碳酸钙疏水改性及性能表征

采用单一改性剂油酸、硬脂酸、二甲基硅油及复合改性剂对碳酸钙颗粒进行疏水改性。介绍了改性碳酸钙的作用机理。探讨了改性剂种类和加入量对碳酸钙颗粒表面疏水程度的影响,并通过活化度表征疏水程度。采用红外光谱仪表征改性前后碳酸钙的结构,说明改性剂被引入到了碳酸钙颗粒表面上;采用Zeta电位仪测定改性前后碳酸钙随pH变化的Zeta电位,得知改性碳酸钙的Zeta电位受pH影响比较大;采用激光粒度仪测定改性前后碳酸钙的粒径,得知改性碳酸钙比未改性碳酸钙的平均粒径小,且其分散稳定性要优于未改性碳酸钙。该研究也提供了随改性剂种类和加量变化来调整颗粒表面疏水程度的方法,有一定实际意义。     

球形碳酸钙的控制合成研究

以硼酸为控制剂,氯化钙和碳酸钠为原料,采用共沉淀法制备了方解石型碳酸钙球形晶体。研究了控制剂浓度、反应温度、反应时间、反应物浓度等因素对碳酸钙粒径和形貌的影响。结果表明：在硼酸浓度为0.4 mol/L、氯化钙浓度为0.1 mol/L、20 ℃饱和碳酸钠溶液滴速为4.9 mL/min、反应时间为60 min、陈化时间为60 min、反应温度为50 ℃、氯化钙与碳酸钠物质的量比为1∶1条件下,制备的球形碳酸钙颗粒大小均匀,平均粒径为1.57 μm。     

Interference of EDTA in the treatment of metal plating wastewater by biosorption

BACKGROUND: The applicability of biosorption for the treatment of metal plating wastewater is adversely affected by the presence of complexing agents. To investigate this limitation on the removal of copper(II) onto peat, batch and column experiments were carried out using EDTA as the model complexing agent. The influence of pH and copper(II):EDTA mass ratios were evaluated for copper(II) concentrations between 5 and 100 mg Cu(II) dm^?3. RESULTS: EDTA negatively affected the copper(II) uptake of peat for pH > 5. Batch and column experiments showed that copper(II)‐EDTA complexes were not sorbed by peat. The leaks of copper(II) detected from the beginning of the column operation matched the copper(II)‐EDTA concentration in the feed solutions. To overcome the interference of EDTA, a novel approach based on the combination of peat + activated carbon was proposed. Nearly complete removal of copper(II) was maintained over 70 h in the treatment of a solution containing 20 mg Cu(II) dm^?3 with 11% of copper(II)‐EDTA complexes. CONCLUSION: A new mass transport model coupling copper(II) speciation in the feed and mass transfer rate‐controlled process simulated the copper(II) breakthrough curves in the presence of EDTA and could be used to successfully predict the breakthrough point. This work demonstrated that biosorption can also be applied for the treatment of wastewater containing complexing agents with the proper combination of sorbent materials. © 2012 Society of Chemical Industry     

Recovery of metals from complexed solutions by electrodeposition

Electrolytic recovery of metals from aqueous solutions containing complexing chelating agents such as EDTA, NTA, and citrate was studied in a two-chamber cell separating with a commercial cation-exchange membrane (CEM). Equimolar solutions of metal and a chelating agent as a catholyte and NaNO₃ as an anolyte were used; the effect of current densities, initial catholyte and anolyte pH, metal concentration and the type of the CEM, chelating agent and metal on the recovery of metals was determined. The recovery of metal increased with higher initial anolyte pH, concentration and current density, whereas it decreased with lower initial catholyte pH. The results show that electrodeposition seems to be an applicable method for the recovery of metals under appropriate conditions.     

聚丁烯异相成核发泡行为的研究

以偶氮二甲酰胺（AC）为发泡剂,采用热塑模压的方法制备了聚丁烯泡沫材料。分别以滑石粉和碳酸钙为异相成核剂,根据经典成核理论,探究了不同种类成核剂的添加量及粒子尺寸对泡沫材料的力学性能与泡孔结构的影响。结果表明,随着成核剂添加量的增加,滑石粉与碳酸钙作为成核剂制备的泡沫材料的平均泡孔直径减小至135 μm,泡孔密度增加至7×105个/cm3;成核剂粒径越小,制得的泡沫材料泡孔密度越大,平均泡孔直径越小,粒径为10 μm的碳酸钙作为成核剂时,添加量为6 %时,制备的泡沫材料的泡孔密度达到106个/cm3,平均泡孔直径为85 μm。     

碳酸钙纳米棒制备研究

研究了以白云石为原料经过煅烧、消化、二次碳化、过滤、洗涤、干燥制备碳酸钙纳米棒的工艺。用扫描电镜（SEM）、X射线衍射（XRD）对合成的样品进行表征。重点考查了二次碳化工序反应温度、氢氧化钙质量浓度、晶型控制剂用量及添加的分散剂种类对产品粒径的影响。结果表明,在二次碳化工序中,在碳化温度为20 ℃、氢氧化钙质量分数为6%条件下,加入2%（质量分数）晶型控制剂和聚乙烯醇分散剂,可以制得平均直径约150 nm、平均长度约1 μm、平均长径比为6~8的碳酸钙纳米棒。     

不同形貌碳酸钙的制备及其对PVC薄膜力学性能的影响

选用偏钒酸铵、聚乙二醇、十六烷基三甲基溴化铵、焦磷酸钠十水和聚乙烯吡咯烷酮作为碳酸钙形貌控制剂,以氯化钙和碳酸钠为原料,用氯化法制备得到了片状、菱形、棒状、球状和立方体状5种不同形貌碳酸钙微粒,并研究不同形貌碳酸钙颗粒形态对软质聚氯乙烯（PVC）薄膜力学性能的影响。结果表明,不同形貌碳酸钙均提高了PVC薄膜的力学性能,PVC薄膜拉伸强度和断裂伸长率均提高显著;其中,棒状形貌碳酸钙对PVC薄膜力学性能的提高效果最好,拉伸强度达到了27.11 MPa;菱形碳酸钙改性PVC薄膜的断裂伸长率最高,为98.23 %。     

异相反应法合成纳米硫化铅

以硫化氢和硝酸铅为原料,在有络合剂的醇/水介质中,采用气/液异相化学反应法合成了纳米硫化铅。对产物硫化铅粒度的影响因素进行了探讨,并通过XRD、SEM和激光粒度仪分别对产物纳米硫化铅的结构、形貌、粒度和粒度分布进行了表征。结果表明：增大EDTA与硝酸铅的初始浓度比（cEDTA /c硝酸铅）、乙醇与水体积比（V乙醇/ V水）和溶液pH,以及减小硫化氢气体流量,都可以减小硫化铅颗粒粒度。当cEDTA /c硝酸铅为1、V乙醇/V水为1、pH为3.5、硫化氢气体流量为20 mL/min时,所得到的纳米立方晶型硫化铅的粒度为69 nm,粒度分布较窄,颗粒形状为球型。     

Hydrothermal synthesis of hierarchical hydroxyapatite: Preparation, growth mechanism and drug release property

Hydroxyapatite (HAP) hierarchical microspheres were synthesized by a facile hydrothermal method using calcium nitrate and ammonium dihydrogen phosphate through controlling complexing agents. The influences of two kinds of complexing agents (potassium sodium tartrate tetrahydrate and trisodium citrate) and reaction time on the morphology of HAP crystals have been investigated. These results indicate that complexing agents have a great influence on the morphology of HAP. When potassium sodium tartrate tetrahydrate was used as complexing agent, HAP flowers were composed of the network of nanosheet building blocks. Well-crystallized HAP dandelions with nanorods radiating from the center can be obtained by the introduction of trisodium citrate. Broader XRD diffraction peaks imply a nanometer scale size. Based on XRD and SEM results, the formation mechanism of HAP crystals has been discussed. The hierarchically structured HAP microspheres were explored as drug carriers. The results indicate that HAP flowers and dandelions showed a favorable sustained release property for ibuprofen; thus, they are very promising for application in drug delivery.     

锌灰制备碱式碳酸锌和超细氧化锌及表征

室温下采用氨浸出锌灰制得碱式碳酸锌,再经煅烧制得超细氧化锌。研究了在合成碱式碳酸锌过程中表面活性剂对碱式碳酸锌和氧化锌颗粒尺寸与形貌的影响。结果表明,聚乙二醇（PEG20000）和聚乙烯吡咯烷酮（PVP-K30）这两种表面活性剂对颗粒的分散效果最好,制得的碱式碳酸锌颗粒为无定形片状且分散均匀,平均粒径为1 μm,煅烧后的氧化锌颗粒为六方晶系纤锌矿结构,粒径约为0.7 μm。添加PVP-K30比添加PEG20000的碱式碳酸锌热分解温度高。添加PEG和PVP的碱式碳酸锌反应活化能分别为139.9 kJ/mol和146.8 kJ/mol。     

新型铝锆偶联剂在纳米CaCO3表面的吸附特性

利用新型铝锆偶联剂对纳米CaCO3进行表面改性,采用光谱学分析方法对铝锆偶联剂在纳米CaCO3表面的吸附特性进行探讨。通过透射电镜(TEM)、沉降体积、浊度测试等实验对纳米CaCO3的表面改性效果进行评价。红外光谱分析表明,铝锆偶联剂以化学键合的方式吸附在纳米CaCO3的表面。但X射线衍射分析证明,纳米CaCO3表面吸附层物质的引入并未对纳米CaCO3粉体的化学组成产生影响。经表面改性,纳米CaCO3的界面性质发生了很大变化,纳米CaCO3在水中的沉降体积减少,悬浮液浊度明显增大,说明纳米CaCO3在水中的分散性得到很大改善。     

Optimization of milling parameters on the synthesis of stearic acid coated CaCO3 nanoparticles

Surface modification of precipitated calcium carbonate particles (calcite) in a planetary ball mill using stearic acid as a modification agent for making dispersion in hydrocarbon oil was investigated. Different parameters for processing (milling) such as milling time, ball-to-sample ratio, and molar ratio of the reactant were varied and analyzed for optimization. The physical properties of the hydrophobically modified calcium carbonate particles were measured; the particle size and morphology of the resulting samples were characterized by transmission electron microscopy and X-ray diffraction. The surface coating thickness was estimated using small angle X-ray scattering.     

Synthesis of CaCO3 nanoparticles by controlled precipitation of saturated carbonate and calcium nitrate aqueous solutions

Calcium carbonate nanoparticles (CCNP) were synthesised by precipitation from saturated sodium carbonate and calcium nitrate aqueous solutions. The effect of agitation rate, mixing time, calcium/carbonate ions concentration and temperature on particle size and morphology were investigated. Particles were characterised using X‐ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Increasing the mixing time from 30 to 180 min resulted in a decrease in particles size. Mixing rate variation between 300 and 14 000 rpm decreased the particle size. Temperature increase favoured a significant growth in particle size and in the formation of aragonite beginning from 80°C. Calcium and carbonate ion concentrations are key parameters controlling the CCNP particle size. Calcite is the main polymorph obtained as revealed by XRD analysis. © 2011 Canadian Society for Chemical Engineering     

Non-isothermal decomposition kinetics of nano-scale CaCO3 as a function of particle size variation

We report the synthesis of nanocrystalline calcium carbonate with varying particle sizes by precipitation techniques from an aqueous solution of calcium nitrate and sodium carbonate at controlled pH. The particle size of the carbonate powder was precisely controlled by changing the precursor concentration. The synthesized carbonate powders were characterized by using scanning electron microscopy, X-ray diffraction technique, and transmission electron microscopy. The particle size, along with the crystallite size of as-synthesized carbonate powder, decreases with increasing precursor concentration. The non-isothermal decomposition kinetics of the carbonate powder was also evaluated by using near to the modified Arrhenius equation's exact solution. The experimental results were best fitted at n = 0.5, and the one-dimensional diffusion-controlled transport process mechanism (D₁) and one-dimensional phase boundary movement mechanism (R₁) was found to be very close fit of the corresponding evaluated g(α) value. The apparent activation energy of the nano calcium carbonate decomposition was found in the range of 120–175 kJ/mol, which is also inherently functioning with the average particle size. The apparent activation energy of decomposition of CaCO₃ found to be decreased with decreasing average particle size of nanocrystalline calcium carbonate.     

Dispersion Polymerization of Styrene by Initiation Within Monomer Phase with Lauroyl Peroxide

Dispersion polymerization kinetics of styrene was investigated in this study. A monomer phase soluble initiator, namely lauroyl peroxide, and a water phase soluble emulsifier, namely sodium dodecyl sulfate, were used. the polymerizations were carried out in a magnetic drive, sealed, cylindrical polymerization reactor, in nitrogen atmosphere. Two different fatty alcohols, cetyl and lauryl alcohols, were tried as particle size increasing agents. the effects of initiator, emulsifier concentrations, monomer/water ratio, and the weight ratio of particle size increasing agent to emulsifier on the total monomer conversion, average size, and size distribution of the large latex particles were studied. the agglomeration conditions were tested by changing the polymerization temperature, initiator, and emulsifier concentrations. the results indicated that the polymerization rate and the average size of the latex increased with increasing emulsifier concentration. the average size of the latex was also increased with increasing initiator concentration. the use of cetyl alcohol in the presence of emulsifier resulted in an appreciable increase in the polymerization rate and in the average size of the latex. the effect of fatty alcohols on the polymerization rate in the dispersion polymerization system was completely different than that in the swollen emulsion polymerization. the agglomeration of the large latex particles was increased with decreasing emulsifier and increasing initiator concentrations.     

Influence of Carrier Agents on the Physicochemical Properties of Mussel Protein Hydrolysate Powder

The objective of this work was to evaluate the influence of carrier agents, maltodextrin 10 dextrose equivalent (DE) and gum arabic, on the physicochemical properties of mussel meat protein hydrolysate powder produced by spray drying. Hydrolysate was obtained by enzymatic hydrolysis using Protamex (Novozymes, Bagsvaerd, Denmark) and was carried out at 51°C, 4.5 g enzyme/100 g protein, and pH 6.85. The hydrolysate, without and with 15 and 30% of carrier agent, was spray dried at 180°C inlet air temperature and 0.8 L/h feed flow rate. Moisture content, hygroscopicity, particle size, glass transition temperature, morphology, antioxidant capacity, and volatile loss of powders were evaluated. Powder moisture content decreased with the increase in carrier agent concentration. Glass transition temperature increased with carrier agent addition and consequently powder hygroscopicity was reduced, increasing its physical stability. Higher feed solution viscosity was obtained for 30% of maltodextrin and 15 and 30% of gum arabic. The particles obtained from these solution presented a greater number of dents and larger particle size. The use of carrier agents reduced volatile loss and preserved the powder's antioxidant capacity.     

制备碳酸锂结晶的工艺优化

主要针对含锂卤水通过氯化锂与碳酸钠反应结晶制备高纯度碳酸锂过程中存在的结晶问题做了实验研究。通过考察反应结晶初始浓度、反应温度、进料速率、晶种用量、搅拌速率、进料浓度以及添加剂等对碳酸锂产品的平均粒度及晶体形貌的影响,优化了反应结晶制备碳酸锂的工艺参数。研究表明：在不同优化参数的作用下,通过调控碳酸锂的反应结晶过程,可改变碳酸锂晶体的形貌、粒度及固液分离效果。     

配位剂对Al_2O_3陶瓷表面化学镀铜的影响

研究了EDTA,NaKC4H4O6以及两者复配后,对Al2O3陶瓷表面化学镀铜沉积速率、微观形貌、表面粗糙度和镀液稳定性的影响。结果表明:EDTA为配位剂时,化学镀铜镀速为3.86μm/h,镀层表面粗糙度为0.39μm,镀层铜微粒形成团聚,均匀性较差;NaKC4H4O6为配位剂时,镀速为4.55μm/h,表面粗糙度为0.46μm,镀层表面有直径达2~5μm的杂质微粒;EDTA和NaKC4H4O6复配使用时,镀速为4.17μm/h,表面粗糙度为0.35μm,铜镀层微观组织致密,铜微粒大小分布均匀,排列紧密,表面平滑、洁净。     

成核剂对聚丙烯釜压发泡的影响

用超临界二氧化碳（CO2）釜压发泡的方法,研究了成核剂类型、成核剂粒径以及成核剂添加量对聚丙烯（PP）发泡材料泡孔结构的影响。结果表明,用碳酸钙（CaCO3）作成核剂时PP泡沫的泡孔完整性高,泡孔尺寸分布均匀,且发泡倍率比添加蒙脱土及滑石粉时的要大;成核剂粒子粒径越小,体系的成核点越多,发泡时产生的气泡核越多,所得到的PP泡沫的泡孔密度越大,但是由于纳米碳酸钙（nano-CaCO3）更容易出现团聚现象,直接导致最终发泡制品产生泡孔破裂以及发泡倍率的降低;成核剂CaCO3的添加量为3份时,与添加1份和5份相比,可得到发泡倍率更高,泡孔密度更大的PP泡沫。     

电石渣制备碳酸钙微粉的晶型转变

为了提高电石渣的附加值,在未使用晶型诱导剂的情况下,研究盐酸的用量、提取温度和二氧化碳的流量对电石渣合成碳酸钙形貌的影响。用XRD、FT-IR 表征了合成的产物,用扫描电子显微镜（SEM）观察研究了产物粒子的形状,结果表明,盐酸的用量和提取温度均会对碳酸钙的晶型和形状有影响。随着盐酸用量的增大,碳酸钙由不规则的方解石型转变为部分规则的球状结构,当浸取剂完全是盐酸的时候,碳酸钙的晶型从方解石型完全转变为球霰石型结构,颗粒粒径为4~5 μm。另外,当提取温度从18 ℃升高到30 ℃以上后,碳酸钙由方解石和球霰石两种晶体结构并存的状态转变为单一的球霰石型结构。