采用恒界面池法研究双(2-乙基己基)磷酸酯(HDEHP)-乳酸复合体系萃取镧和铈动力学

研究在乳酸络合体系中HDEHP萃取镧和铈的动力学。通过恒界面池装置分别研究不同搅拌速度、比界面积、温度和溶液组分浓度对萃取速率的影响。当搅拌速度为130~180 r/min时,萃取反应速率以化学反应控制为主,并且随着比界面和温度的升高,萃取速率变快。萃取动力学研究表明,萃取反应符合准一级反应,传质过程发生在有机相与液相界面而不是在相体内。萃取反应吉布斯自由能ΔG<0,能够自发进行反应,表观活化能的计算表明HDEHP在萃取中更易与铈结合。

Evaluation of Various Modification Methods for Enhancing the Performance of Recycled Concrete Aggregate

Due to the existence of the attached mortar,the performance of the recycled concrete aggregate(RCA)is inferior to the natural aggregate,which significantly limits its wide application in industry.In this study,five kinds of modified solutions were used to modify the surface of RCA,and the modification effects were compared.The results showed that sodium silicate,nano-silica(NS),Bacillus pasteurii and soybean powder had relatively good modification effects on RCA,which could reduce the crushing value and water absorption,and increase apparent density.The composite solution(15%sodium silicate and 2%NS)and soybean powder solution had better modification effect.The 28 d compressive strength and splitting tensile strength of recycled aggregate concrete(RAC)prepared by RCA modified by soybean powder solution were 4.6%and 5.2%higher than those prepared by RCA modified by composite solution,respectively.This indicates that among the five kinds of modified solutions,soybean powder solution has the best modification effect on RCA,and the optimal soaking time of soybean powder solution is 8 h.At this time,the crushing value,water absorption and apparent density of RCA are 12.8%,5.3%,and 2653 kg/m^(3),respectively.The research results of this study provide a reference for the modification of RCA and its efficient utilization.

Review of the research on the development and utilization of clay-type lithium resources

Since the demands for lithium have been in explosive growth recently and several great clay lithium resources were founded in China,the development and utilization of clay-type lithium resources become a hot topic.In order to provide a guidance for the concentration and extracting lithium of clay-type lithium resources,this review systematically summarized the main types and characteristics of clay-type lithium resources and the research status of lithium extraction from clay lithium resources.Meanwhile,the flotation research status of the main mineral of clay lithium ore was also summarized.Furthermore,we discussed the difficulties in the development and utilization of clay-type lithium ore and put forward the subsequent research orientation.This paper can provide a guidance for the con-centration and extracting lithium of clay-type lithium resources in the future.

Extract lithium from clay-type lithium ore by mixed acid and its mechanism Author links open overlay panel

A roasting-leaching test was carried out for the efficient utilization of clay-type lithium ore in the central region of Yunnan province.The test used the mixed acid of sulfuric acid and phosphoric acid as the leaching agent.Under the conditions of roasting temperature of 600℃,roasting time of 1 h,liquid-solid ratio of 5:1,volume ratio of H_(2)SO_(4)solution to H_(3)PO_(4)solution of 45:5,leaching time of 2 h and leaching temperature of 80℃,the leaching rate of lithium was as high as 97.83%.The leaching mechanism was studied by SEM,pore property analysis,XRD and XPS.It was found that the morphology of the ore changed obviously after roasting and leaching,and a certain degree of collapse and fragmentation occurred,which provided favorable spatial conditions for the leaching of lithium.The porosity,total intrusion volume and total pore area also increased after roasting and leaching,thus promoting the leaching of Li^(+).The results showed that chemical reaction taken placed during the roasting and leaching.The phase of the sample changed from chlorite,kaolinite and diaspore(boehmite)mainly to corundum,hematite,periclase and quartz after roasting.However,after leaching,no new phase was produced in the ore sample,and no S and P elements were found on the surface of the ore sample,indicating that the leaching mechanism of lithium might be the ion exchange between H^(+)and Li^(+).

云南某富银锌精矿锌银浮选分离实验研究

云南某富银锌精矿中银主要以类质同象形式存在于白铅矿中,本工作以该矿样为研究对象,根据其性质,采用抑铅浮锌的工艺流程进行浮选,考察了磨矿细度、抑制剂、活化剂及捕收剂等因素对浮选分离指标的影响。结果表明,–19+10μm粒级中银含量最高。在磨矿细度–74μm占90%,硅酸钠用量为2000 g/t,硫酸铜用量为200 g/t,丁基黄药用量为300 g/t,松醇油用量为30 g/t的条件下,1次粗选、1次精选、1次扫选,中矿顺序返回的全流程闭路实验,可获得含锌61.08%,回收率95.89%的锌精矿和含银1548.32 g/t,回收率为71.17%的银精矿,实现了锌银的浮选分离及伴生银的高效富集。

Solvent extraction and separation of light rare earths from chloride media using HDEHP-P350 system

Solvent extraction is the most important method for rare earth extraction and separation.Currently,di(2-ethylhexyl)phosphoric acid(HDEHP)and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester(HEH/EHP)are widely used in industrial production,but there are still obvious deficiencies that require further research to resolve.In this paper,the unsaponification extraction of light rare earth ions in a hydrochloric acid medium by di(2-ethylhexyl)phosphoric acid-di(1-methyl-heptyl)methyl phosphonate(HDEHPP350)system was studied.The results show that the addition of P350 reduces the extraction capacity of HDEHP,and also greatly reduces the concentration of acidity required for the back-extraction.It still has a good separation factor for light rare earths without saponification,and the extractant is not easy to emulsify.With an aqueous phase of pH=2.85,and HDEHP mole fraction XHDEHP=0.9(compared with O/A=2),the separation effect of light rare earth is the best,resulting in the separation coefficientβCe/La=3.39,βPr/Ce=1.67 andβNd/Pr=1.45,respectively.The loaded light rare earth ions extracted by HDEHP-P350 can be easily stripped when 2 mol/L HCl is used as the stripping agent.Finally,the extraction mechanism is discussed using a slope method,and the final structure of the extracted complex is determined to be RECl[(DEHP)_(2)]_(2)P350_((o)),based on a combination of infrared spectra and 1 H NMR and 31P NMR analyses.

Photosensitive peptide hydrogels as smart materials for applications

Photosensitive peptide hydrogels(PPHs) which allow photo-modulation on the self-assembly of peptides were broadly developed over the recent decades. The real-time and spatial modulation of hydrogel properties upon non-contact light illumination, allow the PPHs serving as super "smart" soft materials.Herein, we briefly summarized the PPHs preparing from the integration of diverse photosensitive moieties with peptides through gelation abilities, "smart" manner and applications. Moreover, a novel type of PPHs based on intramolecular biorthogonal photo-click reaction developed by our group has been demonstrated with relative mechanism and applications.

Bisphosphonate-based nanocomposite hydrogels for biomedical applications

Nanocomposite hydrogels consist of polymeric network embedded with functional nanoparticles or nanostructures,which not only contribute to the enhanced mechanical properties but also exhibit the bioactivities for regulating cell behavior.Bisphosphonates(BPs)are capable of coordinating with various metal ions and modulating bone homeostasis.Thanks to the inherent dynamic properties of metal–ligand coordination bonds,BPbased nanocomposite hydrogels possess tunable mechanical properties,highly dynamic structures,and the capability to mediate controlled release of encapsulated therapeutic agents,thereby making them highly versatile for various biomedical applications.This review presents the comprehensive overview of recent developments in BP-based nanocomposite hydrogels with an emphasis on the properties of embedded nanoparticles(NPs)and interactions between hydrogel network and NPs.Furthermore,various challenges in the biomedical applications of these hydrogels are discussed to provide an outlook of potential clinical translation.

Self-sorting double network hydrogels with photo-definable biochemical cues as artificial synthetic extracellular matrix

In soft connective tissues,the extracellular matrix(ECM)provides spatiotemporally well-defined mechanical and chemical cues that regulate the functions of residing cells.However,it remains challenging to replicate these essential features in synthetic biomaterials.Here,we develop a self-sorting double network hydrogel(SDNH)with spatially well-defined bioactive ligands as synthetic ECM.Specifically,the SDNH is made of two peptides that can independently self-assemble into fibers of different microscopic features,mimicking the hierarchical protein assemblies in ECM.Each peptide contains a photo-reactive moiety for orthogonally patterning bioactive molecules(i.e.,cyclic arginine-glycine-aspartate(cRGD)and osteogenic growth peptide(OGP))using UV and visible light.As a proof-of-principle,we demonstrate the engineering of SDNH with spatially separated or colocalized cRGD and OGP molecules to control the response of encapsulated stem cells.Our study represents an important step towards defining the mechanical and biochemical cues of synthetic ECM using advanced chemical biology tools.

Collectorless flotation of marmatite with pine oil

The interaction between pine oil and marmatite without collectors and activators was investigated by flotation,scanning electron microscope and energy-dispersive spectrometer（SEM-EDS）,infrared（IR） spectroscopy,Zeta potential,and first-principle theory calculations.The flotation results show that marmatite exhibits considerable floatability with the addition of pine oil.SEM-EDS results show that carbon atomic ratios on the surface are significantly high,which suggests that the flotation of marmatite is caused by the adsorption of pine oil.Further evidence of the adsorption mechanism was given by IR,and Zeta potential examining pine oil depends on the physical adsorption on the surface independently.The first-principle theory calculations indicate that pine oil molecule adsorbs on Zn and Fe atom surfaces by ionic bond and covalent bond of adsorption energies of-1.23and-1.51 eV,respectively.P orbital of O atom,s orbital of Zn atom,and d orbital of Fe are the major participants.

Bisphosphonate-based hydrogel mediates biomimetic negative feedback regulation of osteoclastic activity to promote bone regeneration

The intricate dynamic feedback mechanisms involved in bone homeostasis provide valuable inspiration for the design of smart biomaterial scaffolds to enhance in situ bone regeneration.In this work,we assembled a biomimetic hyaluronic acid nanocomposite hydrogel(HA-BP hydrogel)by coordination bonds with bisphosphonates(BPs),which are antiosteoclastic drugs.The HA-BP hydrogel exhibited expedited release of the loaded BP in response to an acidic environment.Our in vitro studies showed that the HA-BP hydrogel inhibits mature osteoclastic differentiation of macrophage-like RAW264.7 cells via the released BP.Furthermore,the HA-BP hydrogel can support the initial differentiation of primary macrophages to preosteoclasts,which are considered essential during bone regeneration,whereas further differentiation to mature osteoclasts is effectively inhibited by the HA-BP hydrogel via the released BP.The in vivo evaluation showed that the HA-BP hydrogel can enhance the in situ regeneration of bone.Our work demonstrates a promising strategy to design biomimetic biomaterial scaffolds capable of regulating bone homeostasis to promote bone regeneration.