A biosorbent's low chemical stability against oxidative attack and its poor regenerability are problems that limit the applicability of biosorption in addressing the problem of recovering chromate in industrial wastewater. To provide a sufficient premise for such an argument, original equilibrium and kinetic data on the biosorption of chromate by the biomass of the brown seaweed Sargassum siliquosum are presented and benchmarked with other related reports. It is established that the optimal condition for chromate biosorption is around pH 2. It is shown that electrochemical reduction of some of the chromate in the solution occurs in parallel with biosorption. Aside from the solution pH, the other factors shown to influence the equilibrium and the kinetics of both biosorption and reduction are the amount of biomass and the total chromate concentration. The chromate bound by the seaweed is found to be difficult to desorb using H2SO4 without first reducing the hexavalent chromate into a trivalent chromium. These findings are shown to be common among other reported studies using different biosorbents. In conclusion, it is argued that biosorption is not a highly viable option for the recovery of chromate in industrial wastewaters.

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Cellulose-based nanofiber membrane fabrication remains a global challenge, especially the use of alternative and sustainable sources of cellulosic materials. Herein, an easy and highly scalable cellulose-based nanofiber membrane was successfully fabricated using a solution blow spinning (SBS) method. Such membrane fabrication was carried out with the assistance of an easy-to-spin precursor polymer (i.e. polyacrylonitrile (PAN)). Through this strategy, cellulose acetate (CA) was successfully spun into a ready-to-use membrane. The formation of CA with the PAN nanofiber is concentration-dependent and requires high air pressure to effectively overcome the composite precursor’s surface tension and eventually produce nanofibers. Favourable CA concentration in PAN (i.e. 50%–65% v/v CAN/PAN) is important to the formation of sufficient molecular entanglement with PAN in solution. Upon fulfilling the optimized CA concentration, high air pressure (i.e. ≥3 bars) is used to produce jet-like polymeric fibers of PAN dragging off CA, forming numerous nanofibers which are then collected into a substrate forming a membrane. Characterizations of the CA/PAN composite nanofiber were carried out using scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis and differential scanning calorimetry (DSC). Such unique composite nanofiber membranes have potential as filters and adsorbent membranes for air and water/wastewater applications, as well as for biorefinery applications.