nano multi-functional polymeric adsorbents for the removal of fluoride and arsenic(V) from wastewater

The contamination of ground water by fluoride and arsenic has recently considerably increased, especially in some regions of India. In this context, the development of efficient adsorbents for the control of fluoride and arsenic, which are the common pollutants in wastewater, assumes significance. Herein, we describe the synthesis, characterization, and application of bi-metals (Fe and Al) doped micro- and nanoparticles based adsorbents for the removal of fluoride and arsenic(V) ions from water. The adsorbents were prepared by suspension polymerization. Fe and Al were incorporated during a polymerization step. The bi-metals doped beads (~ 0.8 mm) thus prepared were carbonized and activated to create porous structure inside the materials. Nanoparticles (~ 100 nm) were produced by milling of the beads, which were carbonized and activated. The adsorption tests carried out on Al/Fe-doped adsorbents revealed significant loading of those ions. The equilibrium loading of fluoride on nanoparticles based adsorbents was determined as ~ 100 mg/g corresponding to the aqueous phase concentration range of 0–90 ppm, whereas that of arsenic(V) was determined as 40 mg/g corresponding to the range of 0–70 ppm. The methodology adopted in this study is a step towards developing multi-functional adsorbents for the removal of different types of solutes from wastewater