265
surface and structural properties (Babel and Opiso 2007). For this purpose, various
raw natural materials such as red mud (Gupta et al. 2001a), silicates (Chiron et al.
2003; Zendelska et al. 2018a), glauconite (Belousov et al. 2019), and natural
(Zendelska et al. 2015a, b, 2018b, 2019) and modified zeolites (Wingenfelder et al.
2005) are used. The removal of chromium, Cr(VI), is tested with adsorbents such as
activated carbon (Srivastava et al. 1996), Spirogyra biosorbents (Gupta et al. 2001b),
and fly ash (Bayat 2002; Gupta and Ali 2004). The soybean, tires, shells from hazelnuts, and sawdust have also been used for the same purpose. In recent years, the
elimination of heavy metals from wastewater is achieved by the use of certain types
of natural or agricultural wastes (Chatterjee et al. 2010; Khambhaty et al. 2009),
containing various functional groups such as hydroxyl, aldehyde, aliphatic acid
group, alkene, amide, nitroaromatics, silicate, sulfonate, and others. It is the existence of these functional groups in the organic adsorbents that enables the adsorption of Cr(VI). Also for this purpose, in recent years, the effectiveness of removal of
the six-valent chromium using natural low-cost adsorbents, such as sunflower stalks
(Sun and Shi 1998), crust of Eucalyptus (Sarin and Pant 2006), bran of corn (Singh
et al. 2006), coconut shell, leaves of trees, shells of peanuts, and nuts (Karthikeyan
et al. 2005), has been explored. Chromium six-valent as well as other pollutants can
also be removed with inorganic raw materials such as bentonite, aksil, and pemza
(pumice) (Memedi et al. 2016a, b, 2017; Belousov and Krupskaya 2019).
Republic of North Macedonia is rich in natural inorganic materials such as
clayey diatomite (Pavlovski et al. 2011; Cekova et al. 2013; Reka et al. 2016,
2019b), perlites (Reka et al. 2019a), and diatomite (Reka et al. 2014, 2017) that
represent industrial minerals which could be used to successfully remove various
metal ions from aqueous solutions.
9.2 Materials and Methods
The inorganic raw material used as adsorbent of Cr(VI) during this research is collected from the village of Suvodol, Bitola, Republic of North Macedonia. During
this research clayey diatomite is used in its natural state, without any modification
or activations.
The chemical composition of the material was determined with the classical silicate analysis, while the XRPD analysis was performed on the DRON diffractometer, 36 kV, 18 mA, CuKα/Ni. The infrared analyses were performed on PerkinElmer
FTIR 2000, by KBr tablet technique. The scanning electron microscopy (SEM) of
clayey diatomite was performed with energy dispersive X-ray spectroscopy (EDX)
employing FEI Quanta 3D FEG dual beam microscope, and the transmission electron microscopy was performed with Hitachi H-7650 apparatus (120 kV automatic
microscope).
For the preparation of solutions of Cr(VI) with a particular initial concentration,
K 2 Cr 2 O 7 standard solution with a concentration of 1000 mg/l was used. pH of
9 Removal of Chromium(VI) from Aqueous Solution by Clayey Diatomite: Kinetic…
surface and structural properties (Babel and Opiso 2007). For this purpose, various
raw natural materials such as red mud (Gupta et al. 2001a), silicates (Chiron et al.
2003; Zendelska et al. 2018a), glauconite (Belousov et al. 2019), and natural
(Zendelska et al. 2015a, b, 2018b, 2019) and modified zeolites (Wingenfelder et al.
2005) are used. The removal of chromium, Cr(VI), is tested with adsorbents such as
activated carbon (Srivastava et al. 1996), Spirogyra biosorbents (Gupta et al. 2001b),
and fly ash (Bayat 2002; Gupta and Ali 2004). The soybean, tires, shells from hazelnuts, and sawdust have also been used for the same purpose. In recent years, the
elimination of heavy metals from wastewater is achieved by the use of certain types
of natural or agricultural wastes (Chatterjee et al. 2010; Khambhaty et al. 2009),
containing various functional groups such as hydroxyl, aldehyde, aliphatic acid
group, alkene, amide, nitroaromatics, silicate, sulfonate, and others. It is the existence of these functional groups in the organic adsorbents that enables the adsorption of Cr(VI). Also for this purpose, in recent years, the effectiveness of removal of
the six-valent chromium using natural low-cost adsorbents, such as sunflower stalks
(Sun and Shi 1998), crust of Eucalyptus (Sarin and Pant 2006), bran of corn (Singh
et al. 2006), coconut shell, leaves of trees, shells of peanuts, and nuts (Karthikeyan
et al. 2005), has been explored. Chromium six-valent as well as other pollutants can
also be removed with inorganic raw materials such as bentonite, aksil, and pemza
(pumice) (Memedi et al. 2016a, b, 2017; Belousov and Krupskaya 2019).
Republic of North Macedonia is rich in natural inorganic materials such as
clayey diatomite (Pavlovski et al. 2011; Cekova et al. 2013; Reka et al. 2016,
2019b), perlites (Reka et al. 2019a), and diatomite (Reka et al. 2014, 2017) that
represent industrial minerals which could be used to successfully remove various
metal ions from aqueous solutions.
9.2 Materials and Methods
The inorganic raw material used as adsorbent of Cr(VI) during this research is collected from the village of Suvodol, Bitola, Republic of North Macedonia. During
this research clayey diatomite is used in its natural state, without any modification
or activations.
The chemical composition of the material was determined with the classical silicate analysis, while the XRPD analysis was performed on the DRON diffractometer, 36 kV, 18 mA, CuKα/Ni. The infrared analyses were performed on PerkinElmer
FTIR 2000, by KBr tablet technique. The scanning electron microscopy (SEM) of
clayey diatomite was performed with energy dispersive X-ray spectroscopy (EDX)
employing FEI Quanta 3D FEG dual beam microscope, and the transmission electron microscopy was performed with Hitachi H-7650 apparatus (120 kV automatic
microscope).
For the preparation of solutions of Cr(VI) with a particular initial concentration,
K 2 Cr 2 O 7 standard solution with a concentration of 1000 mg/l was used. pH of
9 Removal of Chromium(VI) from Aqueous Solution by Clayey Diatomite: Kinetic…