Microwave-enforced green synthesis of novel magnetic nano composite adsorbents based on functionalization of wood sawdust for fast removal of calcium hardness from water samples.

Developing new generation of adsorbents for water treatment to reduce calcium hardness and producing high quality water is important and continuous trend. This manuscript is devoted with this direction. Thus, two novel magnetic nanocomposite adsorbents were synthesized by covalently binding of tartaric acid (TA) and citric acid (CA) to wood sawdust coated magnetic nanoparticles (WSD@Fe O NPs) using green microwave solvent-less technique. The adsorbents thus prepared WSD@Fe O NPs-TA and WSD@Fe O NPs-CA were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Preliminary batch experiments were performed to evaluate percentage of Ca(II) adsorbed by the bare WSD@Fe O NPs and its functionalized forms by TA and CA, as a function of pH (initial concentration 80 mg/L), indicated 59.5%, 84.70%, and 99.29%, respectively, at pH 7 as optimal value. To attain maximum adsorption capacity, effect of adsorbent dosage and contact time were also optimized for the two modified adsorbents. Accordingly, Ca(II) adsorption capacity was determined to be 18.4 mg/g as exhibited by WSD@Fe O NPs-TA. However, WSD@Fe O NPs-CA showed higher capacity value recorded to be 27.2 mg/g. The novel adsorbents were successfully applied for fast reduction of calcium hardness from real water samples, during 15-20 min and via two consecutive in situ batch operations. PRACTITIONER POINTS: This manuscript aims to minimize Ca(II) hardness in aqueous solutions by performing magnetic separation under external magnetic field. WSD was magnetized using Fe O then modified by using safe organic modifiers using of the benefits of solvent-less microwave radiation technique for adsorbent synthesis and functionalization. Two novel environmentally magnetic nanocomposites WSD@Fe O NPs-TA and WSD@Fe O NPs-CA were checked on real water samples.