煤层气的解吸/吸附机理研究综述

通过对国内外制约煤层气开发的因素和能源需求的分析,指出了研究煤层气的解吸吸附机理的意义。通过分析国内外解吸吸附机理的研究历史和现状,将煤层气的解吸吸附机理归纳综合为单分子层吸附和多分子层吸附两大类;将煤层气的解吸吸附机理模型归纳为五类,即Lang-muir等温吸附及其扩展模型、BET多分子层吸附模型、吸附势理论模型、吸附溶液模型和实验数据拟合分析模型等。对影响煤层气解吸吸附的因素,如煤层的性质、孔隙性结构、煤层气的组分、压力条件和温度条件等进行了详细的分析说明指出,解吸吸附机理未来研究的重点方向是在考虑目前已认识的复杂因素条件下,以研究煤层气吸附状态和煤层气的解吸动态过程为主,尤其是甲烷与水和煤层中碳分子的结合与分离的方式。

煤体变形与瓦斯解吸/吸附关系的研究实验

专门针对瓦斯解吸及吸附作用与煤岩形变的相关性做出实验认证,条件是恒压恒温,利用物理上的排水法间接获得瓦斯体积,又由于解吸量与吸附量是一对互逆过程,那么即可利用回归分析便能够算出朗格缪尔体积常数a以及压力常数b,进而把所获得数据进行拟合分析,得到了体积变化与解吸量的关系式,最终分析出瓦斯解吸及吸附作用和煤岩体积形变的定量关系。

废弃矿井煤层气资源量计算范围研究

“三带”理论及煤层气的解吸 /吸附理论 ,结合残余瓦斯压力理论及国内外的相关经验数据 ,从理论上对废弃矿井煤层气资源量的计算范围的确定进行了探讨。

Solvent impregnated resin prepared using ionic liquid Cyphos IL 104 for Cr(VI) removal

Ionic liquid (IL) trihexyl (tetradecyl) phosphonium bis 2,4,4-trimethylpentylphosphinate (Cyphos IL 104) was impregnated on XAD-7 resin. The solvent impreganated resin (SIR) was prepared and applied in Cr(VI) removal. The morphology and the thermal stability of the resins were explored. The effects of equilibrium time and initial pH value on Cr(VI) adsorption were investigated. Adsorption isotherm, separation and desorption of the SIR, and selectivity of SIR were also explored. The results show that Cyphos IL 104 exists in the inner XAD-7 resin, and the optimum pH value range of the SIR for Cr(VI) extraction is 0 to 2. When NaOH used as desorption solution, the Cr(VI) can be effectively desorbed from the SIR.

Effective adsorption of sulfate ions with poly(m-phenylenediamine) in aqueous solution and its adsorption mechanism

Sulfate adsorption by poly（m-phenylenediamine）s（PmPDs） with various oxidation states synthesized through chemically oxidative polymerization was investigated.Series of sorption experiments were conducted,and the adsorption mechanism and the relationship between oxidation state and adsorption performance were studied with the characterization of Fourier transform infrared spectroscopy（FTIR）,X-ray photoelectron spectroscopy（XPS）,pH tracking and energy calculation.The results show that the adsorption performance in acidic solution is improved with the decrease of oxidation state of poly（m-phenylenediamine）（PmPD）.The rate constant is as high as 425.5 mg/（g·min） in the short equilibrium time of 30 min.The estimated highest adsorptivity of sulfate ions is 95.1%.According to the Langmuir equation,the adsorbance is 108.5 mg/g.The sulfate desorption efficiency is about 95% and the accumulative adsorbance is up to 487.95 mg/g in 5 cycles.

Adsorption and Desorption Characteristics of Cadmium and Lead in Typical Paddy Soils of Jiangxi Province and Its Environmental Risk Assessment

[Objective] This study aimed to investigate the adsorption and desorption characteristics of cadmium and lead in typical paddy soils of Jiangxi Province. [Method] Gleyed paddy soil and waterloggogenic paddy soil were collected from Jiangxi Province and used as experimental materials to investigate single and com- petitive adsorption and desorption behaviors of cadmium and lead by batch equilib- rium method. The environmental risk of the presence of cadmium and lead in paddy soils was assessed using distribution coefficients. [Result] Under equal ratio condi- tions, the adsorption capacity of lead by two types of paddy soils was higher than that of cadmium, and the adsorption rate in waterloggogenic paddy soil was higher than that in gleyed paddy soil. The desorption capacity of cadmium by two types of paddy soils was higher than that of lead, and the desorption rate in gleyed paddy soil was higher than that in waterloggogenic paddy soil. Under competitive condi- tions, the adsorption capacity of cadmium and lead by paddy soils was significantly reduced compared with single ion system, while the desorption rate was remarkably improved. The potential environmental risk of cadmium contamination was greater than that of lead in paddy soils. Moreover, environmental risks of cadmium and lead were reduced with the increase of pH, which increased significantly under the coex- istence state. [Conclusion] In the coexistence of cadmium and lead, cadmium con- tamination should be controlled and avoided compared with lead contamination in paddy soils.

Adsorption and Desorption of Natural Zeolite on NH_4^+

The adsorption and desorption kinetic of natural zeolite on NH4＋ was stud-ied by lab analysis. The results showed that the adsorption and desorption kinetic of natural zeolite on NH4＋ coincided with the first-order kinetics, modified Freundlich equation, parabolic diffusion model, and heterogeneous diffusion model. The desorp-tion of the adsorbed NH4＋ was far rapider than the adsorption, which can be fin-ished within 60 min.

Adsorption Kinetics of NH_4^+ by Purple Soils with Different pH Values

Ammonium adsorption and desorption properties by purple soils with dif- ferent pH were studied. The results showed that the adsorption and desorption amounts of NH4＋ by purple soils increased with the increase of NH4＋ concentration, regardless of soil pH values; the largest adsorption and desorption amounts of NH4＋ by purple soil at pH 6.0 were 10.3 and 7.96 mg/g, respectively; the largest adsorp- tion and desorption amounts of NH4＋ by purple soil at pH 7.2 were 12.8 and 4.62 mg/g, respectively; the largest adsorption and desorption amounts of NH4＋ by purple soil at pH 8.0 were 13.5 and 2.23 mg/g, respectively. The isothermal adsorption ki- netics of NH4＋ by purple soils fits the Freundlich equation best （R〉0.95）. This study shows that the adsorption of NH4＋ by purple soils with different pH values is multi- molecular layer uneven surface adsorption.

Adsorption and desorption behaviors of ssDNA molecules on mica surface by surface forces apparatus

An approach for studying the adsorption and desorption behaviors of single-stranded DNA（ ssDNA） molecules on the mica surface by the surface forces apparatus（ SFA） is reported,which can be used to characterize the precise thickness,configuration and mechanical properties of ssDNA layers on the mica surface at a certain buffer solution. The formation of ss DNA layers is first studied by tuning the ssDNA concentrations, and the experimental results indicate that the ss DNA concentration of 100 ng / μL is ideal for forming a ssDNA monolayer structure on the mica surface, and the hardwall value measured to be 1.04 nm under this circumstance is regarded as the thickness of the ssDNA monolayer confined on mica. The desorption behavior of ssDNA molecules from the mica surface is further studied by observing and comparing different shapes of the force-distance curves under certain conditions. It is found that the desorption of ss DNA molecules from the mica surface occurs as the monovalent salts are added into the gap buffer. It is inferred that the competition effect between monovalent and divalent salts can induce the release of ssDNA from substrate.The results also reveal that 10 mmol / L monovalent salts（ Na~＋）is sufficient for the desorption of ssDNA from mica. This work provides an applicable method to study the binding mechanism of ss DNA molecules on inorganic substrates.

Adsorption and desorption behavior of silver ions onto valonia tannin resin

Valonia tannin （VT） was gelated through polymerization with formaldehyde to prepare an adsorbent, which was found effective to remove Ag＋ from aqueous solution. The adsorption-desorption behaviors of valonia tannin resin （VTR） were investigated under various initial Ag＋ concentrations, solution temperatures, pH values etc. The applicability of empirical kinetic models was also studied. The pseudo-second-order model studies revealed the Ag＋ sorption was very rapid. VT and VTR were characterized using FTIR and SEM before and after adsorption. The Ag＋ biosorption on VTR increased with a rise in initial concentration of Ag＋ and with a decrease in temperature. Desorption experiments were conducted at low pH values and the solutions of H2SO4, HNO3 and HCl were used for desorption. The VTR shows high adsorption capacity to Ag＋ in a wide pH range of 2.0-7.0, and a maximum adsorption capacity of 97.08 mg/g was obtained at pH 5.0 and 296 K when the initial concentration of Ag＋ was 100.0 mg/L. Ag＋ ion desorption could reach 99.6% using 1 mol/L HCl＋1% thiourea （NH2CSNH2） solution. By utilizing such characteristics of VTR, it is expected that it can be applied to recovering Ag＋ efficiently and simply with low cost.

Zinc adsorption and desorption characteristics in root cell wall involving zinc hyperaccumulation in Sedum alfredii Hance

Radiotracer techniques were employed to characterize 65Zn adsorption and desorption in root-cell-wall of hyperac-cumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) species of Sedum alfredii Hance. The results indicated that at the end of a 30 min short time radioisotope loading period, comparable amounts of 65Zn were accumulated in the roots of the two ecotypes Sedum alfredii, whereas 2.1-fold more 65Zn remains in NHE root after 45-min desorption. At the end of 60 min uptake period, no difference of 65Zn accumulation was observed in undesorbed root-cell-wall of Sedum alfredii. However, 3.0-fold more 65Zn accumulated in desorbed root-cell-wall of NHE. Zn2+ binding in root-cell-wall preparations of NHE was greater than that in HE under high Zn2+ concentration. All these results suggested that root-cell-wall of the two ecotypes Sedum alfredii had the same ability to adsorb Zn2+, whereas the desorption characteristics were different, and with most of 65Zn binding on root of HE being available for loading into the xylem, as a result, more 65Zn was translocated to the shoot.

Temperature Effect on Boron Adsorption-Desorption Kinetics in Soils

The effect of temperature on the properties of boron adsorption-desorption in brown-red soil, yellowbrown soil and calcareous alluvial soil of Hubei Province was investigated with the mobile displacement technique. The experimental data of B adsorption-desorption amounts and reaction t line at 25 and 40℃ were fitted by the zero-order, first-order and parabolic diffusion kinetic equations. The adsorption process was in conformity with the parabolic diffusion law at both the temperatures, and the values of rate constant of the parabolic diffusion equation in B adsorption were 0.138, 0.124 and 0.105 mg kg-1 min-1/2 at 25℃, and 0.147, 0.146 and 0.135 mg kg-1 min-1/2 at 40℃ for the brown-red soil, yellow-brown soil, and calcareous alluvial soil, respectively. The relationship between amount of B desorption and reaction time could be well described by the first-order kinetic equation, and the corresponding values of rate constant were 0.0422, 0.0563 and 0.0384 min-1 at 25℃, and 0.0408, 0.042 3 and 0.0401 min-1 at 40℃ for the brown-red soil, the yellow-brown soil and the calcareous alluvial soil, respectively. Therefore, the desorption process of B might be related to the amount of B adsorbed in soil. The higher the temperature, the lower the amount of B adsorption for the same soil in the same reaction time. The values of the apparent activation energy of B adsorption in the three soils calculated with the rate constants of parabolic diffusion equation were 3.27, 8.44 and 12.99 kJ mol-1, respectively, based on the experimental data of B adsorption amounts and reaction time at 25 and 40℃.

Effect of Organic Manure on Phosphorus Adsorption－Desorption and Availability in Paddy Soil Derived from Red Earth

A field test with the traditional rotation of paddy rice/upland crop (wheat) was carried out on a paddysoil derived from red earth to elucidate the effect of organic manure on the phosphorus adsorption-desorptionby soil and its P availability Soil samples were taken from different treatments at rice harvesting stage andanalysed. The isothermal adsorption of P by the samples fitted very well with Langmuir equation, and hence,the parameters in the equation, i.e., maximum adsoaption (qm), constant related to bonding energy (k) andtheir product (k x qm) could be used as a comprehensive index to characterize the potential P adsorptivityof the soil.Organo-inorganic fertilization and organic manuring conld decrease qm and k, while mineral P appli-cation had little effect on them. The isothermal desorption of P was significantly correlated with initiallyadded and isothermally adsorbed P. Part of P added was fixed, which represented the P fixation capacityof soil, and organic manuring could obviously lower the P fixation. The content of soil available P had asignificant negative correlation with qm, k and fixed P. It is concluded that organic manure could increase theP availability of paddy soil derived from red earth by decreasing qm, k, maximum buffering capacity (MBC=k x qm) and fixation capacity.

Adsorption and Desorption Behavior of Tannic Acid in Aqueous Solution on Polyaniline Adsorbent

Tannic acid is generally considered as one of polyphenolic pollutants, which may cause severe threats to the environment. In this study, polyaniline adsorbent was synthesized by chemical oxidation to remove tannic acid in aqueous solutions. The adsorption amount of tannic acid varied greatly with pH of solution and strong adsorption was at pH 5.8-6.7. Coexisting cations, such as Na＋, K＋, and Ca2＋, can enhance the adsorption of tannic acid on poly- aniline, which may be contributed to the electrostatic interaction between tannic acid and polyaniline. The adsorp- tion process could be well described by Langmuir model and the maximum adsorption capacity was 117.65 rag.g〈 at 35℃and pH 6.0. The thermodynamic parameters calculated from the adsorption isotherms indicate that the ad- sorption of tannic acid is spontaneous and endothermic process. The polyaniline saturated with tannic acid can be desorbed in alkaline solution and regenerated adsorbent can be used repeatedly with high adsorption capacity, which implies that polyaniline adsorbents have a great potential in water purification for the removal of tannic acid.

Scandium recovery from raffinate copper leach solution as potential new source with ion exchange method

Raffinate copper leach solution of the Iran Sarcheshmeh copper complex has up to 3 mg/L scandium(Sc),which is significantly better than many existing sources,making it a possible source for the recovery of Sc using the ion exchange method.Visual Minteq software was employed to ascertain the ionic species likely to be formed under operational conditions in the mine and for selecting the suitable ion exchange resin.The cationic resin thus chosen was employed statically with ions-bearing synthesized solutions and statically/dynamically for actual copper mining raffinate solution.Room temperature and pH of 1.5 showed the highest Sc adsorption.The dynamic tests established the full saturation of the resin at 450 BV of the raffinate solution flow.Using sodium carbonate for elution,desorption of Sc,Y and Ce from the resin during static elution tests at constant duration was higher than that of Fe,Al and Cu.The results from the dynamic tests followed similar trends for the priority and the extent of the elution process.Desorption results from specimens of dynamic tests show a 60:1 concentration ratio leading to a 186 mg/L Sc-rich solution.

Effects of Organic Anions on Phosphate Adsorption and Desorption from Variable-Charge Clay Minerals and Soil

Effects of citrate and tartrate on phosphate adsorption and desorption from kaolinite, goethite, amorphous Al-oxide and Ultisol were studied. P adsorption was significantly decreased as the concentration of the organic anions increased from 10-5 to 10-1 M. At 0.1 M and pH 7.0, tartrate decreased P adsorption by 27.6% - 50.6% and citrate by 37.9 - 80.4%, depending on the kinds of adsorbent. Little Al and/ or Fe were detected in the equilibrium solutions, even at the highest concentration of the organic anions. Effects of the organic anions on phosphate adsorption follow essentially the competitive adsorption mechanism.The selectivity coefficients for competitive adsorption can be used to compare the effectiveness of different organic anions in reducing P adsorption under given conditions.Phosphate desorption was increased by 3 to 100 times in the presence of 0.001 M citrate or tartrate compared to that in 0.02 M KC1 solution alone. However, for all the soil and clay minerals studied the amount of P desorbed by citrate or tartrate was generally lower than or close to that of isotopically exchangeable P. The effect of organic anions on phosphate desorption arises primarily from ligand exchange.

Effects of Phosphate Adsorption on Adsorption-Desorption and Availability of Cu and Zn Ions in Ultisols and Alfisols

Surface charge, secondary adsorption- desorption and form distribution of Cu2+ and Zn2+ in Ultisols and Alfisols having adsorbed phosphate were studied by potentiometric titration, adsorption equilibrium and sequential extraction method, respectively. The soil surface negative charges increased whereas the amount of positive charges decreased with increase of P adsorbed. The soil secondary adsorption capacity for Cu2+ and Zn2+ was positively significantly correlated with the amount of P adsorbed by the soils, which could be described by the Langmuir equation. The amounts of Cu2+ and Zn2+ desorption from soils were decreased after P adsorption by the soils and the relationship between them was linear. After the soils adsorbed P, form distribution of Cu2+ and Zn2+ in soils changed remarforbly.

Biosorption and desorption of Cd^(2+) from wastewater by dehydrated shreds of Cladophora fascicularis

The adsorption and desorption of algae Cladophora fascicularis and their relation with initial Cd2+ concentration, initial pH, and co-existing ions were studied. Adsorption equilibrium and biosorption kinetics were established from batch experiments. The adsorption equilibrium was adequately described by the Langmuir isotherm, and biosorption kinetics was in pseudo-second order model. The experiment on co-existing ions showed that the biosorption capacity of biomass decreased with an increasing concentration of competing ions. Desorption experiments indicated that EDTA was efficient desorbent for recovery from Cd2+. With high capacities of metal biosorption and desorption, the biomass of Cladophora fascicularis is promising as a cost-effective biosorbent for the removal of Cd2+ from wastewater.

Adsorption and Desorption of Exogenous Rare Earth Elements in Soils:Ⅰ. Rate and Forms of Rare Earth Elements Sorbed

Adsorption and desorption of exogenous rare earth elements (REE) in soils were studied.Results showed that soils had strong adsorbability for REE and the rate of adsorption of REE was over 95% of the added REE in these tests.The characteristics of adsorption isotherms corresponded well with the both Freundlich and Temkin equations,but deviated from the Langmuir equation.The adsorption of REE tended to increase with the rising of soil pH.A sequential extraction method used for studing the desorption and distribution of REE sorbed in soils are also discussed.

Purification of chlorogenic acid in Flos Lonicerae with system of polar ordered resins

A system of polar ordered resins was established for purification of chlorogenic acid in Flos Lonicerae. It was composed of three reversed phase resins, AB-8, DM-130 and NKA-9, representative for their gradually increased polarity and selectivity. A method of RP-HPLC was used for determination of chlorogenic acid. And the performance of adsorption and desorption for chlorogenic acid with the system of polar ordered resins was studied. Furthermore, the effects of concentration, pH and flow rate of the adsorbate on adsorption ability were researched. It is indicated that the optimum parameters for chlorogenic acid are as follows: pH 3.5 with a flow rate of 2.5 BVh, the concentration of extract solution at 0.50, 0.40, 0.30 gL respectively for the adsorptive operation twice, and 6.93, 8.66, 10.39 molL ethanol used as gradient eluants. The purity of resulted product of chlorogenic acid arrives 70.20% with yield of 89.79%. With simple procedures, low costs and high purity product, the method of system of polar ordered resins followed by sequential reversed phase separations can be used to refine the chlorogenic acid in the extraction of Flos Lonicerae.