Hydrothermal decomposition of brominated epoxy resin in waste printed circuit boards

Brominated flame retardant (BFR), which containing in printed circuit boards (WPCBs), brings a series of environmental and health problems. Hydrothermal technology was applied to decompose brominated epoxy resin in WPCBs at subcritical or supercritical water conditions. The brominated epoxy resin was decomposed into oil and the environmental influence of BFR was eliminated. The experiment was carried out in a 5.7 ml tube reactor and heated by a salt-bath. The variation of degradation rate of brominated epoxy resin with reaction temperature, time and additives were studied. The compositions of liquid products were analyzed by gas chromatography-mass spectrometry (GC-MS). When reaction temperature exceeded 300 °C, retention time stayed over 30 min and alkaline additive existed, more than 80% brominated epoxy resin could be mainly decomposed into phenol, which can be used as chemical material. Two different hydrothermal decomposition pathways were discussed according to the characterization of products. The results indicated that brominated epoxy resin in WPCBs could be handled effectively by hydrothermal decomposition.     

Voltammetric method for the determination of Zn, Cd, Pb, Cu and Ni in interstitial water

To determine heavy metals in interstitial water from Baltic sea sediments a sampling method with subsequent voltammetric determination is described. Copper, lead, zinc and cadmium are determined in the UV-digested samples of interstitial water by differential pulse anodic stripping voltammetry while nickel is determined by adsorption voltammetry. The determination of five metals in one sample in a wide concentrations range is possible using a low cost apparatus. The profiles of the metal concentrations in interstitial water of subsequent layers of sediments, sampled from Puck Bay, Gdask Bay, the Bornholm area and the Supsk area are presented.     

Voltammetric method for the determination of Zn,Cd, Pb,Cu and Ni in interstitial water

To determine heavy metals in interstitial water from Baltic sea sediments a sampling method with subsequent voltammetric determination is described. Copper, lead, zinc and cadmium are determined in the UV-digested samples of interstitial water by differential pulse anodic stripping voltammetry while nickel is determined by adsorption voltammetry. The determination of five metals in one sample in a wide concentrations range is possible using a low cost apparatus. The profiles of the metal concentrations in interstitial water of subsequent layers of sediments, sampled from Puck Bay, Gdańsk Bay, the Bornholm area and the S?upsk area are presented.     

Closed-vessel microwave digestion technique for lichens and leaves prior to determination of trace elements (Pb,Zn, Cu) and stable Pb isotope ratios

A reliable and robust procedure using closed-vessel microwave digestion of lichens and leaves for precise and accurate determination of trace elements (Pb, Zn and Cu) and stable Pb isotope ratios is presented. The method was developed using certified reference material CRM 482 Pseudovernia furfurea (Lichens), NIST 1515 (Apple Leaves) and NIST 1547 (Peach Leaves) and tested on lichens from a mining site in Russia. A mixture of 3?mL of HNO₃, 3?mL of H₂O₂, 2?mL of H₂O and 0.8?mL of HF ensured complete sample dissolution with 100?±?5% recovery for Pb, Zn and Cu at a maximum temperature of 210°C and pressure of 350?psi. The amount of HF and microwave pressure significantly influenced Pb, Zn and Cu recovery. Comparison between EMMA-XRF and ICP-AES showed a good correlation between Pb, Zn and Cu concentrations. Using the newly developed digestion method, Pb isotopes in lichens from the mining site were determined with an internal precision better than 0.02%.     

废弃印刷电路板材料裂解产物的高分辨裂解气相色谱-质谱分析

采用高分辨裂解气相色谱-质谱法(PyGC-MS)分析了FR-4型印刷电路板粉末样品的裂解产物。在氦气氛围中,分别在350,450,550,650和750 ℃下对印刷电路板粉末样品进行热裂解,并通过毛细管气相色谱-质谱对裂解产物进行分析,研究了不同裂解温度下裂解产物分布以及主要裂解产物的产率与裂解温度的关系,根据热分解产物的组成,探讨了热分解反应机理。     

Simultaneous determination of Cd,Cr, Cu,Ni, Pb and Zn in sewage sludge by slurry introduction ICP-OES method

In order to evaluate the slurry nebulisation method as an alternative method for analysis of sewage sludge, the metal content of sludge samples of different origins was determined. The concentrations of six elements: Cd, Cr, Cu, Ni, Pb, and Zn were determined by introducing the sludge as a slurry into an inductively coupled plasma optical emission spectrometer (ICP-OES). Calibration was performed by using aqueous standard solutions. For comparison, the sewage sludge was also digested by microwave digestion and introduced into the plasma as an aqueous solution. The accuracy of the method was checked by analysing a sewage sludge certified reference material (CRM 007-040 Sewage Sludge). The Student's t-test showed that values obtained using slurry nebulisation were close to the certified values at a 95% confidence level. The values of elements Cd 11.1?±?0.8; Cr 37.7?±?3.3; Cu 563.3?±?38.4; Pb 119.2?±?10.1; Zn 729?±?68.2?mg?kg^?1 obtained using this method were comparable with those obtained using the conventional method. The slurry method can, therefore, be successfully applied to the determination of content of each element in sewage sludge with RSD less than 3%, without the need to predissolve them. This could avoid the use of hazardous chemicals, incomplete dissolution and loss of volatile analytes.     

Decomposition of vegetables for determination of Zn,Cd, Pb and Cu by stripping voltammetry

A simple and accurate digestion method using nitric acid, perchloric acid and hydrogen peroxide has been developed for use in trace analysis for heavy metals in vegetables by differential pulse anodic stripping voltammetry. The recovery of the metals from the samples is lower if the hydrogen peroxide is omitted from the digestion mixture. Standard reference materials have been analysed satisfactorily by this method.     

Anodic stripping voltammetric determination of Zn, Pb and Cu traces in whisky samples

The simultaneous “in natura” determination of trace Zn, Pb and Cu in whisky samples by anodic stripping voltammetry (ASV), using a hanging mercury drop electrode, without previous treatment or addition of supporting electrolyte is described. The choice of an appropriate stripping voltammetric method and deposition potential minimizes the influence of the organic content and ensures a good reproducibility of the measurements. The reliability of the method was tested comparing the results with those of atomic absorption spectroscopy (AAS), with differences of about 10%. The method allows the determination of heavy metal ions in the μg L^–1 range. Received: 14 August 1997 / Revised: 10 December 1997 / Accepted: 11 December 1997     

废弃线路板化学分析采样、制样及检测方法

介绍废弃线路板中有回收价值元素和有害物质分析的采样、制样及检测技术。样品经过分类采样、剪切破碎和高温灰化制样,采用样品全分析或副批混合样分析。通过提高称样量、多次测定求平均值的办法,火试金富集-重量法测定贵金属金、银。湿法王水溶解样品,碘量法测定主体元素铜。电感耦合等离子体发射光谱(ICP-AES)法测定其它杂质元素,被测元素质量浓度在0~10μg/mL范围内与光谱强度呈良好线性关系,相关系数均大于0.9998。测定结果的相对标准偏差小于10%(n=5),加标回收率为97.0%~102.5%。该方法简单、快速,有效地解决了线路板样品不均匀而难采样,以及硬度、韧性强制样难,金属易包裹难分解的技术瓶颈,测定结果准确,具有代表性。该方法适用于废弃线路板化学成分分析,其它废弃电子产品检测可参考此方法。     

Determination of Cr,Fe, Co,Ni, Cu,Zn, As and Pb in liquid chemical waste by energy dispersive X-ray fluorescence

A method for simultaneous determination of Cr, Fe, Co, Ni, Cu, Zn, As e Pb in liquid chemical waste using Energy Dispersive X-Ray Fluorescence (EDXRF) technique was evaluated. A small sample amount (200 μL) was dried on a 6.35 μm thickness Mylar film at 60 °C and the analyses were carried out using an EDXRF spectrometer operated with an X-ray Mo tube (Zr filter) at 30 kV/20 mA. The acquisition time was 300 s and the Ga element was utilized as internal standard at 25 mg/L for quantitative analysis. The method trueness was assessed by spiking and the detection limit for those elements ranged from 0.39 to 1.7 mg/L. This method is notable because it assists the choice of the more appropriated waste treatment procedure, in which inter elemental interference is a matter of importance. In addition, this inexpensive method allows a non-destructive determination of the elements from ₁₉K to ₉₂U simultaneously.     

Current trends in direct transformation of waste printed circuit boards (WPCBs) into value-added materials and products

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Anodic stripping voltammetric determination of Zn, Pb and Cu traces in whisky samples

The simultaneous “in natura” determination of trace Zn, Pb and Cu in whisky samples by anodic stripping voltammetry (ASV), using a hanging mercury drop electrode, without previous treatment or addition of supporting electrolyte is described. The choice of an appropriate stripping voltammetric method and deposition potential minimizes the influence of the organic content and ensures a good reproducibility of the measurements. The reliability of the method was tested comparing the results with those of atomic absorption spectroscopy (AAS), with differences of about 10%. The method allows the determination of heavy metal ions in the μg L^–1 range.     

Road dust pollution of Cd, Cu, Ni, Pb and Zn along Islamabad Expressway, Pakistan

Islamabad Expressway is one of the busiest roads in the capital of Pakistan. For the assessment of heavy metal pollution level in dust generated on the Expressway, 13 samples of dust were collected from various places around the highway and four samples of soil were obtained from the undisturbed green land in Islamabad. The samples were analyzed for five heavy metals using FAAS (flame atomic absorption spectrometry). The average concentration values of the metals Cd, Cu, Ni, Pb and Zn were found to be 5 ± 1, 52 ± 18, 23 ± 6, 104 ± 29 and 116 ± 35 mg kg^{- 1} respectively, which were generally lower than the values cited in literature. The inter-elemental correlation of Cu and Pb indicated that they belonged to common anthropogenic sources. The pollution level was estimated based on the geoaccumulation index (I_geo), the pollution index (PI), and the integrated pollution index (IPI). The values of IPI were in the following order: Cu > Pb > Zn > Cd > Ni. All the indices for the metals under consideration were either low or corresponded to middle level of pollution. The pollution level is expected to increase due to rapid urbanization of the area. Some protective measures have therefore been proposed.     

熔融盐对印刷线路板热解影响实验研究

在固定床反应器中进行热解实验,考察不同热解终温、不同熔融盐添加量下印刷线路板热解过程中碳的气相转化率,并对热解液体和固体产物进行特性分析。结果表明,熔融盐的存在可以明显提高热解过程碳的气相转化率,减少液体产物产率。在未添加熔融盐的条件下,热解终温900℃时,碳的气相转化率为35.94%,液体产物产率为28.29%。添加 (71%Na2CO3-29%K2CO3) 熔融盐后,热解终温700℃时,碳的气相转化率为40.76%,液体产物产率为22.34%。添加 (8.3%Na2CO3-91.7%NaOH) 熔融盐后,碳的气相转化率达到59.36%,液体产物产率减少为6.88%。元素分析结果表明,熔融盐的存在可以减少固体残渣中的含碳量,而液体产物的H/C原子比为1.12～1.20。     

Comparative study of raw and HNO3-modified porous carbon from waste printed circuit boards for sulfadiazine adsorption: Experiment and DFT study

A huge amount of waste printed circuit boards (WPCBs) was produced while the electronic manufacturing industry developed rapidly. WPCBs mainly consist of organic compounds, which makes it possible to prepare them into porous carbon as valuable adsorbent. However, WPCBs are also rich in valuable metals. Cu makes up the most of these metals. It is worth studying whether the residual metal will affect the application of carbon materials. In this study, the porous active carbon (AC) was prepared from WPCBs as an adsorbent. Sulfadiazine (SD), a widely detected antibiotic contaminant, was used as a target pollutant. Nitric acid (HNO₃) was used to modify AC (AC-HNO₃) to remove the residual Cu. The experiment results showed that the adsorption kinetics of SD by AC (k = 0.0025) and AC-HNO₃ (k = 0.0029) can be described better using a pseudo-second-order kinetic equation. The adsorption isotherms of AC and AC-HNO₃ on SD could be fitted by the Langmuir model. AC had a larger adsorption capacity than AC-HNO₃. Density functional theory (DFT) calculation results suggested that the −OH group and Cu on the surface of AC could be the adsorption sites and promote the SD adsorption. This work provides practical methods to recycle WPCBs into wealth and realized waste control by waste.     

ICP-AES法测定环境水样中的微量镉铬铜镍铅锌

应用ＩＣＰ－ＡＥＳ法对环境水样中Ｃｄ、Ｃｒ、Ｃｕ、Ｎｉ、Ｐｂ、Ｚｎ等６种微量元素进行直接测定。考察了环境水样中钙、镁离子对的影响。通过对国标样品及实际样品的测定,加标回收实验,建立了简便、快速、准确、稳定、重现性较好的ＩＣＰ－ＡＥＳ法测定环境水样中６种微量元素的分析方法。     

Extraction-flame atomic absorption determination of microtraces of Ag, Bi, Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn in ammonium sulphate

Summary A method was developed for the determination of 10 trace elements in ammonium sulphate, or sulphuric acid, respectively. The detection limits for the separate elements vary from 1×10^–5 to 5×10^–7%. The method includes a new approach for calibration in organic medium, consisting of conversion of the aqueous metal standards into chelate compounds in a homogeneous solution.A three-step optimization scheme for pulse aspiration of organic extracts is proposed which permits to obtain a highly reproducible and accurate signal. The solutions of the organic reagents used are subjected to a purification procedure, which lowers their impurity level for approx. one order of magnitude.

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Extraktions-flammenatomabsorptiometrische Bestimmung von Mikrospuren Ag, Bi, Cd, Co, Cu, Fe, Mn, Ni, Pb und Zn in Ammoniumsulfat

Zusammenfassung Ein Verfahren wurde entwickelt zur Bestimmung dieser 10 Elemente in Ammoniumsulfat bzw. Schwefelsäure. Die Nachweisgrenzen der Elemente liegen zwischen 1 · 10^–5 und 5 · 10^–7%. Das Verfahren beinhaltet auch eine neue Methode zur Eichung in organischem Medium, die auf Umwandlung der wässrigen Metallstandardlösungen in Chelatverbindungen in homogener Lösung beruht. Eine dreistufige Optimierung des pulsierenden Ansaugens der organischen Extrakte wird vorgeschlagen, wodurch genaue und reproduzierbare Signale erhalten werden. Die Lösungen der organischen Reagentien werden einem Reinigungsverfahren unterzogen, das die Konzentration an Verunreinigungen um etwa eine Größenordnung senkt.

     

Determination of mobile form contents of Zn, Cd, Pb and Cu in soil extracts by combined stripping voltammetry

The amount of mobile forms of Zn, Pb, Cd and Cu in extracts obtained by treating soil samples with ammonium nitrate were determined by an appropriate combination of anodic and cathodic stripping voltammetry with hanging mercury drop electrode. Every analysis required three mercury drops: on the first one, zinc was determined; on the second, cadmium and lead; on the third, copper was determined. Zinc, lead and cadmium were determined by conventional differential-pulse anodic stripping voltammetry. For copper determination, adsorptive differential-pulse cathodic stripping voltammetry with amalgamation using chloride ions as a complexing agent was applied. The standard deviation of the results was from 1 to 10% depending on the metal content in the sample. Voltammetric results were in good agreement with the AAS analysis. No microwave digestion of soil extracts was necessary.     

Simultaneous determination of suspended particulate trace metals (Co, Ni, Cu, Zn, Cd and Pb) in seawater with small volume filtration assisted by microwave digestion and flow injection inductively coupled plasma mass spectrometer

A new technique for the determination of suspended particulate trace metals (P-metals >0.2 μm), such as Co, Ni, Cu, Zn, Cd and Pb, in open ocean seawater has been developed by using microwave digestion coupled with flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS). Suspended particulate matter (SPM) was collected from 500 mL of seawater on a Nuclepore filter (0.2 μm) using a closed filtration system. Both the SPM and filter were completely dissolved by microwave digestion. Reagents for the digestion were evaporated using a clean evaporation system, and the metals were redissolved in 0.8 M HNO₃. The solution was diluted with buffer solution to give pH 5.0 and the metals were determined by FI-ICP-MS using a chelating adsorbent of 8-hydroxyquinoline immobilized on fluorinated metal alkoxide glass (MAF-8HQ). The procedure blanks with a filter were found to be 0.048 ± 0.008, 10.3 ± 0.3, 0.27 ± 0.05, 3.3 ± 1.8, 0.02 ± 0.03 and 0.85 ± 0.09 ng L⁻¹ for Co, Ni, Cu, Zn, Cd and Pb, respectively (n = 14). Detection limits defined as 3 times the standard deviation of the blanks were 0.023, 0.90, 0.14, 5.3, 0.078 and 0.28 ng L⁻¹ for Co, Ni, Cu, Zn, Cd and Pb, respectively. Accuracy was evaluated using certified reference materials of chlorella (NES CRM No. 3) and marine sediment (HISS-1). The method was applied to the determination of vertical distributions for P-Co, Ni, Cu, Zn, Cd and Pb in the Western North Pacific.     

Co-precipitative pre-concentration with sodium diethyldithiocarbamate and ICP-AES determination of Se, Cu, Pb, Zn, Fe, Co, Ni, Mn, Cr and Cd in water

Sodium diethyldithiocarbamate in the presence of a weak oxidizing agent is used as a co-precipitative agent for the pre-concentration of Se, Cu, Pb, Zn, Fe, Co, Ni, Mn, Cr and Cd. A procedure was developed for ICP-AES determination of these elements after pre-concentration in river and waste water (an enrichment factor of 40). The recovery of all the elements tested for was more than 98%. The limits of determination (mg l⁻¹) (10 S.D. blank) are 0.001 (Cu, Co, Cr, Mn), 0.0007 (Zn, Cd), 0.003 (Se), 0.004 (Fe), 0.007 (Ni), and 0.01 (Pb).