Removal and recycling of copper from aqueous solutions using treated Indian barks

Removal of copper from aqueous solutions containing 100–1000 ppm, using different Indian bark species, was performed on laboratory scale. The percentage removal of metal ions depends on the solution pH, bark species and time. The efficiency of copper removal by the used raw barks increases with a rise of solution pH and reaches a maximum of about 65–78% around pH 4–5. However, the decontaminated aqueous solutions were colored due to the dissolution of soluble organic compounds contained in the raw bark. This increases the biological and chemical oxygen demand (BOD and COD) of the solutions as well as the total organic carbon content (TOC). For this reason, raw bark should be treated either by chemical or biological means. Such treatment will allow the extraction of the soluble organic compounds and increase the chelating capacity and efficiency of the treated bark. Depending on the pH value, the chelating efficiency of treated barks is about 1.2–2.2 times that of the raw ones. Moreover, the retention capacity of the Indian treated bark varies from about 42–51 mg/g of dry bark. It is equal to or higher than that of common European species. About 1.8 mols of H₃O⁺ are released, by the treated barks, for every mol of chelated copper ions. Moreover, scanning electron microscopy (SEM) observations show uniform distribution of metal ions throughout the copper saturated bark. Infra red (IR) spectra suggest that the copper ions are chelated to hydroxyl and/or carboxyl functional groups of organic compounds contained in the treated bark. It seems that the interaction of the copper ions with the bark follows a cation exchange mechanism. This hypothesis is supported by elution experiments that allow recovery of about 99% of the contained copper. The retention capacity of the treated bark is almost constant after five cycles of chelation–elution, suggesting that the ‘life time cycle' is sufficiently long for continuous industrial application. The spent copper loaded barks can either be incinerated or pyrolysed. It generates solids containing either ≈80% of CuO or ≈14% of Cu°, respectively. Such materials can be used either in the secondary or primary copper production, thus offering a friendly environmental solution of effluents' treatment. The suggested process can be used as an alternative to the classical technologies for effluent decontamination. It is also efficient for polishing effluents treated by other methods.     

57Fe Mssbauer spectroscopic study on the barks of several three species grown in Lanzhou,China

Using ⁵⁷Fe Mssbauer effect, the chemical states of iron components were investigated for the barks of Platycladus orientalis, Cedrus deodara and Platanus acerifolia sampled from Lanzhou City, China. All bark samples showed two overlapping doublets with large and small quadruple splitting. Only Platycladus orientalis's barks exhibited one sextet. Based on Mssbauer parameters, they were attributed to paramagnetic ferrous, paramagnetic ferric and magnetic iron, respectively. For the sampling site which is about 6 kilometers from Lanzhou Steel Factory, the ratio of ferrous to ferric was higher in the sample of Platanus acerifolia's barks, whereas the barks of Platycladus orientalis and Cedrus deodara gave similar values of this ratio. Platycladus orientalis was the most effective in accumulating iron complexes in barks among the three trees. Platanus acerifolia's barks sampled at Lanzhou Steel Factory's area exhibited higher absolute intensities of iron components and lower ration of ferrous to ferric, indicating that industrial air pollution is a contributing factor in accumulating iron compounds in the tree barks of this region.     

大气氢氧自由基测量技术研究进展

大气氢氧自由基在对流层大气化学中占有重要地位，但由于其浓度极低而活性极高，所以至今没有合适的测量方法。文章通过总结２０多年来大气氢氧自由基测量技术研究的成果，分析讨论了大气氢氧自由基浓度测量的研究现状和发展趋势。     

Enzymatic preparation of hydrophobic biomass with one-pot synthesis and the oil removal performance

Oil pollution is causing deleterious damage to aquatic ecosystems and human health. The utilization of agricultural waste such as corn stalk (CS) to produce biosorbents has been considered an ecofriendly and efficient approach for removing oil. However, most previous studies focused on the modification of the whole CS, which is inefficient due to the heterogeneity of CS. In this study, corn stalk pith (CP), which has excellent amphipathic characteristics, was selected to prepare a high-efficienc...     

共沉淀富集原子吸收法测定水中5种重金属元素

使用有机共沉淀剂DDTC钠盐（铜试剂）。La^3＋作载体离子富集和乙炔火焰原子吸收分光光度法测定监测井水中Cu,Ni,Zn,Pb和Cd,结果表明，该方法精密度较高、结果准确，回收率满足微量元素测定要求,适用于达标排放水，监测井水中常见污染指标元素Cu,Ni，Zn,Pb和Cd的测定。     

应用红外方法探讨耐镉菌株高积累Cd2+的机理

从安徽某冶炼厂污染土壤中分离出一株能耐高浓度镉的菌株(J5),经初步鉴定为假单胞菌属(Pseudomonas sp.).该菌株在液体培养基中耐受40 mmol·L-1 CdSO4,在固体培养基上耐受75mmol·L-1 CdSO4.培养基中Cd2+、Zn2+、Pb2+、Cu2+浓度分别为100 mg·L-1和Mn2+浓度为275mg·L-1时,菌株生长正常.在重金属Cu2+、Pb2+、Zn2+、Mn2+存在时,采用红外光谱与原子吸收光谱分析菌株对Cd2+的积累,结果表明,在低浓度Cd2+溶液中菌株细胞对Cd2+的积累,主要靠细胞壁上-NH2与Cd2+配位结合;在高浓度Cd2+溶液中,细胞壁上-NH2、-OH、-COOH、-PO43-、-M-O(O-M-O)基团吸附Cd2+的能力显著.Mn2+可以增加细胞壁上有效官能团活性,提高Cd2+积累率;但当有Zn2+、Pb2+、Cu2+重金属离子共存时,即使有Mn2+存在,菌体对Cd2+吸附积累能力未见提高.     

Distribution of aluminum species and the characteristics of structure of poly-aluminum-chloride-sulfate(PACS)

ＩｎｔｒｏｄｕｃｔｉｏｎＰｏｌｙａｌｕｍｉｎｕｍｃｈｌｏｒｉｄｅ (ＰＡＣ) ,ｗｈｉｃｈｗａｓｄｅｖｅｌｏｐｅｄｉｎｔｈｅ 1960’ｓｉｎＪａｐａｎ ,ｈａｓｃｏｍｅｔｏｂｅｕｓｅｄｅｘｔｅｎｓｉｖｅｌｙｉｎ ｐｌａｃｅｏｆａｌｕｍｉｎｕｍｓｕｌｆａｔｅｉｎｗａｔｅｒａｎｄｗａｓｔｅｗａｔｅｒｔｒｅａｔｍｅｎｔｂｅｃａｕｓｅｏｆｉｔｓａｂｉｌｉｔｙｔｏａｃｈｉｅｖｅａｄｅｑｕａｔｅａｇｇｒｅｇａｔｉｏｎｅｖｅｎａｔｌｏｗｔｅｍｐｅｒａｔｕｒｅｓａｎｄｔｏｆｏｒｍｆｌｏｃｓｒｅｌａｔｉｖｅｌｙｒａｐｉｄｌ…     

Fluorescence fingerprints to monitor total trihalomethanes and N-nitrosodimethylamine formation potentials in water

Water samples from 56 lakes of Missouri, USA, were analysed for their fluorescence excitation/emission matrix (EEM) spectroscopy and the formation potentials of total trihalomethanes (TTHM) and N-nitrosodimethylamine (NDMA). Comparing the excitation/emission matrix fingerprints with trihalomethanes formation revealed that water with higher fluorescence intensity generally exhibited higher trihalomethanes formation potential. Moreover, waters with fluorescence centre at excitation: 290–310 nm/emission: 330–350 nm were related to high N-nitrosodimethylamine and trihalomethanes formation potentials. The results suggest that excitation/emission matrix fingerprints could be used as surrogate parameters for monitoring trihalomethanes and N-nitrosodimethylamine formation potentials.     

Detection of combustion formed nanoparticles

UV–visible extinction and scattering and two extra situ sampling techniques: atomic force microscopy (AFM) and differential mobility analysis (DMA) are used to follow the evolution of the particles formed in flames. These particle sizing techniques were chosen because of their sensitivity to detect inception particles, which have diameters, d<5 nm, too small to be observed with typical particle measurement instrumentation. The size of the particles determined by AFM and DMA compares well with the size determined by in situ optical measurements, indicating that the interpretation of the UV–visible optical signal is quite good, and strongly showing the presence of d=2–4 nm particles. UV–visible extinction measurements are also used to determine the concentration of d=2–4 nm particles at the exhausts of practical combustion systems. A numerical model, able to reproduce the experimentally observed low coagulation rate of nanoparticles with respect to soot particles, is used to investigate the operating conditions in the combustion chamber and exhaust system for which 2–4 nm particles survive the exhaust or grow to larger sizes. Combustion generated nanoparticles are suspected to affect human and environmental health because of their affinity for water, small size, low rate of coagulation, and large surface area/weight ratio. The ability to isolate nanoparticles from soot particles in hydrosols collected from combustion may be useful for future analysis by a variety of techniques and toxicological assays.     

Contributions of root cell wall polysaccharides to Cu sequestration in castor (Ricinus communis L.) exposed to different Cu stresses

Cell wall polysaccharides play a vital role in binding with toxic metals such as copper(Cu)ions.However, it is still unclear whether the major binding site of Cu in the cell wall varies with different degrees of Cu stresses.Moreover, the contribution of each cell wall polysaccharide fraction to Cu sequestration with different degrees of Cu stresses also remains to be verified.The distribution of Cu in cell wall polysaccharide fractions of castor(Ricinus communis L.) root was investigated with various Cu concentrations in the hydroponic experiment.The results showed that the hemicellulose1(HC1) fraction fixed 44.9%–67.8% of the total cell wall Cu under Cu stress.In addition, the pectin fraction and hemicelluloses2(HC2) fraction also contributed to the Cu binding in root cell wall,accounting for 11.0%–25.9% and 14.1%–26.6% of the total cell wall Cu under Cu treatments, respectively.When the Cu levels were ≤ 25 μmol/L, pectin and HC2 contributed equally to Cu storage in root cell wall.However, when the Cu level was higher than 25 μmol/L, the ability of the pectin to bind Cu was easy to reach saturation.Much more Cu ions were bound on HC1 and HC2 fractions, and the HC2 played a much more important role in Cu binding than pectin.Combining fourier transform infrared(FT-IR) and twodimensional correlation analysis(2 D-COS) techniques, the hemicellulose components were showed not only to accumulate most of Cu in cell wall, but also respond fastest to Cu stress.