高铝粉煤灰蒸压制品强度的研究

利用X射线衍射、扫描电镜、红外光谱对高铝粉煤灰进行了分析,在不同蒸压制度下通过未反应CH量的测定、结合水量的测定、冷热盐酸中溶出量的变化以及XRD、SEM等方法对该粉煤灰的蒸压性能进行了研究。结果表明,该粉煤灰的主要矿物组成为刚玉、莫来石、赤铁矿和少量玻璃相,不含二氧化硅。在不同蒸压制度下,该粉煤灰石灰蒸压试样中水化产物主要为C-S-H(I)和水石榴石,水石榴石的量较多,蒸压试样的强度很低,其原因与粉煤灰中可参与反应的硅的量少有关。     

含锰废水的粉煤灰处理

为解决含锰工业废水对环境、土壤及生物带来的危害,研究采用热电厂废弃物粉煤灰作为吸附剂,希望能找到最佳吸附条件,同时为粉煤灰的综合利用提供更多机会;采用EDTA滴定法,对含锰废液进行了吸附研究,模拟测定了影响粉煤灰吸附特性的几种因素:重金属离子浓度、吸附时间、粉煤灰颗粒度以及待吸附液的pH等;结果表明:在其它条件相同的情况下,随着废液Mn2 浓度的增大,去除率逐渐降低;在吸附中60min为最佳震荡时间;随着粉煤灰粒度的减小,去除率增加;pH值应控制在中性偏碱性(pH值约为8.0最好)范围;可见,采用粉煤灰吸附含锰工业废水在适当工艺条件下可以有很好的处理效果,这种方法较简便,成本低廉,能达到以废治废的目的。     

粉煤灰处理含氟废水单因素实验研究

为处理含氟废水,本实验采用粉煤灰作为吸附材料,并进行了影响粉煤灰处理含氟废水的各种单因素条件下的实验.结果表明最佳处理条件是pH值为3,水灰比小于11:1,振荡时间为135min,氟浓度小于400mg/L.在此条件下对400mg/L的含氟废水可达到94%以上的去除率.粉煤灰对处置含氟废水是一个很好的吸附材料,但除氟后饱和灰的处置也应引起重视.     

采煤废弃物对作物生长的影响

通过室内栽培试验,研究了煤矸石和粉煤灰作为培养基对作物生长的影响。结果表明:(1)粉煤灰物理性质不适于作物生长,对作物长势影响最大,在粉煤灰排放场不覆土直接种植作物不可取;(2)煤矸石和粉煤灰会对作物产生重金属污染,尤其是细颗粒煤矸石的污染最大;(3)充填采煤废弃物复垦应该保证足够的覆土厚度。     

水工泄水建筑物高性能抗冲磨混凝土试验研究

针对水工泄水建筑物高性能混凝土高抗裂性和高抗冲磨性的要求,通过掺用具有梳型结构的聚羧酸减水剂实现水工泄水建筑物高性能混凝土,同时研究了聚丙烯纤维、粉煤灰和硅粉等因素对混凝土抗冲磨性能的影响。研究表明：聚羧酸减水剂掺量为1.0%,粉煤灰掺量为15%,硅粉掺量为10%,聚丙烯纤维掺量0.9 kg/m3时,混凝土的抗裂性和抗冲磨性能满足水工泄水建筑物高性能混凝土工程的使用要求。     

Foliar residue dynamics of azadirachtins following direct stem injection into white and green ash trees for control of emerald ash borer

BACKGROUND: Azadirachtins are natural insecticides derived from the neem tree. The emerald ash borer (EAB) is an exotic invasive insect pest that infests various ash tree species and has the potential for significant economic, aesthetic and ecological impacts throughout North America. The initial translocation and foliar residue dynamics of azadirachtins were examined following direct injection into white and green ash trees growing in urban scenarios as a potential control for EAB. RESULTS: Substantial concentrations of azadirachtins A and B [mean maxima > 0.98 mg kg^?1 fresh weight (f.w.)] were observed within 2 days of injecting a specifically designed formulation of azadirachtins. Foliar residues declined exponentially through time, with half‐life estimates ranging from 5.1 to 12.3 days. At the time of leaf senescence, foliar residue levels approximated 0.01 mg kg^?1 f.w., strongly mitigating the potential effects of non‐target biota in soil or aquatic compartments. CONCLUSION: The magnitude and duration of exposures observed in this field study were considered to be above the thresholds required for biological effectiveness against both larval and adult life stages of EAB. Results support the use of azadirachtins as an environmentally acceptable systemic insecticide for control of EAB and protection of high‐value ash trees in urban environments. Copyright © 2011 Society of Chemical Industry     

生物质气化站玉米芯飞灰的特性及其综合利用

作为玉米生产加工过程的农业废弃物,玉米芯的产量巨大,生物质气化工业利用玉米芯原料制备生物质燃气的过程中将产生大量的玉米芯灰。为了全面认识这些废弃玉米芯灰的灰特性及可能的应用,通过激光粒度分析、X射线荧光(X-ray fluorescence,XRF)、X射线衍射(X-ray diffraction,XRD)、热重和差热分析(thermal gravimetric and differential thermal analysis,TG-DTA)、扫描电镜(scanning electron microscopy,SEM)、能谱分析(energy dispersive X-ray,EDX)等方法对其进行深入研究。结果表明:玉米芯灰的粒度较小且分布不均,平均粒径为12.96μm;灰的元素组成中K和Si所占的比重最大;富含K、Ca、S和Cl等元素使玉米芯灰可用作土壤改良剂,而且灰中大量的Si O2和Al2O3使其可以用来制备抗压强度较高的水泥混凝土;灰中存在多种含钾元素的KHCO3、KAl Si O4、KAl Si2O6、KCl和K2SO4等结晶相矿物成分;灰粒的形状极不规则,树枝状的团聚灰渣具有丰富的空隙,易逐级吸附小颗粒,灰粒表面存在大量弱粘结的絮状物,断面多为孔状结构;熔融灰粒表面存在富钾现象,且多以KCl形式存在;飞灰的热解具有分段机制,加热到1 200℃时,其总失重和最大失重速率均随着氧气浓度的升高而增加;氮气中620℃的吸热峰是由KCl熔融吸热所致,而有氧气氛中在630℃处的放热峰则是未燃尽的残碳继续燃烧或有机物分解放热所致。     

Evaluation of fly ash,apatite and rice straw derived-biochar in varying combinations for in situ remediation of soils contaminated with multiple heavy metals

ABSTRACT

In

-situ sorbent amendment is a relatively low-cost, low-impact approach for remediation of soil contaminated with heavy metals (HMs), and thus is considered a way to be favored in developing countries. In this study, materials of non-hazardous, alkaline agronomic and industrial by-products were used as sorbents to explore their capacity of in situ immobilization of multiple HMs in mining-impacted arable soil. These sorbents included fly ash (FA), biochar (BC) and apatite (AP) and they were implemented with varying ratios of combinations. Results of soil microcosm tests showed that after incubation for 90 days, concentrations of Pb, Zn, and Cd in their exchangeable forms determined by a sequential extraction method significantly decreased in amended soils, as opposed to the unamended control. Of the five sets of amendments, the composite of FA, BC, and AP resulted in the maximum reduction (up to 80%) in the mobility of Pb, Zn, and Cd in soils. The mechanisms underlying the immobilization of HMs in amended soils might involve processes of surface precipitation, ion exchange and complexation, in which the physicochemical properties of sorbent materials played an important role. The immobilization efficacy of sorbent amendments on HMs in soil was further supported by pot experiments in which significant inhibition of HM accumulation in the belowground and aboveground tissues of maize was observed after 50-day cultivation in amended soils as compared with control soil. Together, these results suggest that the application of cost-saving and environmentally friendly materials derived from wastes as sorbents to remediate soils contaminated with multiple HMs is promising for developing countries like Vietnam.     

Mineralization and volatile loss of nitrogen from soils treated with coal combustion byproducts

There is an increasing need to find a suitable means for disposal of coal combustion byproducts because of the increasing world-wide production of these byproducts. This need has prompted interest in the use of land disposal, but there are concerns that this use may degrade the quality of soil. To determine the influence of coal combustion byproducts on the transformation and fate of soil N and assess the potential impact of land disposal on soil quality, we studied the effects of two combustion byproducts (fly ash and bed ash) applied at rates of 22.5, 45, 90, and 180 Mg ha^-1 on mineralization and volatile loss of N from soil. Studies comparing the influence of the byproducts on these processes showed that whereas fly ash had little influence on the fate of soil N, bed ash caused substantial mineralization of organic soil N and volatile loss of this N as NH₃. Studies monitoring the pH of soils treated with bed ash showed that soil pH increased immediately after this treatment, with values reaching as high as 12.8. These studies indicated that such extreme alkaline conditions caused chemical degradation and volatile loss of as much as 10% of the organic N in soil, and they provide strong evidence that the improper disposal of bed ash on land can have a substantial negative impact on soil quality.     

Dry farming with soils under natural tephra cover in Lanzarote, Spain

Abstract. The volcanic island of Lanzarote (Canary Islands, Spain) is one of the most arid parts of the European Union. During the eruptions of 1730–36, a third of the island was covered with lava and pyroclastic material. In areas under basaltic tephra, an agrosystem has been developed that allows a form of dry farming that has become a key component of the local economy. This article illustrates the effectiveness of the layer of natural tephra mulch in conserving soil and water.