發(fā)布時間：2018-01-16 06:02

  本文關鍵詞：楊樹葉吸附水中硝基苯研究　出處：《南京林業(yè)大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： 楊樹葉 硝基苯吸附 改性 炭化 聯(lián)用

【摘要】：近年來硝基苯污染事件時有發(fā)生,硝基苯在自然界中難以有效降解,往往需要借助吸附、高級氧化等技術進行處理。將林業(yè)廢棄物——楊樹葉進行循環(huán)利用,通過研磨成粉、制備成粒、改性、炭化和與其它工藝聯(lián)用等方式,探究楊樹葉在不同條件下對硝基苯的吸附性能,并確定其用于硝基苯吸附處理的有效工藝參數(shù),主要研究結果如下:(1)楊樹葉的主要組成元素是O、C、Si、Ca、K等,其中C重量在30%以上。通過電鏡掃描圖發(fā)現(xiàn)楊樹葉內(nèi)部具有豐富的孔隙,它們?yōu)闂顦淙~吸附水中硝基苯提供了有利的通道和空隙。(2)20°C下,投加20g/L楊樹葉粉末、成型顆粒處理10mg/L硝基苯廢水時,吸附率分別為62.7%、59%。粉末、顆粒的吸附過程分別較好地符合準一級吸附動力學模型、準二級吸附動力學模型;它們的吸附等溫線都更符合Langmuir等溫方程,是放熱吸附過程,也表明楊樹葉粉末、顆粒與硝基苯分子主要通過單層吸附發(fā)生相互作用。對吸附飽合后的楊樹葉粉末、顆粒展開6次解吸重吸附后,吸附率各為首次解吸后的2/3、3/4。(3)利用磷酸對楊樹葉進行改性時,做了改性溫度、改性劑濃度和用量三個因素的影響實驗,并由此確定了最佳改性條件:25°C;2mol/L;15ml/g。對改性后的楊樹葉做靜態(tài)吸附實驗。25°C下,向5mg/L的硝基苯溶液中分別投加35g/L的粉末和顆粒,振蕩70min和50min后,吸附率達到95%和83%。它們的吸附過程均與準二級吸附動力學模型有較好的擬合,等溫吸附符合Freundlich方程。通過紅外光譜對改性楊樹葉進行吸附的主要官能團展開分析,發(fā)現(xiàn)主要是羥基的作用。(4)在300°C下炭化楊樹葉后,對其展開吸附實驗。向10mg/L硝基苯中分別投加35g/L楊樹葉粉末、顆粒,振蕩50min后吸附率分別可達到91%、80%,較沒炭化之前提高了約30%、15%。吸附過程分別較好地符合Langmuir等溫方程和Freundlich等溫方程。(5)在與活性炭聯(lián)合吸附實驗中,為使40mg/L的硝基苯廢水達到國家排放標準,對于粉末型吸附劑,需投加4g/L的活性炭粉末和15g/L以上的楊樹葉粉末;對于顆粒型吸附劑,需投加10g/L的活性炭顆粒和至少20g/L的楊樹葉成型顆粒。在臭氧與楊樹葉吸附聯(lián)用實驗中,為使100mg/L硝基苯廢水達到國家排放標準,要先調節(jié)pH為10,在35°C下曝氣氧化35min,然后投加30g/L楊樹葉粉末或40g/L楊樹葉成型顆粒進行吸附。綜上所述,楊樹葉對硝基苯具有較好的去除能力,特別對其改性或炭化后,吸附性能明顯加強,適用于處理中低濃度的硝基苯廢水。針對較高濃度的硝基苯廢水,可以運用楊樹葉與活性炭聯(lián)合吸附、臭氧氧化與楊樹葉吸附聯(lián)用的方法使其濃度達到國家排放標準。
[Abstract]:In recent years, nitrobenzene pollution events occur from time to time, nitrobenzene in nature is difficult to effectively degrade, often need to use adsorption, advanced oxidation and other technologies to deal with the forest waste-poplar leaves for recycling. The adsorption properties of nitrobenzene in poplar leaves under different conditions were investigated by grinding, granulation, modification, carbonization and combined with other processes. The main results are as follows: (1) the main components of poplar leaves are Ocarinus sinensis, CaAK and so on. The weight of C is more than 30%. It is found that there are abundant pores in poplar leaves by scanning electron microscope, which provide favorable channels and voids at 20 擄C for absorbing nitrobenzene in water of poplar leaves. When 20 g / L poplar leaf powder was added, the adsorption rates of 10mg / L nitrobenzene wastewater were 62.7% and 59.9%, respectively. The adsorption process of the particles is in good agreement with the quasi-first-order adsorption kinetic model and the quasi-second-order adsorption kinetic model respectively. Their adsorption isotherms are more in line with the Langmuir isotherm equation, which is an exothermic adsorption process, which also indicates that poplar leaf powder. The adsorption rate of the adsorbed poplar leaf powder was 2/3 after the first desorption of poplar leaves after 6 desorption resorption. 3 / 4. 3) when poplar leaves were modified with phosphoric acid, the effects of modification temperature, concentration and dosage of modifier on poplar leaves were studied, and the optimum modification conditions were determined as follows: 25 擄C; 2 mol / L; The static adsorption experiment of modified poplar leaves was carried out at 15 ml / g. At 25 擄C, 35 g / L powder and particle were added to 5 mg / L nitrobenzene solution, respectively. After oscillating for 70min and 50min, the adsorption rates reached 95% and 83.The adsorption processes were all fitted well with the quasi-second-order adsorption kinetic model. The isothermal adsorption accords with Freundlich equation. The main functional groups of modified poplar leaves were analyzed by infrared spectroscopy. It was found that hydroxyl group mainly acted on poplar leaves at 300 擄C. after carbonization, adsorption experiments were carried out. 35g / L poplar leaf powder was added to 10mg / L nitrobenzene. After shaking for 50 minutes, the adsorption rate can reach 91% and 80% respectively, which is about 30% higher than that before carbonization. The adsorption process was in accordance with Langmuir isothermal equation and Freundlich isothermal equation respectively. In order to make the 40 mg / L nitrobenzene wastewater meet the national discharge standard, 4 g / L of activated carbon powder and 15 g / L of poplar leaf powder should be added to the powder adsorbent. For granular adsorbents, 10 g / L of activated carbon particles and at least 20 g / L of poplar leaf forming particles should be added. In order to make 100 mg / L nitrobenzene wastewater meet the national discharge standard, the pH should be adjusted to 10, and aeration oxidation at 35 擄C for 35 min. Then 30 g / L poplar leaf powder or 40 g / L poplar leaf molding particles were added for adsorption. In conclusion poplar leaves have better removal capacity of nitrobenzene especially after modification or carbonization. It is suitable for the treatment of middle and low concentration nitrobenzene wastewater. For the higher concentration of nitrobenzene wastewater, poplar leaves and activated carbon can be used to combine adsorption. The combination of ozone oxidation and poplar leaf adsorption makes its concentration up to the national emission standard.
【學位授予單位】：南京林業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X703;O647.3

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