| Tetracycline with high solubility and biodegrading resistantance was frequently detected from both surface and ground water,which exposed negative impact on water environment and human health.Adsorption,with adsorbent as the core,is an effective method to treat TC wastewater.And how to develop an effective adsorbent to remove TC is a hot topic in current research.Municipal sludge is an important sewage treatment product with high yield and difficulty in treatment.Therefore,the treatment of municipal sludge is also one of the hot spots for researchers.Due to its relatively rich carbon content and large output,the preparation of municipal sludge into biochar can not only realize the harmless utilization of sludge,but also provide a new idea for sludge treatment.In this paper,a new type of modification on sludgebased biochar was studied to overcome its existing problems.A variety of modification methods and modified materials are studied,and synthetic materials are systematically studied.and the composite was applied to treat tetracycline wastewater.The full text was divided into the following 3 sections.In the first study,KOH activating municipal sludge-based biochar with different nanoscale Fe/Cu addition was prepared and applied in removing TC from water with high performance.The removal amount of the composite was found to be significantly improved after loading Fe/Cu particles and the highest removal amount was reached to 386.93 mg/g under the optimum molar ratio of Fe:Cu=5:3.Results of kinetics showed that the adsorption process was described well by pseudo-second order model,and isotherm results suggested a chemisorption process occurred between TC and the composite.The higher solution temperature was more farvorable to adsorption process between TC and the composite.The analytical results suggested that excellent removal performance of TC obtained by this material,and adsorption process involved many mechanisms,for instance,physisorption,hydrogen bond,π-π stacking,complexation and electronic transferring.The removal mechanisms of TC and the characteristics of composite were also confirmed by FTIR,XRD,XPS and BET determination.In the second study,a novel sludge-based material was synthesized by ZnCl2 activation and Fe S modification,and was employed to TC removal from water.To detect the detailed structure of this adsorbent,FTIR,XRD,BET,XPS,etc.characterization methods were also employed.And removal mechanisms of TC by the material were investigated by taking experimental data into many mathematical models.Besides,the effect of foreign ions on adsorption,the removal performance of TC from natural water and recyclability of the synthetic material were also investigated.Results of kinetics showed that the adsorption process was described well by pseudo-second order model,and isotherm results suggested a chemisorption process occurred between TC and the composite.The higher solution temperature was more infarvorable to adsorption process between TC and the composite.In addition,the analysis of the diffusion mechanism suggests that the TC diffuses on the composite material within the diffusion model of the composite particles.The influence of natural water on adsorption processs was also studied in this case,and the outcome showed that the Yellow River water lessened TC adsorption amount by the composite,however,the general adsorption amount remained a good performance.The results demonstrated the composite was an excellent sorbent in removing TC with maximum adsorption amount 174.06 mg/g at 298 K.The detailed mechanisms could be attributed to pore filling,π-π stacking,hydrogen bonding,ion exchange,complexation,electro-static attraction and so on.In the third study,a novel wasted sludge-based biochar modified by chitosan and Fe/S was prepared for TC removal in water.This section focused on investigating the similarities and disparities between sole biochar and the composite.Otherwise,characterizations,kinetic,isotherm and thermodynamic study were also discussed in this paper.Batch experiments results displayed that the TC adsorption capacity reached 51.78 mg/g by sole biochar,while it was 183.01 mg/g by the composite at 298 K.Meanwhile,electro-static attraction,π-π stacking,porous filling,silicate bonding and hydrogen bonding were the main adsorption mechanisms for TC removal by biochar.Besides above mechanisms,chelating and ion exchange were also accounted for adsorption mechanisms for TC uptake by the composite.Diffusion analysis shows that the adsorption of biochar conforms to the membrane diffusion model and the adsorption of composite material accords with the particle diffusion model.The surface of biochar is significantly different from that of the synthesized material,the adsorption site distribution is significantly different,and the surface uniformity is also significantly different,which is one of the important reasons for the difference in the adsorption TC between the two materials.Findings of this work could offer valuable information in designing adsorbents and investigating adsorption mechanisms.And we hope our composite could be a potential material for antibiotics wastewater treatment.The research in the next stage will focus on the removal of other kinds of antibiotics and the treatment effect of actual antibiotic wastewater.The author hopes to provide a reasonable way out for these materials,and an effective measure for the recycling and utilization of municipal sludge through the application of practical engineering. |
