Study On Ca²⁺ Removal In Hotwater Using Zeolite

Reversible cation exchange is one of the most important properties of zeolite because of their special crystal structure. By this exchange, adsorption and catalytic performance of zeolite can be improved and it has a widly application on environment such as repair purification and substitution.4A zeolite is one kind of the zeolite minerals and also a kind of new mineral resources reaching more attention in recently. Meanwhile the researching of calcium ion on-line monitor is still on a initial stage,which is not perfect on technology. So in this paper exchange properties of Ca²⁺ on zeolite and calcium ion on-line monitor were studied, which is theoretical guiding significance to 4A zeolite using and development as well as calcium field on-line monitor.The exchange properties of 4A zeolite with calcium ion in static and stirring state were studied in this paper, ion exchange property were discussed using thermodynamic method, the influence of concentration,PH values and reaction temperature on the adsorption were also studied. Also the adsorption were compared with clinoptilolite. Meanwhile determination of calcium electrode to calcium ion was investigated, which is compared with traditional EDTA mensuration,on-line exchange of Ca²⁺ on zeolite were performed under simulated field conditions. The results can be known by the analysise. The reaction was fitted a pseudo-first-order ,the process was liquid film controlled. 4A zeolite was better at calcium removal; The adsorption accorded with langmuir adsorption isotherm.;The removal rate of Ca²⁺ gradually decreased with the increasing of the concentration of calcium ion,but exchange amount of per unit mass 4A zeolite to Ca²⁺ increased; Ca²⁺ adsorption was also increase with the increasing of the temperature,but not significance above 70℃; PH value increased, adsorption rate of Ca²⁺ increased also,and have a higher adsorption quantity in alkaline condition. Under different calcium concentration ,the calcium removal rate of 4A zeolite is larger than clinoptilolite,and increased proportion. The performance of calcium electrod is excellent,compared with EDTA mensuration the result of electrode mensuration is accurate, and there is a linear relationship between the electrode potential and temperature,which is increased with the temperature. Under stirring state, calcium electrod had a ideal nernst response at the calcium concentration range of 1×10^-5-10^-1mol/L.It is considered that, 4A zeolite has the function of on-line removing hardness ions in hotwater. It obtaines the removal and detection methods of Ca²⁺ in hotwater using zeolite, provides some basis to work out scale problem in industrial thermal system,and the results have reference value to application.