Flocculation performance and mechanism of hydroxamate flocculants on synthetic hematite or goethite suspension

Suitable amounts of Al(OH)3, Na OH and synthetic hematite or goethite were taken to be digested under the simulated condition of the Bayer process and subsequently diluted with simulative Bayer red mud lotion, then the synthetic hematite or goethite suspension was obtained. The flocculation effect of self-made modified poly(acrylic acids) flocculants containing hydroxamic acid groups(abbreviated as HPAA) on the synthetic hematite or goethite suspension was studied. The experimental results show that with the increase of the dosages of added flocculants, the average settling rate of the synthetic hematite or goethite suspension in the first 1min speeds up, the supernatant solids decrease. It could also be found that there is generally a decrease in the average settling rate of the synthetic hematite or goethite suspension in the first 1 min with increasing solid content of the suspension. When the solid content of hematite or goethite of the suspension is 50 g/L with 240 g/t dosage of HPAA, HPAA has a better flocculation effect on the synthetic goethite suspension than on the synthetic hematite suspension. The adsorption mechanism of HPAA on the surface of hematite or goethite was investigated by Fourier transform infrared spectroscopy(FT-IR) and X-ray photoelectron spectroscopy(XPS).All the results suggest that HPAA is adsorbed on the hematite or goethite surface by a chemisorption, and it has a stronger adsorption on the goethite surface than on the hematite surface.     

Adsorption of sodium oleate at the microfine hematite/aqueous solution interface and its consequences for flotation

The adsorption of sodium oleate(NaOL) at the microfine hematite/aqueous solution interface was investigated in this paper. Experimental research indicated that negative effects stemmed from the dissolution of the microfine hematite(D50=19.21 μm) could be effectively eliminated via the appropriate dosage of NaOL at alkali pH conditions. Solution chemistry calculation and adsorption test results indicated that RCOO^- and(RCOO)₂^2- ions were responsible for microfine ...     

重金属Cu(Ⅱ)在球黏土中的吸附特性

通过批式吸附试验,考察球黏土对Cu(Ⅱ)的吸附效果,重点分析吸附时间、吸附剂用量、pH值以及初始质量浓度的影响。结果表明,Cu(Ⅱ)在球黏土上的吸附是一个先快速而后缓慢的过程,在60 min基本达到吸附平衡,且吸附量和吸附率随球黏土用量和Cu(Ⅱ)初始质量浓度的升高而提高。pH值对球黏土的吸附量有较大的影响,当pH值为6时,球黏土的吸附量可达97.93 mg/g。球黏土对Cu(Ⅱ)的吸附符合Langmiur等温吸附模型,拟合得到的最大吸附量为202.383 mg/g,准二阶动力学模型更适合描述球黏土对Cu(Ⅱ)的吸附过程,说明控制吸附速率的主要是化学吸附。与其他常见的黏土吸附剂材料相比,球黏土对Cu(Ⅱ)具有良好的吸附性能,可以作为天然矿物吸附剂来处理含Cu(Ⅱ)废水。     

Adsorption characteristics of thiobacillus ferrooxidans on surface of sulfide minerals

1INTRODUCTION Thefeatureofmineralsurfaceismodifiedlike thecellsurfacebyfixingbacteriaonitssurface whilethefeatureofcellsurfaceisdeterminedbyits livingcondition[1].Thecomponentofbacterial surfaceplaysanimportantroleinthebacterialat tachmentonminerals[2,3].Itisprovedthatcell wallandoutermembraneareinvolvedintheadhe sionbetweenmineralsandmicrobes,whilethein nermembraneandotherorganelleshardlyhaveany influenceonthisprocess.Thesephysiological structuresofbacteria,especiallytheoutermem brane,af…     

SYNERGISTIC EFFECT OF MINERAL SURFACE CONSTITUENTS IN DEXTRIN ADSORPTION

Abstract:As part of a systematic research on the interaction mechanismbetween polysaccharides and mineral surfaces,we extend the studies ondextrin adsorption to real minerals such as oxides and salt-type minerals,based on previous studies of model systems(surface-modified quartz).Theminerals tested include hematite,rutile,fluorite,calcite,apatite,etc.Itis obseroed that dextrin adsorption on these minerals is strongly pH-depen-dent,with adsorption maxima appearing at pH values around the isoelec-tric points of the minerals,indicating interactions with surface metal hydroxide species.X-ray photoelectron spectroscopy(XPS)measurements re-veal electronic binding energy shifts or Auger parameter changes Of miner-al surface elements after dextrin adsorption,pointing to a chemical mecha-nism of interaction.Furthermore,it is observed that the reaction of miner-als with moderate amounts of fatty acids prior to dextrin addition resultsin an increase in dextrin adsorption,whereas excessive fatty acids do theOpposite     

羟基丁二酸对α－Fe_2O_3单分散溶胶的絮凝──稳定性

研究了羟基酸系列之一的羟基丁二酸（苹果酸）体系对α－Ｆｅ＿２Ｏ＿３单分散溶胶稳定性的影响，讨论了该体系的絮凝机理．实验表明：①羟基丁二酸对α－Ｆｅ＿２Ｏ＿３溶胶的聚沿作用有别于一般电解质．②影响该体系的絮－稳定性的主要因素是体系的酸度和絮凝剂浓度．③羟基丁二酸对α－Ｆｅ＿２Ｏ＿３单分散溶胶的絮凝和再稳定是受表面化学反应所控制．属于特殊吸附絮凝．     

天然锰矿对水体中磷的去除研究

研究了天然锰矿对水体中磷的去除效果,考察了温度、光照、锰矿用量、溶液pH及共存离子对除磷效果的影响。结果表明,pH对磷的吸附影响很大。离子影响中,Ca2+、Mg2+、CO32-、HCO3-、SiO32-和SO24-的影响不大,而AsO43-和AsO3-却能明显抑制锰矿对磷的吸附。Freundlich等温吸附模型(r2=0.984 4)能很好的描述磷的吸附。动力学数据符合二级动力学模型(r2=0.999 9),最大吸附量为30.40μg/g。FTIR和SEM结果显示磷主要是通过与锰矿表面的羟基发生置换或生成内层络合物而被吸附。天然锰矿,具有较大的比表面积,强选择性,是一种很有前景的去除天然水体中磷的吸附剂。     

Flotation behavior of four dodecyl tertiary amines as collectors of diaspore and kaolinite

The flotation of diaspore and kaolinite by one of a series of tertiary amines (DRN, DEN, DPN and DBN) was investigated. The tertiary amines show better floating recovery for kaolinite compared to diaspore. The maximum recovery D-value is 45% over a pH range from 3 to 8. FT-IR spectra confirm the presence of hydroxyl groups on the surface of kaolinite and diaspore. Zeta potential measurements show that the mineral surfaces are negatively charged over a wide pH range. Ionization of hydroxyl groups mainly accounts for the surface charging mechanism. The adsorption of tertiary amines onto the mineral surface is due mainly to electrostatic effects and the difference in electrostatic effect between a collector and the two minerals can explain the flotation separation. Inductive electronic and steric effects from the substituent groups result in different collecting powers for the four tertiary amines.     

Effect and mechanism of dolomite with different size fractions on hematite flotation using sodium oleate as collector

The effect of dolomite with different particle size fractions on hematite flotation was studied using sodium oleate as collector at p H of about 9. The effect mechanism of dolomite on hematite flotation was investigated by means of solution chemistry, ultraviolet spectrophotometry(UV), inductively coupled plasma atomic emission spectrometry(ICP-AES) and X-ray photoelectron spectroscopy(XPS). It is observed that dolomite with different size fractions has depressing effect on hematite flotation using sodium oleate as collector, and dolomite could be the "mineral depressant" of hematite using sodium oleate as collector. The reasons for that are concerned with sodium oleate consumption and the adsorption onto hematite of dissolved species of dolomite.     

超声波处理垃圾渗滤液中有机物的研究

为探讨超声对渗滤液中有机物的影响,采用超声波处理垃圾渗滤液,发现超声频率,初始pH值,辅助曝气,反应温度和渗滤液初始浓度都有限地影响渗滤液COD的去除率。对UV-Vis扫描光谱和特定波长比值进行分析,认为·OH与芳香性物质反应,优先与羰基、羧基、羟基、酯类等基团,之后与以脂肪链为主的基团反应,最后参与芳香环的破坏。     

Adsorption mechanism of N-laurel-1,3-diaminopropane in a hematite-quartz flotation system

The strong collecting performance of N-laurel-13-diaminopropane (ND13) with respect to quartz encouraged us to study its separation of hematite and quartz mixtures in a laboratory cell flotation test.The results show that the best separation results can be achieved when the pulp pH is 7.27 and 583 mg/L collector plus 6.67 mg/L depressant are added to the mixture. Products with 58.45%, 62.78% and 63.72%iron grades can be achieved respectively when mass ratio of hematite to quartz is 2:3, 1:1, and 3:2. The adsorption mechanism of ND13 on a quartz surface was investigated by zeta-potential and X-ray photoelectron spectroscopy measurements. The results reveal that electrostatic and hydrogen bonding adsorption take place between ND13 and the quartz surface, and that ND13 mainly interacts with the oxygen atoms on the quartz surface.     

Adsorption characteristics of thiobacillus ferrooxidans on surface of sulfide minerals

By using thiobacillus ferroxidans (T. f) from Qixiashan, Hubei Province, China, the adsorption characteristics of T. f on surface of sulfide mineral were studied. The influences of adsorption time, pH value, temperature, initial inoculated concentration of bacteria, concentration of sulfide mineral powder, and variety of minerals on the adsorption characteristics were firstly investigated by using the ninhydrin colorimetric method, and the changes of contact angles and Zeta potentials of mineral surface during the bacterial adsorption were then determined. The results show that when the leaching experiments are performed for a long time from several days to a month, the maximal quantity of adsorption of T f on the surface of pyrite is obtained under the following conditions: leaching for 20 d, pH value in range of 1–2 and temperature at 30 °C, respectively; when the bio-leaching experiments are performed for a shorter leaching time, the maximal quantity of adsorption is obtained under the conditions: bio-leaching for 2 h, at 2.4×10⁷ cell/mL of initial inoculated bacteria concentration, and at 10% of mineral powder concentration; and the adsorption quantities are different from one sulfide mineral to another, and the adsorption of T. f on the surface of sulfide minerals includes three phases: increasing phase, stationary phase and decreasing phase. Foundation item: Project(50321402) supported by the National Natural Science Foundation of China; project (2004CB619204) supported by the National Key Fundamental Research and Development Program of China     

矿物土壤对氟离子的吸附特性研究

选用三种矿物土壤,研究它们对氟离子的吸附特性,探讨投加量、吸附时间、pH以及煅烧温度等因素的影响．结果表明：不同土壤对氟离子具有不同的吸附能力,郴州土壤对氟离子的饱和吸附量可达909．09mg／kg,吸附行为符合Langmuir方程式;当矿物土壤的投加量为30g/L时,吸附行为可在5h内达到平衡,pH的变化对矿物土壤的吸附能力影响不明显;将土壤经过高温煅烧后,吸附能力会有所增加,经过300℃煅烧的矿物土壤对氟离子的吸附效果最佳,比煅烧前增加了19．2％．     

Enhancing the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect with sodium dodecyl sulfate surfactant

Ameliorating the problem of low leaching efficiency, long leaching period, and high agent consumption should be studied to efficiently exploit ion-absorbed rare earth ore resources. In this study, the surfactant sodium dodecyl sulfate (SDS) is used to enhance the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect for the first time. The effects of surfactant concentration, leaching agent dosage, solution flow velocity, and solution pH on the leaching rate were explored, and the mechanism of SDS was discussed. Under the optimum conditions, the addition of a small amount of SDS (mass fraction 0.04%) can increase the leaching rate by about 5%, shorten the leaching period, and reduce the consumption of the leaching agent. SDS significantly ameliorates the seepage effect of the ore body by reducing the surface tension of the leaching agent and ameliorating the wettability of the mineral surface. This effect is the main factor that improves the leaching efficiency. DFT (density functional theory) calculation results show that SDS can react with rare earth ions, which reduces the adsorption strength on clay mineral surfaces. Hence, rare earth ions are easily exchanged by ammonium ions, and mass transfer is enhanced.     

端羧基超支化铬鞣助剂的合成及应用研究

与一般的高吸收铬鞣助剂相比,端羧基超支化聚合物具有的络合活性基团更多,吸收和固定铬的效果更好,同时还可以节约铬盐,减少铬污染,实现一举两得的效果.通过"一步法"由3,5-二氨基苯甲酸合成了一种端氨基超支化聚合物,经乙醛酸改性后得到一种超支化铬鞣助剂.将其用于羊皮服装革的铬鞣实验,优化出了最佳的应用工艺条件:在铬粉加入前加入2%的铬鞣助剂,铬鞣后期提碱终点pH4.0~4.2.其结果表明,使用该助剂后,铬粉用量仅为5%时,皮革收缩温度(Ts)就能达到常规铬鞣的要求.     

脂类捕收剂DLZ对黄铜矿和黄铁矿浮选的选择性作用

通过浮选实验、吸附量和红外光谱测定,考察了捕收剂DLZ对黄铜矿和黄铁矿浮选性能的影响及作用机理.结果表明:DLZ在pH=2.7～12.05时对黄铜矿的捕收能力强,最大回收率95.7%,而对黄铁矿的捕收能力弱,且PH=6.9～12.05时其回收率小于10%.用CaO作pH调整剂时,在pH=7～11时黄铜矿的回收率与用NaOH调PH相差不大,但黄铁矿可浮性被抑制,回收率低于5%.DLZ在黄铜矿上的吸附量比在黄铁矿上的大,特别是强碱条件下;其吸附量随用量的增加而增大.DLZ与矿物作用的红外光谱分析表明:黄铜矿与DLZ作用后出现了DLZ的相关特征吸收峰,而黄铁矿与DLZ以及Cu~(2+)作用前后的红外光谱曲线基本没有变化,可见DLZ在黄铜矿表面的吸附属于化学吸附,在黄铁矿表面的吸附属于物理吸附.     

α-Fe_2O_3单分散溶胶在EDTA溶液中的稳定性

EDTA的浓度和介质PH的变化可以引起a-Fe_2O_3单分散溶胶的絮凝和再稳定。再稳定是由于带有正电荷的胶体粒子吸附了过剩的负离子,导致粒子表面电性反号引起的。C.C.C和C.S.C强烈依赖于介质的PH。该絮凝机理属于吸附凝机理,受表面化学反应所控制。     

功能化SBA-15-NH2在药物布洛芬吸附与控制释放的研究

采用合成后改性法将氨基嫁接进介孔SBA-15孔道内,对功能化的SBA-15进行药物吸附与控制释放研究。利用X射线衍射（XRD）、智能重量分析仪（IGA）、透射电镜（TEM）、红外光谱仪（IR）等表征手段对它的物理结构、化学组成进行表征,在此基础上,利用分子模拟软件对其空间骨架结构及与药物分子之间的相互作用进行模拟。对目标药物布洛芬（IBU）负载进改性前后的SBA-15材料内表面进行研究。结果表明,药物吸附和缓释性能与SBA-15材料内表面官能团有着密切的关系。由于药物IBU分子与功能化SBA-15-NH2内表面的氨基基团之间存在离子相互作用,故其药物释放时间比单纯的SBA-15更长。     

H_2O_2/Fe(Ⅱ)与PAM协同处理柠檬酸废水的实验研究

对H2O2/Fe(Ⅱ)(芬顿试剂)和PAM协同处理含柠檬酸废水的效果进行了研究,主要考察了PAM的投加量与时间、pH、吸附时间以及吸附温度等几个重要条件对处理效率的影响。实验结果表明,用PAM处理H2O2/Fe(Ⅱ)氧化后的柠檬酸废水比H2O2/Fe(Ⅱ)与PAM同时加入处理具有更好的处理效果。PAM吸附反应的最佳条件:温度为35℃,pH=2,PAM质量浓度为0.06 g/L,反应时间为30 min时,CODCr的去除率为92.70%,达到最高。     

双氧水氧化橡实淀粉的实验研究

以双氧水为氧化剂,Cu2+为催化剂制备橡实氧化淀粉,考察pH值、氧化剂用量、催化剂用量、反应温度及反应时间对橡实氧化淀粉的羰基和羧基质量分数的影响.结果表明,最佳反应条件为:反应温度45℃,反应时间3 h,pH=8,H2O2用量为20%(相对于淀粉干重质量,下同),在此条件下,当催化剂用量为0.052 4%(相对于淀粉干重的质量)时,制得羧基质量分数为0.914 0%的橡实氧化淀粉;在催化剂用量为0.124 4%时,制得羰基质量分数为0.918 3%的橡实氧化淀粉.