RESUMO
This study investigated the feasibility of employing neat chitosan powder, polyacrylamide, and chitosan micro-beads as adsorbents for the rapid and efficient removal of Direct Blue 78 dye from textile industrial wastewater. A series of batch experiments were conducted to examine the impact of adsorbent dose, contact time, and pH on the adsorption process. The physicochemical analysis, including FTIR, zeta potential analysis, and SEM were performed to identify the adsorption mechanism of chitosan powder and micro-beads. It was found that increasing the powder chitosan dose to 4.5 g/L and contact time up to 40 min resulted in achieving a significant increase in dye removal efficiency up to 94%. The highest removal efficiency of 94.2% was achieved at an initial dye concentration of 50 mg/L, a chitosan dosage of 4.5 g/L, and an optimized contact time of 60 min. Utilizing a polyacrylamide gel dose of 45 mL/L reduced the sedimentation time of chitosan from 8 h to 5 min. Equilibrium studies showed an initial L-shaped equilibrium curve, indicating that the adsorption process primarily arises from electrostatic interactions between dye molecules and adsorbent particles (physical forces). The Langmuir isothermal model demonstrated the best fit to the equilibrium data. Combining chitosan powder with polyacrylamide gel emerges as an economically viable choice for dye removal in industrial wastewater effluents, offering a cost-effective alternative to pricey commercial adsorbents. The results of the study revealed that the presence of polyacrylamide dye enhanced the removal efficiency and settling time of DB78 dye using chitosan.
RESUMO
Protection from waves and providing an appropriate calmness ratio are vital requirements in the designing phase of a harbor. Another crucial issue is guaranteeing sufficient water circulation as a key indicator for water quality and avoiding the associated environmental problems of poor water quality conditions. In a coastal harbor, the interior basin's water quality largely depends on the harbor's natural/self-ability to flush out different existing pollutants. El-Burullus fishing harbors is one of the Egyptian coastal fishing harbors that suffer from environmental issues such as accumulated pollutants, particularly in stagnant areas, and deterioration of water quality within the harbor's basin. Investigating water quality status within the coastal harbors necessitates knowledge about the mechanism of water circulation patterns within the harbor. The most common indicator for the water renewal and circulation pattern evaluation is the flushing time. Therefore, a coupled coastal hydrodynamic modeling system and particle tracking model (CMS-PTM) are utilized to investigate the tidal-induced circulation pattern within the El-Burullus fishing harbor, considering two tide scenarios (best and worst). Three locations (where most operational fishing facilities exist) were selected as point sources (instantaneous mass) for particle release. The results highlight the role of tidal actions on the water circulation within El-Burullus harbor and how the residence time varies based on the source release location.
