P. Mirhoseini Moosavi; A. Astaraei; Ali reza Karimi; Gh. Karimi
Abstract
Montmorillonite is the major mineral of Bentonite with many applications in industrial fields but some impurities decreases the quality of the bentonite. The main objective of this study was to investigate the suitable method for purification of Ghaen mine bentonite. A combination of methods was considered ...
Read More
Montmorillonite is the major mineral of Bentonite with many applications in industrial fields but some impurities decreases the quality of the bentonite. The main objective of this study was to investigate the suitable method for purification of Ghaen mine bentonite. A combination of methods was considered including wet sieving and sedimentation, centrifuge and ultrasound. The efficiency of purification methods was determined based on X-ray, particle size, cation exchange capacity (CEC) and ratio peak of the Quartz/Montmorillonite analysis before and after experiments. The results showed that such methods were efficient for preparing of the materials having high quantity of montmorillonite with less than 2 microns particle sizes. Cristobalite was the only mineral remained in samples, however many of particles were exempted from the samples. Cristobalite was the main impurity remained with montmorillonite. Chemical treatment is the only way for its complete removal. The results of this study revealed that by using easy, cheap and fast methods, it is possible for acceptable purification of bentonite.
H.R. Rafiei; M. Shirvani; T. Behzad
Abstract
The remediation of soils and water contaminated with heavy metals generate a great need to develop efficient adsorbents for these pollutants. This study reports the sorption of lead (Pb) by bentonite (Bent), and sepiolite (Sep), that were modified with cetyltrimethyl ammonium (CTMA+) organic cations. ...
Read More
The remediation of soils and water contaminated with heavy metals generate a great need to develop efficient adsorbents for these pollutants. This study reports the sorption of lead (Pb) by bentonite (Bent), and sepiolite (Sep), that were modified with cetyltrimethyl ammonium (CTMA+) organic cations. The natural and surfactant modified clays (organo-clays) were characterized with some instrumental techniques including XRF, XRD, FTIR and SEM. Sorption studies were performed in a batch system, and the effects of various experimental parameters including contact time and initial Pb concentration were evaluated upon the Pb sorption onto sorbents. Maximum sorption of Pb was found to be, 83.26, 71.36, 56.25 and 37 mg g-1 for Sep, CTMA-Sep, Bent and CTMA-Bent adsorbents, respectively. The Pb sorption data were fitted to both the Langmuir and Freundlich models. The Freundlich model represented the sorption process better than the Langmuir model. Lead sorption rate was found to be considerably slower for organo-clays than that for unmodified clays. Sorption kinetics was evaluated by pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models. The sorption processes of organo-clays followed intraparticle diffusion kinetics. The results showed that the cationic surfactant modified bentonite and sepiolite sorbed less Pb than the unmodified clays.
