Adsorption of picloram on clays nontronite,illite and kaolinite: equilibrium and herbicide-clays surface complexes

The picloram (PCM) adsorption on nontronite, illite and kaolinite was studied at pH 3, 5 and 7. The adsorption isotherms had well-fitted to Langmuir and Freundlich models equations. The interactions of PCM with the clay mineral surfaces exhibited an anionic profile adsorption, with a decrease in adsorption when the pH increases. The PCM adsorption capacity increases in the following order: kaolinite?<?illite?<?nontronite. The X-ray diffraction (XRD) analysis of PCM-clay samples revealed that the picloram molecule does not enter into the clays basal space. The interaction of PCM with clays surface sites through nitrogen of the pyridine ring was confirmed by X-ray photoelectron spectroscopy (XPS). Due to the anionic form of PCM, the adsorption onto the external and edges surface sites of the clay minerals was proposed.     

Inhibition of nitrification in soil by metal diethyldithiocarbamates

IntroductionNitrificationisaprocessinwhichammoniumformofnitrogenisconvertedintonitrateform .Nitrogenuseefficiencyintermsofplantuptakeisgenerallylowandvariesgreatlyunderdifferentsoilandcroppingconditions.MostfertilizerNappliedtosoilsisintheformofammonium orammoniumproducingcompoundssuchasurea,andisusuallyoxidizedrapidlytonitratebynitrifyingmicroorganismsinsoils.Applicationofnitrogenfertilizersmorethanoptimumlevelsleadstolownitrogenrecoveriesandgreaternitrogenaccumulationinthesoilprofile .Theac…     

铁(Ⅲ)-羧酸配合物对水溶性染料的光化学脱色动力学的比较研究

铁-柠檬酸，铁-酒石酸，铁-丁二酸，铁-草酸配合物在高压汞灯（λmax＝313nm，250W）的照射下，能使活性艳红X－3B染料水溶液脱色。染料初始浓度在10mg／L～50mg／L时，染料脱色为动力学一级反应，脱色速率随初始浓度增大而降低。在pH2．0～3．0时铁-柠檬酸，铁-滴石酸，铁-丁二酸的染料溶液脱色效果较佳，在pH4．0时铁-草酸的染料溶液脱色效果最好。铁／羧酸盐配比对染料脱色速率也有影响。     

On the dissolution kinetics of humic acid particles. Effect of monocarboxylic acids

The dissolution kinetics of humic acid particles has been studied in batch experiments, and the effects of monocarboxylic (formic, acetic, and propionic) acids are reported. The dissolution rate of the particles is significantly affected by the presence of monocarboxylic acids in the pH range 4–10. At pH 7, for example, propionic acid increases 30 times this dissolution rate. The capacity of increasing the dissolution rate is in the order formic acid < acetic acid < propionic acid, and this dissolving capacity of carboxylics seems to be directly related to their affinity for HA molecules located at the surface of the solid particles. The results indicate that carboxylics and related compounds may affect markedly the mobility and transport of humic substances in the environment.     

黏土矿物不同腐殖质组分团聚体对苯酚的封存特征

为探讨不同腐殖质组分团聚体对苯酚封存能力的影响,应用国际腐殖酸协会推荐的方法提取腐殖质,以Ca²⁺、Al³⁺、Fe³⁺为桥键离子,制备了高岭石、蒙脱石不同腐殖质组分团聚体,并采用平衡吸附/解吸试验、应用饱和吸附量与最大解吸量差减法研究了不同腐殖质组分团聚体对苯酚的封存特征.结果表明,团聚体对苯酚的吸附等温线可用Freundlich吸附/解吸方程（R²=0.991~0.998）和Langmuir吸附/解吸方程（R²=0.993~0.999）描述.高岭石不同腐殖质组分团聚体对苯酚的封存量（Q_m^irr）排序为：富里酸团聚体（（133.71±6.14）mg·kg^-1） > 胡敏酸团聚体（（49.59±8.93）mg·kg^-1） > 胡敏素团聚体（（21.68±2.95）mg·kg^-1）;封存系数（SR）排序为：富里酸团聚体（0.53±0.04） > 胡敏酸团聚体（0.27±0.05） > 胡敏素团聚体（0.18±0.03）;蒙脱石不同腐殖质组分团聚体对苯酚的封存量（Q_m^irr）排序为：富里酸团聚体（（319.44±8.95）mg·kg^-1） > 胡敏酸团聚体（（92.96±22.10）mg·kg^-1） > 胡敏素团聚体（（36.22±6.36）mg·kg^-1）;封存系数（SR）排序为：富里酸团聚体（0.76±0.02） > 胡敏酸团聚体（0.32±0.09） > 胡敏素团聚体（0.23±0.05）.考查腐殖质团聚体对苯酚的封存能力时不但要考虑腐殖质的含量,更要考虑腐殖质的赋存形态,它也是影响团聚体对苯酚封存能力的重要因素.富里酸、胡敏酸和胡敏素与黏土矿物结合形成有机矿质复合体后,对苯酚的封存能力发生了显著改变,团聚体对苯酚的封存系数与团聚体有机碳含量和内表面积呈显著正相关（p<0.01）,团聚体对苯酚的吸附/解吸分配系数（k/k_d）与团聚体有机碳含量和内表面积呈显著正相关（p<0.01）,土壤/沉积物团聚体的有机碳含量和内表面积是影响对苯酚封存特征的重要因素.研究显示,不同腐殖质组分团聚体对苯酚的封存能力排序为：富里酸团聚体 > 胡敏酸团聚体 > 胡敏素团聚体.     

Humic substances. Part III. sorptive interactions with environmental chemicals†

The formation of covalent binding to DNA of a carcinogen is now widely accepted to represent a classical mechanism of tumour induction in mammals. This mechanism does not operate with metals since no covalent binding of these agents to DNA does occur. Nevertheless, somatic mutations as typical consequences of DNA‐damage have been reported to be induced by metals in various model systems. Beside DNA‐alkylation such damages can be caused by changes in the conformation of DNA or in the fidelity of DNA‐repair. The activity of the repair enzymes DNA‐polymerases is indeed impaired by many metal ions at least in vitro. It is not yet established whether these mechanisms are also important in the intact mammalian organism. Much evidence has accumulated during the last years that a disturbance of the balance of cations and especially metal ions represents another possible mechanism of tumour induction. The tumours found with high doses of chelating agents such as nitrilo‐triacetic acid (NTA) have to be discussed in this context. Since most—if not—all of the speculative mechanisms of metal carcinogenesis resemble classical pharmacological reactions the existence of a threshold level is likely. So metal carcinogenesis will not be a problem of the environmental contamination at trace levels but a problem of occupational medicine.     

ATR-FTIR and XPS study on the structure of complexes formed upon the adsorption of simple organic acids on aluminum hydroxide

Information on the binding of organic ligands to metal （hydr）oxide surfaces is useful for understanding the adsorption behaviour of natural organic matter on metal （hydr）oxide. In this study, benzoate and salicylate were employed as the model organic ligands and aluminum hydroxide as the metal hydroxide. The attenuated total reflectance Fourier transform infrared （ATR-FTIR） spectra revealed that the ligands benzoate and salicylate do coordinate directly with the surface of hydrous aluminum hydroxide, thereby forming innersphere surface complexes. It is concluded that when the initial pH is acidic or neutral, monodentate and bridging complexes are to be formed between benzoate and aluminum hydroxide while bridging complexes predominate when the initial pH is alkalic. Monodentate and bridging complexes can be formed at pH 5 while precipitate and bridging complexes are formed at pH 7 when salicylate anions are adsorbed on aluminum hydroxide. The X-ray photoelectron （XP） spectra demonstrated the variation of C 1 s binding energy in the salicyate and phenolic groups before and after adsorption. It implied that the benzoate ligands are adsorbed through the complexation between carboxylate moieties and the aluminum hydroxide surface, while both carboxylate group and phenolic group are involved in the complexation reaction when salicylate is adsorbed onto aluminum hydroxide. The information offered by the XPS confirmed the findings obtained with ATR-FTIR.     

Preliminary Studies on Converting Agricultural Waste into Biodegradable Plastics – Part III: Sawdust

Summary Hardwood sawdust was derivatized either by carboxymethylation, glutaration, maleiation, phthallation, or succination in order to produce anionic materials suitable for complexation with soy protein isolate. Blending each derivative with soy protein isolate resulted in instant precipitation of gels. Infrared spectroscopy and differential scanning calorimetry suggested that each derivative formed a complex with protein. Reaction products could be dried into pellets exhibiting tensile strengths between 0.9–2.4 MPa, suggested that these materials could be promising candidates for biodegradable structural materials.     

强化UV/Fenton法降解水中苯酚的研究

研究了UV/Fenton法处理含苯酚废水时H2 O2 和FeSO4 加入量及苯酚初始浓度对酚去除效果的影响及C2 O2 -4 对UV/Fenton法的增强效果。 [H2 O2 ]=2 0mmol/L ,[FeSO4 ]=5mmol/L ,反应 2 0min ,苯酚初始浓度为 5 0mg/L时 ,酚去除率达 99%。UV/Fenton体系中引入C2 O2 -4 后可有效提高对紫外和可见光的利用率 ,进而提高了对高浓度苯酚废水去除效果     

Effects of grassland degradation on chestnut soil properties in Bashang Plateau, China

ＩｎｔｒｏｄｕｃｔｉｏｎＣｈｅｓｔｎｕｔｓｏｉｌｏｎｔｈｅＢａｓｈａｎｇＰｌａｔｅａｕｉｓｏｎｅｏｆｔｈｅｓｏｉｌｓｉｎｚｏｎａｌｄｉｓｔｒｉｂｕｔｉｏｎ.Ｔｈｅｄｅｇｒａｄａｔｉｏｎｏｆｔｈｅｃｈｅｓｔｎｕｔｓｏｉｌｒｅｓｕｌｔｅｄｆｒｏｍｔｈｅｅ?..