Performance evaluation of surfactant modified kaolin clay in As(III) and As(V) adsorption from groundwater: adsorption kinetics, isotherms and thermodynamics
Abstract:In this paper surfactant modified kaolin clay for As(III) and As(V) was prepared by intercalating hexadecyltrimethylamonium bromide (HDTMA-Br) cationic surfactant onto the clay interlayers. Batch experiments were used to evaluate the effectiveness of surfactant modified kaolin clay towards As(III) and As(V) removal. The results revealed that adsorption of As(III) and As(V) is optimum at pH range 4–8. The maximum As(III) and As(V) adsorption capacities were found 2.33 and 2.88 mg/g, respectively after 60 min co… Show more
“…The obtained results concluded that Ca 2+ and Mg 2+ cations enhanced the positive charges and created more active sites on the adsorbent surface, which led to higher sorption of As(III). Similar results have been reported in previous studies [72,79].…”
Section: Effect Of Co-existing Ionssupporting
confidence: 93%
“…The removal of As(III) was hardly influenced by the presence of Cl − , F − and NO 3 − . However, a much decreased As(III) adsorption capacity was observed in the presence of CO 3 2− and SO 4 2− , which suggested that these anions compete with As(III), leading to its decreased removal efficacy [72] On the other hand, As(III) removal rate was increased in the presence of Ca 2+ and Mg 2+ cations. The As(III) removal rate, in the presence of Ca 2+ cation, increased from 80.9% to 92.5% and 75.8% to 87.3% with HEX-VER and VER, respectively.…”
Section: Effect Of Co-existing Ionsmentioning
confidence: 99%
“…While at moderate pH, the low charge density on adsorbent surface, promotes the Van der Waal attraction forces, which results in optimum As(III) uptake (Equation ( 5)). Moreover, at extreme alkaline pH, both the As(III) and adsorbent surface have negative charges, which create a strong repulsion forces, resulting in a poor As(III) adsorption (Equations ( 6) and ( 7)) [72].…”
Enhanced As(III) removal (>99.7) was achieved by a novel organoclay (HEX-VER) adsorbent in Pearl River Delta water. Single and simultaneous As(III) removal in the presence of Cd(II) and/or Pb(II) by batch adsorption tests was analyzed. Spectroscopic, spectrometric, microscopic, and potentiometric techniques were used for characterization of the adsorbents. The parameters affecting As(III) adsorption, including pH, kinetic, isotherm, thermodynamic, and co-existing ions (Cl−, F−, NO3−, CO32−, SO42−, Ca2+ and Mg2+) were also investigated. The results showed that HEX-VER owned different morphology and larger average pore diameter after functionalization, resulting in an improvement of As (III) adsorption capacity. Further analysis confirmed that adsorption was of the monomolecular layer, well-described by the Langmuir isotherm model. The dominant mechanisms for As(III) removal were ion-exchange and complexation. Moreover, HEX-VER was regenerated for five consecutive cycles, and the removal ratio was ≈ 92%, showing its great regeneration potential. These findings suggest that the proposed inexpensive adsorbent has potential for practical applications of As(III) removal from river water.
“…The obtained results concluded that Ca 2+ and Mg 2+ cations enhanced the positive charges and created more active sites on the adsorbent surface, which led to higher sorption of As(III). Similar results have been reported in previous studies [72,79].…”
Section: Effect Of Co-existing Ionssupporting
confidence: 93%
“…The removal of As(III) was hardly influenced by the presence of Cl − , F − and NO 3 − . However, a much decreased As(III) adsorption capacity was observed in the presence of CO 3 2− and SO 4 2− , which suggested that these anions compete with As(III), leading to its decreased removal efficacy [72] On the other hand, As(III) removal rate was increased in the presence of Ca 2+ and Mg 2+ cations. The As(III) removal rate, in the presence of Ca 2+ cation, increased from 80.9% to 92.5% and 75.8% to 87.3% with HEX-VER and VER, respectively.…”
Section: Effect Of Co-existing Ionsmentioning
confidence: 99%
“…While at moderate pH, the low charge density on adsorbent surface, promotes the Van der Waal attraction forces, which results in optimum As(III) uptake (Equation ( 5)). Moreover, at extreme alkaline pH, both the As(III) and adsorbent surface have negative charges, which create a strong repulsion forces, resulting in a poor As(III) adsorption (Equations ( 6) and ( 7)) [72].…”
Enhanced As(III) removal (>99.7) was achieved by a novel organoclay (HEX-VER) adsorbent in Pearl River Delta water. Single and simultaneous As(III) removal in the presence of Cd(II) and/or Pb(II) by batch adsorption tests was analyzed. Spectroscopic, spectrometric, microscopic, and potentiometric techniques were used for characterization of the adsorbents. The parameters affecting As(III) adsorption, including pH, kinetic, isotherm, thermodynamic, and co-existing ions (Cl−, F−, NO3−, CO32−, SO42−, Ca2+ and Mg2+) were also investigated. The results showed that HEX-VER owned different morphology and larger average pore diameter after functionalization, resulting in an improvement of As (III) adsorption capacity. Further analysis confirmed that adsorption was of the monomolecular layer, well-described by the Langmuir isotherm model. The dominant mechanisms for As(III) removal were ion-exchange and complexation. Moreover, HEX-VER was regenerated for five consecutive cycles, and the removal ratio was ≈ 92%, showing its great regeneration potential. These findings suggest that the proposed inexpensive adsorbent has potential for practical applications of As(III) removal from river water.
“…pH values above the zero point of charge the raw as well as treated kaolin adsorbent will be negatively charged but positively charged below the zero points of charge. The highest value of pHpzc was obtained for beneficiated adsorbent due to its surface cleaned up during the beneficiation process [ 63 ]. Figure 6 Zero points of charge (ZPC) of raw calcined and beneficiated kaolin adsorbents were used for the BY 28 dye adsorption experiments.…”
In the present research, the kaolin adsorbents (beneficiated, raw powder, and calcined) were prepared from Ethiopian natural kaolin through mechanical, wet, and thermal processes. The geochemical and surface properties of kaolin adsorbent were characterized using FTIR, SEM/EDS, XRD, and XRF. In the batch experiment, basic operation parameters (initial dye concentrations, pH, temperature, contact time, and adsorbent dosage) were examined. Percentage removal efficiency basic yellow 28 (BY28) dye were recorded as 94.79%, 92.08%, and 87.08% onto beneficiated, raw, and calcined kaolin absorbents, respectively at an initial dye concentration of 20 mg/L, solution pH of 9, the temperature of 30 C C, and contact time of 60 min and adsorbent dosage of 1g/ 100L. The molar ratio of SiO 2 /Al 2 O 3 was recorded as 2.911 Percent mass composition of Ethiopian kaolin which is higher than the expected pure kaolinite standard which allows us to classify the kaolin clay as a siliceous one. The calculated values of ΔG 0 for beneficiated adsorbent are-1.243, 1.576, and 4.396 kJ/mol at 303.15, 323.15, and 343.15 K, respectively for 20 mg/L of dye concentration and solution pH of 9, suggests that the thermodynamic behavior at lowest temperature is more feasible and spontaneous as compared with the higher temperature one. A similar fashion was calculated for raw and calcined adsorbents. The negative values of ΔH o and ΔS suggest that the adsorption phenomenon is exothermic and the adsorbate molecules are organized on the solid phase in a more disordered fashion than the liquid phase. The pseudo-first-order and pseudo-second-order models have been used to describe the kinetics in the adsorption processes. The Pseudo-second-order model has been fitted for the BY 28 dye adsorption in the studied concentration range. The adsorption of BY 28 dye for raw and calcined adsorbents follows the Langmuir isotherm and the Freundlich isotherm fitted for the beneficiated adsorbent. The amount of BY28 dye taken up by beneficiated, raw, and calcined kaolin adsorbents was found as 1.896, 1.842, and 1.742 mg/g, respectively at a contact time of 1.0 h, the adsorbent dosage of 1.0 g, initial dye concentration ¼ 20 mg/L and solution pH ¼ 9 at 30 C. The results found that these raw and prepared local kaolin adsorbents have a capacity as low-cost alternatives for the removal of dyes in industrial wastewater.
“…In the three FTIR patterns, the bands at 3430 and 1630 cm -1 represent the -OH stretching vibration in adsorbed water molecule [32]. The bands at 1090, 895, and 822 cm -1 represent the vibration of Si-O-Si/Al, Si-OH, and Al-OH, respectively [24]. Moreover, the bands at 573 and 473 cm -1 in kaolin can be ascribed to Si-O-Al/Fe and Si-O-Si, but that at near wavenumber in He@kaolin-1 and He@kaolin-3 can be ascribed to Fe-O-Fe.…”
Section: Analysis Of Fourier Transform Infrared Spectroscopymentioning
With the intensification of human activities, arsenite (As(III)) pollutant from the soil and ground water has been a threat to human health, and the problem gradually becomes the focus of attention. In this study, the effects of several environment factors on As(III) removal ability of complex minerals are determined through the analysis of mineralogical characteristics of the complex synthesis of hematite and kaolin, using X-ray diffraction, Fourier transform infrared, and specific surface area. In the results, the XRD patterns of hematite and kaolin complexes indicate that the loading covers up some characteristic peaks of minerals in kaolin, which can be that hematite loading decrease the order of structure for some minerals. With increasing Fe content, the hydroxyl sites gradually increase, therefore strengthening the As(III) removal ability of complexes. With increasing the As(III) concentration, the removal ratios of kaolin on As(III) almost keep unchanged and that of complexes show no obvious regularity. However, with the pH increasing, the removal ratios of all samples keep increasing. Furthermore, the increasing of As(III) concentration and pH both improve As(III) removal amount significantly, especially for As(III) concentration. In addition, there is no forming of new mineral through it as observed by XRD. Therefore, hematite loading can promote the As(III) removal on kaolin through adsorption in different environments, which can provide a better method for the remediation of arsenic pollution.
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