7种改性硅藻土对Cd2+、Pb2+、Cu2+的吸附性能对比

首次系统地研究了硅藻土经热活化、锰氧化物、Mg(OH)2改性、聚丙烯酰胺、氨丙基三乙氧基硅烷、微乳液和Cu2等7种方法改性后,在不同pH下对Cd2+、pb2+、Cu2+的吸附效果及其主要机理.在实验条件下,重金属吸附效果最佳的是锰氧化物和Mg(OH)2改性硅藻土.对于pb2+、Cu2+和Cd2+的吸附,前者的最大吸附量分别为98、84和78 mg/g,后者是79、76和91 mg/g.SEM、BET、XRD、FTIR结果显示,这2种改性硅藻土的比表面积大大增加,且拥有更多能提高其吸附性能的Si-O-H基团.Mg(OH)2改性硅藻土对Cd2+吸附等温线研究表明,其符合Langmuir等温吸附模型.提供的改性方法和实验结果,为硅藻土处理水体重金属污染提供了新的技术手段和理论依据.     

Real-time measurements of landfill atmospheric ammonia using mobile white cell differential optical absorption spectroscopy system and engineering applications

ABSTRACT

The real-time measurement of atmospheric ammonia at municipal solid waste (MSW) landfills and adjacent areas is necessary for landfill management and the health of nearby residence. Continuous, fast, and real-time monitoring of landfill odor gases is a challenge, especially for ammonia. To our knowledge, this was the first study for the characteristics and seasonal variabilities of atmospheric ammonia at a whole landfill using a Mobile White cell Differential Optical Absorption Spectroscopy (MW-DOAS) system, which also simultaneously offers high sensitivity and fast response. Results show that atmospheric ammonia levels at various landfill areas were significantly dependent on the characteristics of areas, such as municipal solid waste-related areas, leachate-related areas, sludge-related areas, and fly ash-related area, the atmospheric ammonia peak or average level at the active leachate pool of the active MSW site was the highest among all areas of the whole landfill, and the ammonia concentrations at the closed MSW landfill sites were low and dependent on the ages. Moreover, it was found that the seasonal variabilities of ammonia concentrations at most of those areas were significantly dependent on the ambient temperature, and ambient temperature variation caused the atmospheric ammonia level at the active leachate pool and active MSW landfill site in the summer survey to raise 3.5 times and 5.58 times than in the winter survey, respectively.

Implications: Continuous, fast, and real-time monitoring ambient ammonia at or nearby a landfill is critical for landfill operators and local EPAs. This study demonstrates that the mobile White cell Differential Optical Absorption Spectroscopy (MW-DOAS) system is an effective tool for real-time monitoring ambient ammonia of a whole landfill. The results in this article provided a guideline to the characteristics and seasonal changes of ambient ammonia at various types of areas of a whole landfill as well as the impact of age to ambient ammonia at the closed landfill areas.     

Effect of first-stage aeration on treatment of domestic sewage in different hybrid constructed wetlands

Environmental Science and Pollution Research - Two sets of hybrid constructed wetlands (HCWs) with the first-stage aeration were used to treat actual domestic sewage in this paper, where the...     

Enhanced adsorption of tetracycline using modified second pyrolysis oil-based drill cutting ash

Environmental Science and Pollution Research - In this work, second pyrolysis oil-based drill cutting ash (OBDCA-sp) was modified using NaOH and cetyltrimethylammonium bromide (CTAB), respectively....     

How geographic diversification affects corporate social responsibility? The moderating effects of ownership and environmental regulation

Environmental Science and Pollution Research - As a popular strategy for firms to spread risk and reduce cost, geographic diversification might lead to more pressure from multidimensional...     

马尾松松针对磺胺二甲基嘧啶的吸附特性

以马尾松松针为吸附剂,研究其对水中磺胺二甲基嘧啶的吸附特性。考察了磺胺二甲基嘧啶的初始浓度为10 mg·L-1、温度为25 ℃时松针吸附剂饱和吸附量及饱和吸附时间,分析了温度、pH值对其吸附能力的影响,研究了吸附过程的动力学和热力学特点,并进行了相应的分析和计算。实验结果表明,在实验条件下,松针对磺胺二甲基嘧啶的吸附在 35 min达到饱和,其饱和吸附量为 0.229 mg·g-1。经准一级动力学方程拟合出的 qe为 0.24 mg·g-1与实验所得值0.229 mg·g-1接近,且相关系数R2=0.998 1,说明准一级动力学模型能较好地描述松针对磺胺二甲基嘧啶的吸附行为,且满足Langmuir 等温吸附模型。分析表明,松针对磺胺二甲基嘧啶的吸附行为为单分子层的自发吸附,且以物理吸附为主。     

不同粒径垃圾焚烧底渣对固化市政污泥工程特性的影响

在有膜标准养护和自然养护7 d和28 d的情况下,测定了固化体的含水率、有机质含量、抗剪强度、无侧限抗压强度及增容比等工程指标。研究结果表明,固化体含水率随垃圾焚烧底渣颗粒增大而增大;有机质含量则与颗粒大小没有明显相关性;粘聚力随垃圾焚烧底渣颗粒粒径增大而减小;内摩擦角随垃圾焚烧底渣颗粒粒径增大而增大;无侧限抗压强度随垃圾焚烧底渣粒径增大而增大;实验配比为100:20:20情况下的增容比均小于1.08。底渣中2 mm以上大颗粒对固化起到了更加积极的作用。垃圾焚烧底渣作为骨料,增强工程特性、减小固化剂用量、降低成本。研究成果拓展了污泥处理处置途径。     

三元复合吸附剂Ce-Zr-Zn对水中低浓度磷的吸附性能及其机理

为缓解水体富营养化问题,通过沉淀法合成了新型的三元复合吸附剂Ce-Zr-Zn,且将其用于除磷研究。结合XRD、SEM、BET、XPS和FT-IR表征分析,研究了其对水中低浓度磷的吸附性能及可能的吸附机理。结果表明：Ce-Zr-Zn具有优异的除磷特性,磷的去除率可高达96%,出水磷浓度低于0.045 mg·L⁻¹;其对磷酸盐的最大吸附容量为66.61 mg·g⁻¹,磷酸盐吸附过程符合拟二级动力学模型和Freundlich模型。此外,吸附剂具有较宽的pH适用范围(3~9)和良好的磷酸盐选择性。机理分析结果表明,配位体交换和静电吸附是该吸附剂除磷的主要原因。以上结果可为该材料用于水体深度除磷提供参考。     

EDTAD-modified cassava stalks loaded with Fe3O4: highly efficient removal of Pb2+ and Zn2+ from aqueous solution

Environmental Science and Pollution Research - In this study, a novel magnetic cassava stalk composite (M-EMCS) was prepared through modification with ethylenediamine tetraacetic anhydride (EDTAD)...     

优化复合调理促进含油污泥自持燃烧

对石化企业污水厂的含油剩余活性污泥进行超声-臭氧-生物质复合调理,破坏其稳定的胶体体系,降低泥饼的含水率,并对含油污泥复合调理的pH、温度、真空压力、超声波频率等影响因素进行优化;结果表明,在温度为35℃,pH值为3.0~5.0,超声波频率为33.2 kHz时,经生物质复合调理后,保持0.06 MPa真空压力抽滤10 min,滤饼的含水率可降到58.58%,满足污泥自持燃烧的要求;同时,从污泥絮体结 构、能量变化角度分析了不同温度和pH、超声波频率对含油污泥的作用机制;发现在偏酸性条件下,可减小污泥表面亲和力,促进污泥絮体凝聚;添加生物质在降低污泥含水率的同时也会降低污泥强度和可塑性;超声波对污泥除高能量作用外还具有空化作用,优化协调各因素对污泥絮凝沉降乃至自持燃烧作用均显著。