Recovery of rhodium from glacial acetic acid manufacturing effluent using cellulose-based sorbent

Rhodium (Rh) is a rare and highly demanded metal in metallurgy, making its efficient recovery from waste streams essential. However, there is a lack of detailed studies on the recovery of Rh from acidic waste effluents using biosorbents. This study aims to extract Rh-III from acidic effluents using dithiocarbamate-modified cellulose (DMC) as a biosorbent, and subsequently recover the extracted Rh in its elemental form (Rh-0). The parameters affecting the Rh-III extractability of DMC, such as solution pH, acid concentration, Cl- ion concentration, contact time, and sorption capacity at different temperatures, were optimized. The sorption kinetics of Rh-III onto DMC was best fitted to the pseudo-second-order (PSO) model, the equilibrium sorption isotherm data fitted well with the Langmuir model. DMC had a maximum sorption capacity of 2.57 mmol g(-1), which is substantially higher than that reported in previous studies. Waste effluent (Rh-containing glacial acetic acid) obtained from the acetic acid manufacturing industry was used to assess the applicability of DMC in capturing Rh-III from a real sample. DMC was capable of sorbing approximately 90 % of Rh-III from the real sample of Rh-containing glacial acidic acid. The sorbed Rh-III was recovered in elemental form (Rh-0) by incineration of Rh-III-loaded DMC, yielding >99 %. The sorption of Rh-III onto DMC followed a chemisorption mechanism that was confirmed by sorption experiments, Fourier-transform infrared spectroscopy (FTIR), and X-ray absorption spectroscopy (XAS) analyses. This study demonstrates the applicability of DMC in the efficient recovery of Rh from waste streams.