Adsortions Of Dye By Modified Activated Carbon And Heavy Metals By Rice Husk-Based Activated Carbon

Accompany with quick development of the economy, rapid growth of the population and rapid expansion of the city, China has entered a period of frequently emergent pollution accidents. Water pollution, industrial accidents, water pollution caused by persistant pollutant emissions have greatly restricted the economic development and threated the social stability. It has been proved at home and abroad that wastewater reuse can improve the economic, social and ecological benefits. Vigorously promoting the utilization of the wasterwater to develop the circular economy is one of our country's important strategic measures to achieve sustainable development of economy and society. Wastewater containing heavy metals and dye are two kinds of important pollution sources in industrial systems. During the eleventh and twelfth five-year plan, these two kinds of wasterwater have been and will be the priority objects to reduce. To achieve the smooth operation, enterprises should consciously reduce water and energy consumption, and carry out water conservation and water pollution control technology. Activated carbon adsorption equipment is not only simple and small footprint, but also no secondary pollution. There is a broad field of applications in the heavy metal wastewater treatment and advanced treatment of dye wastewater.Three types of surfactants on the common surface modification of activated carbon had been studied, such as cation surfactants cetyltrimethyl ammonium bromide(CTAB), anionic surfactants sodium dodecyl sulfate (SDS), and nonionic surfactant p-Octyl polyethylene glycol phenylether. The impacts of the surface modification on activated carbon adsorption for dyes had been discussed, and the best combinations of dye types and modifier had been selected. The adsorption kinetics and isotherms had been gained by static and dynamic experiments. The modified activated carbon was evaluated for its physical and chemical properties using surface area analyzer and zeta potential analyzer. In addition, activated carbon as an adsorbent was prepared from rice husk by the activation of sodium hydroxide and phosphoric acid. Characteristics of rice husk based activated carbon, and its Cd, Cu, Cr, Zn adsorption had been studied.The results of this thesis were summarized as follows:(1) After modified by CTAB, SDS, Triton X-100, the activated carbons'decoloration on reactive brilliant red X-3B, acid orange, direct fast turquoise blue GL declined, but the activated carbons'decoloration on cation orange rose after modified by SDS. The best combination of factors for SDS modified activated carbon was:SDS density on it's critical micelle concentration (CMC), modification time in 6h, and modification temperature at 28℃The isoelectric points of activated carbons before and after modification by SDS changed from 4.0 to 3.0.(2) The pH of the solution had little effect on dye of cation orange adsorption capacity on modified activated carbon. The sorption kinetics of SDS modified activated carbon followed pseudo-second-order kinetic mode, and isotherms may be fit by Langmuir equation. The results of surface properties revealed that the mechanisms of adsorption of cationic orange was adsorption. The activated carbon's adsorption capacity on dye of cation orange increased from 49.5 mg·g-1 to 73.2 mg·g-1. It meant that the saturated adsorption capacity of the activated carbon on dye of cation orange increased by 47.8%.(3) The rice husk-based activated carbon activated by particulate sodium hydroxide was recorded as NRH, the one by sodium hydroxide solution dipped 24h was recorded as WNRH. NRH and WNRH all could reach to the standards of activated carbon with excellent grade, and their isoelectric point lowed to 2.1.When phosphoric acid was used to activation, rice husk was pre-dipped by dilute solution of sodium hydroxide, and then crushed by 35 mesh sieve was record as WP35; the one crushed by 10 mesh sieve was recorded as WP10. The rice husk-based activated carbon activated by phosphoric acid without pre-dipped by dilute solution of sodium hydroxide was recorded as P35. The P35, WP35 and WP10 all could not reach secondary standards of activated carbon for water purification. Activated carbon made from rice husk pre-dipped by dilute solution of sodium hydroxide was better than rice husk pre-dipped, and moreover rice husk particle size was an important factor in activation of phosphoric acid. WP35 and WP10's isoelectric point were distinguished to 8.1 with 5.5.(4) The rice husk-based activated carbon activated by sodium hydroxide was used for heavy metal adsorption of anionic Cr (Ⅵ)and adsorption was significantly affected by pH. The best pH for the rice husk-based activated carbon adsorption on Cr (Ⅵ)was 2.0. The rice husk-based activated carbon adsorption capacity on Cr (Ⅵ)was up to 86.1 mg·g-1, and its isotherms may be fit by Langmuir equation. For cationic heavy metals (Cd, Cu than Zn), rice husk-based activated carbon had much more adsorption capacity. Their adsorption capacity for Cd was 40.8 mg·g-1, for Cu was 47.9 mg·g-1, and for Zn was 24.9 mg·g-1.