Upcycling Waste Streams from a Biorefinery Process—A Case Study on Cadmium and Lead Biosorption by Two Types of Biopolymer Post-Extraction Biomass

Abstract

This study investigated the possibility of using the spent kind of biomass of Pseudomonas putida CA-3 and Zobelella denitrificans MW1 obtained after the pilot-scale production of polyhydroxyalkanoates (PHAs) as a biosorbent for the bioremediation of aqueous solutions containing toxic cadmium and lead ions. The material was characterized by means of scanning electron microscopy, Fourier-transformed infrared spectroscopy, nuclear magnetic resonance spectroscopy and amino acid profiling. To check the sorption capacity of spent biomass against Pb and Cd ions, equilibrium studies were performed. To learn about the nature of the sorption process, kinetic modelling was carried out and the obtained results showed that the adsorption process is best described by the pseudo-second-order kinetic model (PSO), which suggests that the sorption process is connected with the chemical bonding of the ions on the sorbent surface. Information provided by the amino acid profile made it possible to predict the adsorption mechanism and FTIR analysis proved the participation of different chemical groups in the removal process. According to the equilibrium studies, the best-fitted isotherm was the Freundlich model for all used materials and metal ions considering the correlation coefficient. Summarizing the results, the spent biomass after the PHA production is an effective biosorbent and can be reused for heavy metal bioremediation.

A Study on the Adsorption of Rhodamine B onto Adsorbents Prepared from Low-Carbon Fossils: Kinetic, Isotherm, and Thermodynamic Analyses

“…In the adsorption studies, the cationic dye rhodamine B was used, indicating that the resulting activated carbons will efficiently remove the dye at pH values higher than the pH pzc values of the samples. This is because of the stronger electrostatic attraction between the cationic dye and the negatively charged surface of the activated carbons [ 22 ].…”