| With the expansion of the silk reeling industry, factory is being increased in recent years, especially in Guangxi, China. The wastewater was often discharged directly after simplex aerobiosis exposural pool treatment, of which organics like silk proteins didn’t degrade effectively so as to cause serious environment problems. Therefore, to carry out with a low-cost solution to guarantee the reeling wastewater to process within discharge standard is a burning problem that not only concerned by environmental protection department and filatures, but also attracted urgent concentrations from environment scientists.Aimed at developing an effective low-cost reeling wastewater treatment technology, on the basis of adsorption treatment of organic wastewater, chinese fir sawdust, which has a wealth of sources and is low-cost, were chosen to treat reeling wastewater. In order to improve the adsorption performance, the chinese fir sawdust was subjected to modifications to achieve better effect. In this paper, the results has been gained as follows:(1) The samples with chinese fir sawdust were modified by NaOH and chitosan respectively, and the resulted sawdust was characterized by Fourier Transform Infrared Spectrometer (FT-IR), Scanning Electron Microscopes (SEM) and N2 Absorption-adsorption Spectrometer (BET). Compared with FT-IR absorption peak of NaOH-modified sawdust, it has been shifted and the intensity become stronger to the chitosan-modified sawdust; with the analysis of SEM, the structure of the sawdust has been changed due to the effect of chitosan; the specific surface area of chitosan-modified sawdust is 127 m2·g-1, while that of NaOH-modified sawdust is 113 m2·g-1, which implies specific surface area is not main factors to affect the adsorption, but the chitosan-modified sawdust is with better absorption performances.(2) NaOH-modified chinese fir sawdust was used to study its absorptions of protein-like organics in reeling waste water. And by single-factor tests and orthogonal experiments, the optimum absorption conditions were determined as that the best removal efficiencies of protein and CODCr were up to 59.7% and 46.6% when 20 g·L-1 of NaOH-modified chinese fir sawdust was used to the multi-times absorption of reeling wastewater with concentration of 2781 mg·L-1 at 353 K for 60 min. And the adsorption capacity of protein was 83.01 mg·g-1.(3) The treatment efficiency of protein in reeling wastewater was studied within the flocculation of chitosan. The optimum conditions were determined by single factor experiments and orthogonal experiments, and it showed that the removal efficiency of protein was up to 60.2% when 2781 mg·L-1 of protein in reeling wastewater was stirred at 303 K with a pH of 3.85 in the presence of 0.005 g·L-1 of chitosan for 60 min.(4) Single factor experiments and orthogonal experiments were conducted to determine the optimum conditions, and the results showed that the removal efficiencies of protein and CODcr were up to 79.6% and 82.8% respectively, 0.05 g·L-1 of adsorbent that consisted of chitosan and sawdust in a mass ratio of 1:6 was stirred in 2781 mg·L-1 protein content reeling wastewater at 308 K within pH of 3.78 for 90 min. And the adsorption capacity of protein was 44273.6 mg·g-1.(5) Adsorption mechanism showed NaOH-modified sawdust performed through an endothermic process of monolayer adsorption method while the adsorption behavior of chitosan-modified chinese fir sawdust conforms to the Freundlich equation that is non-uniform monolayer adsorption but interaction between each activity point of adsorption. Both NaOH-modified and chitosan-modified sawdust are double speed process consisted of a fast adsorption and a slow adsorption. |
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