Intraparticle diffusivity of Cd ions in a new biosorbent material

Cadmium equilibrium sorption isotherms were determined for formaldehyde crosslinked Sargassum fluitans, establishing that an effective regeneration of the new biosorbent material is possible by an acid wash. Batch desorption kinetics were investigated at pH values of 1·0 and 2·0. By incorporating the linear and non-linear Langmuir equilibrium isotherm relationships into the rate equations, a mathematical model was proposed for modeling the metal desorption process. The model was solved numerically and a MATLAB computer program was used to curve-fit the experimental data. The model successfully predicted the Cd²⁺ elution concentration profile in a batch reactor. The average values of the intraparticle diffusivity of Cd²⁺ in the algal biosorbent calculated from the model were 3·40 × 10⁻⁶ and 1·65 × 10⁻⁶ cm² s⁻¹, 0·473 and 0·229 times the molecular diffusivity of Cd²⁺ in water, at pH values of 1·0 and 2·0, respectively. These values agreed well with theoretical predictions.     

酒精尾气回收工艺模拟与优化

研究从中药厂酒精尾气中回收酒精的吸收 解吸工艺。采用UNIFAC模型和Wilson模型分别预测吸收塔和解吸塔内的平衡关系,并对吸收塔和解吸塔内的工艺参数进行优化。结果表明：当吸收塔理论板数为25,液气比为0.24 L/m³,常温常压下操作时塔顶排气乙醇质量分数为28×10^-6,塔釜乙醇回收率接近1;解吸塔为简单精馏塔,采用20块理论板,回流比为3,第10块板进料,塔顶可得91.7%的乙醇,塔釜得到几乎纯净的水,经冷却后作为吸收塔的吸收剂,循环套用。模拟结果对工业过程设计和设备改造具有一定指导意义。     

重金属生物吸附的吸附模型

排污系统中的重金属通过生物的方法进行吸附除掉,是一种重金属回收和再利用的较为有效治理方法。本研究通过热平衡的机理分析,采用普通的物质吸附模型,通过大量的实验数据处理,得到了重金属吸附脱俯的数学模型。该模型具有较好计算与实验数据的吻合性。但是实验结果也表明,生物吸附模型不适用于计算在生物质中的重金属离子脱附量,即重金属生物吸附模型没有满足可逆性。这一点在使用该模型时需要给予考虑。因此吸附的机理分析还需要结合实践过程的热力学平衡数据来进行分析回归。     

Ion-exchange properties of mildiomycin on HZ110™ resin

Mildiomycin (MIL) is a novel nucleoside agro-antibiotic which shows a specific and strong inhibitory activity against fungi, especially, powdery mildews. Because of its low action dosage, excellent environmental compatibility and remarkably low toxicity to human and animals, MIL is regarded as a kind of green biological pesticides. In this paper, the recovery and purification of MIL from fermentation broth were investigated by ion-exchange separation technique. The ion-exchange properties of MIL on HZ110™ resin, including ion-exchange equilibrium and dynamics in column process, were discussed. Results showed that the equilibrium exchange capacity of MIL was 26.5 mg per gram of wet resin at optimal pH value of pH 7.0. Ion-exchange isotherms of MIL can be well correlated with Freundlich equation. The ion-exchange capacity increased with raising the temperature. In the dynamic column process, breakthrough capacity was 29.3 mg per gram of wet resin. According to the ratio of desorption and eluent concentration of MIL, 2% ammonia aqueous solution was chosen as the eluent. And the total recovery ratio of MIL in ion-exchange process was up to 94.5%, and the enriched factor was about 8.     

Recovery of gold from the plating rinse by adsorption with nylon fibers

Taking note of the affinity of some reverse osmosis membranes to Au(CN)^-₂ in the citrate buffered gold plating rinse, we accomplished the recovery of gold by the adsorption to some polymers. Among several polymers, tested nylon fibre had the most excellent characteristics of adsorption. The amount of adsorption of gold on nylon fiber increased with a decrease in pH value of the solution, and 7.5 mg of gold was adsorbed on 1 g of nylon fiber at pH 3, 25°C. The rate of adsorption increased with an increase in temperature. In the case of desorption, the solution containing cyanide ions at a pH as high as 10 was desirable to be employed as an eluant. By passing the simulated plating rinse through a column of nylon fiber, the adsorption and desorption of gold was successfully accomplished. The maximum concentration of gold in the eluant was approximately 600 ppm.     

ZIF-8浆液法分离CH4/N2的双吸收-吸附塔工艺流程建模与模拟

由于ZIF-8浆液独特的可流动性，可以借鉴传统的吸收-解吸工艺，实现煤层气中甲烷的多级连续高效富集。在单吸收-吸附塔工艺的基础上，为了进一步降低能耗，提出了高低压双吸收-吸附塔新型分离工艺，并对该工艺进行了全流程建模及模拟。采用平衡级法，建立了工艺流程中各单元传质设备的数学模型，包括吸收-吸附塔、闪蒸罐、解吸塔。此外，还进行了灵敏度分析，探究了平衡级数、进料位置、气液比、解吸压力等因素对产品气中甲烷浓度以及回收率等工艺性能的影响。模拟结果表明，当产品气中甲烷浓度达到90.13%（mol）时，回收率为90.25%。并且单位原料气能耗为0.445 kW·h∙m^-3（原料气），低于单塔能耗（0.510 kW·h∙m^-3）。由此，改进的双塔工艺在满足甲烷纯度和回收率的同时，相较于单塔工艺进一步降低了能耗。     

Congo red attached poly(EGDMA–HEMA) microspheres as specific sorbents for removal of cadmium ions

Poly[ethyleneglycoldimethacrylate (EGDMA)–hydroxyethylmethacrylate (HEMA)] microspheres (150–200 μm in diameter) were produced by suspension copolymerization of EGDMA and HEMA in an aqueous medium. Toluene was included in the formulations in order to produce water-swellable microspheres. Poly(vinyl alcohol) and benzoyl peroxide were used as stabilizer and initiator, respectively. Congo red was chemically attached to the microspheres as a metal chelating ligand for specific adsorption of heavy metal ions. These sorbents were characterized by an optical microscopy and a FTIR. Adsorption/desorption of cadmium (Cd²⁺) ions from aqueous solutions on these sorbents were investigated in batch equilibrium experiments by using an atomic absorption spectroscopy with a graphite furnace atomizer. The maximum cadmium adsorption on to the dye-attached microspheres (i.e., by complex formation) was about 18.3 mg Cd²⁺ ions/g polymer, which was observed at pH 6.8. While adsorption onto the plain poly(EGDMA–HEMA) microspheres (i.e., nonspecific adsorption) was about 0.93 mg Cd²⁺ ions/g polymer at the same conditions. More than 90% of the adsorbed cadmium was desorbed in 1 h by using 2M NaCl as an eluant. The resorption capacity of the sorbent did not significantly decrease during repeated sorption–desorption cycling. © 1996 John Wiley & Sons, Inc.     

大孔吸附树脂分离纯化杜仲中京尼平甙酸

比较了NKA-9、D311、S-8、HPD600、NKA-2、A型、D140、聚酰胺8种树脂对杜仲中的降血压活性成分京尼平甙酸(GPA)的吸附及脱附性能,从中筛选出吸附率(88.17%)及脱附率(97.71%)均较高的A型树脂进行实验。最佳工艺条件为:杜仲皮粉末用φ(乙醇)=50%的水溶液提取后,乙醇沉淀,上清液调节pH=6~9后,用A型树脂吸附220 m in,装柱,用φ(乙醇)=15%的水溶液洗脱,流速为1.5 mL/m in,洗脱液浓缩后,冷冻干燥得产品。京尼平甙酸的收率为84.03%,w(GPA)=84.06%。     

Application of starch xanthates for cadmium removal: A comparative evaluation

Attempts to solve the problem of heavy metals removal and recovery from wastewaters have led to the development and application of several techniques. One of the techniques involves application of starch and cellulose-based products, especially xanthates. Both water-soluble and insoluble starch xanthate processes have been claimed to be successful based on the studies conducted with relatively simple wastewaters. The major objectives of this study have been to evaluate the effectiveness of insoluble starch xanthate (ISX) for the removal of cadmium, study the effect of complexing agents/ligands on the interaction of cadmium with ISX and soluble starch xanthate (SSX), and to make overall comparison of ISX and SSX processes for cadmium removal. Both SSX and ISX can bring down the aqueous phase cadmium concentration to less than 1 mg/liter (Indian effluent discharge standard) irrespective of the pH (in the range of 3 to 7), ionic strength, and initial cadmium concentration. The metal binding capacity of ISX is maximum in the pH range of 4 to 5 and is constant irrespective of equilibrium metal concentrations as well as different doses of ISX used at lower pH values (3 to 5). The metal uptake by ISX/SSX in the presence of EDTA is affected considerably. ISX shows higher uptake of cadmium in the presence of EDTA as compared to SSX. The insoluble xanthate process appears to have an edge over soluble xanthate process in terms of metal removal capacity, reliability, and ease of operation, particularly for cadmium.     

pH值和盐浓度对金属螯合亲和层析分离人胰高血糖素样肽-1融合蛋白的影响

目的探讨pH值和盐浓度对金属螯合亲和层析(Immobilized metal ion affinity chromatography,IMAC)分离含His-Tag标签的人胰高血糖素样肽-1(Glucagon-like peptide-1,GLP-1)融合蛋白的影响,并确定最佳洗脱条件。方法在0.50mol/L盐浓度条件下,分别取pH6.0、7.0、7.8和9.04种缓冲液进行咪唑梯度洗脱;在合适的pH值条件下,分别取氯化钠浓度0.25、0.50和0.75mol/L3种缓冲液进行咪唑梯度洗脱。分析在不同pH值及盐浓度条件下洗脱融合蛋白所需要的咪唑浓度及回收率。结果在所考察的pH值范围内,洗脱融合蛋白所需的咪唑浓度随洗脱液pH值的升高而逐渐降低,当洗脱液pH值为7.8时,融合蛋白的分离效果最佳,大部分杂蛋白被0～40mmol/L咪唑洗脱液去除且不含融合蛋白,而绝大部分融合蛋白在咪唑浓度达80～200mmol/L时被洗出,总回收率达(83.7±1.0)%,且比例较高;在此pH值条件下,氯化钠浓度达0.75mol/L,才会影响融合蛋白的回收率,氯化钠浓度为0.25或0.50mol/L的洗脱液洗出融合蛋白的效果相近;在pH7.8,含0.25mol/L氯化钠的洗脱体系下,用50mmol/L咪唑溶液洗脱杂蛋白,200mmol/L咪唑溶液洗脱融合蛋白,融合蛋白的回收率和比例分别可达(85.2±2.0)%和(80.5±1.0)%。结论在所考察的pH值和盐浓度范围内,提高洗脱液pH值和盐浓度均可降低洗脱融合蛋白需要的咪唑量,但也会降低融合蛋白的回收率。     

Removal of trivalent chromium(III) from solution by biosorption in cork powder

The removal of trivalent chromium from solutions using biosorption in cork powder is described. The adsorption isotherm was determined, along with the effect of different variables, such as biomass particle size, solid–liquid ratio, reaction time, metal concentration and pH, on the efficiency of chromium removal. It was concluded that the adsorption is slow and favoured by an increase in pH. Therefore, using a solid–liquid ratio of 4 g dm^?3 it is possible to reduce the chromium concentration in the solution from 10 mg dm^?3 to less than 1.5 mg dm^?3 in 2 h at 22 °C. The kinetic studies verified that the sorption of chromium by cork was described by a second‐order model. The elution results showed that 50% of the chromium bound to the cork was eluted using 0.5 mol dm^?3 H₂SO₄ and that cork maintains its binding capacity over four cycles of biosorption/elution. © 2002 Society of Chemical Industry     

Coupling of electrodialysis and leaching processes for removing of cadmium from phosphate ore

Phosphate rock is a valuable material that is used for the production of large phosphorus chemicals. However, this natural material usually contains some toxic elements such as cadmium (Cd). Cd is a non-nutritive metal regarded as harmful to both humans and the environment. The main toxic effects of Cd on human health are the kidney and renal cortex diseases. Other effects were observed on pulmonary, cardiovascular, and musculoskeletal systems, in addition to including Cd as a human carcinogen. In order to reduce the cadmium content in the phosphate ore, an original method was studied and consists of coupling both leaching and electrodialysis. The effects of process parameters, such as reaction time, nature, and concentration of the extracting agent, liquid/phosphate ore ratio, pH, temperature, and current density, were investigated. The obtained results show that the cadmium extraction from phosphate ore using simple batch leaching does not reduce the cadmium content to the required level. However, the application of leaching- electrodialysis coupled method at optimum current density of 10 mA cm^?2 increases the cadmium extraction efficiency up to 84.3%. This synergetic process could be applied to the treatment of phosphate ore containing cadmium.     

沉淀转化法回收酸浸渣中铅的酸溶工艺研究

以金精矿焙烧-酸浸除杂后的酸浸渣与碳酸氢铵反应生成的转化渣为原料,进行酸溶浸铅工艺研究。通过正交实验考察了液固质量比、浸出pH和浸出时间等因素对铅浸出率的影响,得到最佳工艺条件：浸出液固质量比为2∶1、浸出液pH=0.5、浸出时间为2 h。在此条件下,金属铅浸出率可达83%。     

Biosorption of lead (II) from aqueous solution by cone biomass of Pinus sylvestris

Biosorption of lead (II) onto a cone biomass of Pinus sylvestris was studied with variation in the parameters of pH, initial metal ion concentration and impeller speeds. Lead removal rate was increased at pH 4.0 and was sharply decreased when pH of the solution was decreased to 2.0. Impeller speed studies indicated maximum lead biosorption at 150 rpm and the biosorption equilibrium was established after about 1 h. The adsorption constants were found from the Freundlich isotherm at 25°C. An increase in lead/biomass ratio caused a decrease in biosorption efficiency. The cone biomass, which is a readily available biosorbent, was found suitable for removing of lead in aqueous solution.     

Sugar-beet pulp pectin gels as biosorbent for heavy metals: Preparation and determination of biosorption and desorption characteristics

The present work reports the feasibility of using sugar-beet pectin gels for the removal of heavy metals from aqueous solutions. Sugar-beet pectin hydro- and xerogels were tested in the batch biosorption and desorption of cadmium, lead and copper. Pectins were successfully extracted and demethylated from the sugar-beet pulp, an agricultural residue, and gelled in the presence of CaCl₂. The stability of the hydro- and xerogel pectin beads made them suitable for biosorption of heavy metals in different conditions. Biosorption data were fitted to the pseudo-second order kinetic model and the Langmuir isotherm model, obtaining the corresponding parameters. Treated and untreated beads were characterized using FTIR and SEM to determine possible binding mechanisms. The main mechanisms involved were ion exchange with calcium of gel structure and chelation or complexation with carboxyl groups. After biosorption, calcium in the gels was substituted by metal cations reorganizing the structure of the gel matrix in a way that was visible using scanning electron microscopy. HNO₃ 0.1 M was the best eluant for the reutilization of the gels and recovered all the adsorbed metal unlike HCl and H₂SO₄. Sugar-beet pectins could be used as an efficient biosorbent for the treatment and recovery of Cu, Pb and Cd from wastewater.     

Adsorption separation of raffinose from sucrose by activated carbon: Equilibrium,kinetics and dynamic breakthrough

Separation of oligosaccharides with a varied number of monosaccharides is an important issue in food chemistry. Raffinose, a functional oligosaccharide, has attracted increasing attentions due to its strong proliferative effect on bacteria. Industrially, cottonseed meal is an important resource for producing raffinose; however, raffinose extracted from the cottonseed meal contains a significant amount of sucrose that debases raffinose’s quality. In this work, an adsorptive separation of raffinose and sucrose on activated carbon was reported. Adsorption isotherms, adsorption kinetics and dynamic column adsorption–desorption were investigated. The activated carbon chosen has a significantly higher adsorption capacity of raffinose (0.60~0.65 g/g) than sucrose (0.35~0.40 g/g) at the equilibrium concentration studied (~35 g/L) and temperature from 293 K to 333 K. Adsorption isotherms and kinetics were fitted by the Freundlich isotherm model and the pseudo-second-order model, respectively. The effect of flow-rate and initial feed concentration on dynamic adsorption were investigated; meanwhile, the separation performance was further confirmed from dynamic desorption using aqueous ethanol of 20% as eluant. Remarkably, raffinose with purity over 90% and recovery of 79.2% could be obtained by the adsorption–desorption cycle using an aqueous feed solution containing 20 g/L of raffinose and 6 g/L of sucrose.     

Removal of nickel from aqueous solutions by citric acid modified Ceiba pentandra hulls: Equilibrium and kinetic studies

The removal of Ni(II) from aqueous solutions using biomass prepared from Ceiba pentandra hulls powder modified with citric acid treatment (CAMCPH) has been studied by batch method. The biosorbent was characterised before and after citric acid modification using SEM, FT‐IR and XRD. Experimental parameters that influence the biosorption of Ni(II), such as pH, biosorbent dose, contact time and initial concentration of metal ion have been investigated. The adsorption of Ni(II) increased with increase in contact time and reached equilibrium within 50 min. The maximum removal of Ni(II) was observed at pH 5.0. The kinetic data were analysed using three adsorption kinetic models: the pseudo‐first, second‐order kinetics and intra‐particle diffusion. The results showed that the pseudo‐second‐order model fits the experimental data very well. The equilibrium data were analysed using Langmuir, Freundlich and Dubinin–Radushkevich isotherm models. Langmuir model provided the best correlation for the adsorption of Ni(II) by CAMCPH and the monolayer biosorption capacity for Ni(II) removal was 34.34 mg/g. Desorption experiments were carried out using HCl solution and the recovery of the metal ion from CAMCPH was found 98%. Desorption experiments showed the feasibility of regeneration of the biosorbent for further use after treating with dilute HCl. © 2011 Canadian Society for Chemical Engineering     

Cadmium biosorption by a glyphosate-degrading bacterium,a novel biosorbent isolated from pesticide-contaminated agricultural soils

In this study, biosorption of cadmium (II) ions from aqueous solutions by a glyphosate degrading bacterium, Ochrobactrum sp. GDOS, was investigated in batch conditions. The isolate was able to utilize 3 mM GP as the sole phosphorous source, favorable to bacterium growth and survival. The effect of different basic parameters such as initial pH, contact time, initial concentrations of cadmium ion and temperature on cadmium uptake was evaluated. The adsorption process for Cd (II) is well fitted with Langmuir adsorption isotherm. Experimental data were also tested in terms of biosorption kinetics using pseudo-first-order and pseudo-second-order kinetic models. Maximum metal uptake q_max was obtained as 83.33 mg g⁻¹. The sorption process of cadmium onto the Ochrobactrum sp. GDOS biomass followed second-order rate kinetic (R² = 0.9986). A high desorption efficiency was obtained in pH 2. Reusability of the biomass was examined under successive biosorption–desorption cycle repeated thrice. The characteristics of the possible interactions between biosorbent and metal ions were also evaluated by scanning electron microscope (SEM), Fourier transform infrared (FT-IR) and X-ray diffraction analysis.     

Adsorption of Divalent Cobalt from Aqueous Solution onto Chitosan–Coated Perlite Beads as Biosorbent

Abstract

Chitosan coated perlite beads are prepared by drop‐wise addition of a liquid slurry containing chitosan and perlite to an alkaline bath. The resulting beads are characterized using FTIR, SEM, EDXRF, and Surface area analysis and the chitosan content of the beads is 23% as determined by a pyrolysis method. Adsorption of Co (II) metal ions from aqueous solution on chitosan coated perlite beads is studied under both equilibrium and dynamic conditions. In the present investigation, a first order reversible rate equation is used to understand the kinetics of metal removal and to calculate the rate constants at different initial concentrations. The equilibrium characteristics of metal ion on newly developed biosorbent are studied and the experimental adsorption data are well fitted to Freundlich and Langmuir adsorption isotherm models and the model parameters are evaluated. The effect of pH, agitation time, concentration of adsorbate, and amount of adsorbent on the extent of the adsorption are investigated. The sorbent loaded with metal is regenerated with 0.10 mol dm^?3 sodium hydroxide solution. The adsorption desorption cycles indicated that the chitosan coated perlite could be regenerated and reused to remove Co (II) from waste water.     

茶皂素提取条件的优化及纯化研究

以油茶茶籽粕为原料，采用乙醇水溶液提取茶皂素。在茶籽粉和乙醇料液比1 : 9(g : mL)，乙醇体积分数60%，提取温度60 ℃和提取时间3 h的最佳条件下茶皂素的提取得率达14.9%。用NKA-9型大孔吸附树脂吸附纯化茶皂素粗品，树脂静态吸附与解吸结果表明：树脂静态吸附茶皂素粗提液0.5 h基本饱和，体积分数80%乙醇解吸率为91.1%；动态吸附与解吸时，上样流速8 mL/min较佳，吸附率为66.04%，体积分数80%乙醇洗脱，洗脱流速5.0 mL/min，洗脱体积50 mL时，可使流出液中茶皂素质量浓度在1.25~1.57 g/L之间，茶皂素纯度为95%。