废弃物中回收镉的国内外现状探析

在查阅国内外文献资料的基础上,对从废弃物中回收镉的国内外现状进行了分析和探讨,指出对镉进行回收利用有很重要的现实意义,既能有效降低生产成本,充分利用资源,又能保护环境。     

芳基胍的合成及表征

以取代芳香胺为原料与氰胺在酸性条件下反应得到16个未见报道的芳基胍化合物。考察了不同溶剂和反应时间对反应的影响,化合物结构均经IR,1H NMR和MS确证。     

电镀废水处理站DTCR辅助氢氧化物沉淀工艺改造

某废水处理站改造前采用传统氢氧化物沉淀工艺处理高浓度含铬、氰镉电镀废水,运行不稳定,出水不能达标排放。工艺改造后增加了高分子重金属捕集沉淀剂DTCR辅助去除重金属,在含铬废水DTCR投加量为50 mg/L、含氰镉废水DTCR投加量为10 mg/L条件下,出水总铬、镉分别稳定在0.5 mg/L、0.2 mg/L以下,远低于《电镀污染物排放标准》(GB 21900—2008)限值。     

Biosorptive removal of Pband Cd onto novel biosorbent: Defatted Carica papaya seeds

Carica papaya seeds, an agricultural waste in Nigeria, were defatted to obtain defatted C. papaya seed biosorbent. The Fourier Transformed Infrared spectrum of defatted C. papaya seed biosorbent suggests the presence of CO, OH of carboxylic acid, lactonic and amide band functional groups. The adsorption of metal ion onto defatted C. papaya seed biosorbent led to small shifts in the IR bands. The adsorption capacity of defatted C. papaya seed biosorbent was evaluated to be 1666.67 mg/g for Pb²⁺ and 1000.00 mg/g for Cd²⁺. In binary metal ion solution, the defatted C. papaya seeds showed decreased adsorption capacity for either metal ion. The influence of different particle sizes was found to have negative impact on the adsorption capacity of C. papaya seed biosorbent in the removal of Pb²⁺ and Cd²⁺ from aqueous solution. The adsorption of both metal ions was observed to follow the Freudlich model better than the Langmuir model suggesting that the adsorption of both metal ions was on multisites on the defatted C. papaya seed biosorbent. The adsorption was found to be highly feasible, spontaneous and exothermic in nature. Optimization results suggests 5 m³ of 100 mg/L of Pb²⁺ and Cd²⁺ requires 43.3 and 49.2 kg of defatted C. papaya seeds to remove 95% of the metal ions from aqueous solution.     

沉降炉生产高质量石灰氮时粘壁问题的探讨

本文介绍了沉降式氮化炉在生产高质量石灰氮时所出现的各种粘壁形式,分析了引起粘壁的各种工艺原因,并提出了相应的改进方法,减少了粘壁现象的发生。     

Homogeneously distributed CdS nanoparticles in the sulphonated poly(ether ether ketone) membrane: preparation,characterisation and visible-light photocatalytic properties

Abstract

In this work, we have developed an ion exchange reaction to fabricate homogeneously distributed CdS nanoparticles with a size in the range of 20–120 nm in the sulphonated poly(ether ether ketone) (SPEEK) membrane. The chemical composition of the composite membrane was characterised by ultraviolet-visible (UV-vis) spectroscopy, powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. The as prepared SPEEK/CdS composite membrane exhibited a remarkable photocatalytic activity towards the photodegradation of rhodamine B under visible light irradiation at room temperature. This work presents a simple and versatile approach to prepare sulphide nanostructures on the surface of polymer membrane, providing a new opportunity for their applications in the photocatalytic reaction.     

两步法合成双氰胺工艺

采用两步法由氰氨化钙合成双氰胺,通过正交试验,考察了水解温度、聚合温度、聚合时间对产品收率的影响,确定了最佳的工艺条件:水解温度42℃、聚合温度70℃、聚合时问150 min,此条件下,双氰胺收率可达85.73％。     

Electrical and optical properties of CdTe films prepared by vacuum evaporation with close spacing between source and substrate

CdTe films for solar cell application were prepared at various growth temperatures by a vacuum evaporation system having close spacing between the source and substrate. The CdTe thin films had a cubic structure highly oriented with the (1 1 1) direction perpendicular to the substrate surface, regardless of the growth temperature. The crystallites are of random shape and reach up to about 2 μm in size with increasing growth temperature. The higher growth temperature contributed to the reduction of dark resistivity from 6×10⁷ Ω cm at room temperature to 5.4×10⁶ Ω cm at 300°C. The photovoltaic properties of the CdS/CdTe solar cell were considerably improved with the increase in the growth temperature, which was caused by the increase of (1 1 1) texture and grain size in CdTe films.     

Characteristics of the CdZnS thin film doped by thermal diffusion of vacuum evaporated indium films

Effects of the thickness of indium films and the annealing temperature on structural, optical and electrical properties of chemically deposited cadmium zinc sulfide (CdZnS) films were investigated. X-ray diffraction patterns of CdZnS films indicate that the minimum thickness and annealing temperature for the formation of an In₂O₃ layer, which acts as a barrier preventing the out-diffusion of indium, are 20 nm and 350°C, respectively. In₂O₃ layers give the high optical transmittance due to their transparent properties. As the thickness of indium film and the annealing temperature increase, the conductivity of CdZnS films improves and the lowest resistivity of 0.3 Ω cm is attained for CdZnS films with 40 nm indium coating and annealed at 450°C.