Adsorption Capacity Of Kaolin Research Articles

Potential of Dimethyl Sulfoxide Modified Kaolin and Cetyl Trimethylammonium Bromide as Amoxycillin Adsorben

The large use of amoxicillin allows this antibiotic to enter the environment in large quantities and cause pollution. The adsorption technique can be used as a method to remove amoxicillin contaminants in wastewater by utilizing kaolin as an adsorbent. This study aims to determine the characteristics of kaolin as an adsorbent and determine the ability of kaolin to adsorb amoxicillin. Kaolin was activated with hydrochloric acid and modified using Dimethyl sulfoxide (DMSO) and cetyl trimethylammonium bromide (CTAB). The results showed that the characteristics of DMSO and CTAB-modified kaolin showed a new peak which was an O-H bending vibration in functional group analysis using FTIR. X-ray diffraction results show that the distance between planes in the kaolin structure is larger. Meanwhile, the results of the SEM analysis showed that the surface morphology of kaolin had a higher level of crystallinity than before which proved an increase in the adsorption capacity of kaolin. The adsorption kinetics follows the Santosa kinetic equation model with an adsorption rate of 0.004 min-1 and an equilibrium constant value of 0.007 L.mol-1 . The adsorption isotherm test follows the Freundlich isotherm equation model with an adsorption constant value of 561.694 L.mg-1 and an empirical constant value of 0.270.

Competitive Adsorption of Lead and Copper by Kaolin

Due to the potential of kaolin as an adsorbent for removal of heavy metals from solution, the competitive adsorption of Lead (Pb) and Copper (Cu) by kaolin was investigated to provide further understanding on the binding behaviors and capacities of these two metals onto kaolin. The Langmuir and Freundlich isotherms were applied to further explain the competition between the metals. Three different solutions were used, each at concentrations 10, 20, 30, 45, 60 and 75mg/L: single-metal solution of Pb (Pb-Only), single-metal solution of Cu (Cu-Only), and solution of both metals at the same concentrations (Binary solution). The kaolin adsorbed Pb about twice more than Cu, both for the binary solution and for the single-metal solutions. This correlated well with predictions of maximum adsorption capacity (Q) for kaolin, where Q for Pb was about twice as much as that for Cu, both in the binary solution and in the single-metal solution. Competition from Cu in binary solution reduced Pb adsorption by 9%, while Cu rather increased by 4.1%, relative to their respective adsorptions in Pb-Only and Cu-Only, respectively. However, during competitive adsorption in the binary solution, the relative proportions of adsorbed Pb increased by 11.4% as the initial metals concentration increased from 10 – 75mg/L, while that of Cu reduced by the same proportion. This was explainable by their respective separation factors (RL), which indicated higher favorability of kaolin for Pb than for Cu. Furthermore, bonding energy (KL) of Pb unto kaolin during competition was about 2.5 times that of Cu, and was likely able to cause Pb to displace Cu from kaolin surface. This study reveals greater adsorption capacity of kaolin for Pb than for Cu, and could provide the basis for future projects/studies that would employ kaolin in Pb and Cu removal.

MODIFIED KAOLIN WITH CATIONIC SURFACTANT FOR GIBBERELLIC ACID CARRIER MATERIALS

Synthesis of surfactant modified kaolin from natural kaolin from Tatakan, Tapin, South Kalimantan and its application for carrier material of gibberellic acid have been conducted. The kaolin modification was done by surface engineering using cationic surfactant cetyltrimethylammonium bromide (C16TMABr). The characterizations of kaolin and surfactant modified kaolin were carried out by XRF, SEM, XRD, FTIR and TGA/DTA. The adsorption capacity of kaolin was determined by Langmuir adsorption isotherm model. The result showed that kaolin from Tatakan, South Kalimantan consist of kaolinite, halloysite, quartz, chlorite, and christobalite. Surface modification using cationic surfactant showed that increasing surfactant content onto kaolin was proportional to the amount of surfactant loaded. Gibberellic acid was partitioned into the organic phase created by the surfactant tails of the C16TMA+ modified kaolin. The calculations result by Langmuir adsorption isotherm model showed that the highest increasing adsorption capacity occurred on surfactant modified kaolin with surfactant/CEC ratio of 2.0, with the adsorption capacity of 28.41 mg/g.

ADSORPTION OF GIBBERELLIC ACID (GA<sub>3</sub>) ONTO ACID ACTIVATED KAOLIN

Preparation, activation and adsorption study of natural kaolin from Tatakan, Tapin, South Kalimantan have been conducted. The activation of kaolin was done using 6 M HCl solutions at 90 °C for 3 h. The characterizations of kaolin were carried out by Fourier Transform Infrared, X-ray diffraction, and surface area analyzer. Adsorption parameters studied included the effect of pH, contact time, and concentration of gibberellic acid (GA3) onto kaolin samples. The amount of gibberellic acid adsorbed was determined using UV spectrophotometer. The adsorption capacity of kaolin was determined by Langmuir adsorption isotherm model. The result showed that activation of kaolin was resulted the larger specific surface area and more homogeneous composition of kaolin without any destruction of kaolin structure. Adsorption of gibberellic acid onto kaolin before and after activation showed that optimal adsorption was obtained at pH » 7 and reached the equilibrium within 4 h. The calculations result by Langmuir adsorption isotherm model showed that the increasing of adsorption capacity of acid activated kaolin is about 35%.

Interaction of Hg(II) with kaolin-humic acid complexes

AbstractThe adsorption and desorption of Hg(II) by humic acid (HA) previously adsorbed on kaolin was studied. In the range of HA concentration investigated (0.0 –26.9 mg g–1), the Hg(II) adsorption capacity of kaolin at pH 4 is enhanced by the presence of HA. For the complexes with the highest HA concentration and for low Hg(II) initial concentrations, adsorption was lower, i.e. as HA concentration on the complexes increases, Hg(II) equilibrium concentration also increases. This behaviour is due to the increasing presence of dissolved organic matter as the HA concentration on the complexes increases. The dissolved organic matter is able to form a soluble complex with Hg, thus decreasing adsorption. Hg(II) adsorption from a 2.5×10–5 MHg(II) solution was influenced by pH. For kaolin, a pHmax (pH where maximum adsorption occurs) of 4.5 was observed. At pH values >pHmax retention decreased with increasing pH. This same behaviour was observed for the kaolin- HA complex containing the lowest HA concentration (6.6 mg g –1). For the other kaolin-HA complexes there was little effect of pH on Hg(II) adsorption between pH 2.5 and pH 6.5. The presence of HA increased the adsorption of Hg(II) on kaolin all along the pH range studied. Desorption experiments showed that the amount of Hg(II) desorbed was quite low (<1%) for all the HA and Hg(II) concentration range studied, except for the kaolin at acid pH (pH 2.5) where the Hg(II) released was >50% of Hg(II) previously adsorbed. The presence of HA dramatically reduced this percentage of desorption to values of <3%, indicating reduced risk of toxicity problems in surface and subsurface waters. The addition of Cu(II) did not favour any Hg(II) desorption, even though Cu exhibits a strong affinity for organic matter.