模拟阳光下Ag／I-TiO2光催化预处理山核桃加工废水

研究了在模拟太阳光下,采用银修饰的碘掺杂二氧化钛光催化剂（Ag／I—TiO2）对某食品厂山核桃加工废水进行光催化预处理的效果。结合x射线衍射（XRD）、比表面积分析（BET）、紫外-可见漫反射光谱（uV—Vis）的表征结果,来分析催化剂结构对于废水处理效果的影响。探讨了Ag含量、废水初始pH（pHi）和光照时间等因素对化学需氧量（COD）去除及水质可生化性（B／C）提高的影响。并得出适宜的反应参数为：3％Ag含量;pHi为6;光照时间为240min。在最佳条件下,COD去除率45％,废水B／C比由0．17上升到0．31。光催化氧化法能够有效降低山核桃加工废水的COD含量,并达到显著提高废水可生化性的目的。     

CNTs/TiO2/CS光降解苯的动力学

综合光催化氧化苯的动力学过程、光辐射场模型和质量守恒定律,采用平板型反应器建立了碳纳米管/二氧化钛/壳聚糖(CNTs/TiO2/CS)催化薄膜光催化氧化气相苯的数学模型;该模型考虑了光强、相对湿度、初始浓度与气体流速对气相苯光降解的影响。结果表明,建立的数学模型与实验结果吻合较好。     

A/O+MBR工艺处理玉米深加工废水的中试研究

实验基于企业污水站的改造工程,研究了MBR对玉米深加工废水的处理效果并对工艺运行参数优化提出建议.结果表明,该工艺对COD的去除率可以达到90％以上,出水稳定在26 mg/L左右;出水NH4-N达到1 mg/L以下;TN去除率达到70％以上,出水TN达到10 mg/L以下,出水完全达到排放标准.通过4种工况的比较,说明在污泥浓度8 g/L左右,曝气池内DO在3 mg/L左右,MBR内DO＞4 mg/L,好氧段停留时间13.5 h,并保证3h以上的缺氧段水力停留段时间的条件下,A/O+ MBR工艺可以有效去除玉米深加工废水中的污染物.     

电吸附对水中盐类、氨氮、COD的去除效果分析

电吸附技术作为高效、环境友好型的除盐、除氨氮技术,可应用与水的深度处理领域内。为了使污水回用达到工业用水的水质标准,对电吸附去除水中盐类、氨氮、COD的效果进行分析,结果表明,电吸附设备处理不同氨氮浓度的废水,对中低浓度的氨氮去除效果稳定,当进水氨氮浓度低于20 mg/L时,处理后出水氨氮浓度低于5 mg/L,COD浓度小于25 mg/L,达到回用标准;随着进水盐浓度的增大电吸附处理效果逐渐变差,在电导率低于2 500 μS/cm时除盐率在75%左右,氨氮去除率达到70%左右,COD去除率达到60%左右。经电吸附处理后的低氨氮浓度废水,TDS、氨氮浓度均可达到工业回用水标准。     

循环式超声强化光催化降解双酚A

设计了一种循环式超声强化光催化反应器,以TiO2作为光催化剂,研究了超声功率、TiO2加入量、循环液流速和空气流量对双酚A(BPA)降解效果的影响。实验结果表明:超声与光催化过程在循环式超声强化光催化反应器中实现了较好的协同效应;在初始BPA质量浓度为20.0mg/L、超声功率为600W、TiO2加入量为7g/L、循环液流速为4.05×10-2m/s、空气流量为200mL/min的条件下,反应150min后,BPA降解率可达90.5%,溶液中剩余BPA质量浓度仅为1.8mg/L,反应240min后TOC去除率可达84.5%。     

改性SiO2气凝胶对废水中Fe3+的吸附性能

制备了改性SiO₂气凝胶,考察了经不同类型、不同配比的改性剂改性的SiO₂气凝胶对模拟含Fe³⁺废水的吸附处理效果。实验结果表明：改性SiO₂气凝胶的最佳制备条件为三甲基氯硅烷（TMCS）作改性剂,V（TMCS）#x02236;V（正己烷）=1#x02236;5;当改性SiO₂气凝胶加入量为75g/L、吸附时间为4h、Fe³⁺质量浓度为10mg/L时,模拟含Fe³⁺废水的Fe³⁺去除率为98.32%,剩余Fe³⁺质量浓度为0.168mg/L;采用改性SiO₂气凝胶动态吸附处理流量为420mL/h、Fe³⁺质量浓度为100mg/L的模拟含Fe³⁺废水,吸附后废水中剩余Fe³⁺质量浓度仅为0.196mg/L。     

An overview on the processes and technologies for recycling cathodic active materials from spent lithium-ion batteries

This paper aims to make an overview on the current status and new tendency for recycling cathodic active materials from spent lithium-ion batteries. Firstly, it introduces several kinds of pretreatment technologies, followed by the summary of all kinds of single recycling processes mainly focusing on organic acid leaching and synergistic extraction. Then, several examples of typical combined processes and industrial recycling processes are presented in detail. Meanwhile, the advantages, disadvantages and prospect of each single process, combined process, as well as industrial recycling processes, are discussed. Finally, based on a novel acidic organic solvent, the authors briefly introduce an environmental friendly process to directly recycle and resynthesize cathodic active material LiNi_1/3Co_1/3Mn_1/3O₂ from spent lithium-ion batteries. The preliminary experimental results demonstrated the advantages of low reaction temperature, high separation efficiency and organic solvent cycling and preventing secondary pollution to the environment. This process may be used for large-scale recycling of spent lithium-ion batteries after further study.     

Quantitative evaluation of environmental risks of flotation tailings from hydrothermal sulfidation–flotation process

Floatation tailings (FT) are the main by-products of the hydrothermal sulfidation–flotation process. FT (FT₁ and FT₂) were obtained by treating two different neutralization sludges (NS) (NS₁ and NS₂). This paper quantitatively evaluated the environmental risks of heavy metals (Zn, Cd, Cu, Pb, and As) in FT versus NS. The total concentration and leaching rates (R ₂) of heavy metals in FT were much lower than those in NS, demonstrating that the hydrothermal sulfidation–flotation process was able to effectively suppress the mobility and leachability of heavy metals. The BCR-three sequence leaching procedure of FT confirmed that all metals were transformed into more stable forms (residue and oxidizable forms) than were found that in NS. The potential ecological risk index indicated that the overall risks caused by heavy metals decreased significantly from 6627.59 and 7229.67 (very serious risk) in NS₁ and NS₂, respectively, to 80.26 and 76.27 (low risk) in FT₁ and FT₂, respectively. According to the risk assessment code, none of the heavy metals in FT posed significant risk to the natural environment except Zn (with low risk). In general, the risk of heavy metals in FT had been well controlled.     

Quantitative and qualitative characteristics of dissolved organic matter from eight dominant aquatic macrophytes in Lake Dianchi, China

The aim of this research was to determine and compare the quantitative and qualitative characteristics of dissolved organic matters (DOM) from eight aquatic macrophytes in a eutrophic lake. C, H, N, and P in ground dry leaves and C, N, and P in DOM of the species were determined, and C/N, C/P, C/H, DOC/C, TDN/N, TDP/P, DOC/TDN, and DOC/TDP were calculated. Chemical structures of the DOM were characterized by the use of multiple techniques including UV-visible, FT-IR, and ¹³C CP/MAS spectra. The results showed subtle differences in quantity and quality of DOM among species and life-forms. Except oriental pepper which had a C/H of 0.7, C/H of all the other species was 0.6. C/N and C/P of ground leaves was 10.5–17.3 and 79.4–225.3, respectively, which were greater in floating and submerged species than in the others. Parrot feather also had a small C/P (102.8). DOC/C, TDN/N, and TDP/P were 7.6–16.8, 5.5–22.6, and 22.9–45.6 %, respectively. Except C/N in emergent and riparian species, C/N in the other species and C/P in all the species were lower in their DOM than in the ground leaves. DOM of the macrophytes had a SUVA₂₅₄ value of 0.83–1.80. The FT-IR and ¹³C NMR spectra indicated that the DOM mainly contained polysaccharides and/or amino acids/proteins. Percent of carbohydrates in the DOM was 37.3–66.5 % and was highest in parrot feather (66.5 %) and crofton weed (61.5 %). DOM of water hyacinth, water lettuce, and sago pondweed may have the greatest content of proteins. Aromaticity of the DOM was from 6.9 % in water lettuce to 17.8 % in oriental pepper. DOM of the macrophytes was also different in polarity and percent of Ar–OH. Distinguished characteristics in quantity and quality of the macrophyte-derived DOM may induce unique environmental consequences in the lake systems.     

Spatial distribution of perfluoroalkyl acids in the Pearl River of Southern China

An intensive campaign was conducted in September 2012 to collect surface water samples along the tributaries of the Pearl River in southern China. Thirteen perfluoroalkyl acids (PFAAs), including perfluorocarboxylates (PFCAs, C4–C11) and perfluorosulfonates (PFSAs, C4, C6–C8, and C10), were determined using high-performance liquid chromatography/negative electrospray ionization–tandem mass spectrometry (HPLC/(-)ESI–MS/MS). The concentrations of total PFAAs (ΣPFAAs) ranged from 3.0 to 52 ng L⁻¹, with an average of 19 ± 12 ng L⁻¹. The highest concentrations of ΣPFAAs were detected in the surface water of the Dong Jiang tributary (17–52 ng L⁻¹), followed by the main stream (13–26 ng L⁻¹) and the Sha Wan stream (3.0–4.5 ng L⁻¹). Perfluorooctanoate (PFOA), perfluorobutane sulfonate (PFBS), and perfluorooctane sulfonate (PFOS) were the three most abundant PFAAs and on average accounted for 20%, 24%, and 19% of ΣPFAAs, respectively. PFBS was the most abundant PFAA in the Dong Jiang tributary, and PFOA was the highest PFAA in the samples from the main stream of the Pearl River. A correlation was found between PFBS and PFOA, which suggests that both of these PFAAs originate from common source(s) in the region. Nevertheless, the slope of PFBS/PFOA was different in the different tributaries sampled, which indicates a spatial difference in the source profiles of the PFAAs.