油田污水中去除阳离子的方法

通过纳滤膜处理油田污水,用ICP-AES测定原液及处理后的样品溶液中剩余阳离子的含量,计算去除率。该法可使污水中大量的阳离子去除,对Ca2＋去除率可达到60%左右,Mg2＋去除率在40%左右,Ba和Si去除率在50%左右,对Na、K的处理效果也能达到了30%以上。去除效果良好,这能使油田污水的矿化度大大降低。该法对防止污水配聚使聚合物粘度降低,提高原油采收率非常有利,同时也可降低油田地下管道结垢的现象。     

Solvent flux through dense polymeric nanofiltration membranes

This work examines the flux performance of organic solvents through a polydimethylsiloxane (PDMS) composite membrane. A selection of n-alkanes, i-alkanes and cyclic compounds were studied in deadend permeation experiments at pressures up to 900 kPa to give fluxes for pure solvents and mixtures between 10 and 100 l m⁻² h⁻¹. Results for the chosen alkanes and aromatics, and subsequent modelling using the Hagen–Poiseuille equation, suggest that solvent transport through PDMS can be successfully interpreted via a predominantly hydraulic mechanism. It is suggested that the mechanism has a greater influence at higher pressures and the modus operandi is supported by the non-separation of binary solvent mixtures and a dependency on viscosity and membrane thickness. The effects of swelling that follow solvent–membrane interactions show that the relative magnitudes of the Hildebrand solubility parameter for the active membrane layer and the solvent(s) are a good indicator of permeation level. Solvents constituting a group (e.g. all n-alkanes) induced similar flux behaviours when corrections were made for viscosity and affected comparable swelling properties in the PDMS membrane layer.     

超支化聚酯低压纳滤膜的制备与表征

通过超支化聚酯(HPE)末端的羟基与戊二醛(GA)之间的羟醛缩合反应,采用简单的浸涂-交联方法,制备了一种以聚砜超滤膜为支撑层,交联的HPE为活性分离层的复合纳滤膜.采用衰减全反射红外光谱(ATR-FTIR)、接触角测定、扫描电子显微镜(SEM)对纳滤膜的表面化学组成、亲水性和膜形貌进行了表征.考察了HPE溶液浓度、GA溶液浓度对膜分离和渗透性能的影响,优化的HPE和GA溶液浓度分别为9.8 g/L和7.4 g/L,此时在0.4 MPa下膜的水通量达69.6 L/(m2.h),对Na2SO4脱除率为93.2%,表现出低操作压力、高通量、高脱盐率的优异性能.纳滤膜对无机盐的截留顺序为Na2SO4>NaCl>MgSO4>MgCl2,呈现明显的荷负电特征.     

Highly stable and antifouling graphene oxide membranes prepared by bio-inspired modification for water purification

Graphene oxide (GO) membranes show great potential in molecular separation for water treatment. However, the inferior stability of GO membranes is a major bottleneck for practical applications. In this study, bio-inspired polydopamine (PDA) deposition is reported for enhancing the stability of GO membranes. Through simple and mild immersion, PDA is self-polymerized on GO membranes. The blocking of PDA chains to membrane defects improves the rejections for various molecules. Because the inherently strong adhesion and crosslinking of PDA greatly strengthen the interactions of substrates to GO layers and the binding force of GO nanosheets, the prepared PDA-GO membranes exhibit impressive long-term stability in cross-flow filtration, and maintain good nanofiltration performance at various feed pressures, tangential velocities, and even after external scratching. Moreover, because the deposited PDA layers obstruct the direct contact between GO and contaminants, the antifouling property of the PDA-GO membranes increases substantially, with recovery ratio about 98%.     

Greener approach for process intensification of iron haematinics by membrane nanofiltration

Iron haematinics are high-volume, low-cost drug products used to treat anaemia. For the preparation of iron haematinics, the manufacturers depend heavily on multipurpose-batch or semi-batch reactors. Here, process intensification of haematinics was carried out using membrane nanofiltration as a major operation. A total of three haematinics namely, iron (III) hydroxide polymaltose, iron gluconate, and iron sucrose complex were prepared, and the process intensified on dead-end filtration set up by using a polymeric membrane. Iron (III) hydroxide polymaltose experimental results were compared with commercially available standard. The membrane performance was characterized by various parameters such as flux, permeability, flux decline ratio, flux recovery ratio, percentage retention, fouling, etc., at different transmembrane pressures. The membrane surface was analysed by Scanning Electron Microscopy (SEM) to understand its morphology and fouling. The iron concentration was detected in the permeate stream using inductively coupled plasma optical emission (ICP-OES) spectroscopy to detect %retention (>99.99%) under all experimental conditions tested. The study led to optimized conditions for haematinics concentration by a membrane at a 10-bar trans-membrane pressure, which was applied for the preparation of iron gluconate salt. Overall, the study resulted in a green process with increased productivity.