Adsorptive Removal of Phosphate from Aqueous Solution by Magnetic-Supported Kaolinite: Characteristics, Isotherm and Kinetic Studies

Abstract

Natural kaolin (NK) and magnetite-modified kaolin (MK) prepared by co-precipitation were used as adsorbents to remove phosphate from aqueous solution. The materials were characterized using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscope (FESEM), and vibrating sample magnetometer (VSM). Batch adsorption experiment was carried out to determine the phosphate removal efficiencies of these materials. The magnetic-supported kaolin showed better dispersion and less co-aggregation which ensured better fusion of the kaolin with magnetite (Fe 3 O 4 ). The removal process of phosphate was governed by physico-chemical process. The results demonstrated that the adsorption of phosphate onto NK and MK was highly pH-dependent and the kinetics of the adsorption followed pseudo-second order equation. The adsorption data of Mk adsorbent fitted better with the Freundlich isotherm equation. The MK showed much better adsorption capacity per mass of MK (52.91 mg/g) than untreated NK (17.61 mg/g). Since the magnetic kaolin can be easily prepared, it enables promising application for the removal of phosphate from aqueous solution. Hence, this new class of efficient adsorbent (MK), can have a variety of application in industrial processes.

Development of Kaolin Clay as a Cost-Effective Technology for Defluoridation of Groundwater

“…Different types of adsorbent materials such as activated carbon [27], clay [28], fluorspar and quartz [29], fly ash [30], kaolinite [31], bone char [32], red mud [33], and bentonite [34] have been employed to find out which one is economically feasible for defluoridation. Kaolin clay and clay minerals are naturally plentiful, renewable, and environmentally sustainable [35][36][37].…”

Removal of Malachite Green Dye from Aqueous Solution by Catalytic Wet Oxidation Technique Using Ni/Kaolin as Catalyst

“…This is in contrast to most other methods, which are ineffectual due to the cost or are ineffective at high and/or low contamination concentrations [ 14 ]. Adsorption has the advantage of being able to be used at extremely low concentrations, as well as the ability to regenerate and reuse the adsorbent [ 16 ]. To effectively remove pollutants, several types of advanced oxidation techniques have been used, such as the wet air oxidation process (WAO); this requires very high temperatures and pressures, resulting in high installation costs, and therefore the practical uses of this process are limited [ 17 , 18 ].…”

“…This process produces free hydroxyl radicals (OH•), powerful oxidants of organic pollutants [ 19 , 20 ] which are cost-effective in decomposing the most complex contaminants [ 21 ] to inorganic compounds such as CO 2 and H 2 O. The most notable benefit of this technique is the widespread use of heterogeneous catalysts, such as supported catalysts for water treatment [ 16 ], to reduce the severity of the oxidation conditions [ 17 , 18 ].…”

“…Kaolin clay is a non–toxic material that has been the subject of substantial research in the field of clays and soils due to its potential use as catalyst support. Kaolin was used as a support in the manufacture of supported catalysts in numerous studies conducted all over the world [ 16 , 20 , 22 , 23 , 24 , 25 ]. These catalysts have been utilized in wastewater treatment to degrade organic pollutants [ 20 , 26 ].…”

“…Due to their availability, low cost, and chemical qualities, transition metals such as cobalt, manganese, iron, copper, nickel, etc., and metal oxides [ 27 , 28 , 29 , 30 , 31 , 32 ] are the most widely utilized in the fabrication of catalysts. However, transition metal ions are dangerous and difficult to recycle, and therefore their application in wastewater treatment systems is restricted [ 16 , 33 ]. On the other hand, because of its high specific capacity, inherent environmental friendliness, low cost, and high efficiency, nickel oxide (NiO) has gained a lot of attention among metal oxides [ 34 ].…”