Immobilized microbial nanoparticles for biosorption

Innovative method for encapsulating highly pigmented biomass from Aspergillus nidulans mutant for copper ions removal and recovery

“…As Fig 2 shows, the amount of copper ions adsorbed increased proportional to metal–biosorbent contact time and the system reached equilibrium at 240 min. Generally, the biosorption is considered a multi-step process, comprising four consecutive elementary steps: 1- the solute transfer from the bulk solution to the liquid film surrounding the biosorbent, 2- the solute transport from the boundary liquid film to biosorbent surface (external diffusion), 3- solute transfer from the surface to the internal active binding sites (intraparticle diffusion), and 4- solute interaction with the active binding sites [ 40 , 54 ].…”

“…Two kinetic models were applied to the experimental data to investigate the copper ion adsorption mechanism (data in S1 Table ), which are important to select the optimum operating conditions for industrial-scale processes. The pseudo-first-order model assumes that the adsorption process is a rapid initial phase [ 55 ], while the pseudo-second-order model assumes that the adsorption is a chemical rate-controlling step [ 40 , 50 , 56 ].…”

“…To address these issues, microbial biomass immobilization systems, including entrapment, adsorption, cross-linking, covalent bonding to the carrier and encapsulation, have been studied [ 5 , 37 – 46 ]. In most studies, biomass is immobilized in polymeric matrices, such as sodium alginate, polysulfone, polyacrylamide and polyurethane, with an appropriate mechanical strength porosity and size [ 40 ]. Nevertheless, this type of immobilization has some disadvantages, including mass transfer limitations and high cost of these matrices, which may not allow its application in large scale processes.…”

“…Nevertheless, this type of immobilization has some disadvantages, including mass transfer limitations and high cost of these matrices, which may not allow its application in large scale processes. Furthermore, these matrices may reduce the removal capacity, obstructing or damaging the metal-binding sites due to irreversible binding between the biosorbent and the immobilizing matrix [ 40 , 47 ].…”

“…In this context, the development of a cost-effective immobilization technique for metal removal/recovery is essential to improve the competitiveness of industrial processes, decreasing the process cost and dependence on a continuous supply of biosorbent [ 2 , 11 , 40 , 47 ]. In the present study, a new method of reversible encapsulation was developed using cheap, nontoxic and readily available semipermeable membrane capsules, in which the fungal biomass can freely float inside the capsule filled with deionized water, without blocking its binding sites and also allowing the passage of copper ions from the solution into the capsule containing the biosorvent immersed in the aqueous phase.…”