Adsorptive Removal of Hexavalent Chromium by Diphenylcarbazide-GraftedMacadamiaNutshell Powder

Abstract

Macadamia nutshell powder oxidized by hydrogen peroxide solutions (MHP) was functionalized by immobilizing 1,5′-diphenylcarbazide (DPC) on its surface. The effectiveness of grafting was confirmed by the Fourier transform infrared spectrum due to the presence of NH and C=C stretches at 3361, 1591, and 1486 cm−1, respectively, on the grafted material which were absent in the nongrafted material. Thermogravimetric analysis revealed that the presence of DPC on the surface of Macadamia shells lowered the thermal stability from 300°C to about 180°C owing to the volatile nature of DPC. Surface roughness as a result of grafting was appreciated on the scanning electron microscopy images. Parameters influencing the adsorptive removal of Cr(VI) were examined and found to be optimal at pH 2, 120 min, 150 mg/L, and 2.5 g/L. Grafting MHP with DPC leads to an increase in the Langmuir monolayer capacity from 37.74 to 72.12 mg/g. Grafting MHP with DPC produced adsorbent with improved removal efficiency for Cr(VI).

Equilibrium and Thermodynamic Studies on Adsorption of Hexavalent Chromium from Aqueous Solution onto Low Cost Activated Carbon

“…The decrease in Cr(VI) adsorption capacity with increase in dosage is attributed to unsaturation of many active sites of the adsorbent during the adsorption process [28]. A similar trend was highlighted in the adsorption of Cr(VI) using diphenylcarbazide-grafted macadamia nutshell powder [29]. Fig.…”

Recent advances in hexavalent chromium removal from aqueous solutions by adsorptive methods

“…These include biological treatment with bacteria or fungi, chemical treatment (or bleaching) with an alkaline solution, and oxidizing agents, physical treatment methods like mechanical agitation or sonication, and physicochemical methods such as steam explosion. 108 In addition to the above, cross-linking, graing, converting to activated carbon or fabricating biocomposites are usually the secondary treatments undertaken. 62,65,67,68,70,72 Recent literature has revealed that new or alternative adsorbents for the removal of Cr(VI) are experimented.…”

Toxic Metal Adsorption from Aqueous Solution by Activated Biochars Produced from Macadamia Nutshell Waste

“…Rodrigues et al also fabricated activated carbon from macadamia nutshell and used it as an adsorbent for the effective removal of organic solvents such as phenol [27]. The macadamia-based biochars were also successfully employed for the removal of toxic metal ions [28][29][30][31][32]. However, the application of macadamia nutshell-derived biochar solely for the removal of Zn 2+ and Cu 2+ seems to be scarce.…”