پديدآورندگان :
Jafarpour Bita - Payam-Noor University, Urmia Branch, Urmia, Iran , Molaie Rahim rahimmolaie@yahoo.com Payam-Noor University, Urmia Branch, Urmia, Iran , Forough Mehrdad - Payam-Noor University, Urmia Branch, Urmia, Iran , Marandi Farzin - Payam-Noor University, Urmia Branch, Urmia, Iran
چكيده فارسي :
Water is one of the most important sources of living beings and is used in daily life which must be tasteless, colorless, and odorless [1]. The sources drinking water have a primary objective of protecting human health, including ensuring access to adequate quantities of safe water. Among water quality parameters, its hardness is an essential factor which is originates existence of cations such as calcium, magnesium; and in lower traces from other bivalent and trivalent cations [2]. In fact, calcium and magnesium are two major elements causing water hardness. Hard water is responsible for several harmful effects such as reducing the household cleaning efficiency, creating scaling and corrosion problems, and other serious difficulties in pipe lines of boilers [2, 3]. Most importantly, hard water affects the health as well as environment. To controls the hardness of water, softening processes are employed. Compared with conventional treatment including ion-exchange resins, zeolites or lime-soda ash treatment methods, development of the new inexpensive sorbent has become a primary motivation for researchers [4]. The primary objective of this work was evaluation of modified eggshell for selective and efficient removal of calcium and magnesium from spiked hardness water samples. Accordingly for this purpose, acidic treatment of calcinated eggshell with citric acid was successfully proceeded and the batch experiments were carried out on the resulting modified sorbent in order to examine its hardness ions-removing capability in spiked distilled water. The obtained results have revealed that prepared bio-sorbent is particularly effective for removing calcium and magnesium, with a maximum remove of 73.3% and 40.6%, respectively. On the other hand, eggshell has a cellulosic structure and contains amino acids [5]; thus in the next stage eggshell-bounded cellulose sorbent was used to softening progress. Under the optimized conditions (such as pH=5.5, time=15 min) the maximum efficiency of hardness removal which was obtained 89% and 51.4% for calcium and magnesium, respectively. Furthermore, the material has demonstrated to be efficiently regenerable by using an acidic treatment up to 10 tests. Finally, the application of this new designed system for the softening of groundwater and tap water samples has been tested.
