Two. A brief introduction of reverse osmosis membrane elements

反渗透膜是实现反渗透的核心元件，是一种模拟生物半透膜制成的具有一定特性的人工半透膜。一般用高分子材料制成。如醋酸纤维素膜、芳香族聚酰肼膜、芳香族聚酰胺膜。表面微孔的直径一般在0.5～10nm之间，透过性的大小与膜本身的化学结构有关。有的高分子材料对盐的排斥性好，而水的透过速度并不好。有的高分子材料化学结构具有较多亲水基团，因而水的透过速度相对较快。因此一种满意的反渗透膜应具有适当的渗透量或脱盐率。

Reverse osmosis membrane is the core component of reverse osmosis. It is a semi permeable membrane with a certain characteristic. It is usually made of polymer materials. Such as cellulose acetate membrane, aromatic polyhydrazide film, aromatic polyamide membrane. The diameter of the surface micropores is generally between 0.5 and 10nm, and the permeability is related to the chemical structure of the membrane itself. Some polymers have good repellency on salt, but water is not good enough to pass through. Some polymer materials have more hydrophilic groups in the chemical structure, and the speed of water transmission is relatively fast. Therefore, a satisfactory reverse osmosis membrane should have the appropriate amount of penetration or desalination rate.

1、反渗透膜应具有以下特征：

1, the reverse osmosis membrane should have the following characteristics:

A、在高流速下应具有高效脱盐率；

A, high efficiency desalination rate should be available at high velocity.

B、具有较高机械强度和使用寿命；

B, with high mechanical strength and service life.

C、能在较低操作压力下发挥功能；

C, it can function under low operating pressure.

D、能耐受化学或生化作用的影响；

D, can tolerate the effects of chemical or biochemical action;

E、受pH值、温度等因素影响较小；

E, pH value, temperature and other factors are less affected.

F、制膜原料来源容易，加工简便，成本低廉。

The raw materials of F and film making are easy to source, easy to process and low in cost.

反渗透膜的结构，有非对称膜和均相膜两类。当前使用的膜材料主要为醋酸纤维素和芳香聚酰胺类。其组件有中空纤维式、卷式、板框式和管式。可用于分离、浓缩、纯化等化工单元操作，主要用于纯水制备和水处理行业中。

The structure of reverse osmosis membrane consists of two types: asymmetric membrane and homogeneous membrane. The membrane materials currently used are cellulose acetate and aromatic polyamide. Its components are hollow fiber type, coil type, plate and frame type and tube type. It can be used in chemical unit operation such as separation, concentration, purification and so on. It is mainly used in pure water preparation and water treatment industry.

2、反渗透膜元件原理

2. Principle of reverse osmosis membrane element

反渗透又称逆渗透，一种以压力差为推动力，从溶液中分离出溶剂的膜分离操作。对膜一侧的料液施加压力，当压力超过它的渗透压时，溶剂会逆着自然渗透的方向作反向渗透。从而在膜的低压侧得到透过的溶剂，即渗透液；高压侧得到浓缩的型线  流水槽模具 景观石 检查井钢模具 保定通风管道 隔离墩模具 保定保洁公司溶液，即浓缩液。若用反渗透处理海水，在膜的低压侧得到淡水，在高压侧得到卤水。

Reverse osmosis, also known as reverse osmosis, is a membrane separation operation that separates solvents from solutions by pressure difference. When the pressure exceeds the osmotic pressure on the side of the membrane, the solvent will reverse osmosis in the direction of natural infiltration. Thus, the permeable solution is obtained on the low pressure side of the membrane, namely the osmotic solution; the concentrated solution is concentrated on the high-pressure side. If seawater is treated by reverse osmosis, fresh water will be obtained on the low pressure side of the membrane and brine will be obtained on the high pressure side.

反渗透时，溶剂的渗透速率即液流能量N为：N=Kh（Δp－Δπ)  式中Kh为水力渗透系数，它随温度升高稍有增大；Δp为膜两侧的静压差；Δπ为膜两侧溶液的渗透压差。稀溶液的渗透压π为： π=iCRT 式中i为溶质分子电离生成的离子数；C为溶质的摩尔浓度；R为摩尔气体常数；T为绝对温度。反渗透通常使用非对称膜和复合膜。反渗透所用的设备，主要是中空纤维式或卷式的膜分离设备。反渗透膜能截留水中的各种无机离子、胶体物质和大分子溶质，从而取得净制的水。也可用于大分子有机物溶液的预浓缩。由于反渗透过程简单，能耗低，近20年来得到迅速发展。现已大规模应用于海水和苦咸水（见卤水）淡化、锅炉用水软化和废水处理，并与离子交换结合制取高纯水，其应用范围正在扩大，已开始用于乳品、果汁的浓

In reverse osmosis, the permeation rate of the solvent, that is, the liquid flow energy N, is that the Kh is a hydraulic permeability coefficient in the N=Kh (delta P - delta). It increases slightly with the temperature, and the delta P is the static pressure difference on both sides of the membrane, and the delta Pi is the osmotic pressure difference between the solutions on both sides of the membrane. The osmotic pressure of the dilute solution is: the number of ions generated by the ionization of the solute molecules in the I =iCRT type; the C is the molar concentration of the solute; the R is the molar gas constant; and the T is the absolute temperature. Reverse osmosis usually uses asymmetric membranes and composite membranes. Reverse osmosis equipment is mainly hollow fiber or coil type membrane separation equipment. Reverse osmosis membrane can intercept all kinds of inorganic ions, colloidal substances and macromolecular solutes in water, thus obtaining net water. It can also be used for pre concentration of macromolecular organic solutions. Because of its simple process and low energy consumption, the process of reverse osmosis has developed rapidly in the past 20 years. It has been widely used in seawater and brine water (brine water) desalination, boiler water softening and wastewater treatment, and combined with ion exchange to make high pure water. Its application scope is expanding and has been used in the concentration of milk and fruit juice.