Chemisorption and Physical Adsorption Roles in Cadmium Biosorption by Chlamydomonas Reinhardtii

Abstract

The aim of this study was to investigate the mechanism of cadmium (Cd) adsorbed by microalgae Chlamydomonas reinhardtii (C.reinhardtii). The kinetic and adsorption isotherm of the process could be well described by mathematical models. Chemical modification experiments and Fourier transform infrared spectra indicated that carboxyl and amine groups were the important functional groups for adsorption of Cd. The maximum contribution of physical adsorption in the overall adsorption process was evaluated as 5.5%. These results indicated that chemisorption was the dominating mechanism of Cd biosorption by C.reinhardtii.     

International trade,Chinese foreign direct investment and green innovation impact on consumption-based CO2 emissions: empirical estimation focusing on BRI countries

Environmental Science and Pollution Research - Recently, The literature has directed concern towards the consumption-based carbon emission (CCE), which is adjusted for trade. This study aims to...     

Klebsiella pneumoniae metabolites enhance Microcystis aeruginosa biomass flocculation

Microcystis aeruginosa is a common aquatic toxin-producing cyanobacterium. This study explores M. aeruginosa biomass recovery using bioflocculation. Bioflocculants produced by Klebsiella pneumoniae significantly enhanced aquatic M. aeruginosa flocculation efficiency. Under neutral and acidic conditions, flocculation efficiency reached 90%, whereas flocculation efficiency was 75% under alkaline conditions. M. aeruginosa flocculation was ion dependent, and Ca²⁺ was determined to be the most effective cationic inducer. Negatively charged proteoglycans were identified as the being the functional components in the flocculants. Optimal conditions for M. aeruginosa flocculation were determined using response surface methodology and are as follows: (1) K. pneumoniae bioflocculant dose, 13.3?mg/L; (2) flocculation time, 1.6 hours; and (3) pH?=?5 for flocculation of 10⁹ cells per litre. Bioflocculation using K. pneumoniae represents a promising method to control development of M. aeruginosa blooms. Further in-field investigations are necessary to fully assess its potential.     

Online single particle analysis of chemical composition and mixing state of crop straw burning particles: from laboratory study to field measurement

Fresh straw burning (SB) particles were generated in the laboratory by the combustion of rice straw and corn straw. The chemical composition and mixing state of the fresh SB particles were investigated by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS). Based on the mass spectral patterns, the SB particles were clustered into four major types: Salt, Organic Carbon (OC), Elemental Carbon (EC), and internally mixed particles of EC and OC (EC-OC). In addition, particles containing ash, polycyclic aromatic hydrocarbons, heavy metals or nicotine were also observed. Physical and chemical changes of the SB particles immediately after the emission were analyzed with highly time-resolved data. During the aging processes, the average particle size increased steadily. Freshly emitted organic compounds were gradually oxidized to more oxygenated compounds in the OC-containing particles. Meanwhile, an important displacement reaction (2KCl+ SO42−→ K₂SO₄ + 2Cl⁻) was observed. The marker ions for SB particles were optimized and applied to identify the SB particles in the ambient atmosphere. The fluctuation of the number fraction of ambient SB particles sorted by ATOFMS agrees well with that of water soluble K⁺ measured by an online ion chromatography, demonstrating that the optimized marker ions could be good tracers for SB particles in field measurements.     

五氯酚的臭氧催化氧化特性

通过五氯酚(PCP)的Fe2+/O3催化氧化实验研究了其臭氧催化氧化特性,结果表明,PCP在反应5 min后几乎可以完全分解,但是TOC在反应30 min后的去除率只有50%左右,说明PCP不能被彻底氧化分解.通过对Cl-浓度的分析可知,伴随着PCP的氧化分解,苯环上的Cl会逐渐从苯环上释放到溶液中,而紫外吸光度值随反应时间的变化说明了臭氧催化氧化可以使得PCP中的苯环打开,将含有不饱和键的有机物转变成饱和的有机物.GC-MS分析结果表明,PCP的臭氧催化氧化首先是苯环的脱氯过程,随着反应的进行,苯环被打开,形成酯、醛、酸、氯代烷等小分子物质,最后被分解成CO2和H2O.     

鲍鱼对2种多环芳烃的富集动力学研究

为探究多环芳烃(PAHs)在海洋生物体内富集过程,选择皱纹盘鲍(Haliotis discus hannai)作为受试生物,应用半静态双箱动力学模型,分别考察了3-甲基菲和9,10-甲基蒽2种多环芳烃在皱纹盘鲍体内的富集动力学过程,通过非线性拟合获得鲍鱼对2种多环芳烃的吸收速率常数(K_1)、释放速率常数(K_2)、生物富集因子(BCF),以及平衡状态下鲍鱼体内2种多环芳烃的含量(Cmax)、生物学半衰期(t_(1/2))等动力学参数。结果表明,鲍鱼对9,10-甲基蒽富集动力学参数K_1、K_2、BCF、Cmax、t_(1/2)的平均值分别为4.9437、0.406、13.59、790.03μg·L~(-1)、3.78 d。鲍鱼对3-甲基菲富集动力学参数K_1、K_2、BCF、Cmax、t_(1/2)的平均值分别为2.3023、0.367、5.97、354.37μg·L~(-1)、3.13 d。鲍鱼在不同浓度下对3-甲基菲和9,10-甲基蒽的生物富集过程均符合双箱动力学模型。     

硫铝酸盐水泥处理冶金固体废弃物的研究

利用硫铝酸盐水泥作为粘结剂,采用水硬化球团加工工艺,对冶金过程的二次资源进行了成球性能研究。研究结果表明:在70%硫酸渣、20%除尘灰和10%精矿粉原料条件下,添加6.5%的硫铝酸盐水泥和1.2%的复合粘结剂,能够获得粒度组成和强度均较理想的小球作为烧结料。该项成果的特点是带入原料的S iO2大量减少,水硬化球团养护期大幅度缩短,在重钢集团铁业公司取得了良好的生产效果。     

2种烷基多环芳烃对仿刺参CYP450和p53基因表达的影响研究

海洋环境中多环芳烃类(PAHs)主要来源于海洋溢油事故以及沿海石油化工企业的废水排放,国内外大量研究发现海洋中的多环芳烃对海洋生物造成了潜在的生态风险。为了揭示不同浓度多环芳烃类污染物对海参的生态毒理效应,将仿刺参(Apostichopus japonicus)分别暴露于不同浓度的2种烷基多环芳烃3-甲基菲(5、10、100μg·L~(-1))和2-甲基蒽(5、10、50μg·L~(-1))中,检测暴露3 d、7 d和14 d后,3-甲基菲和2-甲基蒽胁迫下仿刺参CYP450和p53基因的相对表达量。结果表明,3-甲基菲和2-甲基蒽胁迫下,仿刺参CYP450和p53基因的表达均对毒物产生了不同程度的响应。与对照组相比,3-甲基菲各处理组对仿刺参CYP450和p53基因的表达均产生显著的抑制作用(P0.05); 2-甲基蒽各处理组对仿刺参CYP450和p53基因的表达影响作用不同,暴露7 d后,2-甲基蒽各处理组对仿刺参CYP450基因的表达表现出抑制作用,对p53基因的表达表现出诱导作用。相同浓度与时间胁迫下,2-甲基蒽对仿刺参CYP450和p53基因表达的影响比3-甲基菲的影响大。上述研究结果表明,3-甲基菲和2-甲基蒽均可不同程度影响仿刺参CYP450和p53基因的表达,且与3-甲基菲相比,2-甲基蒽对仿刺参CYP450和p53基因表达的影响较明显。上述结果为多环芳烃类污染物对仿刺参的生物毒性评价提供了基础数据。     

氯化钡废液联产氢氧化钙和氯化钡

讨论了氯化钡废液联产氢氧化钙及高纯氯化钡的方法和主要影响因素。通过复盐共沉淀、热滤、结晶、精制纯化等工序,用氯化钡的蒸发残液制得了工业级的氢氧化钙和高纯度氯化钡,其纯度分别达95％和99．92％以上。采用有机溶剂析出法精制氯化钡,无需重结晶工序,是对传统工艺的一种改进。     

莱茵河化学污染事件及多边反应

莱茵河发源于瑞士境内的阿尔卑斯山,流经法国、德国等9个国家,最后于荷兰汇入北海.该河流域面积15万平方公里,人口约5000万,其中2000万人的饮用水取自菜茵河.