氯化铁溶液赤泥控碱作用及效果

针对赤泥碱性调控过程中存在的碱性强、控碱成本高等难题,以赤泥回收精铁矿生产的FeCl_(3)溶液为控碱药剂,对赤泥进行控碱及陈化处置。结果表明:FeCl_(3)溶液会使赤泥中可溶性钠碱含量显著降低,水化石榴石、方钠石等结合碱出现不同程度的溶解、转化,置换出的Na^(+)、Ca^(2+)等离子以石盐、Ca Cl2等矿相的形式在控碱赤泥表层结晶析出;Fe^(3+)的吸附、聚集作用使得控碱赤泥表层孔径降低、比表面积显著增加、表面更为致密,致使药剂在赤泥控碱前期下渗缓慢,控碱效果受限;FeCl_(3)溶液可以通过中和、沉淀作用显著降低赤泥碱分,控碱反应至30 d时整体控碱赤泥pH稳定在8.50左右,且随着陈化时间的延长其碱性并无显著反弹,反应、陈化历程可依次分为快速反应、迁移转化、溶解反弹、平衡构建4个阶段。

FeCl_(3)赤泥控碱及离子效应研究

为开展赤泥土壤化处置研究,采用FeCl_(3)进行赤泥控碱。研究表明,FeCl;对赤泥具有一定的控碱效果,但赤泥p H值的变化滞后于碱性阴离子质量比的变化。FeCl_(3)赤泥控碱符合二级动力学过程,主要通过Fe^(3+)与OH^(-)、CO_(3)^(2-)进行化学反应而带动其他次一级化学反应共同实现,与Fe^(3+)同体系内的碱性阴离子OH^(-)、CO_(3)^(2-)、HCO_(3)^(2-)和AlO_(2)^(-1)反应平衡有关,并通过陈化时间的增加促使赤泥盐分向化学结合碱转化。投加3 g/kg FeCl_(3)赤泥控碱,陈化120 d时,游离碱、CO_(3)^(2-)、AlO_(2)^(-1)和OH^(-)去除率均在50%及以上,且对OH^(-)的去除效果较好,达到60%;电导率仅增大0.16 m S/cm,盐分以Na Cl为主,矿相总量增加12.9%,形成较大的难溶性颗粒,从而实现赤泥控碱。

赤泥氯化锰控碱及其盐效应

采用氯化锰进行控碱的赤泥土壤化处置试验,结果表明:氯化锰对赤泥具有一定的控碱效果,氯化锰投加量越大,控碱效果越好,但赤泥pH值的变化滞后于碱性阴离子含量的变化;氯化锰赤泥控碱作用与Mn^(2+)同体系内的碱性阴离子OH^(-)、CO_(3)^(2-)、HCO^(-)_(3)、AlO^(-)_(2)反应平衡有关,通过Mn^(2+)与CO_(3)^(2-)、OH^(-)化学反应而带动其他次一级化学反应共同进行,陈化时间延长实现赤泥盐分向化学结合碱转化。6 g/kg MnCl_(2)·4H_(2)O赤泥控碱并陈化120 d,游离碱、CO_(3)^(2-)、HCO^(-)_(3)去除率均在50%左右,电导率仅增大0.17 mS/cm,盐分以NaCl为主,矿相总量增加10%,形成了较大的难溶性颗粒,从而实现赤泥控碱。

几种控盐碱措施对晋北盐碱地的改良效果研究

以晋北盐碱地为对象,采用“改土材料+垫层+覆盖”的技术措施组合,进行了控盐控碱试验。结果表明,浓度为0.25 kg/m^(3),0.5 kg/m^(3)的黑矾作为改土材料时,对土壤pH值及电导率的降低效果明显;对晋北重度盐碱地改良效果较好的技术组合为黑矾0.25 kg/m^(3)+石块垫层+砂子覆盖。

Enhanced dealkalization of bauxite residue through calcium-activated desulfurization gypsum

A novel integrated approach to remove the free alkalis and stabilize solid-phase alkalinity by controlling the release of Ca from desulfurization gypsum was developed.The combination of recycled FeCl_(3)solution and EDTA activated desulfurization gypsum lowered the bauxite residue pH to 7.20.Moreover,it also improved the residual Ca state,with its contribution to the total exchangeable cations increased(68%-92%).Notably,the slow release of exchangeable Ca introduced through modified desulfurization gypsum induced a phase transition of the alkaline minerals.This treatment stabilized the dealkalization effect of bauxite residue via reducing its overall acid neutralization capacity in abating pH rebound.Hence,this approach can provide guidance for effectively utilizing desulfurization gypsum to achieve stable regulation of alkalinity in bauxite residue.

Effect of integration of mechanical ball milling and flue gas desulfurization gypsum on dealkalization of bauxite residue

The synergistic impact of mechanical ball milling and flue gas desulfurization(FGD)gypsum on the dealkalization of bauxite residue was investigated through integrated analyses of solution chemistry,mineralogy,and microtopography.The results showed a significant decrease in Na_(2)O content(>30 wt.%)of FGD gypsum-treated bauxite residue after 30 min of mechanical ball milling.Mechanical ball milling resulted in differentiation of the elemental distribution,modification of the minerals in crystalline structure,and promotion in the dissolution of alkaline minerals,thus enhancing the acid neutralization capacity of bauxite residue.5 wt.%FGD gypsum combined with 30 min mechanical ball milling was optimal for the dealkalization of bauxite residue.

Camptothecin and 10-Hydroxycamptothecin Accumulate Differentially Under Specific Developmental Control in Camptotheca acuminata

Camptotheca acuminata Decaisne is a tree unique to China, producing terpenoid indole alkaloid (TIA), camptothecin (CPT), and 10-hydroxycamptothecin (HCPT), which possesses strong anti-cancer bioactivity. The dynamics of HCPT and CPT during seed maturation, seed germination, postgerminative development and daily growth were measured by High Performance Liquid Chromatography (HPLC). This article provides some evidence for presenting the theory that each characteristic of HCPT and CPT accumulation is under developmental regulation and then attempt to elucidate the metabolic relationships between them. HCPT accumulates particularly in young tissues and organs and is relatively unstable, while the distribution of CPT is more ubiquitous and stable. Their different distribution properties suggest that HCPT and CPT are differentially regulated and play distinct roles:during development.

Variation of alkaline characteristics in bauxite residue under phosphogypsum amendment

Aiming at alkaline problem of bauxite residue,this work focused variation of alkaline characteristics in bauxite residue through phosphogypsum treatment.The results demonstrated that the pH of bauxite residue reduced from initial 10.83 to 8.70 when 1.50 wt%phosphogypsum was added for 91 d.The removal rates of free alkali and exchangeable sodium were 97.94%and 75.87%,respectively.Meanwhile,significant positive correlations(P<0.05)existed between pH and free alkali,exchangeable sodium.The effect of free alkali composition was CO3^2–>OH^–>AlO2^–>HCO3^–.In addition,alkaline phase decreased from 52.81%to 48.58%and gypsum stably presented in bauxite residue which continuously provided Ca^2+to inhibit dissolution of combined alkali.Furthermore,phosphogypsum promoted formation of macroaggregate structure,increased Ca^2+,decreased Na+and Al^3+on the surface of bauxite residue significantly,ultimately promoting soil formation in bauxite residue.

Effect of ammonium chloride on leaching behavior of alkaline anion and sodium ion in bauxite residue

This study focused on leaching behavior of alkaline anion and sodium in bauxite residue through ammonium chloride treatment.The results showed that the pH of bauxite residue decreased from 10.49 to 8.93,total alkaline anion(HCO3^-,CO3^2-,OH^-,AlO2^-)concentration reduced from 38.89 to 25.50 mmol/L,leaching rate of soluble sodium was 80.86%with ammonium chloride addition of 0.75%,liquid/solid(L/S)ratio of 3(mL/g),temperature of 30°C and reaction time of 18 h;L/S ratio was the main factor affecting the removal of alkaline anion and the leaching of sodium.Furthermore,ammonium chloride promoted the dissolution of diaspore and changed the micro/morphological characteristics with the increase of massive structure.The findings of this work will contribute to achieve soil-formation of bauxite residue.

Industrial wastes applications for alkalinity regulation in bauxite residue: A comprehensive review

Bauxite residue is a highly alkaline material generated from the production of alumina in which bauxite is dissolved in caustic soda.Approximately 4.4 billion tons of bauxite residues are either stockpiled or landfilled,creating environmental risks either from the generation of dust or migration of filtrates.High alkalinity is the critical factor restricting complete utilization of bauxite residues,whilst the application of alkaline regulation agents is costly and difficult to apply widely.For now,current industrial wastes,such as waste acid,ammonia nitrogen wastewater,waste gypsum and biomass,have become major problems restricting the development of the social economy.Regulation of bauxite residues alkalinity by industrial waste was proposed to achieve‘waste control by waste’with good economic and ecological benefits.This review will focus on the origin and transformation of alkalinity in bauxite residues using typical industrial waste.It will propose key research directions with an emphasis on alkaline regulation by industrial waste,whilst also providing a scientific reference point for their potential use as amendments to enhance soil formation and establish vegetation on bauxite residue disposal areas(BRDAs)following large-scale disposal.

Isolation of an acid producing Bacillus sp. EEEL02: Potential for bauxite residue neutralization

Bauxite residue deposit area(BRDA)is a typical abandoned mining wasteland representing extreme hostile environment with increased alkalinity.Microbially-driven neutralization of bauxite residue,based on the microbial acid producing metabolisms,is a novel strategy for achieving rapid pH neutralization and thus improving its environmental outcomes.The hypothesis was that these extreme conditions promote microbial communities which are capable of novel ecologically relevant functions.Several alkaliphilic acid producing bacteria were isolated in this study.One strain was selected for its superior growth pattern and acid metabolism(termed EEEL02).Based on the phylogenetic analysis,this strain was identified as Bacillus thuringiensis.The optimized fermentation conditions were as follows:pH 10;NaCl concentration 5%;temperature 25℃;EEEL02 preferred glucose and peptone as carbon and nitrogen sources,respectively.Based on optimal fermentation conditions,EEEL02 induced a significant pH reduction from 10.26 to 5.62 in 5-day incubation test.Acetic acid,propionic acid and CO2(g)were the major acid metabolites of fermentation,suggesting that the pH reduction in bauxite residue may be caused by acid neutralization derived from microbial metabolism.This finding provided the basis of a novel strategy for achieving rapid pH neutralization of bauxite residue.

Colonization of Penicillium oxalicum enhanced neutralization effects of microbial decomposition of organic matter in bauxite residue

Bauxite residue is a highly alkaline waste product from refining bauxite ore.Bioremediation driven by microbial activities has been evidently effective in lowering the alkalinity of bauxite residues,which is critical to the initiation of pedogenesis under engineered conditions.The present study investigated the changes of alkalinity and aggregation of bauxite residue at different depth in response to the colonization of Penicillium oxalicum in columns.The results demonstrated that the inoculation of P.oxalicum decreased the residue’s pH to about 7 after 30 d only at the surface layer,which was exposed to aerobic conditions.The formation of aggregates was improved overall in the organic matter treated bauxite residue.However,the EC of bauxite residue increased with time under the incubation condition,probably due to accelerated hydrolysis of sodium-rich minerals.The inoculation of P.oxalicum had no effects on urease activity,but increased cellulose enzyme activity at surface layer only.

Self-supporting NiFe LDH-MoS_(x) integrated electrode for highly efficient water splitting at the industrial electrolysis conditions

Developing effective and practical electrocatalyst under industrial electrolysis conditions is critical for renewable hydrogen production.Herein,we report the self-supporting NiFe LDH-MoS_(x) integrated electrode for water oxidation under normal alkaline test condition(1 M KOH at 25℃)and simulated industrial electrolysis conditions(5 M KOH at 65℃).Such optimized electrode exhibits excellent oxygen evolution reaction(OER)performance with overpotential of 195 and 290 mV at current density of 100 and 400 mA·cm^(-2) under normal alkaline test condition.Notably,only over-potential of 156 and 201 mV were required to achieve the current density of 100 and 400mA·cm^(-2) under simulated industrial electrolysis conditions.No significant degradations were observed after long-term durability tests for both conditions.When using in two-electrode system,the operational voltages of 1.44 and 1.72 V were required to achieve a current density of 10 and 100 mA·cm^(-2) for the overall water splitting test(NiFe LDH-MoS_(x)/INF||20%Pt/C).Additionally,the operational voltage of employing NiFe LDH-MoS_(x)/INF as both cathode and anode merely require 1.52 V at 50mA·cm^(-2) at simulated industrial electrolysis conditions.Notably,a membrane electrode assembly(MEA)for anion exchange membrane water electrolysis(AEMWEs)using NiFe LDH-MoS_(x)/INF as an anode catalyst exhibited an energy conversion efficiency of 71.8%at current density of 400 mA·cm^(-2)in 1 M KOH at 60℃.Further experimental results reveal that sulfurized substrate not only improved the conductivity of NiFe LDH,but also regulated its electronic configurations and atomic composition,leading to the excellent activity.The easy-obtained and cost-effective integrated electrodes are expected to meet the large-scale application of industrial water electrolysis.

Transcriptional down regulation of hTERT and senescence induction in HepG2 cells by chelidonine

AIM： To investigate the potential effects of chelidonine, the main alkaloid of Chelidonium majus, on telomerase activity and its regulation in HepG2 cells. METHODS： Cytotoxicity of chelidonine for HepG2 cells was determined by neutral red assay. A modified polymerase chain reaction （PCR）-based telomerase repeat amplification protocol was used to estimate relative telomerase activity in chelidonine-treated cells in comparison with the untreated control cells. Relative expression level of the catalytic subunit of telomerase （hTERT） gene and P-glycoprotein （pgp） were estimated using semi-quantitative real-time reverse transcription-PCR （RT-PCR）. Cell senescence in treated cells was demonstrated using a 13-galactosidase test. RESULTS： Cytotoxicity of chelidonine in HepG2 cells was not dose-dependent and tended to reach plateau immediately after the living cells were reduced in number to slightly higher than 50%. However, 12 μmol/L concentration of chelidonine was considered as LD50, where the maximal attainable effects were realized. Real-time RT-PCR data showed that the expression of pgp increased three-fold in chelidonine treated HepG2 cells in comparison with the untreated controls. MoP phologically, treated HepG2 cells showed apoptotic features after 24 h and a small fraction of cells appeared with single blister cell death. The relative expression level of Bcl-2 dropped to less than 50% of control cells at a sub-apoptotic concentration of chelidonine and subsequently increased to higher than 120% at LD50. Telomerase activity was reduced considerably after administration of very low doses of chelidonine, whereas higher concentrations of chelidonine did not remarkably enhance the effect. Real-time RT-PCR experiments indicated a drastic decrease in expression level of hTERT subunit of telomerase under treatment with chelidonine. Repeated treatment of cells with very low doses of chelidonine caused a decline in growth rate by 4 wk and many of the cells appeared to be aged with large volume and dark staining in the β-galactosidase assay. CONCLUSION： Chelidonine reduces telomerase activity through down-regulation of hTERT expression. Senescence induction might not be directly caused by reducing telomerase activity as it occurs after a few population doublings.

Potential control flotation of galena in strong alkaline media

The electrochemical oxidation of galena in collectorless and collector flotation systems, particularly in strong alkaline media, was studied. The results show that, with pH value higher than 12.5 and potentials below 0.17 V, the oxidation products of galena are elemental sulfur and HPbO - 2. Elemental sulfur was present on the mineral surface in excess of oxidized lead species due to dissolution of HPbO - 2, which is beneficial to the flotation of galena. Under the same conditions, sphalerite and pyrite were depressed as a result of significant surface oxidation. Diethyldithiocarbamate (DDTC) was found to be the most suitable collector for galena flotation in strongly alkaline media. The very potential produced hydrophobic PbD 2-the surface reaction product of DDTC with galena, is 0 to 0.2 V. Meantime DDTC can depress the surface over oxidation of galena. Investigations also indicate that, in the range of -0.9 V to 0.6 V, hydrophobic PbD 2 can be firmly adsorbed on galena.

Improvement of alkaline electrochemical characteristics of bauxite residue amendment with organic acid and gypsum

Neutralization of alkaline properties of bauxite residue(BR)by using organic acid and gypsum additions may effectively improve electrochemical properties and alleviate physicochemical barriers to ecological rehabilitation.Mineral acids,citric acid and hybrid acid–gypsum additions were compared for their potential to transform and improve zeta potential,isoelectric point(IEP),surface protonation and active alkaline-OH groups,which are critical factors for further improvement of physicochemical and biological properties later.Isoelectric points of untransformed bauxite residue and six transformed derivatives were determined by using electroacoustic methods.Electrochemical characteristics were significantly improved by the amendments used,resulting in reduced IEP and-OH groups and decreased surface protonation for transformed residues.XRD results revealed that the primary alkaline minerals of cancrinite,calcite and grossular were transformed by the treatments.The treatments of citric acid and gypsum promoted the dissolution of cancrinite.From the SEM examination,citric acid and gypsum treatments contributed to the reduction in IEP and redistribution of-OH groups on particle surfaces.The collective evidence suggested that citric acid and gypsum amendments may be used firstly to rapidly amend bauxite residues for alleviating the caustic conditions prior to the consideration of soil formation in bauxite residue.

Antimalarial Activity of an Alkaloid Mixture Isolated from the Tender Leaves of the Nectandra membranacea （Laureaceae）

Despite the breadth of knowledge about malaria, its transmission, preventive measures and available treatments and its difficulty in controlling the vector and the rapid spread of resistance to current drugs, there is a stimulus to develop new research looking for active molecules. The phytochemical studies of the active extract confirmed the presence of alkaloids, flavonoids, coumarins, tannins, reducing compounds, anthocyanins, terpenes, triterpenes and steroids. In the present work, it was possible to isolate a mixture of isoquinolinic alkaloids from the tender leaves of Nectandra membranacea （Laureaceae） with antimalarial activity. The mixture composed of （-） - gliazovine and （＋） - aplogliazovine showed an IC50 value of 32.18 μg/mL against the P. berghei NK65 strain. It is important to continue with these studies and their chemical components isolated from N. membranacea that could be used as an alternative the treatment of malaria.

Analysis of Synonymous Codon Usage Bias in 09H1N1

A novel subtype of influenza A virus 09H1N1 has rapidly spread across the world. Evolutionary analyses of this virus have revealed that 09H1N1 is a triple reassortant of segments from swine, avian and human influenza viruses. In this study, we investigated factors shaping the codon usage bias of 09H1N1 and carried out cluster analysis of 60 strains of influenza A virus from different subtypes based on their codon usage bias. We discovered that more preferentially used codons of 09H1N1 are A-ended or U-ended, and the intra-genomic codon usage bias of 09H1N1 is quite low. Base composition constraint, dinucleotide biases and translational selection are the main factors influencing the codon usage bias of 09H1N1. At the genome level, we find that the codon usage bias of 09H1N1 is similar to H1N1 (A/swine/Kansas/77778/2007H1N1), H9N2 from Asia, H1N2 from Asia and North America and H3N2 from North America. Our results provide insight for understanding the processes governing evolution, regulation of gene expression, and revealing the evolution of 09H1N1.

Effect of Alkali-NaOH Solution on the Nature of Synthesized Zeolite from 2：1 Tunisian Clays： XRD and MAS-NMR Investigation

This work focuses the effect of alkali-NaOH solution on the nature of synthesized zeolite from 2：1 Tunisian clays. This study was achieved using correlation between results obtained from X-ray diffraction （XRD） and MAS-NMR analysis. Preliminary treatment was adopted to prepare the starting sample that is placed in contact with NaOH solution at variable concentration. A specific hydrothermal reactor, allowing the control ofpH 〉 9, temperature and a continuous stirring of the sample in the NaOH solution; was used to achieve these syntheses. The obtained results showed that, for concentration value ~IN, the final complex presented characteristic XRD and MAS-NMR line of zeolite P. For 3N solution concentration we obtained zeolite HS. All synthesize process are controlled by XRD and MAS-NMR investigation.

谈盐碱土壤环境下的园林树木栽植技术

在盐碱地土壤环境下进行园林绿化工程的建造,关键是要解决"盐胁迫"对园林植物正常的生长发育所产生的危害问题。一般园林植物最适宜的土壤pH范围为5.5～7.5(7.6以上便会产生程度不同的不良影响),土壤pH超过8.0,就会对绝大多数的园林植物产生"盐胁迫"作用。本文主要研究了在盐碱土壤环境下的园林绿化技术。通过选择抗盐碱树种、土壤改良、排盐控碱、种植技术、养护技术等多项措施,保证园林绿化工程的顺利进行。