Impact of Cr(Ⅲ)complexation with organic acid on its adsorption in silts and fine sands

Trivalent chromium(Cr(Ⅲ))can form stable soluble complexes with organic components,altering its adsorption properties in the water-soil environment.This increases the risk of Cr(Ⅲ)migrating to deeper soils and transforming into toxic Cr(VI)due to the presence of manganese oxides in sediments.In this study,Citric Acid(CA)was selected as a representative organic ligand to prepare and characterize Cr(III)-CA complexes.The characteristics,mechanisms and environmental factors influencing the adsorption of Cr(Ⅲ)-CA on porous media(silts and fine sands)were investigated in the study.The results show that Cr(Ⅲ)coordinates with CA at a 1:1 molar ratio,forming stable and soluble Cr(Ⅲ)-CA complexes.Compared to Cr(III)ions,the equilibrium adsorption capacity of Cr(Ⅲ)-CA is an order of magnitude lower in silts and fine sands.The adsorption of Cr(Ⅲ)-CA in silts and fine sands is dominated by chemical adsorption of monolayers,following the pseudo-second-order kinetic equation and the Langmuir isotherm adsorption model.Varying contents of clay minerals and iron-aluminum oxides prove to be the main causes of differences in adsorption capacity of Cr(Ⅲ)-CA in silts and fine sands.Changes in solution pH affect the adsorption rate and capacity of Cr(Ⅲ)-CA by altering its ionic form.The adsorption process is irreversible and only minimally influenced by ionic strength,suggesting that inner-sphere complexation serves as the dominant Cr(Ⅲ)-CA adsorption mechanism.

乙异羟肟酸对Fe(Ⅲ)与羟胺反应动力学的影响

采用分光光度法,对硝酸体系中羟胺(HAN)还原Fe(Ⅲ)的动力学进行了研究,得出了反应速率方程为-dc(Fe(Ⅲ))/dt=k·c^(0.56)(Fe(Ⅲ))·c^(0.88)(HAN),表观速率常数k=-(4.08±0.15)×10^(-4)(mol/L)-0.44·s^(-1);并研究了乙异羟肟酸(AHA)与Fe(Ⅲ)络合对该氧化还原反应的影响,结果显示,反应速率方程变为-dc(Fe(Ⅲ))/dt=-(2.83×10-4-536c3(AHA))·c^(0.76)(Fe(Ⅲ))·c^(0.60)(HAN),反应速率常数随AHA浓度增大而降低,且与AHA浓度的3次方成线性关系,Fe(Ⅲ)浓度对反应速率影响增大,而HAN浓度对反应速率影响减小。

光助类Fenton-柠檬酸体系对甲基紫的脱色研究

以柠檬酸为活化剂,进行了类Fenton反应光解甲基紫的试验,研究了利用UV-H_2O_2-Fe^(3+)-柠檬酸体系对甲基紫进行脱色的各种影响因素。试验结果表明,Fe^(3+)、H_2O_2、柠檬酸浓度均能影响染料脱色,柠檬酸在反应过程中起到活化剂的作用。在甲基紫浓度为40mg/L时,其脱色的适宜条件为3%H_2O_2,100mg/L Fe^(3+),90mg/L柠檬酸,体系pH值约为3,其脱色率可达到80%以上。

1,10-菲啰啉和5-羟基-1,3-苯二甲酸铁(Ⅲ)配位聚合物的合成和晶体结构

采用水热法合成了铁的新配合物{[Fe(phen)3]·2(O-BDC)·H3O+·3H2O}n(1),[phen=1,10-菲啰啉,OBDC=5-羟基-1,3-苯二甲酸],用元素分析、红外光谱和X射线单晶结构等进行了表征。结果表明该配位聚合物属于正交晶系,Pbcn空间群。晶胞参数为:a=1.09818(18)nm,b=2.2400(4)nm,c=1.8615(3)nm,F(000)=2132,Dc=1.494 g·cm-3,V=4.5791(13)nm3,Mr=1029.76,Z=4,μ=0.409 mm-1,R1=0.0477,ωR2=0.0710。该配位聚合物晶体中,5-羟基-1,3-苯二甲酸没有参加配位,1,10-菲啰啉与铁原子形成零维结构,零维结构通过1,10-菲啰啉分子间的π-π堆积作用进一步连接形成一维链状结构,5-羟基-1,3-苯二甲酸与水形成的氢键相连接,形成三维的孔状结构,铁的一维链状结构填充在三维的孔道中。

海水中铁(Ⅲ)-二元有机酸盐配合物的光化学反应研究

采用实验室模拟的方法研究了高压汞灯模拟日光照射下铁()-二元有机酸盐配合物在天然海水中的光化学反应.结果发现,在二元有机酸盐配体的存在下,铁()发生光化学反应生成还原态的铁(),铁()会被溶液中的氧再氧化为铁().铁()的光还原反应速率受到配体浓度、pH、光强以及温度的影响.在二元有机酸与Fe()浓度配比大于2的情况下,Fe()-二元有机酸盐配合物的光还原反应初期铁()浓度的增长符合一级动力学反应规律,100min后浓度趋于稳定,方程式为[Fe()]t=kOA[OA]·[Fe()]ini×[1-exp{-(kOA[OA]+kox)t}]/(kOA[OA]+kox).光强升高和pH降低都能加快光还原反应速率,而改变温度则基本上对光还原反应速率无影响,证明铁()的光还原反应为自由基引发的电子转移过程.

The composition of acid/oil interface in acid oil emulsions

In well stimulation treatments using hydrochloric acid,undesirable water-in-oil emulsion and acid sludge may produce and then cause operational problems in oil field development.The processes intensify in the presence of Fe(Ⅲ),which are from the corroded surfaces of field equipment and/or iron-bearing minerals of the oil reservoir.In order to understand the reasons of the stability of acid emulsions,acid emulsions were prepared by mixing crude oil emulsion with 15% hydrochloric acid solutions with and without Fe(Ⅲ) and then separated into free and upper(water free) and intermediate(with water) layers.It is assumed that the oil phase of the free and upper layers contains the compounds which do not participate in the formation of acid emulsions,and the oil phase of the intermediate layers contains components involved in the formation of oil/acid interface.The composition of the oil phase of each layer of the emulsions was studied.It is found that the asphaltenes with a high content of sulfur,oxygen and metals as well the flocculated material of protonated non-polar oil components are concentrated at the oil/acid interface.In addition to the above,in the presence of Fe(Ⅲ) the Fe(Ⅲ)-based complexes with polar groups of asphaltenes are formed at the acid/oil interface,contributing to the formation of armor films which enhance the emulsion stability.

Sorption of Au(Ⅰ, Ⅲ)complexes on Fe, Mn oxides and humic Acid

THE mobilization and transport processes of gold are associated with gold complexes, such as hydroxides,chlorides, hydrogen sulfide, thiosulphate and organic matter. The newest thermodynamic data ofgold hydrolysis show that the gold solubility is controlled by Au（OH）·H2O rather than by AuCl4- in mostof the supergene water environment. The deposition process of gold is related to the changes of physicaland chemical properties in the environment, and to sorption. A few studies have been done on thesorption of gold complexes on Fe oxides, metal sulfides, Mn oxide and humic acid, respectively. Butno comparison among their sorption has been made under the same experimental conditions. This study deals with the sortition of Au （Ⅲ） chloride, Au （Ⅰ） chloride and thiosulphate

火焰原子吸收法测定胶乳中的铁

用硝酸消解胶乳样品 ,以氨水溶解消解产物 ,加入磺基水杨酸与铁形成三磺基水杨酸铁配合物 ,以工作曲线法测定。建立了在氨性溶液中快速测定胶乳中铁的FAAS法。对样品处理方法、消解产物的溶解性质、磺基水杨酸铁配合物的稳定性、试液和空白溶液粘度一致性、线性范围及检出限进行了考察。测定结果的相对标准偏差为 5 6%,加标回收率 95 0 %～ 99 5 %。

模拟日光照射下草酸协同黄铁矿对Cr(Ⅵ)的还原作用

研究了模拟日光照射下草酸协同黄铁矿对Cr(Ⅵ)的还原作用机理及其影响因素.结果表明,加入草酸后,反应体系中生成了光化学活性高的草酸铁(Ⅲ)配合物,同时还可能阻止了黄铁矿表面Fe(Ⅲ)水解产物Fe(OH)3和CrxFe1-x(OH)3的生成,从而使黄铁矿还原Cr(Ⅵ)的速率明显得到提高.增加溶液酸度、草酸浓度和黄铁矿质量浓度,有利于Cr(Ⅵ)的还原.

抗光晕染料5,6-二氨基-1,3-萘二磺酸铁络合物的合成研究

以吐氏酸 (2 氨基 1 萘磺酸 )为原料 ,用发烟硫酸两次磺化 ,再水解 ,合成染料中间体 6 氨基 1,3 萘二磺酸 中间体与重氮苯反应得偶氮化合物 ,再用Na2 S2 O4断开偶氮双键 ,酸化 ,合成 5 ,6 二氨基 1,3 萘二磺酸 ,它在乙酸钾存在下与FeCl3 反应 ,合成抗光晕染料 5 ,6 二氨基 1,3 萘二磺酸铁络合物 合成方法简便 ,特别是合成 5 ,6 二氨基 1,3 萘二磺酸集偶联 ,还原断链 ,酸化结晶于一浴 ,具有创新性和良好的环保效应 产物进行了红外、紫外光谱测定及高效液相色谱含量分析 产率高 ,产品含量 >98%

Excel在分析化学实验数据处理中的应用

数据处理是分析化学实验中必不可少的一个环节。将Excel应用于磺基水杨酸铁(Ⅲ)配合物的组成及稳定常数测定的数据处理。与我校传统的教学方法——坐标纸法相比,Excel法具有简便、快速、准确、降低主观误差的优势。结果表明,采用该方法的教学设计,能够有效促进学科融合,激发学生学习兴趣,提高学生综合素质。

Ultrasensitive iron-based magnetic resonance contrast agent constructed with natural polyphenol tannic acid for tumor theranostics

Because of the toxicity of Gd(Ⅲ)complexes and the poor T1 magnetic resonance imaging(MRI)contrast of superparamagnetic iron oxide,the development of new stable,non-toxic,and efficient contrast agents is desirable.Herein,tannic acid(TA),a large natural polyphenol,and bovine serum albumin(BSA)were used to construct non-toxic Fe(Ⅲ)complexes with increased relaxivity based on a strategy slowing the molecular spin.Compared with the commercial T1 contrast agent Magnevist■,TA-Fe@BSA not only exhibits comparable T1 MRI contrast enhancement under 0.5,1 and 7 T magnetic fields both in vitro and in vivo,but also has better stability and biocompatibility.Moreover,TA-Fe@BSA with near-infrared(NIR)absorption demonstrates efficient tumor ablation via photothermal effects.These results demonstrate their strong potential as an alternative T1 MRI contrast agent and tumor theranostics agent in clinical settings.

腐殖酸和铁对阿特拉津光降解影响的研究

为考察除草剂在水体中的自净性能,对模拟太阳光(λ>290 nm)下腐殖酸和铁元素对阿特拉津的光化学降解进行了研究。结果表明,单独辐照阿特拉津几乎不降解。在分别加入3、5和10 mg/L的腐殖酸时,阿特拉津的降解率分别为34.36%、40.74%和15.66%;在Fe(Ⅲ)投加量从0.01 mmol/L增加到0.2 mmol/L时,阿特拉津的降解率从24.36%增加到34.97%。而在当腐殖酸与铁共存时,阿特拉津降解率则进一步提高。紫外可见光谱和荧光光谱均表明,腐殖酸-铁络合物的形成及其光化学作用,促进了阿特拉津的降解。