【摘要】：隨著我國社會經(jīng)濟的迅速發(fā)展,水體污染越來越嚴重,重金屬污染問題尤為突出。鎘離子已被世界衛(wèi)生組織確定為優(yōu)先研究對象,在我國的國家環(huán)保法中規(guī)定不得用稀釋法來處理鎘,由此可見鎘污染問題在全球范圍內(nèi)影響之大及被重視程度。處理金屬鎘離子的方法有化學沉淀法、物理吸附法和生物吸附法等。其中物理吸附法是最常用的處理法,其優(yōu)點是材料易得,操作簡單,工藝流程簡潔,并且成本低。常用的吸附材料有沸石、活性炭、潤土、陶粒等,生物質(zhì)炭是目前研究比較熱門的新型吸附材料。但一種填料的吸附效果有限,往往需要通過對吸附材料改性來提高吸附材料的性能,這就大大增加了吸附法的運行成本,并且運行操作也更加復雜。如果多種吸附材料聯(lián)用使用能提高吸附效果,那么在處理污水時可以大大節(jié)約運行成本和簡化運行操作。本論文選用活性炭、沸石和生物質(zhì)碳作為吸附材料,通過靜態(tài)吸附實驗,研究了在不同時間、p H值、固液比、溫度和初始鎘離子濃度等條件下,不同吸附材料吸附鎘離子效果的影響,并且通過單元柱模擬污水處理實驗,討論不同吸附材料及其組合對鎘離子去除的影響,篩選出處理鎘離子的最佳組合。研究表明:活性炭在吸附20min時鎘吸附率即可達到99%,在吸附時間為1h時達到吸附平衡,鎘離子去除率達到99.5%;沸石和生物質(zhì)炭都是在吸附1h時達到吸附平衡,鎘離子的去除率分別為99.75%和95.25%。在不同的p H條件下,低p H值對沸石吸附鎘的影響較大,p H值為3時,沸石對鎘離子的去除率為83.57%,p H值在5~10范圍內(nèi)時,沸石對鎘的吸附呈現(xiàn)先增大后減小的趨勢,在p H為7時達到最大值99.22%;p H值3~6范圍時,生物質(zhì)炭對鎘吸附能力受到的影響產(chǎn)生小幅度波動;在p H為8~10范圍內(nèi)生物質(zhì)炭受p H值的影響較小,對鎘的吸附率穩(wěn)定在95.23%左右;活性炭受p H的影響較小。沸石和活性炭對于鎘的吸附在固液比為3左右時達到了吸附平衡,而不同固液比對生物質(zhì)炭的影響不是很明顯。在溫度的影響下,生物質(zhì)炭和沸石對鎘的吸附能力隨溫度的升高而變化不大;而活性炭對鎘的去除率隨著溫度的升高而呈現(xiàn)先升高后降低的趨勢。沸石對鎘飽和吸附量達到3.205mg/g。三種吸附材料對鎘離子的吸附都可以用準二級動力學模型描述,并且均符合Langmuir吸附等溫式,沸石、生物質(zhì)炭和活性炭的R2分別為0.9872、0.9422和0.9911。多種吸附材料聯(lián)合吸附顯著提高了污水中鎘的去除率,對比三種吸附材料不同組合形式對鎘去除效果發(fā)現(xiàn),吸附材料最佳組合形式是沸石—活性炭—生物質(zhì)炭,其對鎘離子的去除率達到85%。
[Abstract]:With the rapid development of social economy in China, water pollution is becoming more and more serious, especially heavy metal pollution. Cadmium ion has been identified as a priority research object by the World Health Organization. It is stipulated in the national environmental protection law of our country that the dilution method should not be used to deal with cadmium. It can be seen that the problem of cadmium pollution has a great impact on the global scope and has been attached importance to. The methods of treating metal cadmium ions include chemical precipitation method, physical adsorption method and biological adsorption method. Physical adsorption method is the most commonly used treatment method, which has the advantages of easy availability of materials, simple operation, simple process flow and low cost. The commonly used adsorption materials are zeolites, activated carbon, moisturizing soil, ceramsite and so on. Biomass carbon is a hot adsorption material at present. However, the adsorption effect of a kind of packing is limited, so it is often necessary to improve the properties of the adsorption material by modifying the adsorption material, which greatly increases the operating cost of the adsorption method, and the operation is more complex. If the combination of various adsorption materials can improve the adsorption effect, then the operation cost can be greatly saved and the operation can be simplified in the treatment of sewage. In this paper, activated carbon, zeolites and biomass carbon were used as adsorption materials. The, p H value, solid-liquid ratio, temperature and initial cadmium ion concentration at different time were studied by static adsorption experiments. The effects of different adsorption materials on the adsorption of cadmium ions were discussed by simulated sewage treatment experiment by unit column, and the best combination of cadmium ions treatment was selected by discussing the effects of different adsorption materials and their combinations on the removal of cadmium ions. The results show that the adsorption rate of cadmium can reach 99% when 20min is adsorbed by activated carbon, the adsorption equilibrium can be reached when the adsorption time is 1 h, and the removal rate of cadmium ion can reach 99.5%. Both zeolites and biomass carbon reached adsorption equilibrium at 1 h, and the removal rates of cadmium ion were 99.75% and 95.25%, respectively. Under different pH conditions, the low pH value has a great effect on the adsorption of cadmium by zeolites. When the pH value is 3, the removal rate of cadmium ions by zeolites is 83. 57%, and the pH value is in the range of 5: 10. The adsorption of cadmium by zeolites increased at first and then decreased, and reached the maximum value of 99.22% when pH was 7. When the pH value is 3 鈮，

本文編號：2479347