A facile synthesis of Fe3O4-charcoal composite for the sorption of a hazardous dye from aquatic environment.

Herein, we synthesized Fe3O4-charcoal composite using chemical precipitation technique and utilized it for the sorption of methylene blue from aqueous solution. The synthesized composite was characterized by Infra-red spectroscopy, N2 adsorption-desorption isotherm, X-ray diffraction, selected area electron diffraction, transmission electron microscopy, and vibrating sample magnetometer. The composite depicts absorption bands conforming to Fe-O, -OH, CO, and C-O vibrations. The composite was mesoporous in nature with a surface area of 387.30 m(2) g(-1). The observed diffraction planes correspond to face-centered cubic Fe3O4 and disordered graphitic carbon. The spherical Fe3O4 particles (average diameter ∼13.8 nm) were uniformly distributed in the carbon matrix of the charcoal. The saturation and remanent magnetizations demonstrate its potential for magnetic separation and reuse. The composite showed dye sorption capacities of 97.49 mg g(-1) and 90.85 mg g(-1) in batch and fixed-bed system. Pseudo-second order kinetics and Temkin isotherm best represented the sorption data. The sorption process was endothermic, spontaneous, and administered by electrostatic, π-π dispersive interactions, film, and intraparticle diffusion. Microwave irradiations followed by methanol elution regenerated the dye-loaded composite with nearly no loss in sorption capacity. The recovery of energy and potential utilization of bottom ash enhances the prospective of Fe3O4-charcoal composite for industrial applications.

Activated charcoal-magnetic nanocomposite for remediation of simulated dye polluted wastewater.

Herein, we report a straightforward way to fabricate activated charcoal-magnetic nanocomposite (AC-MNC) by chemical precipitation for the sequestration of methylene blue (MB) from a simulated solution. The synthesised nanocomposite was characterised by Fourier transform infra-red (FTIR), Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM) techniques. A good uniformity in the spherical AC-MNC particles is observed from a TEM image with an average particle size diameter of around 25 nm. AC-MNC possesses a specific surface area of 387.28 m2 g(-1) with easy dispersibility and magnetic separation. The nanocomposite demonstrates an MB sequestration capacity of 147.71 mg g(-1). The high efficiency of the nanocomposite is rationalised on the basis of H-bonding and electrostatic interaction between the electropositive N-atom of MB and electronegative oxygen-containing functional groups on the composite surface. Moreover, the exhausted AC-MNC can be efficiently regenerated by microwave irradiation followed by elution with methanol. The renewed nanocomposite showed good reusability. Thus, the synthesised AC-MNC proved to be an interesting and potential material for the remediation of MB-contaminated aqueous solution.

Lignocellulosic-derived modified agricultural waste: development, characterisation and implementation in sequestering pyridine from aqueous solutions.

The development and characterisation of modified agricultural waste (MAW) by H3PO4 activation is addressed in this study for sequestering pyridine from aqueous solutions. The adsorbent is characterised by carbon, hydrogen and nitrogen content of 55.53%, 3.28% and 0.98% respectively. The adsorbent also shows acidic (carboxylic, lactonic, phenolic groups) and basic carbon surface functionalities, functional groups viz. hydroxyl, carboxylic acid and bounded water molecules, BET surface area of 1254.67 m(2) g(-1), heterogeneous surface morphology and graphite like XRD patterns. Adsorption of pyridine is executed to evaluate the adsorptive uptake in batch (q(e)=107.18 mg g(-1)) as well as in column system (q(e)=140.94 mg g(-1)). The adsorption process followed the pseudo-second-order kinetics with the Langmuir isotherm best representing the equilibrium adsorption data. The thermodynamic parameters (ΔH(o)=9.39 kJ mol(-1), ΔG(o)=-5.99 kJ mol(-1), ΔS(o)=50.76 J K(-1) mol(-1)) confirm the endothermic and spontaneous nature of the adsorption process with increase in randomness at solid/solution interface. The adsorption mechanism is governed by electrostatic and π-π dispersive interactions as well as by a two stage diffusion phenomena. Thermally regenerated spent MAW exhibited better adsorption efficiency for five adsorption-desorption cycles than chemically regenerated. The low-cost of MAW (USD 10.714 per kg) and favourable adsorption parameters justifies its use in the adsorptive removal of pyridine.