No abstract

Water with phosphate concentrations above 2 μM may adversely affect aquatic life and human health. In this study, the parameters affecting phosphate removal from aqueous solutions by ion exchange were investigated – contact time and temperature, initial pH, initial phosphate concentration and resin dosage, and the presence of other ions. The best phosphate removal (99%) from 100 mg-P/L initial solution was observed at pH 10 and 25 °C after 3 hours of contact time. No negative phosphate removal results were obtained from phosphate solutions containing sulfate, nitrate and ammonium ions, i.e., resembling real wastewater. Desorption (with NaOH or NaCl) and recovery (with CaO) studies of phosphate sorbed by resin were also carried out, as well as thermodynamic investigations. The proportional desorbability of phosphate from the resin with NaCl was 85.6%. The recovery efficiency of phosphate was 79.4%. The sorption process was spontaneous and endothermic. The ion exchange mechanism was determined using different internal and external diffusion models. The mechanism controlling the removal of phosphate from aqueous solution is both internal and external diffusion. Application of the Langmuir and Freundlich isotherm models showed that the experimental results fit well with the Freundlich model.

In this study, sorption potential of anion exchange resin (Lewatit Monoplus M600) to remove sulphate from real wastewater was investigated. Kinetic studies were performed in batch experiments. A comparison of kinetic models applied to the sorption of sulphate onto resin was evaluated for the "infinite solution volume model" and "unreacted core model". Ratedetermining step is the liquid film control step of the unreacted core model. When pH values increased above 9, more than 80% sulphate removal was observed. Column sorption-elution experiments were performed for the removal of the sulphate from the wastewater by resin. The Thomas and the Yoon-Nelson models were applied to experimental data to determine the characteristic column parameters.

No abstract

The heat accumulated in the inner parts of the earth's crust is transmitted to the fluid in the geothermal aquifer by means of transportation. The geothermal fluid is transported to the surface either by wells or naturally. In this study, the geothermal fluid in Tuzla geothermal field in Çanakkale city was examined due to its high boron content (10.3 mg L -1 ). It was aimed to remove boron from geothermal fluid by adsorption in order to prevent possible negative effects on the environment. Fly ash was obtained from Çan thermal power plant. The specific surface area of the fly ash was 14.6 m 2 g -1 and the particle size was between 1.45 and 186 µm. According to ASTM C618 standard, fly ash was classified as Class C. Fly ash was composed of anhydrite, lime, hematite, cristobalite, quartz, calcite and feldspar. Various parameters such as initial pH, adsorbent dosage, contact time, and temperature were studied experimentally for the removal of boron from the geothermal fluid. The suitability of pseudo-first-order, pseudo-second-order, and intraparticle kinetic models to experimental data was examined. The data obtained from the isotherm studies were applied to the Langmuir, Freundlich and Dubinin-Radushkevich models.