Carmen Zaharia

Study of flocculation with PONILIT GT-2 anionic polyelectrolyte applied into a chemical wastewater treatment

This paper discusses the applications of synthetic PONILIT GT-2 anionic polyelectrolyte in conjuction with ferric sulfate in a chemical wastewater treatment viz. wastewater from ceramics manufacturing. Synthetic wastewaters with different colloid concentrations were prepared and the coagulation-flocculation process followed by sedimentation and/or filtration was studied. Variables associated with the chemical wastewater composition, mixing time, and the coagulant and flocculant dose are considered in order to appreciate the process efficiency in terms of turbidity, chemical oxygen demand (COD), and color removal. The degrees are higher for turbidity and color (> 80 %) removal respectively, and, satisfactory for COD (< 50 %). An empirical model was elaborated by a third order rotatable design 23 type, considering ferric sulfate dose, polyelectrolyte dose, and mixing time as independent variables, while the turbidity and color removal efficiencies were chosen as optimization criteria. The empirical model was found adequate for the chemical wastewater treatment. Also, an analysis of the model was performed to find the optimal operating conditions, in order to apply this process for an efficient chemical wastewater treatment using ferric sulfate as coagulation agent and PONILIT GT-2 anionic polyelectrolyte as flocculation agent. The optimal values correspond to a ferric ions concentration of 6.093 mg/L, a polyelectrolyte dose of 0.651 mg/L, and a mixing time of 24.024 minutes for turbidity removal (95.869 %), respectively, and, to a ferric ions concentration of 6.01 mg/L, a polyelectrolyte dose of 0.69 mg/L, and a mixing time of 26 minutes for color removal (98.741 %).

Equilibrium, kinetic, and thermodynamic studies of Basic Blue 9 dye sorption on agro-industrial lignocellulosic materials

AbstractThe sorptive potential of some lignocellulosic agro-industrial wastes (sunflower seed shells and corn cob) for Basic Blue 9 cationic dye removal from aqueous solutions was examined using the batch technique. The Freundlich, Langmuir, and Dubinin-Radushkevich isotherm models were used in order to determine the quantitative parameters of sorption. The Langmuir isotherm model indicated a maximum sorption capacity for these materials in the range of 40–50 mg dye per g (25°C), slightly higher for corn cob than for sunflower seed shells. The values of the thermodynamic parameters showed that the retention of cationic dye is a spontaneous and endothermic process. The application of pseudo-first order and pseudo-second order intraparticle diffusion models, and a Boyd — Reichenberg model for kinetic data interpretation suggested that sorption of Basic Blue 9 dye onto the studied materials is a process where both surface sorption and intraparticle diffusion contributed to the rate-limiting step. These lignocellulosic wastes can be used with good efficiency for dye removal from aqueous effluents.

Valorization of food wastes as sorbent for dye retention from aqueous medium

AbstractIn this paper, batch removal of Brilliant Red HE-3B (BRed) and Methylene Blue (MB) dyes onto apple seeds powder was studied in order to evaluate the sorptive properties of this food waste. The experimental data equilibrium was analyzed using the Langmuir, Freundlich, and Dubinin–Radushkevich adsorption models. Results of the study reveal that the Langmuir model best describes the dyes sorption processes. The monolayer sorption capacity was established to be 66.225 mg/g BRed and, respectively, 26.316 mg/g MB at 25°C. The values of the mean free energy obtained from the Dubinin–Radushkevich model indicated a porous structure of the sorbents and suggest that physical sorption is the main sorption type involved in the studied processes. The values of the thermodynamic parameters (ΔG, ΔH, and ΔS) showed that sorption of tested dyes was feasible, spontaneous, and endothermic under examined conditions. The Fourier transforms infrared spectroscopy has been used to investigate the interaction between apple...

THE IMPACT OF ENERGY PRODUCTION ON ENVIRONMENT IN ROMANIA

The impact of energy production sector on the environment is evaluated by the pollution of the environmental factor (air, water and soil). The air is considered to be one of the most important affected environmental factors. As important pollutants emitted into air after the burning processes for public power, cogeneration and district heating, commercial, institutional and residential combustion, extraction and distribution of fossil fuels etc. are nitrogen oxides, sulfur oxides, solid ashes, hidrocarbons, carbon monoxide and dioxide carbon (the greenhouse gases). The natural water resources can be also affected by the energy production sector especially by the thermal pollution from cooling water and the organic substances used as inhibitors for chemical or biological stabilization of water or cooling water. The soil quality can be affected by the solid waste and fossil fuels.