Lead Hydroxide-Vermiculite Complex: Preparation and Characterization
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Vermiculite
Characterization
Lead (geology)
The result on NH_3-N saturated adsorption capacity of crude vermiculite and adsorption isotherm were studied by adding (vermiculite) to construted wastewater, and the influence of pH,temperature etc., on the removal rate of NH_3-N and regeneration of (saturated) vermiculite were discussed. The experimental results showed that saturated adsorption capacity of vermiculite is 20.8mg/g; At pH level:2.0～6.0, adsorption capacity of vermiculite increases with pH increases, and the optimal pH value is 4.0～6.0;At (temperature:) 15～35℃, absorption capacity of vermiculite inverses to temperature,and the removal rate of NH_3-N improves with dosage (increases.) The order of influencing factors is pHdosagetimetemperature.This confirms basic parameters of vermiculite as a (newtype) (adsorptive) material.
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Experiment was designed under different pH and temperature conditions to analysis the NH4+ exchange capacity of Na+-vermiculite,Ca2+-vermiculite and Mg2+-vermiculite clay minerals pre-treated using NaCl,CaCl2 and MgCl2 solutions respectively.The results indicated that the exchange reactions occurred most rapidly at the proceeding 80 minutes and approached to equilibrium by about 120 minutes.The exchange quantity of ammonium on the vermiculite(at initial ammonium concentration of 673mg/L)varied with pH with a peak value of 28.36mg/g on Na+-vermiculite,23.01mg/g on Ca2+-vermiculite,20.14mg/g on Mg2+-vermiculite,18.04mg/g on natural vermiculite at pH 7.The exchange and adsorption isotherm of NH4+ on cation-vermiculite can be described by Langmuir equation.
Vermiculite
Cation-exchange capacity
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A vermiculite ore from Chengde, China was modified by the combination of acid treatment, heat treatment and Na ion exchange. Diverse amounts of HDTMAB, equivalent to 1, 1.5, 2, 3, 5 and 10 times of the ore's CEC, respectively, were used for the organic intercalation of the modified and crude vermiculites for comparison. XRD analysis and CEC measurement show that after the organic intercalation of modified vermiculite, the structure is different from that of crude vermiculite because modified vermiculite has lower CEC and hence weaker structure layer linkage. The modified vermiculite with smaller interlayer spacing is obtained when the amount of HDTMAB used for the intercalation is less than 5 times of the CEC of the crude vermiculite. When the amount of HDTMAB used is 5 times of the CEC of the crude vermiculite, the interlayer spacing of the modified vermiculite is equivalent to that of the crude vermiculite intercalated under the same condition. The modified vermiculite with larger interlayer spacing and even exfoliation can be obtained when the amount of HDTMAB used is 10 times of the CEC of the crude vermiculite, which is of importance to the preparation of polymer/vermiculite nanocomposites.
Vermiculite
Exfoliation joint
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Vermiculite
Thermogravimetric analysis
Differential thermal analysis
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Polybenzoxazine-vermiculite nanocomposites were prepared from two kinds of polybenzoxazine precursors and two kinds of organically modified-vermiculite minerals which were consisted of vermiculite ,hydrobiotite and phlogopite. After treatment of vermiculite minerals by hexadecyl trimethylam monium bromide(CTAB), the d 001 of vermiculite layers of vermiculite mineral increased from 1.43?nm to 2.67?nm and developed d 002=1.34?nm. After organically modified vermiculite intercalated with a polybenzoxazine precursor ( bisphenol A type), The d 001 of vermiculite layers increased from 2.67?nm to 3.63?nm further and developed d 002=1.82?nm and d 003=0.91?nm. It was showed that the polybenzoxazine precursor has intercalated into vermiculite layers. Cured the composites, the diffraction peak of vermiculite d 001 in XRD spectrum vanished and the vermiculite layers were exfoliated.
Vermiculite
Phlogopite
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A new filling of vermiculite was introduced in this paper. Vermiculite is one of soil minerals, with characteristic of absorption and large capacity of ion exchange. The impacting on SBR system was tested by added vermiculite. It is showed that vermiculite had a little effect on the decomposition of organic, only 5%. However, the vermiculite-system had better than ordinary system, reaching 20～30%. By regulating the factors of temperature and pH, removel ratio of NH~+_4 had always been at a level higher than 80%.
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Xinjiang vermiculite modified by HDTMAB can form organic vermiculite with 4.850 nm layer distance,charactered by XRD and FT-IR.Through black liquor treatment by organic vermiculite experiments,the influence of temperature,pH value,reaction time and organic vermiculite dosage for chroma removal rate were discussed,and the absorption effect of organic vermiculite,sodium modified vermiculite were compared with raw vermiculite and active carbon also.The results show that there are higher removal rate of organic vermiculite in black liquor treatment.When pH=4,organic vermiculite dosage was 20 g/L,adsorbing time 60 min at room temperature and under moderate speed stirring situation,the chroma removal rate reaches 92.80%,and the content of COD declines 110 mg/L from 12430 mg/L,and the effect of organic vermiculite gets on towards active carbons but much better than raw vermiculite and sodium-vermiculite.
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Several methods for increasing the volume yield of vermiculite were research. The methods comprise of impregnating vermiculite ore by magnesium or aluminum ion solution,oil treatment of vermiculite and calcining of vermiculite under the condition of high pressure,then instantaneous decompression. Experimental results indicated that after modification of vermiculite by ion impregnating or oil treatment,the volume yield of expanded vermiculite can be obviously increased.
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We use cation exchange technology to transform natural vermiculite into Al~(3+) vermiculite and use XRD and DTA to analyze the existing state of Al~(3+) in the vermiculite interlayer.It shows that the Al~(3+) in interlayer of Al exchange vermiculite could not be extracted by KCl solution but by sodium citrate. So the Al~(3+) in interlayer of Al exchange vermiculite is unexchangeable ploy-hydroxide aluminium. Although the ionic potential of Al~(3+) is very high, the dehydrated temperature of Al exchange vermiculite is lower than that of original vermiculite. It indicates when Al~(3+) enters into the interlayer of vermiculite, Al~(3+) is hydrolyzed into Al(OH)~(2+) and Al(OH)~(2+) to reduce the efficient ionic potential of Al~(3+) leading to the decrease of dehydrated temperature of Al exchange vermiculite. The possible dehydrated equation is:[Al(OH_2)_6]~(3+)[Al(OH)_x(OH_2)_(6-x)]~(3-x)+xH~+,in which x3。
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