Sorption of Cr(III) and Cr(VI) to high and low pressure synthetic nano-magnetite (Fe3O4)particles

Abstract

The binding of Cr(III) and Cr(VI) to synthetic nano-magnetie particles synthesized under open vessel conditions and a microwave assisted hydrothermal synthesis techniques was investigated. Batch studies showed that the binding of both the Cr(III) and Cr(VI) bound to the nano-materials in a pH dependent manner. The Cr(III) maximized at binding at pH 4 and 100% binding. Similarly, the Cr(VI) ions showed a maximum binding of 100% at pH 4. The data from the time dependency studies showed for the most part the majority of the binding occurred within the first 5 minutes of contact with the nanomaterial and remained constant thereafter. In addition, the effects of the possible interferences were investigated which showed some effects on the binding of both Cr(III) and Cr(VI). However, the interferences never completely eliminated the chromium binding. Isotherm studies conducted at room temperature showed the microwave synthesized nanomaterials had a binding capacity of 1208 ± 43.9 mg/g and 555 ± 10.5 mg/g for Cr(VI) and Cr(III), respectively. However, the microwave assisted synthesized nanomaterials had capacities of 1705 ± 14.5 and 555± 10.5 mg/g for Cr(VI) and Cr(III), respectively. XANES studies showed the Cr(VI) was reduced to Cr(III), and the Cr(III) remained as Cr(III). In addition, the XANES studies indicated that the chromium remained coordinated in an octahedral arrangement of oxygen atoms.

Adsorption of 2,4-D on magnetic graphene and mechanism study

“…Nevertheless, the application of graphene/graphene based materials on a large scale was a huge challenge for it was difficult to reclaim suspended graphene from water [24,25]. Fe 3 O 4 nanoparticle has long been used as adsorbent in environmental pollution remediation [26][27][28]. The most striking advantage of it was that it could be separated easily from the reaction system with an external magnet.…”

Sorption of Cr(III) and Cr(VI) to K 2 Mn 4 O 9 nanomaterial a study of the effect of pH, time, temperature and interferences

“…Different substitutions of manganese into ferrite nanoparticles has shown Cr(III) and Cr(VI) binding in the ranges of 3 mg/g and 7–10 mg/g, respectively [13]. Synthetic magnetite (Fe 3 O 4 ) particles have been shown to have adsorption capacities for Cr(VI) and Cr(III) of 1,208 mg/kg (1.2 mg/g) and 555 mg/kg (0.555 mg/g), respectively [24]. Activated alumina and activated carbon have shown higher binding for Cr(VI) of 7.44 mg/g and 12.87 mg/g, respectively[25].…”

“…The results from the ΔG study indicate that both Cr(III) and Cr(VI) bind to the K 2 Mn 4 O 9 through an endothermic process, at their respective optimum binding pHs. The thermodynamics for the binding of Cr(III) and Cr(VI) have been studied for inorganic materials including manganese oxides, iron oxides, as well as many other inorganic materials [12–14,24,26]. From the literature is has been indicated that ΔG values smaller the 40 kJ/mol (absolute value) are indicative of physisorption [12].…”

“…Similar ΔG of binding values have been observed in the literature as in the present study. The binding of Cr(III) to iron oxide nanomaterials has been shown to have ΔG’s in the range of −17 to −11.4 kJ/mol, whereas Cr(VI) binding to iron oxides have ΔG values in the range of −7.5 to −7.0 [13,24]. Mn 3 O 4 nanomaterials have been shown to have Cr(III) ΔG values of in the range of −2.7 to −13.7 kJ/mol [14].…”

Nanosized magnetite in low cost materials for remediation of water polluted with toxic metals, azo- and antraquinonic dyes

“…These nanoparticles were used for Cr 3+ and Cr 6 + removals in batch experiences [30]. The size of the nanomaterials was approximately 27 nm for the open vessel synthesis and 25 nm for the microwaveassisted Fe 3 O 4 nanoparticles.…”