Maria Hartono

In this study, composite calcium-alginate/carbon nanotubes/TiO2 beads were prepared and tested for their potential in the removal of bisphenol A (BPA) from aqueous solutions. The removal traits were inspected using a fixed-bed sorption column. By varying parameters such as bed height (15-20 cm), flow rate (2.0-6.0 mL.min(-1)) and inlet BPA concentration (10-30 mg.L(-1)) we assessed the removal capacity of these composites. The highest sorption capacity of 5.46 mg.g(-1) was achieved at 10 mg.L(-1) BPA concentration, 2.0 mL.min(-1) flow rate and 20 cm bed height at saturation. Adams-Bohart, Yoon-Nelson and Dose-Response isotherm models were applied to evaluate the performance of the column at different inlet concentrations. The experimental data satisfactorily fit the Dose-Response model with high correlation (r(2) > 0.97) across the breakthrough curve. Regeneration of the used adsorbent beads were performed by immersion in the desorption solvent followed by light irradiation. It w...

ABSTRACT In recent years, the potential application of carbon nanotubes (CNTs) as sorbent materials in wastewater treatment has garnered tremendous attention. Concerns that CNTs may be toxic to living organism, however, necessitate that the containment of CNTs to prevent their release into the environment in order to realize their practical application in wastewater treatment. In this study, we immobilized multi-walled carbon nanotubes (MWCNTs) within macro-calcium alginate beads. The composite beads were coated with an additional polysulfone (Psf) layer both to provide an external barrier to MWCNTs release into the effluent and also to improve the mechanical integrity of the beads. The hybrid beads were tested for their capacity to remove the bio-refractory endocrine disruptor compound bisphenol-A (BPA) using batch and packed bead column experiments. Maximum BPA removal was achieved at 22% MWCNTs, which was the dispersion limit of MWCNTs in our study. The adsorption of BPA followed Langmuir isotherm model with good correlation. The maximum adsorption capacity of the composite beads of dosage 4 g L−1 as obtained using the Langmuir model was 24.69 mg g−1. Addition of the Psf layer, together with MWCNTs, improved the bead compression performance by up to twelvefold at 40% compressive extension. This study showed that the hybrid alginate-Psf bead may serve as compartment for encapsulation of MWCNTs for removal of BPA. Improved compression performance introduced by addition of Psf layer could protect hybrid beads used, for example, in reactors subjected to extreme conditions such as high flow rates.

The rapidly expanding market for biodiesel has increased the supply and reduced the cost of glycerol, making it an attractive sustainable feed stock for the fuel and chemical industry. Glycerol-based biorefinery is the microbial fermentation of crude glycerol to produce fuels and chemicals. A major challenge is to obtain microbes tolerant to inhibitors such as salts and organic solvents present in crude glycerol. Microbial screening was attempted to isolate novel strain capable of growing on crude glycerol as a sole carbon source. The newly isolated bacteria, identified as nonpathogenic Kluyvera cryocrescens S26 could convert biodiesel-derived crude glycerol to ethanol with high yield and productivity. The supplementation of nutrients such as yeast extract resulted in distinguished enhancement in cell growth as well as ethanol productivity under anaerobic condition. When glycerol fermentation is performed under microaerobic condition, there is also a remarkable improvement in cell growth, ethanol productivity and yield, compared with those under strict anaerobic condition. In batch fermentation under microaerobic condition, K. cryocrescens S26 produced 27 g/l of ethanol from crude glycerol with high molar yield of 80% and productivity of 0.61 g/l/h.