本文選題：生物質(zhì)炭 + 汞　； 參考：《南京師范大學(xué)》2015年碩士論文

【摘要】：目前,我國環(huán)境中汞污染日益嚴(yán)重。傳統(tǒng)處理方法存在汞去除率低,費(fèi)用昂貴、破壞土壤理化性質(zhì)等缺點(diǎn),因此迫切需要發(fā)展廢水和土壤中除汞新技術(shù)。生物質(zhì)炭作為一種新型的環(huán)境功能材料成為當(dāng)前的研究熱點(diǎn)。已有研究表明,生物質(zhì)炭對溶液和土壤中重金屬表現(xiàn)出良好的吸附性能,同時(shí)生物質(zhì)炭在改良農(nóng)業(yè)土壤、提高作物產(chǎn)量、固炭以及減少溫室氣體的排放等環(huán)境功能方面有著巨大的應(yīng)用價(jià)值。本文以木屑、稻稈、稻殼及菹草為原料,600℃下熱解制備生物質(zhì)炭,運(yùn)用掃描電鏡和傅里葉紅外光譜技術(shù)對四種不同原料制備的生物質(zhì)炭的形態(tài)結(jié)構(gòu)和表面化學(xué)特性進(jìn)行表征。通過吸附實(shí)驗(yàn)和室內(nèi)模擬實(shí)驗(yàn),分別比較了不同生物質(zhì)炭對水溶液中重金屬汞吸附特性的差異及施加生物質(zhì)炭對污染土壤環(huán)境質(zhì)量和土壤中汞的形態(tài)變化的影響,并探討了吸附動力學(xué)行為和汞的去除機(jī)理。主要研究結(jié)果如下：(1)四種生物質(zhì)炭的產(chǎn)率、灰分含量、堿性強(qiáng)弱表現(xiàn)出了很好的一致性,均為：菹草炭稻殼炭稻稈炭木屑炭。其中菹草炭、稻殼炭和稻稈炭pH值高于10,屬強(qiáng)堿性物質(zhì)。生物質(zhì)炭的含碳量大小為：木屑炭稻稈炭稻殼炭菹草炭。與其他材料相比,木材來源的生物質(zhì)炭含碳量最高,灰分含量、礦質(zhì)養(yǎng)分含量均較低。四種生物質(zhì)炭表面形態(tài)有很大差異,但均具有豐富的孔隙結(jié)構(gòu),這對于改善土壤的持水能力有非常重要的意義。FTIR分析表明,不同原料制備的生物質(zhì)炭均含有芳香基、羥基和一些含氧官能團(tuán),但吸收強(qiáng)度具有差異性。生物質(zhì)炭的酸性官能團(tuán)數(shù)量為：木屑炭稻稈炭菹草炭稻殼炭。(2)pH值對溶液中Hg2+的凈化性能影響較大,當(dāng)初始溶液pH值為5時(shí),四種生物質(zhì)炭對溶液中Hg2+的去除效果最佳。與其他三種材料相比,木屑炭對溶液中Hg2+的吸附相對較慢。Langmuir等溫方程很好地描述了木屑、稻稈和菹草炭吸附Hg2+的過程,木屑炭吸附Hg2+的能力為60.2mg/g,優(yōu)于其他三種材料。四種生物質(zhì)炭對Hg2+的吸附動力學(xué)過程符合準(zhǔn)二級動力學(xué)模型,且其吸附過程受內(nèi)擴(kuò)散和膜擴(kuò)散共同控制。SEM-EDS分析結(jié)果表明,吸附之后所有生物質(zhì)炭的能譜上均出現(xiàn)了汞峰,且吸附過程中存在離子交換作用；FTIR分析可知生物質(zhì)炭羥基和羧基與汞的絡(luò)合作用。同時(shí)生物質(zhì)炭對Hg2+的吸附機(jī)制可能涉及還原作用和陽離子-π作用。(3)添加四種生物質(zhì)炭后土壤的pH值、CEC和TOC含量均有不同程度地增加,說明生物質(zhì)炭可以改良土壤的酸度,并增加土壤的肥力。在汞濃度為50mg/kg的土壤中,生物質(zhì)炭沒有表現(xiàn)出明顯的穩(wěn)定化作用。生物質(zhì)炭對汞濃度為500mg/kg的污染土壤中的汞的穩(wěn)定作用比較明顯,添加生物質(zhì)炭將土壤中可交換態(tài)和碳酸鹽結(jié)合態(tài)汞轉(zhuǎn)化為殘?jiān)鼞B(tài)汞。菹草炭對汞的固定效果優(yōu)于其他三種材料,而木屑炭、稻稈炭和稻殼炭對土壤中汞的修復(fù)效果不具有顯著性差異。(4)固-液體系中,經(jīng)典動力學(xué)吸附方程存在吸附劑濃度效應(yīng)和參數(shù)的不確定性現(xiàn)象,在實(shí)際應(yīng)用中存在局限性。SCA-準(zhǔn)二級速率方程可以準(zhǔn)確地描述木屑炭-Hg(Ⅱ)體系吸附動力學(xué)中的吸附劑濃度效應(yīng),得出不同時(shí)間點(diǎn)上的吸附量,預(yù)測值與實(shí)測值擬合較好,具有應(yīng)用價(jià)值。
[Abstract]:At present, China's environmental mercury pollution is becoming increasingly serious. The traditional processing method is low, the removal rate of mercury is expensive, destroy the shortcomings of soil physicochemical property, so there is an urgent need for development of wastewater and soil mercury removal in new technology. The biomass carbon as an environmental functional material has become the hotspot. Studies have shown that biomass and soil carbon on heavy metal solution showed good adsorption properties, and biomass carbon in improving agricultural soil, increase crop yield and has great application value of solid carbon and reduce greenhouse gas emissions and other environmental functions. In this paper, sawdust, rice straw, rice husk and crispus as raw material, preparing the pyrolysis of 600 DEG C biomass carbon was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy of four kinds of raw materials for the preparation of biomass carbon structure and surface chemical properties through adsorption experiment and application. The indoor simulation experiment, respectively. The effects of different biochar on mercury adsorption characteristics in aqueous solution and the morphological changes of soil environmental quality and pollution of mercury in soil by biochar, the removal mechanism of adsorption kinetics and mercury are discussed. The main results are as follows: (1) four kinds of biomass carbon the yield, ash content, basicity showed good consistency, are: rice husk rice straw carbon carbon potamogetoncrispus sawdust charcoal. The Potamogeton peat, rice husk and rice straw carbon pH value is higher than 10, strong alkaline substances. The size of carbon biomass carbon: rice straw sawdust charcoal carbon from rice husk carbon Potamogeton peat. Compared with other materials, the biomass carbon source of wood. The highest content of carbon, ash content, mineral nutrient content was relatively low. Four kinds of biomass carbon surface morphology are very different, but all have abundant pore structures, to improve The water holding capacity of soil is very important..FTIR analysis showed that the biomass carbon prepared by different raw materials contain aromatic radical, hydroxyl and oxygen containing functional groups, but the absorption intensity is different. The number of acidic functional groups of biochar: rice straw sawdust charcoal carbon rice husk carbon carbon crispus (2) pH value. Purification of Hg2+ in solution on the larger performance impact when the initial pH value was 5, the removal of Hg2+ in solution of four kinds of biomass carbon best. Compared with the other three kinds of materials, the adsorption of Hg2+ in solution on sawdust charcoal relatively slow.Langmuir isothermal equation well describes the process of rice straw and sawdust, Potamogeton Hg2+ adsorption capacity of peat, sawdust charcoal adsorption of Hg2+ is 60.2mg/g, better than the other three materials. The adsorption kinetics of four kinds of biomass carbon of Hg2+ follows a pseudo two order kinetics model, and the adsorption process is controlled by film diffusion and diffusion of common control .SEM-EDS analysis results show that the adsorption after all biomass carbon spectra showed peaks of mercury, and the adsorption ion exchange process in FTIR; analysis of complexation that biochar hydroxyl and carboxyl groups with mercury. At the same time the adsorption mechanism of biochar on Hg2+ may be related to the reduction and the Cation-n effect (3). Add four kinds of biomass carbon and soil pH, CEC and TOC were increased in different degrees, that biochar can improve soil acidity and increase soil fertility. The mercury concentration of 50mg/kg in soil, the biomass carbon did not show obvious stabilizing effect. The biomass carbon effect on the stabilization of mercury concentration for the pollution of mercury in soil 500mg/kg is quite obvious, adding biochar in soil exchangeable and carbonate bound mercury into residual mercury. The fixed effect is better than that of carbon on the mercury he crispus Three kinds of materials, and sawdust charcoal, rice straw and rice husk carbon restoration effect of carbon on mercury in soil has no significant differences. (4) solid - liquid system, uncertainty of the adsorbent concentration effect and the parameters in the classical kinetic adsorption equation, in the practical application of the limitation of the.SCA- can be accurately described sawdust charcoal -Hg quasi two level rate equation (II) adsorption dynamics in the adsorbent effect, the adsorption capacity of different time points, the predictive value of fitting well with the measured values, and has application value.

【學(xué)位授予單位】：南京師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X505

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