CO_2气体对钢渣组成和性能的影响

热态钢渣降温过程中,对f-CaO有效消解同时实现钢渣渣性能的协同改善是热态钢渣处置的发展趋势。结合热力学分析与实验研究,利用CO_2、CO_2+水蒸气组合气、空气、空气+水蒸气等组合气体对钢渣进行处理,研究气体对物相组成、水化特性、安定性及胶凝性的影响。结果表明:在不同气氛下对钢渣处理后,通过钢渣化学组成、物相、微观结构分析,发现不同气氛对钢渣中f-CaO的消解能力由大到小排序分别是CO_2+水蒸气>空气+水蒸气>CO_2>空气,且CO_2+水蒸气组合气体通入后,钢渣粉的安定性能显著改善。钢渣复合胶凝材料的凝胶活性指数在3,7 d的强度略有降低,但在28 d对其强度影响不大,因此采用CO_2+水蒸气处理气氛通入热态钢渣,对改善钢渣的组成和性能综合效果最好,且热力学分析和实验结果具有良好的一致性。     

钢渣湿法捕获CO_2反应机制研究

以炼钢过程中排放的固体废弃物钢渣为碳捕获剂,进行了钢渣湿法捕获烟气CO2工艺的实验研究。通过分析钢渣的组成成份及反应机理,研究液固比、反应温度、反应时间、pH值及反应产物等主要参数对钢渣湿法碳捕获状况的影响。实验证明,通过合理的设计和适当的操作,可使钢渣湿法碳捕获效率达60%以上,具有一定的应用价值。     

钢渣改性研究进展

综述了中国钢渣的矿物组成和化学成分,指出了中国钢渣化学成分特点。分析了影响钢渣作胶凝材料的主要因素。分别对氧化气氛和还原气氛下针对钢渣改性的研究进行了综述,并提出了钢渣改性研究目前存在的主要问题。     

FeCl3改性钢渣脱除燃煤烟气中Hg0的研究

以钢铁厂废弃钢渣为原料,以丙酮溶液为分散剂制备FeCl₃改性材料,在固定床吸附评价装置上考察了钢渣在FeCl₃改性前后对模拟烟气中Hg脱除效果的影响,并结合吸附试验与微观表征对改性催化剂的脱汞性能进行分析.结果表明:氯是FeCl₃改性钢渣吸附剂的主要活性组分,FeCl₃的掺入使钢渣的比表面积由1.06 m2/g提高到1.32 m2/g,进而提高吸附剂的汞吸附容量,经FeCl₃改性后废弃钢渣对汞的脱除效率比未改性前提升了3.2倍.SO₂的存在降低了FeCl₃改性钢渣材料的脱汞性能,持续通入的SO₂与吸附剂接触占据了部分孔道和表面活性位点,使得对单质汞的吸附效率下降,200℃时含有SO₂时的FeCl₃改性钢渣吸附剂吸附量比未通入SO₂气体的改性材料降低了75.57%;在含有HCl气体的烟气体系中,FeCl₃改性钢渣材料对汞的脱除效率从3432.70 ng/g升至10341.10 ng/g,并且随着反应温度的升高零价汞向氧化态汞转化的效率增加.研究显示,SO₂的存在降低了FeCl₃改性钢渣吸附剂的脱汞性能,而HCl气体有效地促进了FeCl₃改性钢渣吸附剂对零价汞（Hg0）的脱除.      

钢渣改性研究进展及展望

我国钢渣产生量巨大,随着日益严格的环保要求,为使钢渣达到资源化利用的目的,钢渣改性成为需要迫切解决的工作。简述了我国钢铁行业产生的钢渣的组成特点、资源化利用存在的问题;重点综述了钢渣改性的研究进展。结合现存钢渣改性工艺的特点,指出热态钢渣碳酸化改性,不仅可以充分利用钢渣本身的巨大热能,实现钢厂内CO₂减排,还能够实现钢渣稳定性和胶凝性能的改善,是今后钢渣改性研究的重要方向。     

“双碳”目标下钢渣处理及资源化利用探讨

钢渣是炼钢过程排放的固体废弃物,具有年产量大、温度高、化学组成复杂、硬度高和安定性不良等特点。在"双碳"目标下,其处理和资源化利用再次受到关注。针对钢渣特点,对国内外钢渣处理利用情况进行综述,指出了现有处理工艺和资源化利用途径存在的问题,并对"双碳"目标下钢渣的资源化利用途径进行探讨,提出钢渣余热回收、熔融钢渣还原改性和CO₂捕获是未来钢渣处理方向和路径。     

钢渣粉末吸附去除废水中磷的研究

选用平均粒径为0.060mm的钢渣粉末作为除磷吸附剂,分析了其组成和结构,研究了溶液pH和温度对钢渣粉末吸附效果的影响,结合吸附动力学过程和吸附等温模型及钢渣粉末组成成分变化探讨其吸附除磷的机理。结果表明:钢渣粉末吸附除磷的动力学过程符合准二级动力学模型。Langmuir等温吸附模型能较好地模拟钢渣对磷的等温吸附过程,理论饱和吸附量为94.61mg/g。钢渣粉末对磷的吸附量远大于钢渣颗粒,且受pH和温度影响较大。随着溶液pH的增大,钢渣粉末对磷的吸附量逐渐减小,当pH=5时,钢渣粉末对磷的吸附量最大。温度升高,有利于钢渣粉末对磷的吸附。X射线荧光光谱(XRF)和傅里叶红外分析(FITR)结果表明,钢渣粉末中CaO、Fe2O3和SiO2在吸附除磷中均发挥了重要作用。     

探讨钢渣吸附二氧化碳的可行性

钢渣吸附CO2不仅能加速提高钢渣稳定性,而且能减缓CO2排放对环境造成的压力。钢渣的碳化率与粒度成反比,与渣CaO含量成正比。渣气反应的生成物CaCO3是限制反应率的关键因素。钢渣吸附CO2装置可以用于生产和生活现场。     

改性钢渣颗粒除藻的特性研究

以高温活化改性钢渣颗粒为研究对象,对其在机械搅拌条件下对水体中不同种属藻的去除效果和对藻类的光合作用活性的影响进行试验研究,并对其除藻机理进行了初步探讨.结果表明:改性钢渣颗粒对水体中各藻属均有很好的去除效果,对藻类的光合作用活性具有很好的胁迫抑制作用;改性钢渣颗粒在100 r/min的搅拌强度下,对藻类的去除主要以吸附为主,在400 r/min的搅拌强度下,对藻类的去除以吸附和机械损伤为主.     

改性钢渣对镉离子吸附特征的研究

对比不同的改性方法,研究改性钢渣对镉离子去除的效果,并对改性前后钢渣吸附性能进行比较。通过考察粒径、投加量、处理时间、镉溶液初始浓度等因素对吸附效果的影响,拟合吸附等温曲线。实验结果表明,高温活化改性钢渣效果最佳,当改性1.5 h,温度为800℃时镉离子去除率达到最高为94%。在室温条件下,在100 m L含镉溶液(镉离子初始浓度10 mg/L)中,投加1 g粒径为0.15~0.9mm的钢渣,振荡30 min后吸附达到最佳。高温改性钢渣对镉离子的吸附过程符合Freundlich方程,相关系数为0.998 4。     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.