Optimizing electron spin resonance detection of hydroxyl radical in water

The parameters affecting the electron spin resonance (ESR) detection of hydroxyl free radical in water are studied and optimized. The hydroxyl radical is generated by the Fenton reaction with iron (II) ammonium sulfate and hydrogen peroxide reacting in a phosphate buffer using N-tert-butyl-alpha-phenylnitron as the spin trap. The concentrations of Fe²⁺, H₂O₂, and phosphate buffer are the parameters studied. The Taguchi method and the orthogonal experiment design were used to evaluate the effects of these parameters on the ESR signal intensity. By the analysis of the signal-to-noise ratio and the analysis of variance, the order of importance of the various parameters on the hydroxyl radical formation is determined for optimal ESR detection of hydroxyl radical. The results will help the development of water purification technologies using hydroxyl free radical as a green oxidant.     

Pyrolysis of permethrin and formation of precursors of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) under non-oxidative conditions

This article reports the computational and experimental results of the thermal decomposition of permethrin, a potential source of dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). We have performed a quantum chemical analysis by applying density functional theory to obtain the decomposition pathways of permethrin and the formation mechanism of dibenzofuran. We have conducted the pyrolysis experiments in a tubular reactor and identified the pyrolysis products to demonstrate the agreement between the experimental measurements and quantum chemical calculations. The initiation of the decomposition of permethrin involves principally the aromatisation of permethrin into 3-phenoxyphenylacetic acid, 2-methylphenyl ester (J) and concomitant loss of 2HCl. This rearrangement is followed by the rupture of the O–CH₂ linkage in J, with a rate constant derived from the quantum chemical results of 1 × 10¹⁵ exp(−68 kcal/mol/RT) s⁻¹ for temperatures between 700 and 1300 K. This is confirmed by finding that the rate constant for unimolecular rearrangement of permethrin into J is 1.2 × 10¹² exp(−53 kcal/mol/RT) s⁻¹ over the same range of temperatures and exceeds the direct fission rate constant at all temperatures up to 850 ± 120 °C as well as by the experimental detection of J prior to the detection of the initial products incorporating diphenyl ether, 1-methyl-3-phenoxybenzene, 3-phenoxybenzaldehyde and 1-chloromethyl-3-phenoxybenzene. As the temperature increases, we observe a rise in secondary products formed directly or indirectly (via phenol/phenoxy) including aromatics (naphthalene), biphenyls (biphenyl, 4-methyl-1,1′-biphenyl) and dibenzofuran (DF). In particular, we discover by means of quantum chemistry a direct route from 2-phenoxyphenoxy to naphthalene. We detect no polychlorinated dibenzo-p-dioxins and dibenzofurans. Unlike the case of oxidative pyrolysis [Tame, N.W., Dlugogorski, B.Z., Kennedy, E.M., 2007b. Formation of dioxins in fires of arsenic-free treated wood: Role of organic preservatives. Environ. Sci. Technol. 41, 6425–6432] where significant yields of both PCDD and PCDF were obtained, under non-oxidative conditions the thermal decomposition of permethrin does not form appreciable amounts of PCDD or PCDF and the presence of oxygen (and/or a sizable radical pool) appears necessary for the formation of dibenzo-p-dioxin itself or PCDD/F from phenol/phenoxy.     

Co-FeOOH/g-C3N4的制备及其在非均相光芬顿反应中的催化性能

通过化学浴沉淀法制备了Co掺杂的FeOOH与石墨相氮化碳复合材料(Co-FeOOH/g-C₃N₄),作为非均相光芬顿催化剂,以罗丹明B(RhB)为目标污染物,分别考察了Co掺杂量、pH、温度、H₂O₂浓度、催化剂剂量等因素对光催化效率的影响。在最佳反应条件下,Co-FeOOH、g-C₃N₄和Co-FeOOH/g-C₃N₄对RhB的去除率分别为23.7%、59.6%和91.5%。通过阿伦尼乌斯方程计算得到反应的活化能为12.8 kJ·mol⁻¹,通过自由基捕获实验证实·OH与h⁺均为起主要作用的活性物种。Co-FeOOH/g-C₃N₄经过5次循环使用后,对RhB的去除率没有明显下降,说明其具有良好的稳定性。最后,以天然日光作为驱动光源,考察了催化剂对高浓度染料废水的处理性能,反应6 h后,废水的脱色率达到100%,COD去除率为43.9%,延长反应时间至10 h,COD的去除率达到81.6%。在非均相芬顿反应中引进了可见光,在提高降解反应速率的同时降低了催化反应发生的成本,本研究结果可为非均相光芬顿体系的实际应用提供实验基础。     

酸根离子对铝板电絮凝处理含镍废水的影响

电絮凝是去除废水中重金属离子的有效技术。本研究考察了常见酸根离子SO42-、Cl-、NO3-和H2PO2-对铝板电絮凝除Ni2+的影响。结果表明,SO42-、Cl-、NO3-均有利于Ni2+的去除,其中由于NO3-的还原可提高铝阳极溶解效率,因此,当其浓度从0.0186增至0.186 mol/L时,反应30 min后Ni2+去除率从77.9%升至99.8%。H2PO2-会降低絮体絮凝活性并钝化电极,从而显著降低Ni2+去除率,其浓度从0.0186 mol/L增至0.372 mol/L,反应60 min后Ni2+去除率从91.7%降至30.5%。另外,对各阴离子存在下溶解态铝絮体聚合度以及电解过程pH的检测,进一步揭示这4种离子对电絮凝影响机制。     

Theoretical study of the dechlorination reaction pathways of octachlorodibenzo-p-dioxin

The dechlorination reaction pathways of 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (OCDD) by the hydrogen atom are investigated by the density-functional theory B3PW91 method. The dechlorination reactions have large exothermicity and small activation energies. The activation energies (approximately 5 kcal/mol) of the sigma-complex formation due to the hydrogen addition are lower than those (approximately 9 kcal/mol) of the direct chlorine abstraction. It is suggested that the sigma-complex plays an important role in the reactions, although it has scarcely been shown in previous studies of the dechlorination of dioxins. The sigma-complex formation is favored at low temperatures and the chlorine abstraction is favored at high temperatures. Furthermore, it is found that the lateral positions have a marginal preference over the longitudinal positions. The dechlorination of OCDD by the hydrogen atom is thus not likely to result in a dominant formation of the laterally substituted toxic congeners.     

Efficient dehalogenation of automobile shredder residue in NaOH/ethylene glycol using a ball mill

We investigated the effectiveness of sodium hydroxide/ethylene glycol (NaOH/EG) for dehalogenation of automobile shredder residue (ASR) using a ball mill. Efficient dehalogenation was achieved at atmospheric pressure by combining the use of EG (196 degrees C b.p.) as a replacement solvent for NaOH with ball milling, which improved contact between ASR and OH(-) in solution. Moderate NaOH concentrations and increased ball mill rotation speeds produced high dechlorination that was not significantly affected by the weight ratio of ASR to EG. NaOH/EG dechlorination increased with temperature with an apparent activation energy of 50 kJ mol(-1) confirming that the reaction proceeded under chemical reaction control. The modified shrinking-core model was appropriate to explain the dechlorination process. Low chloro levels in our NaOH/EG-treated ASR suggested that this material could be used for feedstock recycling and the wet process may be applicable for dehalogenation of other important waste streams.     

Atmospheric oxidation mechanisms of polychlorinated dibenzo-p-dioxins are different from those of benzene and dibenzofuran: a theoretical prediction

The reaction mechanisms of dibenzo-p-dioxin (DD) and 2,3,7,8-TCDD with OH radical have been studied using density functional theory calculations. Under the atmospheric conditions, ca 42% of DD + OH reaction proceeds as formation of DD − OH-β adduct, which will react with O₂ slowly; while the rest will proceed as formation of DD − OH-γ adduct, which will decompose to the substituted phenoxy radical P1 by the fused-ring C-O bond cleavage. For 2,3,7,8-TCDD + OH, the reaction will predominantly form the substituted phenoxy radical P2. The reaction mechanisms are drastically different from the peroxy mechanism for the atmospheric oxidations of benzene and dibenzofuran.     

Evidence for destruction of PCBs by the OH radical in urban atmospheres

Evidence for reaction of polychlorinated biphenyl (PCB) congeners with the hydroxyl (OH) radical in the troposphere was observed in diurnal variations in ambient gas-phase PCB concentrations at three urban sampling sites located in the Chicago, IL; Baltimore, MD; and Jersey City, NJ urban/industrial areas. The magnitude of the depletion of individual PCB congeners decreased by about 10-20% for each additional chlorine substituent, reflecting slower reaction rates for higher MW congeners with the OH radical. Octa- and nonachlorobiphenyls, which are largely unreactive with the OH radical, were used as tracers to investigate the effects of dilution on diurnal variation. The environmental rate constants for disappearance of the PCBs range from about 1.0 day(-1) for trichlorobiphenyls to about 0.3 day(-1) for hexachlorobiphenyls. Assuming a OH radical concentration of 3 x 10(6) molecules cm (-3), the second-order rate constants for reaction of specific congeners with the OH radical are consistent with laboratory measurements. More importantly, the relative reactivity of PCB homologues agrees well with the relationship predicted by other researchers from laboratory measurements, suggesting that losses of PCBs during daytime tropospheric transport are due at least in part to reactions with the OH radical.     

Molecular docking and dynamics studies of cigarette smoke carcinogens interacting with acetylcholinesterase and butyrylcholinesterase enzymes of the central nervous system

The free radicals produced by cigarette smoking are responsible for tissue damage, heart and lung diseases, and carcinogenesis. The effect of tobacco on the central nervous system (CNS) has received increased attention nowadays in research. Therefore, to explore the molecular interaction of cigarette smoke carcinogens (CSC) 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanol (NNAL), 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone (NNK), and N′-nitrosonornicotine (NNN) with well-known targets of CNS-related disorders, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) enzymes, a cascade of the computational study was conducted including molecular docking and molecular dynamics simulations (MDS). The investigated results of NNAL+AChE_complex, NNK+AChE_complex, and NNK+BuChE_complex based on intermolecular energies (?G) were found to ?8.57 kcal/mol, ?8.21 kcal/mol, and ?8.08 kcal/mol, respectively. MDS deviation and fluctuation plots of the NNAL and NNK interaction with AChE and BuChE have shown significant results. Further, Molecular Mechanics Poisson-Boltzmann Surface Area (MM‐PBSA) results shown the best total binding energy (^Binding?G) ?87.381 (+/?13.119) kJ/mol during NNK interaction with AChE. Our study suggests that CSC is well capable of altering the normal biomolecular mechanism of CNS; thus, obtained data could be useful to design extensive wet laboratory experimentation to know the effects of CSC on human CNS.

Graphical abstract

     

聚多巴胺/聚乙烯亚胺复合非织造布/Fe2+活化过硫酸盐催化氧化酸性红B的效果分析

以聚丙烯(PP)非织造布为基体,采用多巴胺聚乙烯亚胺共沉积法制备了聚多巴胺/聚乙烯亚胺复合非织造布(PDA/PEI@PP),研究了PDA/PEI@PP在Fe²⁺活化过硫酸盐(PS)降解酸性红B(ARB)的中的性能和反应机理。通过SEM对材料结构进行了表征,考察了不同体系(PS、PDA/PEI@PP/PS、Fe²⁺/PS和PDA/PEI@PP/Fe²⁺/PS)中ARB的降解效果,通过电子自旋共振波谱(ESR)和傅里叶红外光谱(FT-IR)分析了PDA/PEI@PP活化PS及自由基生成的机理,此外,考察了PDA/PEI@PP对Fe³⁺的还原作用。结果表明：PDA/PEI@PP非织造材料具有贯穿的孔道结构,利于PDA/PEI@PP表面官能团对PS的活化;PDA/PEI@PP对Fe²⁺/PS体系的催化氧化具有促进作用,当Fe²⁺初始浓度为0.5 mmol·L⁻¹时,90 min内对ARB的降解率为98%,反应速率常数为0.040 min⁻¹;在不添加Fe²⁺的情况下,PDA/PEI@PP可直接活化PS产生自由基降解ARB,降解率为56%;PDA/PEI@PP表面的邻苯二酚基团与邻醌基反应生成半醌,从而活化PS产生硫酸根自由基($ {\rm{SO}}_4^{ \cdot - } $)和羟基自由基(·OH);同时PDA/PEI@PP表面的邻苯二酚基团也对Fe³⁺具有还原作用,生成Fe²⁺持续活化PS。因此,PDA/PEI@PP对于Fe²⁺活化PS的促进作用主要是通过PDA/PEI@PP对PS协同活化和对Fe³⁺的还原作用来实现的。本研究为进一步提高Fe²⁺活化PS氧化降解染料废水的效率提供了一种较好的解决方案。     

The influence of radical architecture on cadmium bioaccumulation in the black mangrove, Avicennia germinans L

Two groups of Avicennia germinans plants with differences in the radical architecture were exposed under hydroponic conditions to 95ppm of cadmium (Cd) for a period of 24h. Later, Cd concentration in roots, stems and leaves was determined by graphite furnace atomic absorption spectrophotometry. Our results showed that, for both groups of plants, the roots accumulated higher concentration of Cd as compared to stems and leaves, though, the plants of group B displayed enhanced radical architecture, better growth performance, and lower Cd concentration as compared to plants of group A. In contrast, low values of leaves/roots Cd transportation index, and bioaccumulation factor were found in plants of group B. These results suggest that the higher radical architecture developed in plants of group B might better adjust the uptake of Cd as a result of an integrated network of multiple response processes for instances, production of organic acids, antioxidative replay, cell-wall lignification and/or suberization. Further studies will be focused in understanding the role of the radical system in mangrove plants with the rhizosphere activation and root adsorption to soil Cd under natural conditions.     

Experimental and theoretical studies on formation and degradation of chloro organic compounds

Studies on oxidation of tert-butyl ethers in the presence of chloride ions proved that acid medium favoured formation of chloro organic compounds. 1,2-Dichloro-2-methylpropane, 3-chloro-2-chloromethylpropene were identified among the reaction products. Presence of these compounds was identified both in the case when methyl-tert-butyl ether (MTBE) and ethyl-tert-butyl ether (ETBE) were subjected to reaction. Reaction products were analysed by gas chromatography method with application of -FID, -MS and -AED detectors. On the basis of experimental data, the path of tert-butyl ethers conversion to dichloro products was proposed. It was found that the identified chloro derivatives could be formed both by ionic and radical reactions. In order to confirm this thesis for the proposed scheme of reaction, the theoretical calculations of molecular simulation of the reaction paths were performed.     

Formation of oxidized products from the reaction of gaseous phenanthrene with the OH radical in a reaction chamber

The reaction of gas phase phenanthrene (Phen) with the OH radical in the presence of NO_x was studied in a reaction chamber. A number of oxidation products were identified by two dimensional gas chromatography–time of flight mass spectrometry (GC × GC–TOFMS). Identified products included 9-fluorenone, 1,2-naphthalic anhydride, 2,2′-diformylbiphenyl, dibenzopyranone, 1, 2, 3, 4 and 9-phenanthrols, 2, 3, 4 and 9-nitrophenanthrenes, 1,4-phenanthrenequinone, 9,10-phenanthrenequinone, and 2- and 4-nitrodibenzopyranones. This is the first study to identify 1,2-naphthalic anhydride and 1,4-phenanthrenequinone as products of the gas phase reaction of Phen with the OH radical. Eight more products were tentatively identified by their mass spectral fragmentation patterns and based on the typical OH radical initiated photochemical reaction mechanisms of simple aromatic compounds and naphthalene. In the reaction chamber, particle formation of products as a function of irradiation time was measured. Phenanthrenequinones, phenanthrol, nitrophenanthrene and nitrobenzopyranone were observed predominantly in the particle phase. This implies that these oxidized products formed from the reaction of Phen with the OH radical in the chamber would be associated with particles in the atmosphere and may, therefore, have an impact on human health. Possible pathways for the formation of these products are suggested and discussed.     

新型吡啶鎓盐分子的合成及其对Fe3+的检测

针对水中铁离子(Fe³⁺)检测存在使用有毒溶剂、对设备要求较高、检测限高等缺点,以四联吡啶和5-溴甲基-间苯二甲酸二甲酯为原料,以N,N-二甲基甲酰胺为溶剂,通过亲核取代和水解反应制备出一种新型的铁离子检测探针——吡啶鎓盐分子。运用一系列的表征技术分析了吡啶鎓盐分子的性质,并通过实验探察了共存离子、Fe³⁺的浓度等对吡啶鎓盐分子识别Fe³⁺的影响。表征实验结果表明,吡啶鎓盐分子结构具有三齿吡啶氮和羧基,使其与Fe³⁺之间具有很高的亲和力,可以与Fe³⁺配位形成金属络合物。识别实验结果表明,吡啶鎓盐分子对Fe³⁺的络合显色实现了对Fe³⁺的专一性检测,其检测限为4.8 ×10⁻⁷ mol·L⁻¹;在Cd²⁺、Zn²⁺、Mn²⁺、Ni²⁺、Cu²⁺、Fe²⁺和K⁺ 等多种干扰离子存在条件下,对Fe³⁺仍具有良好的识别效果,体现出较强的抗干扰性能。综上所述,新型吡啶鎓盐分子结构中具有三齿吡啶氮和羧基,使其对水中Fe³⁺具有易识别、灵敏度高、选择性好等优点。     

A new model of tropospheric hydroxyl radical concentrations

A chemistry model of the global troposphere is presented which focuses on the hydroxyl radical, OH. Global distributions of OH are calculated based on known chemical reaction pathways, experimentally measured values of precursor species O3, H2O, NOx (defined as NO+NO2), CO, CH4, and actinic flux (which includes the effects of cloud cover and O3 column absorption). Model grid resolution is 1 km in altitude by 10 degrees latitude, and zonally divided into land or ocean. Species are calculated as seasonal averages. Global annual mean OH in the troposphere (up to 14 km altitude) is calculated to be 9.2 x 10(5) molcm(-3) with averages of 9.8 x 10(5) in the northern hemisphere, and 8.5 x 10(5) in the southern hemisphere. Global CO and CH(4) oxidation rates by OH are calculated to be 1840 Tgyear(-1) and 580 Tgyear(-1), respectively. OH is found to be most sensitive to O3 and H2O concentrations, as well as to the photolysis rate of O3 to O1D. Sensitivity of CO and CH4 oxidation rates to cloud presence shows an inverse relationship to cloud amount and optical depth. Model results are shown to be consistent with results from two other published models.     

Decomposition and mineralization of cefaclor by ionizing radiation: kinetics and effects of the radical scavengers

There has been recent growing interest in the presence of antibiotics in different environmental sectors. One considerable concern is the potential development of antibiotic-resistant bacteria in the environment, even at low concentrations. Cefaclor, one of the beta-lactam antibiotics, is widely used as an antibiotic. Kinetic studies were conducted to evaluate the decomposition and mineralization of cefaclor using gamma radiation. Cefaclor, 30 mg/l, was completely degraded with 1,000 Gy of gamma radiation. At a concentration of 30 mg/l, the removal efficiency, represented by the G-value, decreased with increasing accumulated radiation dose. Batch kinetic experiments with initial aqueous concentrations of 8.9, 13.3, 20.0 and 30.0mg/l showed the decomposition of cefaclor using gamma radiation followed a pseudo first-order reaction, and the dose constant increased with lower initial concentrations. At a given radiation dose, the G-values increased with higher initial cefaclor concentrations. The experimental results using methanol and thiourea as radical scavengers indicated that ()OH radicals were more closely associated with the radiolytic decomposition of cefaclor than other radicals, such as e(aq)(-) or ()H. The radical scavenger effects were tested under O(2) and N(2)O saturations for the enhancement of the TOC percentage removal efficiencies in the radiolytic decomposition of cefaclor. Under O(2) saturation, 90% TOC removal was observed with 100,000 Gy. Oxygen is well known to play a considerable role in the degradation of organic substances with effective chain reaction pathways. According to the effective radical reactions, the enhanced TOC percentage removal efficiencies might be based on the fast conversion reactions of e(aq)(-) and ()H with O(2) into oxidizing radicals, such as O(2)(-) and HO(2)(), respectively. 100% TOC removal was obtained with N(2)O gas at 20,000 Gy, as reducing radicals, such as e(aq)(-) and ()H, are scavenged by N(2)O and converted into ()OH radicals, which have strong oxidative properties. The results of this study showed that gamma irradiation was very effective for the removal of cefaclor in aqueous solution. The use of O(2) or N(2)O, with radiation, shows promise as effective radical scavengers for enhancing the TOC or COD removal efficiencies in pharmaceutical wastewaters containing antibiotics. However, the biological toxicity and interactions between various chemicals during the radiolytic treatment, as well as treatments under conditions more representative of real wastewater will require further studies.     

Temperature dependence of hydroxyl radical formation in the hv/Fe3+/H2O2 and Fe3+/H2O2 systems

The thermal enhancement of the formation of *OH by the hv/Fe(III)/H2O2 system (including the Fe(III)/H2O2 system) was quantitatively investigated with reaction temperatures ranging from 25 to 50 degrees C. A temperature dependent kinetic model for the hv/Fe(III)/H2O2 system, incorporating 12 major reactions with no fitted rate constants or activation energies, was developed, and successfully explained the experimental measurements. Particularly, the thermal enhancement of Fe(OH)2+ photolysis which is the most significant step in the hv/Fe(III)/H2O2 system was effectively explained by two factors; (1) the variation of the Fe(OH)2+ concentration with temperature, and (2) the temperature dependence of the quantum yield for Fe(OH)2+ photolysis (measured activation energy=11.4 kJ mol(-1)). Although in both the hv/Fe(III)/H2O2 and Fe(III)/H2O2 systems, elevated temperatures enhanced the formation of *OH, the thermal enhancement was much higher in the dark Fe(III)/H2O2 system than the hv/Fe(III)/H2O2 system. Furthermore, it was found that the relative thermal enhancement of the formation of *OH in the presence of *OH scavengers (tert-butyl alcohol) was magnified in the Fe(III)/H2O2 system but was not in the hv/Fe(III)/H2O2 system.     

Photochemistry in the mixed aqueous solution of nitrobenzene and nitrous acid as initiated by the 355 nm UV light

The 355 nm photon-initiated microscopic reaction mechanisms of the mixed aqueous solution of nitrobenzene and nitrous acid in the presence or absence of O(2) were studied by the laser flash photolysis technique. The main transient absorption peaks in the recorded spectra were assigned and the growth/decay trends of several transient species were investigated. It was found that the OH radical formed from the photolysis of nitrous acid triggered most of the subsequent radical reactions. The rate constant of the reaction between OH radical and nitrobenzene was measured to be (3.4 +/- 0.1) x 10(9) l mol(-1) s(-1). The product from this reaction, namely C(6)H(5)NO(2)-OH adduct, was found to react with O(2) to yield C(6)H(5)NO(2)-OHO(2) adduct with a rate constant of (1.6 +/- 0.2) x 10(9) l mol(-1) s(-1). Final steady-state products were identified by GC/MS analysis and were in accordance with the transient spectroscopic results. The possible reaction pathways were proposed.     

An expanded reaction kinetic model of the CuO surface-mediated formation of PCDD/F from pyrolysis of 2-chlorophenol

An expanded reaction kinetic model, including 17 surface reactions, is proposed to explain the yields of PCDD/F obtained in an experimental study of the reaction of 2-chlorophenol over a CuO/silica surface. The mechanism is loosely based on the gas-phase mechanism for PCDD/F formation widely discussed in the literature. The principal differences are the impact of chemisorption of 2-chlorophenols to metal oxides on radical formation and the steric hindrance of oxygen-centered radicals on the surface inhibiting radical-radical reaction pathways that lead to formation of dibenzo-p-dioxin (DD). Gas-phase molecule-surface-bound adsorbate reactions are the preferred route of DD formation, while radical-radical surface reactions are the main channel for dichloro-dibenzofuran (DCDF) formation. These results suggest that the Langmuir-Hinshelwood (LH) mechanism, involving radical-radical surface reactions, and the Eley-Rideal mechanism, involving a gas-phase molecule and surface-bound adsorbate, are responsible for PCDF and PCDD formation on surfaces, respectively. The calculated yields of DCDF and DD are in reasonable agreement with experimental results.     

一株产絮酵母菌废菌体对Cd2+的吸附特性

将一株产絮酵母菌(编号B-02号)发酵后的废菌体制成生物吸附剂,研究该生物吸附剂对废水中Cd2+的生物吸附特性。结果表明:(1)pH值对Cd2+会产生较大的影响,偏酸性(pH=4～6)条件利于吸附;该吸附剂对Cd2+吸附速率较快,8～10 min就可达到吸附平衡;(2)吸附剂的吸附动力学符合二级动力学模型,吸附Cd2+的实验数据对Langmuir等温式的拟合情况良好,吸附剂吸附Cd2+的最大吸附量为70.752 mg/g。用0.5 mol/L HNO3对吸附Cd2+的酵母菌进行解吸,解吸率可达89.7%。