Removal of Paracetamol from Wastewater by Calcined Gypsum: Adsorption and Kinetics Study

It has been established that the presence of paracetamol in wastewaters can cause a potential risk to the environment. This work examined the possibility of using calcined gypsum in removing paracetamol from aqueous solutions. At neutral pH conditions, calcined gypsum was successful in removing paracetamol via adsorption, from aqueous solutions with a removal efficiency that ranged between 56.8 to 65.3 % of an initial concentration of 600 ppm. Increased temperature (from 20 to 500C) had a minor effect on the removal % of paracetamol while increasing the initial calcined gypsum dose (from 0.5 gm to 3 gm) and contact time (up to 15 min) increased by the removal % of paracetamol. Thermodynamically, the adsorption of paracetamol by calcined gypsum process was found to be spontaneous and endothermic, and more likely a physical process, while kinetically; the Pseudo-Second order model was found to be the best fit compared to the Elovich model. The removal process mainly consists of two stages, and it could be deduced from the kinetic behavior of paracetamol adsorption that the recrystallization process can be another rate-limiting step in the process.

Utilization of Calcined Gypsum in Water and Wastewater Treatment: Removal of Ibuprofen

Adsorption is a widely used technique for the removal of pharmaceutical organic micro-pollutants. In this article, calcined gypsum (CaSO4.0.5H2O) was utilized for the removal of ibuprofen medicine from polluted water. Several factors including the adsorbent dose, contact time, and temperature were studied. The influence of the ions in the solution on the precipitation of gypsum and its setting time was investigated because it significantly affects the percentage removal. The fast the setting time gypsum, the lower the percentage removal precipitate. From thermodynamic parameters, the negative values of ΔGo indicated a spontaneous and physisorption of ibuprofen onto the calcined gypsum surface. Kinetic study results showed that the adsorption of ibuprofen on gypsum follows pseudo-first-order kinetics.

Studies Regarding Production of the Moulding Form from Calcined Gypsum

In the pressing form made from calcined gypsum fixed in metal, wax can be cast with pressure. The device used to tide the pressing form should not bend. If the handling work is done carefully and correct one pressing form made from gypsum can be used for multiple wax models. To be used in construction the pressing forms, calcined gypsum must meet certain requirements regarding its constitution and functionality. To provide these requirements research work must be done to investigate characteristics such as: minimum compressive strength (wet and dry state), hardening time of calcined gypsum, gypsum dilatation after curing. To produce the pressing forms from calcined gypsum the following methods and operations have been used: operations concerning production of gypsum with the best physicochemical and mechanical properties in order to be used for construction of pressing forms (determining the quality of gypsum based on water and plaster ratio; establishing the influence of epoxy and curing solution on the mechanical resistance of the obtained gypsum; determining the influence of lime, boric acid, zinc chloride, sodium chloride on the hardening period of calcined gypsum); production of the models from wood and metal; fixing the model on the gypsum cushion; finding on the model the separation line and restrict the area used for gypsum moulding; applying grease on the model, on the plate under the model, on the walls and on all parts that come in contact with liquid gypsum to be poured; preparation of the gypsum solution.

On Experimental Study of Development Calcined Gypsum from Flue Gas Desulfurization by Microwave Technology

Flue gas desulfurization gypsum (FGD gypsum) was irradiated with microwave, it could be changed calcined gypsum from flue gas desulfurization (CGD). The microwave respectively irradiated five groups FGD gypsum at 100-110°C, 110-120°C, 120-130°C, 130-140°C and 140-150°C, then the fineness and setting time were respectively measured, and compressive/flexural strength were also determined after 2 hours. Experiments show that, CaSO4·0.5H2O crystal of CGD would be more quantity and bigger volume with irradiation temperature increasing. The reason was considered that there were special effect of microwave irradiation to calcium sulfate crystalsthat by scanning electron microscope, and found the Ca, S, O and other elements in cylindrical crystal by Edax. The formation mechanism of CaSO4·0.5H2O crystal by microwave irradiation is different from traditional CaSO4·0.5H2O crystal formation theories.