| Waste incineration is one of China’s most crucial waste treatment methods.The slag is the main product of the incineration process,which can be used as a building material for resource utilization by wet treatment.The dissolved salts in the slag are washed out and migrated during the flushing process,in which chloride ions cause corrosion to the washing equipment and increase the treatment cost.Hence,it is necessary to desalinate the high brine for waste incineration slag washing.Membrane distillation technology has been widely studied because of its low-temperature heat source,simple modular design,and good desalination effect.However,membrane distillation technology has problems,such as membrane contamination and wetting.In this study,membrane distillation is optimized to improve the surface properties of the membrane and improve the influence of the operating parameters.In this paper,Polytetrafluoroethylene-Polyvinyl alcohol/Graphene oxide(PTFE-PVA/GO)bilayer membranes were prepared by a surface coating method using Glutaraldehyde(GA)as a cross-linking agent.The effects of PVA,GA,and GO contents on the membrane structure and properties were systematically investigated.ATR-FTIR,XRD,and DSC characterization tests on the hydrophilic layer show that PVA is tightly bonded with GO after GA as a cross-linking agent and esterification reaction with PVA catalyzed by hydrochloric acid,and the addition of GO forms stable hydrogen bonds with PVA.XRD results react that GO can reduce the degree of crystallization of PVA,and DSC tests can prove this conclusion.The water contact angle,AFM,and SEM characterization tests on the bilayers demonstrated that the large quantity functional groups in GO and PVA promoted the construction of cross-linked lattices more stably under the cross-linking effect,and the network could still cover the stomata on the membrane after the reaction was finished.Furthermore,GO has better dispersion on the membrane,which reduces the roughness of the membrane.It can reduce the surface energy of the composite membrane,lower the water contact angle and improve the hydrophilicity of the PTFE-PVA/GO membrane.According to the results of the DCMD test,GO has the best effect at 3%addition,and the water flux can reach 12.52 Kg/(m~2h),which is 58%higher than the original PTFE membrane,and the desalination rate is kept above 99.99%,and the anti-wetting property is also significantly improved Polytetrafluoroethylene membrane,In order to investigate the effect of operating conditions on membrane distillation,PTFE-3%PVA/GO membranes were selected for membrane distillation technology to treat waste incineration slag cleaning high brine.The efficiency of membrane distillation in treating waste incineration slag cleaning high brine was investigated by changing three operating parameters:feed water temperature,feed water flow rate,and feed water p H.The results show that the membrane distillation process of a double-layer membrane has a strong desalination ability for waste incineration slag cleaning high brine,with a desalination rate of more than 99.7%,and can operate stably for a long time,with significant anti-pollution and anti-wetting effects.The water flux can be effectively increased by adjusting the feed water p H to acidic,increasing the feed water temperature,and increasing the flow rate.It is worth noting that raising the temperature and flow rate of the influent may hasten membrane contamination,while lowering the p H of the influent will raise the possibility of membrane wetting.The satisfaction function and genetic algorithm obtained the optimal conditions,and the feed temperature was 44°C,the feed flow rate was 613.83 m L/min,and the feed p H was 4.75.The experiments were conducted under optimal conditions,and the water flux was 18.2Kg/(m~2h)with a thermal efficiency of 53%. |
PDF Full Text Request