Adsorption behavior and mechanism of cadmium on strong-acid cation exchange resin

The adsorption behavior of Cd2+ on 001×7 strong-acid cation exchange resin was studied with the static adsorption method. The adsorption process was analyzed from thermodynamics and kinetics aspects. The influences of experimental parameters such as pH, temperature, initial concentration and adsorption rate were investigated. The experimental results show that in the studied concentration range, 001×7 resin has a good sorption ability for Cd2+, and the equilibrium adsorption data fit to Freundlich isotherms. The adsorption is an exothermic process which runs spontaneously. Kinetic analysis shows that the adsorption rate is mainly governed by liquid film diffusion. The best adsorption condition is pH 4-5. The saturated resin can be regenerated by 3 mol/L nitric acid, and the desorption efficiency is over 98%. The maximal static saturated adsorption capacity is 355 mg/g (wet resin) at 293 K. The adsorption mechanism of Cd2+ on 001×7 resin was discussed based on IR spectra.

Direct extraction of Mo(VI) from acidic leach solution of molybdenite ore by ion exchange resin:Batch and column adsorption studies

The adsorption behavior of ion exchange resin D301 in the extraction of hexavalent molybdenum from high acidic leach solution was investigated. SEM, EDS and Raman spectra analyses were applied to studying the adsorption capacity, reaction kinetics and possible adsorption mechanism in detail. Results showed that the adsorption capacity of D301 resin for molybdenum from high acidic leach solution was up to 463.63 mg/g. Results of the kinetic analysis indicated that the adsorption process was controlled by the particle diffusion with the activation energy 25.47 k J/mol（0.9-1.2 mm） and 20.38 k J/mol（0.6-0.9 mm）. Furthermore, the molybdenum loaded on the resin could be eluted by using 2 mol/L ammonia hydroxide solution. Besides, dynamic continuous column experiments verified direct extraction of molybdenum from acidic leach solutions by ion exchange resin D301 and the upstream flow improved dynamic continuous absorption.

Study on the influence of humic acid of different molecular weight on basic ion exchange resin's adsorption capacity

In this paper, humic acid （HA） was ultra-filtered into different molecular weight sections and was characterized by multielement analysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric. Since humic acids of different molecular weights have different hydrophilic and molecular size, the maximum adsorption capacity of basic ion exchange resins appears on the humic acid whose molecular weight ranges from 6000 to 10,000 Da.

Kinetic Study of Esterification of Lactic Acid with Isobutanol and n-Butanol Catalyzed by Ion-exchange Resins

The esterification reactions of lactic acid with isobutanol and n-butanol have been studied in the presence of acid ion-exchange resin Weblyst D009. The influences of catalyst loading, stirrer speed, catalyst particle size, initial reactant molar ratio and temperature on the reaction rate have been examined. Experimental kinetic data were correlated by using the pseudo-homogeneous, Langnluir-Hinshelwood and Eley-Rideal models. Nonideality of the liquid phase was taken into account by using activities instead of molar fractions. The activity coefficients were calculated according to the group contribution method UNIFAC. Provided that the nonideality of the liquid is taken into account, the esterification kinetics of lactic acid with isobutanol and n-butanol catalyzed by the acid ion-exchange resin can be described using all threemodels with reasonable errors.

Adsorption equilibrium, kinetics, and dynamic separation of Ca2+ and Mg2+ ions from phosphoric acid–nitric acid aqueous solution by strong acid cation resin

The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.

Removal of Co(Ⅱ) from aqueous solutions by NKC-9 strong acid resin

A strong acidic ion exchange resin(NKC-9)was used as a new adsorbent material for the removal of Co(Ⅱ)from aqueous solutions.The adsorption isotherm follows the Langmuir model.The maximum adsorption capacity of the resin for Co(Ⅱ)is evaluated to be 361.0 mg/g by the Langmuir model.It is found that 0.5 mol/L HCl solution provides effectiveness of the desorption of Co(Ⅱ)from the resin.The adsorption rate constants determined at 288,298 and 308 K are 7.12×10-5,8.51×10-5and 9.85×10-5s-1, respectively.The apparent activation energy(Ea)is 12.0 kJ/mol and the adsorption parameters of thermodynamic are-H Θ=16.1 kJ/mol,-SΘ=163.4 J/(mol·K),-G Θ 298 K=-32.6 kJ/mol,respectively.The adsorption of Co(Ⅱ)on the resin is found to be endothermic in nature.Column experiments show that it is possible to remove Co(Ⅱ)ions from aqueous medium dynamically by NKC-9 resin.

Cleaning the Ion Exchange Resin Sorption of Uranium from Silicic Acid Solution ＂Ayanat＂

The authors discovered a new way to clean the ion exchange resin sorption of uranium from silicic acid used solution ＂Ayanat＂. The method reduces the costs of regeneration of ion exchange resin and its reuse in the sorption of uranium.

Elution Behaviour of Monocarboxylic Acids on a Cation-exchange Resin Column

The retention mechanism of monocarboxylic acids on a cation-exchange resin column was investigated. It was assumed that both Donnan membrane equilibrium and adsorption equilibrium were involved in the chromatographic process. On the basis of the proposed mechanism, an equation was derived for correlating distribution coefficient, Kd, dissociation constant, Aa, and adsorption equilibrium constant, K, of the analyzed acid. By this approach, retention data for some aliphatic acids under different operating conditions were predicted. Results are reasonably in agreement with experiment.

Atmospheric Sulfur and Nitrogen Deposition in Five Nature Reserves of Sichuan Basin to Qinghai-Tibetan Plateau Transect Region,Southwest-ern China

Enhanced sulfur and nitrogen deposition has been observed in many transect regions worldwide,from urban/agricultural areas to mountains.The Sichuan Basin(SCB),with 18 prefectural cities,is the most economically-developed region in western China,while the rural Qinghai-Tibetan Plateau(QTP)lies west of the SCB.Previous regional and national atmospheric modeling studies have sug-gested that large areas in the SCB-to-QTP transect region experience excessive deposition of sulfur and nitrogen.In this study,we applied a passive monitoring method at 11 sites(one in urban Chengdu and 10 from fivenature reserves)in this transect region from September 2021 to October 2022 to confirm the high sulfur and nitrogen deposition fluxes and to understand the gaps between the modeling and observation results for this transect region.These observations suggest that the five reserves are under eutrophication risk,and only two reserves are partially under acidification risk.Owing to the complex topography and landscapes,both sulfur and nitrogen deposition and critical loads exhibit large spatial variations within a reserve,such as Mount Emei.Regional atmospheric modeling may not accurately capture the spatial variations in deposition fluxes within a reserve;however,it can capture general spatial patterns over the entire transect.This study demonstrates that a combination of state-of-the-art atmospheric chemical models and low-cost monitoring methods is helpful for ecological risk assessments at a regional scale.

用732强酸性阳离子交换树脂去除铬酸盐钝化液中的锌离子

对732强酸性阳离子交换树脂再生铬酸盐钝化液进行了探索。研究了交换处理时间、溶液初始pH、Zn（II）初始浓度及树脂用量对树脂吸附的影响，并考察了树脂的脱附和再生性能。结果表明，该树脂对Zn（II）的吸附速率快，30min达到吸附平衡，最佳吸附pH为3～6。用树脂再生钝化液不会对Cr（VI）浓度产生影响，能达到“去锌保铬”的目的。该树脂对Zn（II）的吸附符合Langmuir吸附等温模型，为单分子层吸附，具有吸附饱和性，饱和吸附量约为85．6mg／g。

四种732型树脂对猫豆中左旋多巴交换性能的比较

目的通过比较四种不同产地732型强酸性阳离子交换树脂对左旋多巴的静态吸附和动态交换性能,筛选出适合工业化生产的最佳树脂。方法采用以0.2mol/L的盐酸溶液溶解左旋多巴,离子交换层析柱法对左旋多巴溶液做静态吸附和动态吸附,再用0.3mol/L的氨水为洗脱液进行动态洗脱收集,用高效液相色谱法测出洗脱液的浓度并计算出左旋多巴的含量,从而计算出收率。结果在同一实验条件下,宜宾某树脂厂产树脂对左旋多巴的吸附性能最好,收率达92.93%。结论经四种树脂筛选比较得出,宜宾某树脂厂产树脂对左旋多巴提取收率最大,比较适合用于左旋多巴工业化生产。

离子色谱法测定荔枝核及其732树脂洗脱液的游离氨基酸

为测定荔枝核中的游离氨基酸,采用ICS-2500离子色谱分析仪,分别测定了荔枝核提取液与732阳离子交换树脂洗脱液中的氨基酸的组成和含量。离子色谱条件:固定相为Amino PACPA-10离子交换柱,流动相:250 mmol/L NaOH、1 mol/L NaAC和水作为洗脱液进行梯度洗脱,柱温30℃,流速0.25 mL/min。在稀释100倍的荔枝核提取液中含有12种游离氨基酸,其中苏氨酸、精氨酸和甘氨酸总相对含量为64%,且含有3种未知氨基酸,但未知氨基酸不稳定,离子交换树脂未起到预期的分离效果。因此,离子色谱法可有效的检测荔枝核中及分离纯化过程中的游离氨基酸。其中未知氨基酸的适宜分离条件有待进一步研究。

The Synthesis of Cyclic Amino Acids

Several cyclic amino acids (1-4) were synthesized from glycine. Isocyanate ester was prepared as the key intermediate and reacted with dibromoalkanes to afford the target compounds.

732阳离子交换树脂对全细胞谷氨酸脱羧酶活性的促进机制

通过对全细胞和纯酶的对比分析,从732阳离子交换树脂对细胞转化体系pH、产物效应和底物效应的影响,对732阳离子交换树脂促进屎肠球菌全细胞谷氨酸脱羧酶(glutamate decarboxylase,GAD,EC4.1.1.15)活力的机制进行了探讨。结果显示:γ-氨基丁酸(γ-aminobutyric acid,GABA)对全细胞GAD活性具有抑制作用,而L-谷氨酸(L-glutamic acid,L-Glu)却无此现象,并且当L-Glu浓度达到200 mmol/L以上时,全细胞GAD活性才达到最大;在pH4.2~5.8条件下,GABA解离为阳离子较L-Glu多,可与树脂平衡时所结合的L-Glu和H+发生离子交换,补充游离L-Glu,减少游离GABA,稳定反应体系pH。研究表明,732阳离子交换树脂可以通过离子交换作用而释放H+、L-Glu和结合GABA,增加反应液游离底物浓度和降低游离产物浓度,并调节反应液p H,增大细胞内外浓度差,加快细胞内外物质运送速度,从而提高全细胞GAD的表观活力。

732强酸性阳离子树脂催化合成盐酸维生素B1

以硫羟硫胺为原料,经双氧水氧化得硫酸维生素B1(VB1·H2SO4);VB1·H2SO4经纯化水稀释后,流经732强酸型阳离子交换树脂,用稀盐酸洗脱,浓缩后用85%乙醇重结晶得盐酸VB1,其结构经1H NMR,13C NMR,MS和元素分析确证。

732阳离子交换树脂对屎肠球菌谷氨酸脱羧酶活性的促进作用

通过对732阳离子交换树脂对屎肠球菌谷氨酸脱羧酶(glutamate decarboxylase,GAD,EC4.1.1.15)活性的影响进行探讨,构建了732阳离子交换树脂-细胞GAD复合转化体系。结果表明:经含0.2 mol/L L-谷氨酸(L-glutamic acid,L-Glu)的0.2 mol/L乙酸-乙酸钠缓冲液(pH 4.2)平衡的732阳离子交换树脂可显著提高屎肠球菌细胞GAD的转化活性,γ-氨基丁酸(γ-aminobutyric acid,GABA)产量较对照组增加了32.30%;L-Glu/谷氨酸一钠(monosodium glutamate,MSG)(2∶1)固体混合物能有效调节反应体系的pH值和维持反应液的底物浓度,显著增加GABA产量,当添加量为30 g/L时,GABA产量较不添加L-Glu/MSG(2∶1)固体混合物的对照组提高了52.40%;732阳离子交换树脂与L-Glu/MSG(2∶1)固体混合物对细胞GAD的转化活性具有协同促进作用,适宜的732阳离子交换树脂-细胞GAD复合转化体系组成为732阳离子交换树脂10 g、0.3 mol/L MSG溶液(溶于0.2 mol/L乙酸-乙酸钠缓冲液,pH 4.2)10 mL、100 mg/mL屎肠球菌细胞悬液10 mL和L-Glu/MSG(2∶1)混合物30 g/L。在该反应体系下,80 r/min、40℃水浴振荡器反应24 h,GABA产量为(4.57±0.11)mmol,较对照组GABA产量((2.29±0.08)mmol)提高了99.56%。

Removal of Copper from Acid Mine Drainage (AMD) or Acid Rock Drainage (ARD)

Acid mine drainage is wastewater from a mine having a low pH and an elevated level of dissolved heavy metals. These metals are harmful to aquatic, animal and human life. This paper looks at the removal of copper from acid mine drainage using ion exchange to less than 1 mg/l. A weak acidic cation resin was used. Spectrophotometric determination of copper with sodium diethyldithiocarbamate was used to determine the copper concentrations in the treated water. Using regression analysis, the experimental results gave a correlation coefficient of 0.977 and a coefficient of determination of 99.5%. Results indicated that the higher the flows rate the shorter the period after which the copper concentration in the treated water reaches 1 mg/l. At pH 3.85 and 5.09, the resin performed better and at pH above 6.62 and between pH 3.0 and below the resin’s does not perform well. The higher the resin height the greater is the resin exchange capacity and the longer it takes for the copper concentration to reach 1 mg/l in the treated water. The higher the wastewater copper concentration the shorter the time it takes the resin to reach 1 mg/l. The results for this experiment indicated that acid mine drainage can be treated well by ion exchange resins, but it is also very important to establish suitable operating conditions.

酸性矿山废水中多种有价金属的高效分离

酸性矿山废水(AMD)中多种有价金属的高效分离回收,是重金属减排和资源化利用的关键。文章通过中和沉淀实验和静态吸附实验探究回收有价金属的最佳沉淀和吸附pH,成功开发了中和沉淀—离子交换—中和沉淀组合工艺,并应用于大宝山AMD的处理。结果表明,AMD在pH为3.00和9.80中和沉淀时,分别沉获64%的Fe_(2)O_(3)富铁渣和51%的Mn O富锰渣。采用离子交换树脂分别在pH 3.95和6.10条件下对AMD中的Cu和Zn进行吸附,得到质量浓度为Cu^(2+)11~26 g/L,Zn^(2+)10~20 g/L的两种解吸液。通过该组合工艺,AMD中的各金属Fe、Cu、Zn和Mn的回收率分别为:96%、81%、70%和60%,实现了有价金属的高效分离回收。若采用此工艺回收大宝山2000 m^(3)/d的AMD中的铜、锌、锰硫酸盐,每年的利润为119万元,经济效益非常显著。此处理工艺为酸性矿山废水的高效资源化利用提供了新路径。

强碱性阴离子交换树脂从粗钨酸铵溶液中分离钼的研究

研究了采用ZGA351大孔强碱性阴离子交换树脂从粗钨酸铵溶液中吸附分离钼的工艺方法,考察了树脂型号、料液硫含量、料液陈化时间、料液陈化温度、料液pH值、吸附流速、吸附温度对树脂吸附分离钼效果的影响。结果表明:使用100 mL ZGA351树脂进行动态吸附试验,在料液硫含量为理论量1.1倍、料液陈化时间48 h、料液陈化温度40℃、料液pH值10.0、吸附流速15 mL/h、吸附温度40℃的最优条件下,料液钨损失率仅为0.54%,树脂钼穿透容量为107.77 g/L_(湿树脂),相比目前工业生产应用的HBDM-1树脂钼穿透容量提高了3.15倍。另外,重复试验稳定性良好,ZGA351树脂吸附后得到的纯钨酸铵溶液平均钼钨比为0.88×10^(-4),满足工业生产APT产品用纯钨酸铵溶液钼钨比小于2×10^(-4)的需求。综合而言,采用强碱性阴离子交换树脂从粗钨酸铵溶液中分离钼具有钼穿透容量高、钨损失率低、钨钼分离效率高等优势,为工业化应用提供了一种有效技术参考。

增强型离子交换树脂催化醚化汽油TAME的合成

在高压釜式反应器中,以甲醇和异戊烯为原料,增强型离子交换树脂Amberlyst为催化剂,制备了高辛烷值醚化汽油组分TAME。改变反应温度、催化剂用量等单一实验变量,探索得到了最佳工艺条件:反应温度70℃,催化剂用量为20%,醇/烯比为2。在最优条件下,该催化反应只需进行4.5h,TAME的摩尔产率就达到70%。