Removal of Paraquat from Aqueous Solutions onto Zeolite LTL

Zeolite LTL (K_LTL and H_LTL) was used as adsorbent for the adsorption of herbicide paraquat from an aqueous solution. The characterization of zeolite LTL has been carried out through various techniques: X-ray diffraction, X-ray fluorescence spectroscopy, FTIR and surface analysis. The adsorption occurred through cation exchange and the results showed that the adsorption capacity of paraquat onto K_LTL (161.71 mg/g) is higher than H_LTL (25.67 mg/g). These results can be explained by the amount of Al in the structure of zeolite and affinities of negative sites in zeolite and extra-framework cations (K+ and H+). The equilibrium data was best adjusted using the Langmuir model which has high correlation coefficient values (0.99).Zeolite LTL (K_LTL and H_LTL) was used as adsorbent for the adsorption of herbicide paraquat from an aqueous solution. The characterization of zeolite LTL has been carried out through various techniques: X-ray diffraction, X-ray fluorescence spectroscopy, FTIR and surface analysis. The adsorption occurred through cation exchange and the results showed that the adsorption capacity of paraquat onto K_LTL (161.71 mg/g) is higher than H_LTL (25.67 mg/g). These results can be explained by the amount of Al in the structure of zeolite and affinities of negative sites in zeolite and extra-framework cations (K+ and H+). The equilibrium data was best adjusted using the Langmuir model which has high correlation coefficient values (0.99)

Morphology-Controlled Synthesis of Zeolite and Physicochemical Properties

Zeolite L is a crystalline aluminosilicate compound and a typical chemical composition of K9Al9Si27O72•nH2O (n = 0 - 36). The structure and chemical properties, as well as their sizes and morphologies of zeolite L has led to various applications in different fields. The aim of this study is to investigate the effects of chemical compositions of the starting gel on the synthesis, size and morphology of zeolite L crystals. Zeolite L had been synthesized hydrothermally at 180oC for 2 days, from gels with the molar compositions of 2.62-3.78 K2O: 0.8-1.4 Al2O3: 8-12 SiO2: 80-200 H2O. The variation of chemical compositions led to the differences in morphologies and crystal sizes. Their morphologies varied from ice hockey to cylindrical shapes and their crystal sizes varying from 1.50-7.53 µm. With an increase in H2O and SiO2, the crystal size was also increased but decreased with an increase in K2O. In varying Al2O3, there was no effect on their shapes which were still cylindrical but with different crystal sizes. Moreover, the adsorption of ethylene on zeolite L samples depended significantly on crystal shapes and sizes

Facile Hydrothermal Synthesis of Zeolitic ANA Membrane from Raw Kaolin

The present paper reported a preparation of zeolitic ANA (analcime) membrane on porous ceramic support by in situ synthesis method using raw kaolin as SiO2 and Al2O3 source with the molar composition of Al2O3 ∙ 2.3SiO2 ∙ 3.6Na2O ∙ 140.4H2O at hydrothermal temperature 200ºC. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the ANA membrane. The effects of aging time and hydrothermal time on the synthesis were investigated. The porous ceramic supports were prepared by adding 10.0 wt% of cristobalite and varying an amount of pore formers (activated carbon and calcite) by sintering at 1400ºC. This resulted in the high crystallinity of ANA observed on the support which was prepared from mixing of 2.5 wt% of activated carbon and 2.5 wt% of calcite. In addition to aging, it was observable that small crystals seemed to spread completely on the support within 3 days of aging. It seems that the longer the hydrothermal time is, the more obvious the crystals tightly bound with the support becomes

Thermal and acid treatment on natural raw diatomite influencing in synthesis of sodium zeolites

โครงการหนึ่งอาจารย์หนึ่งผลงาน ประจำปี 254

Facile Method by Bentonite Treated with Heat and Acid to Enhance Pesticide Adsorption

In this work, simple conditions were applied to modify bentonite for the removal of pesticides from aqueous solution. Bentonite was modified in a single step as BA0.5 (with HCl 0.5 M) and BC500 (calcined at 500 °C) and combined steps with different sequences (BA0.5C500 and BC500A0.5). These adsorbents were characterised by XRD, XRF, FT-IR, 27Al MAS NMR, BET, NH3-TPD, TGA, HPLC, particle size analysis and zeta potential. Single-component adsorption with atrazine, diuron, 2,4-D and paraquat was used in aqueous solution at various pesticide concentrations, contact times and pH levels. It was found that the sequence of the treatment significantly affected atrazine adsorption. BC500A0.5 exhibited the highest efficiency for atrazine adsorption in a broad pH range of 3.0–9.0. Its adsorption at pH 6.0 was about 12 times greater than that of other adsorbents with an initial atrazine concentration of 50 mg L−1, which indicates BC500A0.5 specifically for the adsorption of atrazine. In addition, for the simultaneous adsorption of all four pesticides, BC500A0.5 was found to remove the maximum total amount of the pesticides, indicating that it could be used as a good multifunctional adsorbent. All modified bentonites showed similar diuron adsorption better than that of unmodified bentonite. The greatest adsorption of 2,4-D prefers BA0.5C500, occurring at pH 2–4. In the case of paraquat adsorption, all adsorbents are good at absorbing paraquat, but bentonite had the highest rate of paraquat removal, whereas BA0.5C500 was found to have the lowest, and the adsorption increased with increasing pH. Furthermore, the adsorption process on the adsorbents fits well with the Langmuir isotherm and pseudo-second-order kinetics models, as the thermodynamic parameters showed a spontaneous and endothermic process

Hydrothermal Synthesis of High Crystalline Silicalite from Rice Husk Ash

The objective of this research work was to evaluate the hydrothermal synthesis of silicalite with high crystallinity within a small particle size. The current study focused on investigating the effects of silica sources such as rice husk ash (RHA) and silica gel (SG), crystallization time, and ratios of NaOH/SiO2, H2O/NaOH, and SiO2/TPABr. The crystallinity, particle size, and morphology were characterized by FT-IR, XRD, particle size analyser, and SEM. The conclusion of the main findings indicated that the XRD patterns of these samples clearly showed a pure phase of MFI structure corresponding to FT-IR spectra with vibration mode at 550 and 1223 cm−1. The highest crystallinity was obtained at reaction time only 6 hours with the mole ratios of NaOH/SiO2, H2O/NaOH and SiO2/TPABr as 0.24, 155, and 30, respectively. When SG was used as a silica source, it was found that the particle size was smaller than that from RHA. The morphologies of all silicalite samples were coffin and cubic-like shape

ลักษณะของ ออร์แกโนเคลย์ ที่ถูกดัดแปรด้วย เฮกซะเดซิลไตรเมธิลแอมโมเนียม คลอไรด์ โดยเตรียม แบบทั่วไปและไมโครเวฟ

หนึ่งอาจารย์หนึ่งผลงาน ประจำปี 255