改性柠檬渣的结构特征及其对Cu2+的吸附性能

为研究柠檬渣对污水中Cu2+的吸附性能,利用H₂SO₄与NaOH对柠檬渣进行改性制备吸附剂,并采用响应曲面法对制备工艺进行了优化. 测试了吸附剂的比表面积、孔容与孔径等性能,并利用红外光谱(IR)、紫外光谱(UV)、差热分析(TG-DTA)、X射线衍射(XRD)、电镜(SEM)和能谱(EDS)对吸附剂进行了表征. 通过响应面法优化后的最佳改性条件:H₂SO₄改性后的炭化温度为80 ℃,NaOH改性后的炭化温度为90 ℃,w(NaOH)∶w(H₂SO₄)为0.3.改性后的柠檬渣较原柠檬渣比表面积由88.3 m2/g增至392.2 m2/g,灰分率降低了90.7%,碘吸附值提高了近5倍,孔径分布主要是中孔;柠檬渣属于无定型结构,改性后的柠檬渣有CC生成,形成了芳香烃,表面形成了密集的孔;改性后柠檬渣主要由碳元素组成,从而能有效吸附Cu2+,对Cu2+的吸附率能达到85.3%. 由红外分析可知,改性后的柠檬渣吸附Cu2+后3 804 cm-1处的吸收峰消失,说明Cu2+取代了这个吸收峰所代表的官能团及部分O—H中的H+.      

从含铬铝泥中回收铝的新工艺

采用"打浆水洗除Cr(Ⅵ)—电渗析除Cr(Ⅵ)—碱浸提铝—碳酸化分解法精制Al_2O_3"的新工艺处理含铬铝泥(以下简称铝泥),并回收Al_2O_3。实验结果表明:铝泥在70℃下经3次打浆水洗后,w(Na_2CrO_4)(以干铝泥计)降至5.0%;采用电渗析除Cr(Ⅵ)工艺可有效去除铝泥中以结合态和结晶态形式存在的Na_2CrO_4,在55 V直流电压下电渗析6h后铝泥中的w(Na_2CrO_4)降至0.98%;在碱浸温度为100℃、碱浸时间为3 h、NaOH质量浓度为150 g/L的优化碱浸条件下,铝浸出率(以Al_2O_3计)高达90.0%;经3次碳酸化分解处理后,Al_2O_3产品的纯度达98.65%,满足GB/T 24487-2009《氧化铝》中的一级标准,Al_2O_3回收率为96.37%。     

曝气强化非离子表面活性剂洗涤法修复柴油污染土壤

采用异位修复法,利用非离子表面活性剂洗涤柴油污染土壤,并在洗涤过程中曝气强化。考察了洗涤效果的影响因素,并通过表面张力和接触角的测定探讨了洗涤机理。实验结果表明:曝气对污染土壤中柴油的洗脱有强化作用,可提高洗脱率10%~20%;3种非离子表面活性剂的洗脱效果优劣次序为聚氧乙烯月桂醚(Brij-35)曲拉通X-100(TX-100)吐温-80(Tw-80);在表面活性剂浓度为1倍临界胶束浓度、曝气量为7.5 L/min、洗涤时间为60 min、洗涤液pH为11.0的优化条件下,Brij-35对柴油的洗脱率达77.4%,污染土样的含油率从7.0%降至1.6%,接触角从24.12°降至6.65°,可基本恢复土壤的亲水性;洗涤液的表面张力随表面活性剂浓度的增加而降低,但不受洗涤液pH的影响。     

ClO_2溶液去除烟气中NO的效果及工程应用

采用实验室规模喷淋脱硝装置对ClO_2溶液去除NO的效果及影响因素进行探讨,通过脱硝产物的测定对ClO_2溶液去除NO的能力及机理进行分析;在此基础上考察ClO_2溶液对供热厂燃煤锅炉烟气的实际脱硝效果。实验结果表明:在液气比为20L/m~3、反应温度为20℃,反应pH为4.0、进气NO质量浓度为250 mg/m~3,ClO_2质量浓度为200 mg/L的条件下,NO去除率达97%以上;ClO_2溶液可将NO氧化吸收为NO_3~-,氧化后产生的NO_x也可被NaOH溶液吸收转化为NO_2~-和NO_3~-;在ClO_2质量浓度为200~500 mg/L,反应pH为5.5~7.0的条件下处理初始NO质量浓度为212~230 mg/m~3的燃煤锅炉烟气,NO去除率为85.7%~94.6%,NO_x去除率为80.4%~88.8%,出口NO_x质量浓度低于46 mg/m~3,远低于GB 13271—2014规定的排放限值。     

新型类Fenton催化剂表征及其降解染料废水的试验研究

钴基和铜基类Fenton催化剂是近年来的研究热点,对新型类Fenton催化剂进行SEM,EDS,XPS表征,得知催化剂中的金属元素主要为钴和铜。通过单因素分析法,研究影响该催化剂处理甲基橙模拟废水效果的因素。结果表明:该催化剂在pH为3~9的范围内均表现出较好的催化降解能力;当双氧水的添加量达到20 mL/L时,催化降解能力不再增加;催化剂的投加量影响催化降解能力达到最大的时间;此外,双氧水的投加方式影响降解所需的时间而对最终的处理效果影响不大。     

Experimental study of the evaporation of spreading liquid nitrogen

The investigation of cryogenic liquid pool spreading is an essential procedure to assess the hazard of cryogenic liquid usage. There is a wide range of models used to describe the spreading of a cryogenic liquid pool. Many of these models require the evaporation velocity, which has to be determined experimentally because the heat transfer process between the liquid pool and the surroundings is too complicated to be modeled. In this experimental study, to measure the evaporation velocity when the pool is spreading, liquid nitrogen was continuously released onto unconfined concrete ground. Almost all of the reported results are based on a non-spreading pool in which cryogenic liquid is instantaneously poured onto bounded ground for a very short period of time. For the precise measurement of pool spreading and evaporation weight with time, a cone-type funnel was designed to achieve a nearly constant liquid nitrogen release rate during discharge. Specifically, three nozzles with nominal flow rates of 3.4 × 10⁻² kg/s, 5.6 × 10⁻² kg/s and 9.0 × 10⁻² kg/s were used to investigate the effect of the release rate on the evaporation velocity. It is noted that information about the release rate is not necessary to measure the evaporation velocity in case of the non-spreading pool. A simultaneous measurement of the pool location using thermocouples and of the pool mass using a digital balance was carried out to measure the evaporation velocity and the pool radius. A greater release flow rate was found to result in a greater average evaporation velocity, and the evaporation velocity decreased with the spreading time and the pool radius.     

液气燃料烟气的最大余热量与节能率计算研究

在中国能源结构中,燃油与天然气所占比例迅速上升.燃烧后排烟温度一般为160℃~180℃,仍含有较多能量,可以二次利用.本文通过对液、气体燃料中具有代表性的0号轻质柴油及天然气烟气的余热量与节能率进行计算,发现低温烟气余热中的水蒸气余热量占有很大比例,柴油烟气为55.08%,天热气烟气为79.41%.回收烟气余热,尤其是其中水蒸汽的潜热对低温烟气的热回收具有重要意义.若有效回收利用,既是对一次能源的二次利用,更符合"十三五"期间国家节能减排的相关政策要求.     

铀胁迫对5种牧草种子萌发的影响

为进一步探究放射性重金属铀污染环境对植物种子萌芽及生长所产生的迫害,根据我国铀矿冶废水中铀的质量浓度(5 mg/L)选择不同质量浓度(0、1 mg/L、5 mg/L、10 mg/L、15 mg/L、20 mg/L)的铀溶液进行试验,用以胁迫5种1年生牧草(三叶草、苜蓿草、黑麦草、高丹草和苏丹草)种子,同时观察记录各自的萌发状况(发芽数和第7 d幼苗生长长度),计算其发芽率、发芽势、发芽指数(GI)、活力指数(VI)及耐性指数,并与对照组进行量化指标比较。最后比较各牧草种子所受到的危害并做出评价。结果表明:对于不同程度的铀污染,多数植物表现为低质量浓度促进其种子萌发,高质量浓度则严重抑制甚至致死。对于三叶草、苜蓿草和黑麦草种子,低质量浓度(1 mg/L)铀溶液促进种子的萌发,质量浓度升高则为抑制,其中黑麦草表现稍异常,质量浓度为5 mg/L时对种子萌发有促进作用,使最终发芽率较对照提升14%;对于高丹草,低质量浓度(5 mg/L)时促进种子萌发,而在质量浓度稍低于或超过5 mg/L时表现出明显的抑制现象,各指标低于对照13%左右;苏丹草则仅呈现抑制现象,铀质量浓度为5mg/L时抑制现象稍轻,最终发芽率较对照组仅降4%,小于或大于5mg/L时均受抑制,且质量浓度越高抑制现象越明显,最终发芽率最高仅28%。     

Living at the Edge: Local versus Positional Factors in the Long‐Term Population Dynamics of an Endangered Orchid

Abstract: Populations at the margin of geographic ranges of distribution have been considered more vulnerable than central ones, but recent reviews have caste doubt on this generalization. We examined the reproductive and demographic performance of a rare Euroasiatic orchid (Cypripedium calceolus) at its southwesterly range limit and compared our findings with those of previous studies of nine central populations at the center of the orchid's range. We sought to test the central‐marginal model and to evaluate factors involved in long‐term performance of forest Eurosiberian species with peripheral populations in southern European mountains. We characterized (structure, temporal fluctuations, herbivory, reproductive success, and recruitment at different habitats) four Pyrenean populations of C. calceolus of different sizes (5–3500 ramets) and monitored three of them for up to 13 years. Two quantitative stochastic models (count data and matrix models) were used to assess population trends and viability and the effect of herbivory. Contrary to expectations, and despite the negative effect of sporadic events of herbivory, the peripheral populations we studied (except the smallest one) performed similarly or better than populations occurring in central part of the species’ range in terms of reproductive success and population growth rates. Landscape changes over the last 50 years suggest that natural reforestation could be involved in the success of this plant at its southern limit. Forest expansion in the mountain regions of southern Europe may provide new opportunities for plants with geographic distributions centered mainly at higher latitudes and give some hope for their recovery in future scenarios dominated by biodiversity loss.     

Potential Misuse of Avian Density as a Conservation Metric

Abstract: Effective conservation metrics are needed to evaluate the success of management in a rapidly changing world. Reproductive rates and densities of breeding birds (as a surrogate for reproductive rate) have been used to indicate the quality of avian breeding habitat, but the underlying assumptions of these metrics rarely have been examined. When birds are attracted to breeding areas in part by the presence of conspecifics and when breeding in groups influences predation rates, the effectiveness of density and reproductive rate as indicators of habitat quality is reduced. It is beneficial to clearly distinguish between individual‐ and population‐level processes when evaluating habitat quality. We use the term reproductive rate to refer to both levels and further distinguish among levels by using the terms per capita fecundity (number of female offspring per female per year, individual level) and population growth rate (the product of density and per capita fecundity, population level). We predicted how density and reproductive rate interact over time under density‐independent and density‐dependent scenarios, assuming the ideal free distribution model of how birds settle in breeding habitats. We predicted population density of small populations would be correlated positively with both per capita fecundity and population growth rate due to the Allee effect. For populations in the density‐dependent growth phase, we predicted no relation between density and per capita fecundity (because individuals in all patches will equilibrate to the same success rate) and a positive relation between density and population growth rate. Several ecological theories collectively suggest that positive correlations between density and per capita fecundity would be difficult to detect. We constructed a decision tree to guide interpretation of positive, neutral, nonlinear, and negative relations between density and reproductive rates at individual and population levels.