Preparation Of Graphene Oxide Membrane And And Its Effect On Rejection Of Micro-organic Pollutants

Micro-organic pollutants in drinking water and recycled water has received increasing attention.Nanofiltration membrane technology is widely used because the molecular weight that can be retained is similar to the molecular weight of micro-organic pollutants The two-dimensional material represented by graphene oxide is an ideal membrane material.At present,direct filtration is the simplest and most common method for preparing graphene oxide membranes.However,the membrane is immersed in the solution,and the hydrogen bond and the?-?structure between the membrane layers are destroyed to cause swelling,which greatly limits the application and development.In order to solve the above problems,this experiment firstly prepared a stable graphene oxide membrane,and then studied its interception characteristics and mechanism for typical micro-organic pollutants.This experiment provides theoretical and technical support for the use of graphene oxide membranes for the retention of micro-organic pollutantsThe experiment uses a dopamine-coated base membrane,a combination of dopamine-coated base membrane and an ethylenediamine cross-linking to modify the graphene oxide membrane.The optimal GO loading is 40 mg/m~2.The water fluxes of the two modified membranes are 17 L/(m~2·h)and 34.5 L/(m~2·h).The retention rates are respectively 76.2%and 65%.Both modified membranes have good stability.In order to further improve the permeation flux and retention of the membrane,the amination-modified?-cyclodextrin is cross-linked with graphene oxide.The optimum ratio of?-cyclodextrin to GO is 0.5:1.At this time,the water flux of the membrane is 34 L/(m~2·h),and the retention rate is 71.9%.Compared with the other two modified membranes,the water flux is nearly doubled,and the retention rate is increased by 9.6%.The modified three kinds of stable graphene oxide membranes are used to test the interception performance of three kinds of micro-organic pollutants with similar molecular weights but different electrical properties,such as sulfadiazine,carbamazepine and propranolol.Under neutral conditions,the retention of the three membranes for different micro-organic pollutants is:propranolol<carbamazepine<sulfamethazine,which shows the selective separation characteristics of typical negatively charged nanofiltration membranes.For different GO membranes,the interlayer channel has a great influence on the interception effect.The ethylenediamine cross-linking modified membrane has the largest spacing,the screening effect is limited,and the interception effect is the worst.In order to explore the mechanism of interception,adsorption and interception experiments under different p H conditions are carried out.The results show that the change of p H of water will affect the charge of micro-organic pollutants and membranes,thus changing the electrostatic and adsorption effects to affect the interception effect.At the initial stage of filtration,the adsorption promotes the retention of micro-organic pollutants.In the middle and late stages of filtration,the adsorption is gradually saturated,the dissolution and diffusion reduce the interception effect of micro-organic pollutants.