A NEW MODEL FOR PHYSICAL ADSORPTION ON SOLID SURFACES

The principal assumptions about equivalence and energy distribution of the asdorption sites on solidsurfaces used by Langmuir for deriving the equation of monomolecular adsorption are generalized and anew physical adsorption model is proposed and tested with experimental data published in literature.Themodels of Langmuir,Freundlich,Temkin etc.are only the special cases.Assuming uniform density distributionof adsorption energy,the isotherm equation is given asn=K.1n[1+（bop）1/Mor n=K.1n[1+（boC）1/M]where n is the amount of adsorption per unit weight or area of solid p or C is tbe pressure of gas or the concen-tration of solution respectively.K,bo,M are constants with physical meanings as described in this paper.This equation can be used over wide range to quantitatively represent the five types of physical adsorptionclassified by Brunauer.

ADSORPTION OF SULFOXIDES ON SOLID FROM AQUEOUS SOLUTIONS——Ⅲ.THE ADSORPTION ON CARBON BLACK

The adsorption of decylmethylsulfoxide(DEMS)onto carbon black and the effects of temperature,salt(NaCl)and acid (HCl)have been measured.Typical two plateaux type adsorption isotherms were obtained.Applying the two step model of surfactant adsorption on solid/liquld interface and the general adsorption isotherm equation[9]the experimental results were interpreted qualitatively and quantitatively.

Numerical simulation of influence of Langmuir adsorption constant on gas drainage radius of drilling in coal seam

To determine reasonable distance of gas pre-drainage drillings in coal seams, a solid–gas coupling model that takes gas adsorption effect into account was constructed. In view of different adsorption constants,the paper conducted the numerical simulation of pre-drainage gas in drillings along coal seam, studied the relationship of adsorption constants and permeability, gas pressure, and effective drainage radius of coal seams, and applied the approach to the layout of pre-drainage gas drillings in coal seams. The results show that the permeability of coal seams is on the gradual increase with time, which is divided into three sections according to the increase rate: the drainage time 0–30 d is the sharp increase section;30–220 d is the gradual increase section; and the time above 200 d is the stable section. The permeability of coal seams is in negative linear and positive exponent relation with volume adsorption constant VLand pressure adsorption constant PL, respectively. The effective drainage radius is in negative linear relation with VLand in positive exponent relation with PL. Compared with the former design scheme, the engineering quantity of drilling could be reduced by 25%.

Comparison study of phosphorus adsorption on different waste solids:Fly ash,red mud and ferric–alum water treatment residues

The adsorption of phosphorus （P） onto three industrial solid wastes （fiy ash, red mud and ferric-alum water treatment residual （FAR）） and their modified materials was studied systematically ufa batch experiments. Compared with two natural adsorbents （zeolite and diatomite）, three solid wastes possessed a higher adsorption capacity for P because of the higher Fe, A1 and Ca contents. After modification （i.e., the fly ash and red mud modified by FeC13 and FARs modified by HC1）, the adsorption capacity increased, especially for the modified red mud, where more Fe bonded P was observed. The P adsorption kinetics can be satisfactorily fitted using the pseudo-second-order model. The Langmuir model can describe well the P adsorption on all of the samples in our study, pH and dissolved organic matter （DOM） are two important factors for P adsorption. Under neutral conditions, the maximum adsorption amount on the modified materials was observed. With the deviation from pH 7, the adsorption amount decreased, which resulted from the change of P species in water and surface charges of the adsorbents. The DOM in water can promote P adsorption, which may be due to the promotion effects of humic-Fe（A1） complexes and the pH buffer function exceeds the depression of competitive adsorption.

A New 4.0-Generation Dendrimer Phosphorescence Labeling Reagent and Its Application to Determination of Trace Alkaline Phosphatase by Affinity Adsorption Solid Substrate-room Temperature Phosphorimetry

A Triton X-100-4.0G-D （4.0G-D refers to a 4.0-generation dendrimer） was brought forward as a new phosphorescence labeling reagent. Two types of specific affinity adsorption （AA） reactions （direct method and sandwich method） were carried out between the labeling product of Triton X-100-4：0G-D-Wheat germ agglutinin （WGA） and alkaline phosphatase （ALP）, the product of AA reaction preserved the good characteristics of room temperature phosphorescence （RTP） of 4.0G-D and △Ip of the product was proportional to the content of ALP. According to the fact stated above, a new method for the determination of trace ALP by affinity adsorption solid substrate-room temperature phosphorimetry （AA-SS-RTP） was established on the basis of WGA labeled with the Triton X-100-4.0G-D. The detection limits were 0.20 ag·spot^-1 （corresponding concentration： 5.0×10^-16 g·mL^-1, namely 5.0×10^-18 mol·L^-1） for a direct method and 0.14 ag·spot^-1 （corresponding concentration： 3.5×10^-16 g·mL^-1, namely 3.5×10^-18 mol·L^-1） for a sandwich method, respectively. For their high sensitivity, good repeatability and high accuracy, the direct method and sandwich method have been successfully appfied to determine the content of ALP in human serum, and the results were coincided with the clinical detection results of the enzyme-linked immunosorbent assay method by the Zhangzhou Hospital of Traditional Chinese Medicine. Meanwhile, the mechanism for the determination of trace ALP by AA-SS-RTP was discussed.

Investigation of Quantitative Relationship between Adsorbed Amount of Solute and Solvent Concentration at Relatively High Solute Concentration by Frontal Analysis in RPLC

In previous paper a new adsorption isotherm which relates the amount of solute absorbed to the solvent concentration is proposed and simplified, and it only can be used at lower solute concentration. In this article the scope of the new adsorption isotherm is extended and the expressions with three and four parameters are obtained. The equations with multi parameters are valid when the adsorbed amounts are larger and show non linear logarithmic relationships. Tests with a homologue of aromatic alcohols by frontal analysis in reversed phase liquid chromatography demonstrate that the experimental results fit those equations well. In addition, the predicted values by the multi parameters were found to fit the experimental values well also. The parameters have physical meaning only for the two parameter equation for the aromatic alcohols.

Insights into properties of activated carbons prepared from different raw precursors by pyrophosphoric acid activation

Low-cost activated carbons（ACs） were prepared from four kinds of solid wastes：petroleum coke,Enteromorpha prolifera,lignin from papermaking black liquid and hair,by pyrophosphoric acid（H_4P_2O_7） activation.Thermo-gravimetric analysis of the pyrolysis of H_4P_2O_7-precursor mixtures implied that H_4P_2O_7 had different influences on the pyrolysis behavior of the four raw materials.N_2 adsorption/desorption isotherms,scanning electron microscopy,Fourier transform infrared spectroscopy and adsorption capacities for dyes were used to characterize the prepared activated carbons.AC derived from E.prolifera exhibited the highest surface area（1094 m^2/g） and maximum monolayer adsorption capacity for malachite green（1250 mg/g）.Kinetic studies showed that the experimental data were in agreement with the pseudo-second-order model.The adsorption isotherms were well described by the Langmuir isotherm model,indicating the adsorption of dye onto the ACs proceeded by monolayers.