以废弃磷石膏为原料水热合成碳酸钙品须的研究

以废弃磷石膏为钙源水热合成碳酸钙晶须,研究了不同反应前驱物和添加剂对碳酸钙样品晶形的影响,利用奥林巴斯显微镜和扫描电镜（SEM）观察晶体形貌,并用X衍射（XRD）和红外光谱（FTIR）对样品进行了表征。实验结果表明,采用柠檬酸钠为添加剂,在反应时间12h,反应温度120℃,柠檬酸钠浓度2％的工艺条件下,可制得晶须长度约为50～120μm、长径比为40～100：1、大小相对均匀的文石型碳酸钙晶须。同时,实验还制得了形貌独特的稻草捆状和竹叶状碳酸钙晶体。     

以废渣磷石膏为原料水热法制备硫酸钙晶须

以磷石膏为原料,采用水热法制备硫酸钙晶须。借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)及红外光谱仪(FT-IR)等仪器对产物进行表征,研究了反应温度和时间、料浆初始固液比及不同添加剂等因素对产物形貌及可溶磷含量等的影响。结果表明,最佳反应条件为:反应温度140℃,反应时间2 h,料浆固液比为1∶10,最佳添加剂及剂量为丙三醇(V醇/V总液为50%)。所得产物为六方晶系的CaSO4.0.5H2O,直径1～3μm,晶须长径比为45左右,合成率约95%,产物可溶磷含量由原样的0.41%降至0.21%。     

晶种及晶型助长剂对磷石膏制备硫酸钙晶须的影响

实验以磷石膏为原料,硫酸钙为晶种,镁盐为晶型助长剂,采用水热法制备硫酸钙晶须。实验详细考察了晶种的用量,镁盐晶型助长剂种类及用量,晶种、晶型助长剂、结晶稳定剂三者的协同效应等对硫酸钙晶须形态的影响。用偏光显微镜和扫描电镜(SEM)及X射线衍射分析了硫酸钙晶须的形貌和相组成。结果表明在硫酸镁作为晶型助长剂,晶种∶晶型助长剂∶结晶稳定剂的用量为1∶3∶4时制备出的硫酸钙晶须产品优,其光滑,反应完全,长度最长可达150μm左右,直径细度可细达0.5μm。     

硫酸铅在柠檬酸钠-乙酸体系中的浸出转化

硫酸铅可以在柠檬酸钠-乙酸体系中脱硫转化生成柠檬酸铅.考察了柠檬酸钠投加量、反应时间、固液比以及反应温度对PbSO4浸出转化的影响.实验结果表明,PbSO4的转化率随着柠檬酸钠投加量和反应时间的增加而增大,固液比和反应温度对浸出过程影响不大.溶液中溶解的铅含量随着柠檬酸钠投加量的增大而增大,其他条件对其影响不明显.最佳浸出工艺条件是:柠檬酸钠与PbSO4的物质的量之比为2:1,固液比为1/5～ 1/3,反应温度为25℃,反应时间为2h,此时PbSO4的转化率可达到99％左右,溶液中的铅含量为总铅的3.8％左右.PbSO4浸出得到[Pb3(C6H5O7)2]·3H2O,它在350℃左右可完全分解,得到PbO/Pb粉末.     

不同Ca/P比下碳酸根对磷酸钙沉淀反应回收磷的影响

以模拟污水处理厂污泥厌氧消化液为处理对象,进行磷酸钙沉淀除磷小试实验,考察了不同Ca/P物质的量比下碳酸根(CO2-3)对磷酸钙沉淀反应回收磷的影响;利用扫描电镜(SEM)、X射线衍射仪(XRD)和傅里叶变换红外光谱(FTIR)对沉淀产物进行表征。结果表明,磷酸钙沉淀反应是一个快速过程,CO2-3的存在并未改变这一显著特征。磷酸钙沉淀反应过程中,CO2-3的存在降低了磷的去除率,改变了沉淀物形貌、结构和组分;实验设定范围内,磷酸钙的过饱和度越高,越难形成晶体态羟基磷灰石((Ca5(PO4)3OH,HAP);当pH值为9.0,Ca/P比为1.67时,CO2-3取代HAP晶格中的PO3-4,形成碳磷灰石(CHAP);当pH值为9.0,Ca/P比为3.33和5.01时,CO2-3和PO3-4之间竞争,形成碳酸钙(CaCO3);增大Ca/P能有效提高磷的去除率,降低CO2-3对磷酸钙沉淀反应的抑制作用,但综合考虑实际效果,选择Ca/P比为3.33作为适宜的反应条件。     

无机、有机添加剂对磷矿浆脱硫强化的影响

为了对磷矿浆湿法脱硫技术进行强化,研究了添加剂种类、添加剂的比例、SO2进口浓度对磷矿浆脱硫的影响。结果表明:在矿浆固液比为5%、反应温度为25℃、气体流量为0.3 L·min-1、添加剂比例为2%、O2含量为5%的实验条件下,处理SO2浓度为3 000 mg·m-3,反应120 min时,可得出最佳硝酸盐添加剂为硝酸铁、最佳金属氧化物添加剂为二氧化锰,最佳有机添加剂为己二酸,硝酸铁、二氧化锰、己二酸的最佳添加比例分别为4%、6%、2%。在以上3种添加剂的最佳添加比例条件下,选取不同浓度的SO2进行实验,反应120 min时,二氧化锰对磷矿浆的强化脱硫效果最好,硝酸铁对磷矿浆的强化脱硫效果次之,而己二酸对磷矿浆的强化脱硫效果最差,它的波动较大。     

甲酸刻蚀缺陷MOFs电芬顿高效降解磺胺甲恶唑

采用甲酸刻蚀MIL-88B(Fe)制备了一系列缺陷MOFs并用于催化降解水中磺胺甲恶唑(SMX)为代表的抗生素污染物,通过SEM、XPS、XRD分析手段对材料的形貌和结构进行了表征和分析,考察了pH、电流、SMX初始浓度等因素对SMX去除的影响,探究了SMX催化降解反应的动力学特性以及缺陷MOFs材料的可循环利用性和稳定性,探究了SMX催化降解反应的电流利用效率与能耗,通过自由基淬灭实验推测了SMX催化降解反应发生机理。结果证明,缺陷MOFs材料催化降解SMX性能优于未经刻蚀的MIL-88B(Fe),对于10 mg·L^-1 SMX,在电流为40 mA、电压为3.5 V、持续通氧气、搅拌的条件下,反应120 min后,5 mmol甲酸刻蚀制得的5A-MIL-88(Fe)对SMX的去除率可达98.72%。以5A-MIL-88(Fe)作为催化剂,协同电芬顿(Fenton)反应构建的处理体系为水中抗生素污染物高效去除提供参考。     

硫酸铅在柠檬酸钠-酸体系中的浸出转化

硫酸铅可以在柠檬酸钠-乙酸体系中脱硫转化生成柠檬酸铅。考察了柠檬酸钠投加量、反应时间、固液比以及反应温度对PbSO4浸出转化的影响。实验结果表明,PbSO4的转化率随着柠檬酸钠投加量和反应时间的增加而增大,固液比和反应温度对浸出过程影响不大。溶液中溶解的铅含量随着柠檬酸钠投加量的增大而增大,其他条件对其影响不明显。最佳浸出工艺条件是：柠檬酸钠与PbSO。的物质的量之比为2：1,固液比为1／5～1／3,反应温度为25℃,反应时间为2h,此时PbSO4的转化率可达到99％左右,溶液中的铅含量为总铅的3．8％左右。PbSO4浸出得到[Pb,（C。H,O,）,]·3H2O,它在350℃左右可完全分解,得到PbO／Pb粉末。     

钙基矿物固硫剂对不同煤种固硫效果的影响研究

对肥城煤(FC)、淮南煤(HN)和大同煤(DT)3种典型的高中低硫煤作了煤岩学分析,利用DTA、XRD、SEM、光学显微镜和粒度分析仪对钙基矿物添加剂及其固硫灰渣进行了矿物学研究.主要研究了温度、钙硫比、矿物添加剂等因素对煤种固硫率的影响.实验表明,相同的燃烧条件下,不同煤种对碳酸钙适应性有很大差异,淮南煤和肥城煤对碳酸钙的适应性明显好于大同煤,高硫煤更有利于950℃和1050℃下固硫;煤样自身固硫能力较差,碳酸钙固硫效果显著,当Ca/S=4,燃烧温度分别为1050、850和950℃时,肥城煤、大同煤和淮南煤固硫率分别达到最高值(89%、72%和89%);膨润土促进大同煤固硫,却降低了肥城煤和淮南煤固硫率;钙基矿物添加剂协同作用能更有效地提高低硫煤的固硫效果,在1050℃时,可将固硫率由51%提高到74%.     

糠醛生产废渣直接转化为复合肥:添加剂(Ⅱ)配方与蒸馏条件的研究

采用复合添加剂 (Ⅱ ) ,主要成分为 :重钙、磷酸、亚硫酸氢钠和碳酸钙等 ,以稻草 (或麦杆 )为原料 ,用硫酸酸化水解制取糠醛 ,硫酸浓度为 6 % (摩尔 % ) ,液固比为 1∶1～ 2∶1 (wt /wt) ,复合添加剂 (Ⅱ )与原料的比为 0 .0 5∶1 (wt/wt) ,出醛率 :稻草为 1 0 % ;麦杆 1 1 % ,废渣全部转化为中性复合肥。     

Chloroaromatic pollutants in mussels incubated in two finnish watercourses polluted by industry

Concentrations of different chlorinated compounds were measured in mussels incubated in two polluted watercourses, a river (the River Kymijoki) and a lake (Lake Vanaja) for four weeks in summer 1995. The sum concentrations of polychlorinated phenols (PCP) and biphenyls (PCB) were both about 1 μg/g lipid weight (lw) in Lake Vanaja mussels, while in the River Kymijoki mussels PCPs were non-detectable and PCBs were measured 120 ng/g lIw. The concentrations of toxic polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners ranged between <17 and 370 pg/g Iw in Lake Vanaja mussels and between <38 and 11,000 pg/g lw in the River Kymijoki mussels. Polychlorinated diphenyl ethers (PCDE) were detected in the mussels incubated in the River Kymijoki (0.4–1.1 ng/g Iw), but not in those incubated in Lake Vanaja. Polychlorinated phenoxyanisoles (PCPA) were measured 33 ng/g lw and polychlorinated phenoxyphenols (PCPP) 300 ng/g lw in the mussels incubated in the River Kymijoki. PCPAs were also detected in reference samples, which were sediment and pike from the River Kymijoki and Baltic salmon, seal and white-tailed sea eagle.     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

Book review

The Pesticide Manual ‐ A World Compendium, 8th Edition, C.R. Worthing, Editor and S.B. Walker, Assistant Editor, British Crop Protection Council, BCPC Publications Sales, Bear Farm, Binfield, Bracknell, Berkshire RG12 5QE, England. 1987, 1100 pp., UK £50; Overseas £56. ISBN 0–948404–01–9.     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.     

Organochlorine compounds in a three-step terrestrial food chain

The concentrations of 15 organochlorine chemicals (PCBs and pesticides) were studied in a Central European oak wood food chain system: Great tit (Parus major), caterpillars (Tortrix viridana, Operophtera brumata, Erannis defoliaria), and oak-leaves (Quercus robur). Juvenile tits receive organochlorines from the mother via egg transfer and, eventually to a greater extent, from the caterpillar food source during nestling period. The concentrations of PCB 153 (2,2′,4,4′,5,5′-hexachlorobiphenyl, the most abundant in this study) was found in leaf material at ca. 1 ng/g, in caterpillars 10 ng/g, and in bird eggs 170 ng/g on an average and on a dry mass basis.     

The chemical stability of formulations of some hydrolyzable insecticides in aqueous mixtures with hydrolysis catalysts

Abstract

The active ingredients in commercial formulations of malathion, oxamyl, carbaryl, diazinon, and chlorpyrifos diluted to “spray tank”; concentrations with buffered distilled or natural water of pH 4–9 were stable for at least 24 hr. Formulations of trichlorfon were not stable at pH 7 or above but disappearance rates were slower than for the pure chemical in homogeneous solution. Cupric ion was observed to be an effective catalyst for the hydrolysis of a variety of pure organophosphorus insecticides but did not catalyze hydrolysis of the active ingredients of the formulations examined. Increasing the dilution of the formulation increased the susceptibility of malathion, oxamyl, and carbaryl to hydrolysis.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

Teratological effects of pesticides in vertebrates: a review

Abstract

In the last decades, the use and misuse of pesticides in the agriculture have increased, having a severe impact on ecosystems and their fauna. Although the various effects of pesticides on biodiversity have been already documented in several studies, to our knowledge no consistent overview of the impact of pesticides in vertebrates, both terrestrial and aquatic, is available. In this review, we try to present a concise compilation of the teratogenic effects of pesticides on the different classes of vertebrates – mammals, birds, reptiles, amphibians and fish.     

Radionuclides in pinon pine (Pinus edulis) nuts from los alamos national laboratory lands and the dose from consumption

Abstract

One of the dominant tree species growing within and around the eastern portion of Los Alamos National Laboratory (LANL), Los Alamos, NM, lands is the pinon pine (Pinus edulis). Pinon pine is used for firewood, fence posts, and building materials and is a source of nuts for food—the seeds are consumed by a wide variety of animals and are also gathered by people in the area and eaten raw or roasted. This study investigated the (1) concentration of ³H, ¹³⁷Cs, ⁹⁰Sr, ^totU, ²³⁸Pu, ^{239, 240}Pu, and²⁴¹ Am in soils (0‐ to 12‐in. [31 cm] depth underneath the tree), pinon pine shoots (PPS), and pinon pine nuts (PPN) collected from LANL lands and regional background (BG) locations, (2) committed effective dose equivalent (CEDE) from the ingestion of nuts, and (3) soil to PPS to PPN concentration ratios (CRs). Most radionuclides, with the exception of ³H in soils, were not significantly higher (p < 0.10) in soils, PPS, and PPN collected from LANL as compared to BG locations, and concentrations of most radionuclides in PPN from LANL have decreased over time. The maximum net CEDE (the CEDE plus two sigma minus BG) at the most conservative ingestion rate (10 lb [4.5 kg]) was 0.0018 mrem (0.018 μSv); this is far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem (1000 μSv). Soil‐to‐nut CRs for most radionuclides were within the range of default values in the literature for common fruits and vegetables.     

Degradation and sorption of imidacloprid in dissimilar surface and subsurface soils

Degradation and sorption/desorption are important processes affecting the leaching of pesticides through soil. This research characterized the degradation and sorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine) in Drummer (silty clay loam) and Exeter (sandy loam) surface soils and their corresponding subsurface soils using sequential extraction methods over 400 days. By the end of the incubation, approximately 55% of imidacloprid applied at a rate of 1.0 mg kg^?1 degraded in the Exeter sandy loam surface and subsurface soils, compared to 40% of applied imidacloprid within 300 days in Drummer surface and subsurface soils. At the 0.1 mg kg^?1 application rate, dissipation was slower for all four soils. Water-extractable imidacloprid in Exeter surface soil decreased from 98% of applied at day 1 to > 70% of the imidacloprid remaining after 400 d, as compared to 55% in the Drummer surface soil at day 1 and 12% at day 400. These data suggest that imidacloprid was bioavailable to degrading soil microorganisms and sorption/desorption was not the limiting factor for biodegradation. In subsurface soils > 40% of ¹⁴C-benzoic acid was mineralized over 21 days, demonstrating an active microbial community. In contrast, cumulative ¹⁴CO₂ was less than 1.5% of applied ¹⁴C-imidacloprid in all soils over 400 d. Qualitative differences in the microbial communities appear to limit the degradation of imidacloprid in the subsurface soils.