Removal of Phosphate from Aqueous Solution with Modified Bentonite

Bentonite combined with sawdust and other metallic compounds was used to remove phosphate from aqueous solutions in this study. The adsorption characteristics of phosphate on the modified bentonite were investigated, including the effects of temperature, adsorbent dosage, initial concentration of phosphate and pH on removal of phosphate by conducting a series of batch adsorption experiments. The results showed that 98% removal rate of phosphate was obtained since sawdust and bentonite used in this investigation were abundantly and locally available. It is concluded that modified bentonite is a relatively efficient, low cost and easily available adsorbent for the removal of phosphate from aqueous solutions.     

褐煤活性炭吸附苯酚的研究

The feasibility and adsorption effect of lignite activated carbon for phenol removal from aqueous solutions were evaluated and investigated. A series of tests were performed to look into the influence of various experimental parameters such as contact time, initial phenol concentration, temperature, and pH value on the adsorption of phenol by lignite activated carbon. The experimental data were fitted well with the pseudo-second-order kinetic model. The adsorption is an endothermic process and conforms to Freundlich thermodynamic model. The results indicate that the lignite activated carbon is suitable to be used as an adsorbent material for adsorption of phenol from aqueous solutions.     

改性大豆皮吸附剂对Pb2+的生物吸附性能研究

Using soybean hull residue after the soluble dietary fiber being removed during the soybean processing industry as crude material,a novel absorbent,modified soybean hulls,is prepared.Its adsorption behavior for Pb2+ is studied.The adsorbent has a large and efficient adsorption capacity for Pb2+,up to 20% of the mass of dry ad-sorbent.Its maximum adsorption capacity for Pb2+ reaches 217 mg·g-1 at initial Pb2+ concentration of 2000 mg·L-1,which is twice that of yeast absorbent and threefold greater than that of chitosan absorbent.The adsorption ability is sensitive to pH value in the solution and the optimal pH for adsorption of Pb2+ is 7.0.In the presence of other metal ions (Ca2+,Mg2+ and Na+) in the solution,their effect on the adsorption capacity for Pb2+ is not obvious.After 5 cy-cles of adsorption,80% adsorption capacity of Pb2+ is maintained.Compared with various available commercial resins,the modified soybean hulls are a plentiful,inexpensive and effective medium for the capture of dissolved Pb2+ from waste streams.     

皮胶原纤维负载钦对核工业废水中铀的去除(英文)

Effective recovery of UO2+2 from wastewater is essential for nuclear fuel industry and related industries.In this study,a novel adsorbent was prepared by loading titanium(Ti4+) onto collagen fiber(TICF),and its physical and chemical properties as well as adsorption to UO2+2 in nuclear fuel industrial wastewater were investigated.It is found that TICF can effectively recover UO2+2 from the wastewater with excellent adsorption capacity.The adsorption capacity is 0.62 mmol·g-1 at 303 K and pH 5.0 when the initial concentration of UO2+2 is 1.50 mmol·L-1.The adsorption isotherms can be described by the Langmuir equation and the adsorption capacity increases with temperature.The effect of co-existed F on the adsorption capacity for UO2+2 is significant,which can be eliminated by adding aluminum ions as complexing agent,while the other co-existed ions in the solutions,including HCO-3,Cl-,NO-3,Ca2+,Mg2+ and Cu2+,have little effect on the adsorption capacity for UO2+2.The saturated TICF after UO2+2 adsorption can be regenerated by using 0.2 mol·L-1 nitrate(HNO-3) as desorption agent,and the TICF can be reused at least three times.Thus the TICF is a new and effective adsorbent for the recovery of UO2+2 from the wastewater.     

Role of intrinsic defects on carbon adsorbent for enhanced removal of Hg2+ in aqueous solution

Carbon is a normally used adsorbent for removal of heavy metal ion in aqueous solutions,but the efficient adsorbent needs intensive modification by heteroatom doped or supported noble metals that cause severe pollution and easy leaching of active components during use.In this paper,the role of intrinsic defects on Hg²⁺ adsorption for carbon adsorbent was investigated.The maximum adsorbing capacity of defectrich carbon has been improved up to 433 mg·g^-1 which is comparable t...     

用椰壳制活性炭吸附去除三价铋离子(英文)

In present study,we report the preparation of coconut shell activated carbon as adsorbent and its appli-cation for Bi(Ⅲ) removal from aqueous solutions.The developed adsorbent was characterized with scanning elec-tron microscope(SEM),Fourier Transform Infrared(FTIR),C,H,N,S analyzer,and BET surface area analyzer.The parameters examined include agitation time,initial concentration of Bi(Ⅲ),adsorbent dose and temperature.The maximum adsorption of Bi(Ⅲ)(98.72%) was observed at 250 mg·L-1 of Bi(Ⅲ) and adsorbent dose of 0.7 g when agitation was at 160 r·min-1 for 240 min at(299±2) K.The thermodynamic parameters such as Gibb’s free energy(△Gθ),enthalpy(△Hθ) and entropy(△Sθ) were evaluated.For the isotherm models applied to adsorption study,the Langmuir isotherm model fits better than the Freundlich isotherm.The maximum adsorption capacity from the Langmuir isotherm was 54.35 mg?g?1 of Bi(Ⅲ).The kinetic study of the adsorption shows that the pseudo second order model is more appropriate than the pseudo first order model.The result shows that,coconut shell ac-tivated carbon is an effective adsorbent to remove Bi(Ⅲ) from aqueous solutions with good adsorption capacity.     

油页岩灰渣合成Na-A沸石用于去除水溶液中Cu2+（英文）

Na-A zeolite was synthesized using oil shale ash （OSA）, which is a solid by-product of oil shale proc- essing. The samples were characterized by various techniques, such as scanning electron microscopy, X-ray diffrac- tion and Brunaner Emmet Teller method. The batch isothermal equilibrium adsorption experiments were performed to evaluate the ability of Na-A zeolite for removal of Cu （II） from aqueous solutions. The effects of operating pa- rameters, such as concentration of copper solutions, adsorbent dosages, pH value of solutions and temperature, on the adsorption efficiency were investigated. The equilibrium adsorption data were fitted with Langmuir and Freundlich models. The maximum adsorption capacity of Na-A zeolite obtained from the Langmuir adsorption iso- therm is 156.7 mg.g-t of Cu （lI）. The increase of pH level in the adsorption process suggests that the uptake of heavy metals on the zeolite follows an ion exchange mechanism. The batch kinetic data fit the pseudo-second order equation well. The thermodynamic parameters, such as changes in Gibbs free energy （AG）, enthalpy （AH） and en- tropy （AS）, are used to predict the nature of the adsorption process. The negative AG values at different tempera- tures confirm that the adsorption processes are spontaneous.     

Adsorption of Hg(Ⅱ) from aqueous solution using thiourea functionalized chelating fiber

A fast and selective adsorbent for Hg(II) from aqueous solutions using thiourea(TU) functionalized polypropylene fiber grafted acrylic acid(PP-g-AA),PP-g-AA-TU fibers,was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.The adsorption behavior of the functionalized chelating fibers for Hg(II) was investigated by static adsorption experiments,and the effects of some essential factors on adsorption of Hg(II) were examined,such as pH,initial concentration,adsorption time,coexisting cations,and temperature.The results showed that the adsorptive equilibrium could be achieved in 10 min,and the equilibrium adsorption quantity of PP-g-AA-TU fibers was 20 times that of PP-g-AA fibers.The PP-g-AA-TU fibers showed a very high adsorption rate and a good selectivity for Hg(II) over a wide range of p H.The adsorption isotherm can be well described with Langmuir model,with the maximum adsorption capacity for Hg(II) up to52.04 mg·g~(-1)and the removal of Hg(II) more than 97%.The kinetic data indicate that the adsorption process is best-fitted into the pseudo-second-order model.     

菌丝体-甲壳素水处理剂对重金属离子吸附性能的研究

The adsorption properties of chitin adsorbent from mycelium of fermentation industries for the removal of heavy metal ions were studied.The result shows that the chitin adsorbent has high adsorption capacity for many heavy metal ions and Ni^2 in citric acid.The influence of pH was significant:When pH is higher than 4.0,the high adsorption capacity is obtained.otherwise H^ ion inhibits the adsorption of heavy metal ions.The comparison of the chitin adsorbent with some other commercial adsorbents was made,in which that the adsorption behavior of chitin adsorbent is close to that of commercial cation exchange adsorbents,and its cost is much lower than those commercial adsorbents.     

Unravel the potential of zinc oxide nanoparticle-carbonized sawdust matrix for removal of lead(Ⅱ) ions from aqueous solution

Zinc oxide nanoparticles(ZnOnp) are molecular nanoparticles synthesized by a chemical precipitation method from zinc nitrate tetrahydrate and sodium hydroxide.Carbonized sawdust(CSD) was prepared from sawdust obtained from a local wood mill.The matrix of both provides a better material as an adsorbent.The present study applied the functionality of ZnOnp,CSD,and ZnOnp-CSD matrix as adsorbent materials for the removal of Pb(Ⅱ) ions from aqueous solution.The method of batch process was employed to investigate the potential of the adsorbents.The influence of pH,contact time,initial concentration of adsorbate,the dosage of adsorbents,and the temperature of adsorbate-adsorbent mixture on the adsorption capacity were revealed.The adsorption isotherm studies indicate that both Freundlich and Langmuir isotherms were suitable to express the experimental data obtained with theoretical maximum adsorption capacities(q_m) of 70.42,87.72,and 92.59 mg·g~(-1) for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix,respectively.The separation factors(R_L) calculated showed that the use of the adsorbents for the removal of Pb(Ⅱ) ions is a feasible process with R_L 1.The thermodynamic parameters obtained revealed that the processes are endothermic,feasible,and spontaneous in nature at 25-50℃.Evaluation of the kinetic model elected that the processes agreed better with pseudo-second order where the values of rate constant(k_2) obtained for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix are 0.00149,0.00188,and 0.00315 g·mg~(-1)·min~(-1),respectively.The reusability potential examined for four cycles indicated that the adsorbents have better potential and economic value of reuse and the ZnOnp-CSD matrix indicates improved adsorbent material to remove Pb(Ⅱ) ions from aqueous solution.     

土茯苓中鞣质提取工艺的优化

为了提高土茯苓的应用价值,对土茯苓中鞣质的提取工艺进行了探究.以丙酮溶液作为提取剂回流提取,采用络合滴定法测定鞣质的提取量,通过单因素实验和正交实验对土茯苓中鞣质的提取工艺进行优化,并采用精密度实验、重复性实验以及加标回收率实验对方法进行了评价.结果表明,最佳提取工艺为：提取温度70℃、丙酮浓度40％、料液比1：15（g：mL）、提取时间90 min.在此条件下,土茯苓中鞣质的提取量为20.77 mg·g-1.该提取工艺经济可行,方法的精密度高、重现性好.     

微波辐射提取石榴皮单宁的研究

以丙酮为提取溶剂,采用微波辐射提取石榴皮中的单宁,考察了溶剂浓度、微波功率、微波辐射时间、液料比等因素对单宁提取量的影响。结果表明,当溶剂体积浓度50%、微波辐射功率320 W、微波辐射时间5 m in和液料比18∶1(g/g)时,单宁的提取量为268.54 mg/g,比普通水浴提取提高了30.39 mg/g。     

我国栲胶标准的制定与修订

概述了栲胶系列标准制定、修订的历程;介绍了近年来新标准《栲胶分析试验方法》、《栲胶原料分析试验方法》、《毛杨梅栲胶》、《余甘栲胶》、《落叶松栲胶》、《橡椀栲胶》、《马占相思栲胶》的主要制定、修订内容。     

栲胶脱硫副产物NaCNS溶解度的测定及关联

采用静态平衡法测定了NaCNS在不同浓度栲胶溶液中的溶解度,并用数学方程对NaCNS的溶解度进行了关联,拟合出了NaCNS溶解度的对数与绝对温度倒数的一元线性方程,用来估算NaCNS在不同温度下的溶解度,为NaCNS的提取回收提供了一定的理论依据。     

Loss of Tannins and Other Phenolics from Willow Leaf Litter

A litter bag experiment was conducted to determine the fate of condensed tannins during the initial phase of willow leaf decomposition. Chemical methods and HPLC were used to identify and quantify the phenolics in aqueous acetone extracts of the leaves during the first eight weeks after leaf fall. Extractable phenolics and tannins were lost rapidly from the leaves and had half lives of about 2.4 weeks. Lower molecular weight tannins were lost more rapidly than higher molecular weight tannins, suggesting that the primary route for loss of tannins is leaching. There was no evidence for decomposition of the tannin during the leaf decay process. After leaching, the tannin apparently sorbs tightly to the soil.     

胶体滴定法测定橡椀栲胶中的单宁含量

用胶体滴定法测定了橡椀栲胶中的单宁含量。实验结果表明,pH值为5,橡椀栲胶中单宁质量在0.6～3.0 mg范围内,栲胶的电荷量(以滴定值表示)与单宁质量呈良好的线性关系。样品XK-2和XK-3的平均回收率分别为101.1%、103.4%,RSD分别为5.4%和1.5%,皮粉法和胶体滴定法测定的单宁含量的差值小于2.1%。与皮粉法相比,胶体滴定具有快速、简便、样品用量少的特点。     

单宁紫外吸收特性及其在PVA薄膜中的应用

采用紫外可见分光光度计对单宁酸、橡梳单宁和黑荆树单宁等进行定性扫描,探讨了不同种类单宁的紫外吸收特性,并考察了不同种类单宁的混和物的紫外吸收特性。将单宁添加到聚乙烯醇树脂中制成薄膜,探讨了单宁的种类和添加量对聚乙烯醇薄膜的紫外吸收特性的影响。结果表明：聚乙烯醇薄膜的紫外吸收特性不仅与单宁的种类有关,还与单宁的添加量有关。随着聚乙烯醇薄膜中单宁含量的增加,其对紫外吸收的效果越好。     

Recovery and recycle of tannins in the leather industry by nanofiltration membranes

The aim of this work was the study of the application of membrane concentration to exhausted tanning baths from vegetable tannage operations in order to increase the tannin/non‐tannin (T/NT) ratio and obtain recyclable material. For this purpose four samples of tanning baths at different T/NT ratios (from 0.7 to 1.4) were processed using six different types of membranes which ranged from reverse osmosis (RO) to nanofiltration (NF). The membrane module Fluid Systems TFC S 2540 gave the best results in terms of permeate flux and also in terms of increased T/NT ratio in the retentate (from 1.4 to 1.7). In order to compare the permeate flux reduction with time (J_t) for the different modules, the osmotic pressure differences (Δπ) between permeate and retentate were estimated by electrical conductivity measures. The fouling phenomena for the different membranes in the processing of each sample were evaluated by comparing the pressures required to obtain the same VRF (volume reduction factor), NPF (normalized permeate flux) and membrane performances with tap water before and after tannin concentration. The retention of tannins, which are polyphenols capable of significant hydrogen bonding, was found to be governed by the chemistry of the interactions between their complexes and the polyamide membrane material. Copyright © 2004 Society of Chemical Industry     

Extraction of tannin from fresh and preserved leaves

The extractability of tannin from fresh, lyophilized, and dried leaves collected at various times in the growing season was determined using the radial diffusion assay for protein-precipitating phenolics. The amount of tannin extracted depended on the method of leaf preservation and on the maturity of the leaf. Early in the season, more tannin was extracted from lyophilized leaves than from fresh leaves, but late in the season more tannin was extracted from fresh leaves. At all times, more tannin was extracted with aqueous acetone than with aqueous or acidic methanol.     

Tannin-based adsorbents from green tea for removal of monoaromatic hydrocarbons in water: Preliminary investigations

In this study, we report the adsorption of benzene and toluene from water using rarely reported tannin adsorbents. Tannin gel and tannin powder were synthesized by adding formaldehyde to green tea extract, while iron nanoparticles were synthesized by the addition of FeSO₄?·?7H₂O. The surface morphology of the synthesized adsorbents was determined using SEM and FTIR prior to application to contaminated water. The results show up to 88% removal of benzene and toluene in a batch system after 30?min of reaction time, with a higher rate of removal of toluene compared to benzene. A low pH value of 2 had an adverse effect on the tannin gel, reducing the total adsorption of benzene to approx. 37.5%. On the other hand, iron nanoparticles were least affected by the pH with an adsorption of 62.9% for benzene and 83.3% for toluene.