Microwave-accelerated sorption of cationic dyes onto green marine algal biomass.

Monolithic algal green powder (MAGP) was fabricated based on the marine green macroalga Enteromorpha flexuosa. It was scrutinized by using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared (FT-IR), point of zero charge (PHPZC), and Brunauer-Emmett-Teller (BET) surface area. The ability of Enteromorpha flexuosa to capture both crystal violet (CV) and methylene blue (MB) from aqueous solutions was evaluated. The influence of variable conditional parameters on CV dye and MB dye batch sorption was investigated. Results showed that percentage removal of 90.3% and 93.4% were obtained under optimum conditions of variables for CV and MB, respectively. Effect of microwave radiation on dye sorption was also appraised. Processing the sorption under microwave irradiation (microwave-enforced sorption, MES) increases mass transfer and a contact time as low as 1 min is sufficient under optimized conditions (exposure time and power) reaching the equilibrium. The reusability of MAGP sorbent was achieved for four cycles of sorption/desorption by using 0.5 M HCl. The ability of MAGP for cationic dyes removal from spiked tap water and petrochemical plant discharge wastewater samples was successfully registered. Ultimately, the displayed data showed a superior and excellent ability of algal powder to be exploited as a green, harmless, and effective sorbent for cationic dye removal.

Magnetic Schiff's base sorbent based on shrimp peels wastes for consummate sorption of chromate.

Magnetic Schiff's base chitosan composite has been prepared starting from shrimp peels as a raw material. Chitosan extraction involved three main stages as preconditioning, demineralization deproteinization and deacetylation. Chitosan modification process took place through the reaction between chitosan and polymeric Schiff's base of thiourea/glutaraldehyde in the presence of magnetite. The synthetic hybrid composite was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy-energy dispersive X-ray analyses and tested as sorbent for Cr(VI) recovery from aqueous solution. The performance of the sorbent was systematically evaluated by batch sorption experiments, followed by equilibrium and kinetic studies with different mathematical models. The isotherm study demonstrate that the sorbent achieved 99.1% (sorption capacity; 252.45 mg g-1) removal efficiency in Cr(VI) solution with concentrations up to 400 mg/L. Experimental data gave better mathematical fitting towards pseudo-second-order kinetic model and Langmuir isotherm model. The distribution coefficient was obtained at different temperatures and the thermodynamic parameters have been calculated: the sorption is endothermic, spontaneous and contributes to increase the randomness of the system. The sorbent could be recycled for three cycles of sorption/desorption.