Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(Ⅱ), zinc(Ⅱ), and chromimum(Ⅱ), from aqueous solution in the concentration range of 10\_100 m...Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(Ⅱ), zinc(Ⅱ), and chromimum(Ⅱ), from aqueous solution in the concentration range of 10\_100 mg/L was studied by using both entrapped activated sludge and inactivated free biomass at pH≤5. A biphasic metal adsorption pattern was observed in all immobilized biomass experiments. The biosorption of metal ions by the biosorbents increased with the initial concentration increased in the medium. The adsorption rate of immobilized pre-treated activated sludge(PAS) was much lower than that of free PAS due to the increase in mass transfer resistance resulting from the polymeric matrix. Biosorption equilibrium of beads was established in about 20 h and the adsorbed heavy metal ions did not change further with time. No significant effect of temperature was observed in the test for free biomass while immobilized PAS appeared to be strong temperature dependent in the test range of 10 and 40℃. Besides, the content of activated sludge in the calcium alginate bead has an influence on the uptake of heavy metals. The sorption equilibrium was well modeled by Langmuir isotherm, implying monomolecular adsorption mechanism. Carboxyl group in cell wall played an important role in surface adsorption of heavy metal ions on PAS.展开更多
An aminated hypercrosslinked macroporous polymeric adsorbent was synthesized and characterized. Adsorption isotherms for 1 amino 2 naphthol 4 sulfonic acid(1, 2, 4 acid) and 2 naphthol obtained from various bin...An aminated hypercrosslinked macroporous polymeric adsorbent was synthesized and characterized. Adsorption isotherms for 1 amino 2 naphthol 4 sulfonic acid(1, 2, 4 acid) and 2 naphthol obtained from various binary adsorption environments can be well fitted by Freundlich equation, which indicated a favorable adsorption process in the studied range. Adsorption for 1, 2, 4 acid was an endothermic process in comparison with that for 2 naphthol of an exothermic process. 2 naphthol molecules put a little influence on the adsorption capacity for 1, 2, 4 acid. However, the adsorption to 1, 2, 4 acid depressed that to 2 naphthol in a large extent for the stronger electrostatic interaction between 1, 2, 4 acid and adsorbent. The predominant mechanism can be contributed to the competition for adsorption sites. And the simultaneous environment was confirmed to be helpful to the selective adsorption towards 1,2,4 acid based on the larger selectivity index.展开更多
Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alk...Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alkyl(1-phenylsulfonyl) cycloalkane carboxylate com- pounds to their chromatographic retention (capacity factor lgKW) and the toxicity for photo- bacterium phosphoreum (–lgEC50) were developed by using the molecular structural parameters as theoretical descriptors (r2 = 0.9501, 0.9488). The two quantitative correlation equations were consequently cross validated by leave-one-out (LOO) validation method with q2 of 0.9113 and 0.9281, respectively. The result showed that the two equations achieved in this work by B3LYP/6-31G* are both more advantageous than those from AM1, and can be used to predict the lgKW and –lgEC50 of congeneric organics.展开更多
Holographic quantitative structure activity relationship(HQSAR) is an emerging QSAR technique with the combined application of molecular hologram, which encoded the frequency of occurrence of various molecular fragme...Holographic quantitative structure activity relationship(HQSAR) is an emerging QSAR technique with the combined application of molecular hologram, which encoded the frequency of occurrence of various molecular fragment types, and the subsequent partial least squares(PLS) regression analysis. In this paper, the acute toxicity data to the guppy( poecilia reticulata) for a series of 56 substituted benzenes, phenols, aromatic amines and nitro aromatics were subjected and this resulted in a model with a high predictive ability. The influence of fragment size and fragment distinction parameters on the quality of HQSAR model was investigated. The robustness and predictive ability of the model were also validated by leave one out (LOO) cross validation procedure and external testing data set.展开更多
Adsorption equilibrium isotherms of phenolic compounds, phenol, p cresol, p chlorophenol and p nitrophenol, from aqueous solutions by Amberlite XAD 4 polymeric adsorbent and its acetylized derivative M...Adsorption equilibrium isotherms of phenolic compounds, phenol, p cresol, p chlorophenol and p nitrophenol, from aqueous solutions by Amberlite XAD 4 polymeric adsorbent and its acetylized derivative MX 4 within temperature range of 283 323K were obtained and fitted to the Freundlich isotherms. The capacities of equilibrium adsorption for all four phenolic compounds from their aqueous solutions increased around 20% on the acetylized resin, which may be contributed to the specific surface area and the partial polarity on the network. Estimations of the isosteric enthalpy, free energy, and entropy for the adsorption process were reported.展开更多
Adsorption of catechol from aqueous solution with the hypercrosslinked polymeric adsorbent NDA-100 and its derivatives AH-1, AH-2 and AH-3 aminated by dimethylamine, the commercial resin Amberlite XAD-4 and weakly bas...Adsorption of catechol from aqueous solution with the hypercrosslinked polymeric adsorbent NDA-100 and its derivatives AH-1, AH-2 and AH-3 aminated by dimethylamine, the commercial resin Amberlite XAD-4 and weakly basic anion exchanger resin D301 was compared. It was found that the aminated hypercrosslinked resins had the highest adsorption capacities among the tested polymers. The empirical Freundlich equation was successfully employed to describe the adsorption process. Specific surface area and micropore structure of the adsorbent, in company with tertiary amino groups on matrix affected the adsorption performance towards catechol. In addition, thermodynamic study was carried out to interpret the adsorption mechanism. Kinetic study testified that the tertiary amino groups on the polymer matrix could decrease the adsorption rate and increase the adsorption apparent activation energy.展开更多
The qualitative and quantitative analyses of reactive oxygen species are essential to determine their steady-state concentration and related reaction mechanisms in environmental aquatic systems. In this study, salicyl...The qualitative and quantitative analyses of reactive oxygen species are essential to determine their steady-state concentration and related reaction mechanisms in environmental aquatic systems. In this study, salicylic acid was employed as an innovative molecular probe of hydroxyl radical(OH) generated in aqueous nitrate and nitrite solutions through photochemical reactions. Kinetic studies showed that the steady-state concentrations of OH in aqueous NO- 3(10 mmol/L, pH=5) and NO- 2(10 mmol/L, pH=5) solutions under ultraviolet irradiation were at a same magnitude, 10 -15 mol/L. Apparent quantum yields of OH at 313 nm were measured as 0.011 and 0.07 for NO- 3 and NO- 2 respectively, all comparable to the results of previous studies.展开更多
The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid(2,4-D)in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent(NDA-99)modified by dimethylamine group as well as a no...The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid(2,4-D)in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent(NDA-99)modified by dimethylamine group as well as a nonionic macroporous adsorbent(XAD-4).The Langmuir and Freundlich isotherm models were employed to fit the experimental data to describe adsorption mechanism.It shows that NDA-99 resin exhibits an adsorption affinity for 2,4-D higher than XAD-4 resin owing to its exceptional micropore structure and the amine group of the hypercrosslinked matrix. Further studies indicate that the hydrogen bonding interaction and the stronger π-π conjugation play a significant role in the course of the adsorption of 2,4-D on NDA-99 resin,which is in agreement with the IR spectroscopic results and the ΔE values of HOMO(the highest occupied molecular orbit)of adsorbent and LUMO(the lowest unoccupied molecular orbit)of adsorbate calculated from the MINDO/3 model.展开更多
Based on quantum chemical calculations, TLSER model(theoretical linear solvation energy relationships) and atomic charge approach were applied to model the partition properties(water solubility and octanol/water parti...Based on quantum chemical calculations, TLSER model(theoretical linear solvation energy relationships) and atomic charge approach were applied to model the partition properties(water solubility and octanol/water partition coefficient) of 96 aromatic sulfur-containing carboxylates, including phenylthio, phenylsulfinyl and phenylsulfonyl carboxylates. In comparison with TLSER models, the atomic charge models are more accurate and reliable to predict the partition properties of the kind of compounds. For the atomic charge models, the molecular descriptors are molecular surface area(S), molecular shape(O), weight(M W), net charges on carboxyl group(Q OC), net charges of nitrogen atoms(Q N), and the most negative atomic charge(q -) of the solute molecule. For water solubility(log S W) and octanol/water partition coefficient(log K OW), the correction coefficients r 2 adj(adjusted for degrees of freedom) are 0.936 and 0.938, and the standard deviations are 0.364 and 0.223, respectively.展开更多
Using the molecular electronegativity distance vector descriptors derived directly from the molecular topological structures, the aqueous solubilities of polychlorinated biphenyls (PCBs) were predicted. A three-variab...Using the molecular electronegativity distance vector descriptors derived directly from the molecular topological structures, the aqueous solubilities of polychlorinated biphenyls (PCBs) were predicted. A three-variable regression equation with correlation coefficient of 0.9739 and the root mean square errors of 0.26 was developed. The descriptors included in the equation represent three interactions between three pairs of atomic types, i.e., atom -C= and >C=, -C= and -Cl, and -Cl and -Cl. It has been proved that the aqueous solubilities of 137 PCB congeners can be accurately predicted as long as there are more than 65 calibration compounds.展开更多
The adsorption behaviors of phenol and aniline on nonpolar macroreticular adsorbents(NDA100 and Amberlite XAD4) were investigated in single or binary batch system at 293K and 313K respectively in this study. The resul...The adsorption behaviors of phenol and aniline on nonpolar macroreticular adsorbents(NDA100 and Amberlite XAD4) were investigated in single or binary batch system at 293K and 313K respectively in this study. The results indicated that the adsorption isotherms of phenol and aniline on both adsorbents in both systems fitted well Langmuir equation, which indicated a favourable and exothermic process. At the lower equilibrium concentrations, the individual amount adsorbed of phenol or aniline on macroreticular adsorbents in single-component systems was higher than those in binary-component systems because of the competition between phenol and aniline towards the adsorption sites. It is noteworthy, on the contrast, that at higher concentrations, the total uptake amounts of phenol and aniline in binary-component systems were obviously larger than that in single-component systems, and a large excess was noted on the adsorbent surface at saturation, which is presumably due to the cooperative effect primarily arisen from the hydrogen bonding or weak acid-base interaction between phenol and aniline.展开更多
Enrichment of volatile organic compounds(VOC) and semi-volatility organic compounds(SVOC) in surface microlayer(SM) of three drinking water sources were studied. The enrichment factor( EF s) were 0.67 to 13.37 and 0.1...Enrichment of volatile organic compounds(VOC) and semi-volatility organic compounds(SVOC) in surface microlayer(SM) of three drinking water sources were studied. The enrichment factor( EF s) were 0.67 to 13.37 and 0.16 to 136, respectively. The results showed some VOC and most SVOC could enrich in SM. Some EF s of SVOC was quite high. Suspension and temperature could affect EF s of SVOC, slim wind and water movement do not destroy enrichment of organic in SM.展开更多
The logarithms of retention factors normalized to a hypothetical pure water eluent(log k w) were determined on a reversed phase high performance liquid chromatography(RP HPLC) column (Li Chrosorb RP 18 column...The logarithms of retention factors normalized to a hypothetical pure water eluent(log k w) were determined on a reversed phase high performance liquid chromatography(RP HPLC) column (Li Chrosorb RP 18 column) for 20 new α\|branched phenylsulfonyl acetates. The atomic charge method was applied to develop quantitative structure retention relationships(QSRRs). Among the available geometric and electronic descriptors, surface area (S), ovality (O), and the charge of carboxyl group(Q OC ) are significant. In the model, the contribution of surface area (S) is the greatest. The molecular mechanism of retention was demonstrated through the model. With the correlation coefficient ( r 2 adj , adjusted for degrees of freedom) of 0.964, the standard error of 0.164 and the F value of 170.39, the model has good predictive capacity.展开更多
Single and binary adsorption behaviors of salicylic acid and 5-sulfosalicylic acid onto hypercrosslinked polymeric adsorbents,i.e.NDA-101 and NDA-99 were investigated.The Freundlich model can successfully describe all...Single and binary adsorption behaviors of salicylic acid and 5-sulfosalicylic acid onto hypercrosslinked polymeric adsorbents,i.e.NDA-101 and NDA-99 were investigated.The Freundlich model can successfully describe all the adsorption isotherms tested,which indicates a favorable and exothermic adsorption process.The adsorption of salicylic acid relies on π-π interaction,while the electrostatic interaction further influences the adsorption of 5-sulfosalicylic acid onto NDA-99.The adsorptive capacity of salicylic acid on NDA-99 decreases but increases on NDA-101 with 5-sulfosalicylic acid as the background component in a binary solute system.The amount of 5-sulfosalicylic acid adsorbed was decreased with the increase in initial concentration of salicylic acid on both adsorbents.The competition for the adsorption sites is considered to be predominant in the solid-to-liquid interaction process.The adsorption selectivity of salicylic acid onto NDA-101 is higher than onto NDA-99 by more than an order of magnitude.Thus,combination technique involving NDA-101 followed by NDA-99 can be effectively applied to separate and recover salicylic acid and 5-sulfosalicylic acid from wastewater.展开更多
In this paper,the adsorption behaviors of phenol on polymeric adsorbents(Amberlite XAD4,NDA101,and D301) were investigated in batch system at 293,303,and 313 K,respectively.As the results shown,the adsorption isotherm...In this paper,the adsorption behaviors of phenol on polymeric adsorbents(Amberlite XAD4,NDA101,and D301) were investigated in batch system at 293,303,and 313 K,respectively.As the results shown,the adsorption isotherms of phenol on all adsorbents can be well fitted by Langmuir and Freundlich equations,which indicate a favorable and exothermic process.The adsorption capacity on a newly developed aminated adsorbent,NDA101,on which adsorption could be achieved by both hydrogen bonding interaction and π-π interaction,are higher than that on a weak base adsorbent,D301,on which adsorption could be achieved by hydrogen bonding interaction only,and on a nonpolar adsorbent,XAD4,on which adsorption could be achieved by π-π interaction only.The results of this paper indicate that the synergistic effect of some weak interactions,which occur simultaneously would contribute more to the adsorption than that occur individually.展开更多
A new method of quantitative structure retention relationship(QSRR) studies was reported for predicting gas chromatography(GC) relative retention times(RRTs) of chlorinated phenols (CPs) using a DB 5 column. Chemica...A new method of quantitative structure retention relationship(QSRR) studies was reported for predicting gas chromatography(GC) relative retention times(RRTs) of chlorinated phenols (CPs) using a DB 5 column. Chemical descriptors were calculated from the molecular structure of CPs and related to their gas chromatographic RRTs by using multiple linear regression analysis. The proposed model had a multiple square correlation coefficient R 2=0.970, standard error SE =0.0472, and significant level P =0.0000. The QSRR model also reveals that the gas chromatographic relative retention times of CPs are associated with physicochemical property interactions with the stationary phase,and influenced by the number of chlorine and oxygen in the CP melecules.展开更多
The biological effects of most organophosphate compounds (OP) are arising by inhibition of the enzyme acetylcholinesterase (ACHE). The 3D-quantitative structure-activity relationship (3D-QSAR) on the acute toxicity to...The biological effects of most organophosphate compounds (OP) are arising by inhibition of the enzyme acetylcholinesterase (ACHE). The 3D-quantitative structure-activity relationship (3D-QSAR) on the acute toxicity to housefly (Musca nobulo L.) of 35 dialkyl phenyl phosphate compounds are studied by using comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) methods, and the reaction mechanism between the OP and the AChE are discussed. In contrast to classical QSAR methods, CoMFA and CoMSIA, especially the combination of both approaches, can give more comprehensive and accurate perspectives on the mechanism of the reaction between OP and ACHE. The results show that the length of alkyl, and the electronegative of substituent on phenyl of OP have significant effects on the AChE activity,whereas, the hydrophobicity of OP has little influence. The steric and electronic properties of OP have a dominant influence on the reaction between OP and ACHE.展开更多
: Phytochelatins (PCs) may function as a potential biomarker for metal toxicity. However, less attention has been paid to the effects of metal interactions on the production of PCs and glutathione (GSH), the most prom...: Phytochelatins (PCs) may function as a potential biomarker for metal toxicity. However, less attention has been paid to the effects of metal interactions on the production of PCs and glutathione (GSH), the most prominent cellular thiol. In the present study, the effects of interactions between cadmium (Cd) and plumbum (Pb) on the production of PCs and GSH were monitored over a period of 14 d in wheat (Triticum aestivum L.) tissues. The results showed that combination of Cd and Pb led to synergistic growth inhibition in wheat. Exposure to Cd or Pb increased levels of PCs in a concentration-, tissue-, and time-dependent manner. Cadmium was more effective that Pb in increasing PCs production. Compared with the effects of Cd or Pb alone on the production of PCs, the combination of Cd and Pb acted synergistically, resulting in an enhanced production of PCs. Cadmium also stimulated GSH production in a concentration-, tissue-, and time-dependent manner. However, Pb had no obvious effects on GSH levels. The combination of Pb and Cd antagonized GSH production over the course of the growth period. The results of the present study suggest that metal interactions should be considered in the application of PCs and GSH as potential biomarkers for the evaluation of metal toxicity.展开更多
The molecular volumes of dioxins,organic phosphorous compounds and n-alkanols were computed at the B3LYP/6-311G** level,and were then correlated with their toxicity.It was surprisingly found that there exists the so-c...The molecular volumes of dioxins,organic phosphorous compounds and n-alkanols were computed at the B3LYP/6-311G** level,and were then correlated with their toxicity.It was surprisingly found that there exists the so-called“critical volume of toxicity”(CVT)in each series of compound of the present study,i.e.the toxicity increases with increase of the molecular volume when less than CVT,while decreasing with increase of the molecular volume when lar-ger than CVT.The CVT for the three series of compounds is quite similar,ranging 0.309—0.320nm3.It was proposed that the ordinary linear solvation energy relationship (LSER) should be modified with respect to the new findings,and ac-cordingly the anaesthetic potency of partial fluorinated n-alkanols was predicted.展开更多
文摘Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(Ⅱ), zinc(Ⅱ), and chromimum(Ⅱ), from aqueous solution in the concentration range of 10\_100 mg/L was studied by using both entrapped activated sludge and inactivated free biomass at pH≤5. A biphasic metal adsorption pattern was observed in all immobilized biomass experiments. The biosorption of metal ions by the biosorbents increased with the initial concentration increased in the medium. The adsorption rate of immobilized pre-treated activated sludge(PAS) was much lower than that of free PAS due to the increase in mass transfer resistance resulting from the polymeric matrix. Biosorption equilibrium of beads was established in about 20 h and the adsorbed heavy metal ions did not change further with time. No significant effect of temperature was observed in the test for free biomass while immobilized PAS appeared to be strong temperature dependent in the test range of 10 and 40℃. Besides, the content of activated sludge in the calcium alginate bead has an influence on the uptake of heavy metals. The sorption equilibrium was well modeled by Langmuir isotherm, implying monomolecular adsorption mechanism. Carboxyl group in cell wall played an important role in surface adsorption of heavy metal ions on PAS.
文摘An aminated hypercrosslinked macroporous polymeric adsorbent was synthesized and characterized. Adsorption isotherms for 1 amino 2 naphthol 4 sulfonic acid(1, 2, 4 acid) and 2 naphthol obtained from various binary adsorption environments can be well fitted by Freundlich equation, which indicated a favorable adsorption process in the studied range. Adsorption for 1, 2, 4 acid was an endothermic process in comparison with that for 2 naphthol of an exothermic process. 2 naphthol molecules put a little influence on the adsorption capacity for 1, 2, 4 acid. However, the adsorption to 1, 2, 4 acid depressed that to 2 naphthol in a large extent for the stronger electrostatic interaction between 1, 2, 4 acid and adsorbent. The predominant mechanism can be contributed to the competition for adsorption sites. And the simultaneous environment was confirmed to be helpful to the selective adsorption towards 1,2,4 acid based on the larger selectivity index.
基金This work was financially supported by the National Basic Research Program of China (2003CB415002), the China Postdoctoral Science Foundation (No. 2003033486) and the Natural Science Research Fund of University in Jiangsu (04KJB150149)
文摘Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alkyl(1-phenylsulfonyl) cycloalkane carboxylate com- pounds to their chromatographic retention (capacity factor lgKW) and the toxicity for photo- bacterium phosphoreum (–lgEC50) were developed by using the molecular structural parameters as theoretical descriptors (r2 = 0.9501, 0.9488). The two quantitative correlation equations were consequently cross validated by leave-one-out (LOO) validation method with q2 of 0.9113 and 0.9281, respectively. The result showed that the two equations achieved in this work by B3LYP/6-31G* are both more advantageous than those from AM1, and can be used to predict the lgKW and –lgEC50 of congeneric organics.
文摘Holographic quantitative structure activity relationship(HQSAR) is an emerging QSAR technique with the combined application of molecular hologram, which encoded the frequency of occurrence of various molecular fragment types, and the subsequent partial least squares(PLS) regression analysis. In this paper, the acute toxicity data to the guppy( poecilia reticulata) for a series of 56 substituted benzenes, phenols, aromatic amines and nitro aromatics were subjected and this resulted in a model with a high predictive ability. The influence of fragment size and fragment distinction parameters on the quality of HQSAR model was investigated. The robustness and predictive ability of the model were also validated by leave one out (LOO) cross validation procedure and external testing data set.
文摘Adsorption equilibrium isotherms of phenolic compounds, phenol, p cresol, p chlorophenol and p nitrophenol, from aqueous solutions by Amberlite XAD 4 polymeric adsorbent and its acetylized derivative MX 4 within temperature range of 283 323K were obtained and fitted to the Freundlich isotherms. The capacities of equilibrium adsorption for all four phenolic compounds from their aqueous solutions increased around 20% on the acetylized resin, which may be contributed to the specific surface area and the partial polarity on the network. Estimations of the isosteric enthalpy, free energy, and entropy for the adsorption process were reported.
文摘Adsorption of catechol from aqueous solution with the hypercrosslinked polymeric adsorbent NDA-100 and its derivatives AH-1, AH-2 and AH-3 aminated by dimethylamine, the commercial resin Amberlite XAD-4 and weakly basic anion exchanger resin D301 was compared. It was found that the aminated hypercrosslinked resins had the highest adsorption capacities among the tested polymers. The empirical Freundlich equation was successfully employed to describe the adsorption process. Specific surface area and micropore structure of the adsorbent, in company with tertiary amino groups on matrix affected the adsorption performance towards catechol. In addition, thermodynamic study was carried out to interpret the adsorption mechanism. Kinetic study testified that the tertiary amino groups on the polymer matrix could decrease the adsorption rate and increase the adsorption apparent activation energy.
文摘The qualitative and quantitative analyses of reactive oxygen species are essential to determine their steady-state concentration and related reaction mechanisms in environmental aquatic systems. In this study, salicylic acid was employed as an innovative molecular probe of hydroxyl radical(OH) generated in aqueous nitrate and nitrite solutions through photochemical reactions. Kinetic studies showed that the steady-state concentrations of OH in aqueous NO- 3(10 mmol/L, pH=5) and NO- 2(10 mmol/L, pH=5) solutions under ultraviolet irradiation were at a same magnitude, 10 -15 mol/L. Apparent quantum yields of OH at 313 nm were measured as 0.011 and 0.07 for NO- 3 and NO- 2 respectively, all comparable to the results of previous studies.
文摘The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid(2,4-D)in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent(NDA-99)modified by dimethylamine group as well as a nonionic macroporous adsorbent(XAD-4).The Langmuir and Freundlich isotherm models were employed to fit the experimental data to describe adsorption mechanism.It shows that NDA-99 resin exhibits an adsorption affinity for 2,4-D higher than XAD-4 resin owing to its exceptional micropore structure and the amine group of the hypercrosslinked matrix. Further studies indicate that the hydrogen bonding interaction and the stronger π-π conjugation play a significant role in the course of the adsorption of 2,4-D on NDA-99 resin,which is in agreement with the IR spectroscopic results and the ΔE values of HOMO(the highest occupied molecular orbit)of adsorbent and LUMO(the lowest unoccupied molecular orbit)of adsorbate calculated from the MINDO/3 model.
文摘Based on quantum chemical calculations, TLSER model(theoretical linear solvation energy relationships) and atomic charge approach were applied to model the partition properties(water solubility and octanol/water partition coefficient) of 96 aromatic sulfur-containing carboxylates, including phenylthio, phenylsulfinyl and phenylsulfonyl carboxylates. In comparison with TLSER models, the atomic charge models are more accurate and reliable to predict the partition properties of the kind of compounds. For the atomic charge models, the molecular descriptors are molecular surface area(S), molecular shape(O), weight(M W), net charges on carboxyl group(Q OC), net charges of nitrogen atoms(Q N), and the most negative atomic charge(q -) of the solute molecule. For water solubility(log S W) and octanol/water partition coefficient(log K OW), the correction coefficients r 2 adj(adjusted for degrees of freedom) are 0.936 and 0.938, and the standard deviations are 0.364 and 0.223, respectively.
文摘Using the molecular electronegativity distance vector descriptors derived directly from the molecular topological structures, the aqueous solubilities of polychlorinated biphenyls (PCBs) were predicted. A three-variable regression equation with correlation coefficient of 0.9739 and the root mean square errors of 0.26 was developed. The descriptors included in the equation represent three interactions between three pairs of atomic types, i.e., atom -C= and >C=, -C= and -Cl, and -Cl and -Cl. It has been proved that the aqueous solubilities of 137 PCB congeners can be accurately predicted as long as there are more than 65 calibration compounds.
文摘The adsorption behaviors of phenol and aniline on nonpolar macroreticular adsorbents(NDA100 and Amberlite XAD4) were investigated in single or binary batch system at 293K and 313K respectively in this study. The results indicated that the adsorption isotherms of phenol and aniline on both adsorbents in both systems fitted well Langmuir equation, which indicated a favourable and exothermic process. At the lower equilibrium concentrations, the individual amount adsorbed of phenol or aniline on macroreticular adsorbents in single-component systems was higher than those in binary-component systems because of the competition between phenol and aniline towards the adsorption sites. It is noteworthy, on the contrast, that at higher concentrations, the total uptake amounts of phenol and aniline in binary-component systems were obviously larger than that in single-component systems, and a large excess was noted on the adsorbent surface at saturation, which is presumably due to the cooperative effect primarily arisen from the hydrogen bonding or weak acid-base interaction between phenol and aniline.
文摘Enrichment of volatile organic compounds(VOC) and semi-volatility organic compounds(SVOC) in surface microlayer(SM) of three drinking water sources were studied. The enrichment factor( EF s) were 0.67 to 13.37 and 0.16 to 136, respectively. The results showed some VOC and most SVOC could enrich in SM. Some EF s of SVOC was quite high. Suspension and temperature could affect EF s of SVOC, slim wind and water movement do not destroy enrichment of organic in SM.
基金TheNationalNaturalScienceFoundationofChina (No .2 9837180 )
文摘The logarithms of retention factors normalized to a hypothetical pure water eluent(log k w) were determined on a reversed phase high performance liquid chromatography(RP HPLC) column (Li Chrosorb RP 18 column) for 20 new α\|branched phenylsulfonyl acetates. The atomic charge method was applied to develop quantitative structure retention relationships(QSRRs). Among the available geometric and electronic descriptors, surface area (S), ovality (O), and the charge of carboxyl group(Q OC ) are significant. In the model, the contribution of surface area (S) is the greatest. The molecular mechanism of retention was demonstrated through the model. With the correlation coefficient ( r 2 adj , adjusted for degrees of freedom) of 0.964, the standard error of 0.164 and the F value of 170.39, the model has good predictive capacity.
基金This work was supported by the National Natural Science Foundation of China(No.20274017)
文摘Single and binary adsorption behaviors of salicylic acid and 5-sulfosalicylic acid onto hypercrosslinked polymeric adsorbents,i.e.NDA-101 and NDA-99 were investigated.The Freundlich model can successfully describe all the adsorption isotherms tested,which indicates a favorable and exothermic adsorption process.The adsorption of salicylic acid relies on π-π interaction,while the electrostatic interaction further influences the adsorption of 5-sulfosalicylic acid onto NDA-99.The adsorptive capacity of salicylic acid on NDA-99 decreases but increases on NDA-101 with 5-sulfosalicylic acid as the background component in a binary solute system.The amount of 5-sulfosalicylic acid adsorbed was decreased with the increase in initial concentration of salicylic acid on both adsorbents.The competition for the adsorption sites is considered to be predominant in the solid-to-liquid interaction process.The adsorption selectivity of salicylic acid onto NDA-101 is higher than onto NDA-99 by more than an order of magnitude.Thus,combination technique involving NDA-101 followed by NDA-99 can be effectively applied to separate and recover salicylic acid and 5-sulfosalicylic acid from wastewater.
基金This study was funded by the National Natural Science Foundation of China(No.20274017)the Natural Science Foundation of Jiangsu Province(No.BK2004415)
文摘In this paper,the adsorption behaviors of phenol on polymeric adsorbents(Amberlite XAD4,NDA101,and D301) were investigated in batch system at 293,303,and 313 K,respectively.As the results shown,the adsorption isotherms of phenol on all adsorbents can be well fitted by Langmuir and Freundlich equations,which indicate a favorable and exothermic process.The adsorption capacity on a newly developed aminated adsorbent,NDA101,on which adsorption could be achieved by both hydrogen bonding interaction and π-π interaction,are higher than that on a weak base adsorbent,D301,on which adsorption could be achieved by hydrogen bonding interaction only,and on a nonpolar adsorbent,XAD4,on which adsorption could be achieved by π-π interaction only.The results of this paper indicate that the synergistic effect of some weak interactions,which occur simultaneously would contribute more to the adsorption than that occur individually.
文摘A new method of quantitative structure retention relationship(QSRR) studies was reported for predicting gas chromatography(GC) relative retention times(RRTs) of chlorinated phenols (CPs) using a DB 5 column. Chemical descriptors were calculated from the molecular structure of CPs and related to their gas chromatographic RRTs by using multiple linear regression analysis. The proposed model had a multiple square correlation coefficient R 2=0.970, standard error SE =0.0472, and significant level P =0.0000. The QSRR model also reveals that the gas chromatographic relative retention times of CPs are associated with physicochemical property interactions with the stationary phase,and influenced by the number of chlorine and oxygen in the CP melecules.
文摘The biological effects of most organophosphate compounds (OP) are arising by inhibition of the enzyme acetylcholinesterase (ACHE). The 3D-quantitative structure-activity relationship (3D-QSAR) on the acute toxicity to housefly (Musca nobulo L.) of 35 dialkyl phenyl phosphate compounds are studied by using comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) methods, and the reaction mechanism between the OP and the AChE are discussed. In contrast to classical QSAR methods, CoMFA and CoMSIA, especially the combination of both approaches, can give more comprehensive and accurate perspectives on the mechanism of the reaction between OP and ACHE. The results show that the length of alkyl, and the electronegative of substituent on phenyl of OP have significant effects on the AChE activity,whereas, the hydrophobicity of OP has little influence. The steric and electronic properties of OP have a dominant influence on the reaction between OP and ACHE.
基金中国科学院资助项目，Innovation Foundation of Advanced Universities' Graduate of Jiangsu Province, China，the Ecogeochemical Investigation Foundation of Jiangsu Province, China
文摘: Phytochelatins (PCs) may function as a potential biomarker for metal toxicity. However, less attention has been paid to the effects of metal interactions on the production of PCs and glutathione (GSH), the most prominent cellular thiol. In the present study, the effects of interactions between cadmium (Cd) and plumbum (Pb) on the production of PCs and GSH were monitored over a period of 14 d in wheat (Triticum aestivum L.) tissues. The results showed that combination of Cd and Pb led to synergistic growth inhibition in wheat. Exposure to Cd or Pb increased levels of PCs in a concentration-, tissue-, and time-dependent manner. Cadmium was more effective that Pb in increasing PCs production. Compared with the effects of Cd or Pb alone on the production of PCs, the combination of Cd and Pb acted synergistically, resulting in an enhanced production of PCs. Cadmium also stimulated GSH production in a concentration-, tissue-, and time-dependent manner. However, Pb had no obvious effects on GSH levels. The combination of Pb and Cd antagonized GSH production over the course of the growth period. The results of the present study suggest that metal interactions should be considered in the application of PCs and GSH as potential biomarkers for the evaluation of metal toxicity.
文摘The molecular volumes of dioxins,organic phosphorous compounds and n-alkanols were computed at the B3LYP/6-311G** level,and were then correlated with their toxicity.It was surprisingly found that there exists the so-called“critical volume of toxicity”(CVT)in each series of compound of the present study,i.e.the toxicity increases with increase of the molecular volume when less than CVT,while decreasing with increase of the molecular volume when lar-ger than CVT.The CVT for the three series of compounds is quite similar,ranging 0.309—0.320nm3.It was proposed that the ordinary linear solvation energy relationship (LSER) should be modified with respect to the new findings,and ac-cordingly the anaesthetic potency of partial fluorinated n-alkanols was predicted.
