饮用水用竹炭的制备及工艺研究

发布时间：2018-09-12 17:21

【摘要】：竹炭是竹材在无氧或缺氧条件下高温热解得到的产物,竹炭产业在我国已初具规模,开发了许多产品,但在饮用水用竹炭领域存在市场先行研究滞后,竹炭本身的重金属含量,矿物质含量,饮用水应用情况及其作用机理鲜有报道,通过这些研究可为饮用水竹炭的生产和应用提供理论依据。本文选用不同立地条件、部位、竹龄的毛竹,在炭化温度650℃/750℃,反应时间3 h/5 h炭化工艺条件下,按照L9(34)×L4(23)正交乘积法设计试验方案,在机械炭化炉中制得竹炭;采用比表面积测定仪、电感耦合等离子光谱发射光谱仪等仪器,参照国家相关标准分别对其灰分、挥发分、固定碳、密度、比表面积和溶解pH值等理化性能及微量元素含量进行测试、分析和比较,得出各因素及其相互间交互作用的影响;从中筛选出不同重金属含量的几组竹炭进行饮用水应用试验,从煮水炭水比例、沸腾时间、循环次数、水质,沸水冲泡及常温浸渍等诸因素考虑试验,最终获得竹炭饮用水应用的最佳工艺;并利用傅立叶红外光谱仪、孔隙度测试分析仪、超景深三维显微镜和粉末X-射线衍射仪,分别对竹炭煮水前后官能团变化、微观结构变化及晶体结构变化进行了表征与分析,初步探索了竹炭饮用水应用作用机理。研究结果表明:不同因素对竹炭的理化性能及微量元素含量有不同程度的影响,竹炭应用于饮用水主要受常量元素溶解量及溶解焦油量的影响,而与竹炭本身重金属含量影响小,自身重金属几乎不会溶解到水中。(1)在本试验条件下,炭化工艺与原料条件及其交互作用对竹炭灰分、挥发分及固定碳有不同程度的影响,未经营的毛竹稍部在750℃/3 h下炭化时灰分含量较少;反应时间5 h时挥发分含量较少;炭化温度750℃时固定碳含量比650℃的高。本试验竹炭的密度在0.367-0.705 g·cm-3之间,主要与毛竹部位的选择有关。本试验竹炭比表面积受炭化温度的影响明显,也与毛竹部位的选择和反应时间大小有关,毛竹稍部在750℃/3 h下炭化比表面积较大。本试验竹炭的溶解pH值在7.02-9.57之间,均属于碱性,适合饮用水应用。(2)毛竹砷(As)、铅(Pb)、镉(Cd)含量及钾(K)、钙(Ca)、钠(Na)、镁(Mg)、磷(P)、硫(S)常量元素总含量随竹龄的增加而增加,从稍部到基部依次增加,且与土壤中含量密切相关;各因素影响程度从大到小均依次为立地条件、毛竹部位和竹龄。毛竹炭化后其As、Pb、Cd含量及常量元素总含量都有一定程度的降低,炭化工艺与原料条件及其交互作用有不同程度的影响,未经营的毛竹稍部在750℃/3 h下炭化As、Pb、Cd含量较少。毛竹基部在650℃/5 h的条件下炭化常量元素总含量较高。(3)竹炭用于自来水煮水、冲泡或浸渍,持续煮水或循环煮水,用于超纯水、矿物质水及自来水煮水,其饮用水微量元素指标均符合生活饮用水卫生标准GB5749-2006,竹炭煮水或沸水冲泡后自来水常量元素总含量增加明显,焦油含量也增加,竹炭煮水或沸水冲泡的较佳炭水比例为1:75。随着竹炭常温浸渍时间或煮水沸腾时间的增加,常量元素总含量增加明显,同时焦油含量也增加,竹炭常温浸渍饮用水3 h前饮用较佳;沸腾时间应尽量不超过30 min。随着竹炭煮水的循环使用,对焦油的溶解量降低,竹炭煮水至少可循环使用4次。竹炭对不同水质中微量元素吸附溶解量不同,会溶解常量元素和少量的焦油,从而增加水质的色度和浊度,但影响不大,满足生活饮用水卫生标准GB 5749-2006;同时竹炭煮水可以吸附自来水中的余氯。(4)傅立叶红外光谱仪对竹炭煮水前后官能团分析表明,竹炭中可能存在醇或酚中缔合的-OH,它在酸性条件下,与溶液中的H+作用而形成-OH2+等酸性官能团正离子而发生化学吸附;煮水对竹炭的化学结构影响不大。利用比表面积及孔隙度分析仪对竹炭煮水前后孔隙结构进行表征,竹炭煮水后其比表面积提高,平均孔径变小,比孔容增加。用超景深三维显微镜对竹炭煮水前后孔隙进行了观测,发现许多裂纹,这些裂纹可能是竹炭孔隙结构中的中孔及微孔,起到了主要的物理吸附作用。竹炭煮水前后XRD分析表明,竹炭煮水前后本身组成总体上变化较小,推测竹炭煮水以物理变化为主,兼具少量化学变化,即竹炭可以循环重复应用于饮用水煮水。综合分析本试验竹炭理化性能和微量元素含量及饮用水应用试验,饮用水用竹炭的较佳生产工艺为未经营的毛竹基部在650℃/5 h下炭化,可以应用于纯水、矿物质水及自来水等,应用方法可以是煮水、沸水冲泡和常温浸渍,工艺以炭水比例1:75,煮水沸腾时间不超过30 min,煮水循环使用4次以上,常温浸渍3 h前饮用为佳。
[Abstract]:Bamboo charcoal is the product of bamboo pyrolysis under anaerobic or anoxic conditions at high temperature. Bamboo charcoal industry has taken shape in China and developed many products. However, in the field of bamboo charcoal for drinking water, the market research lags behind. The heavy metal content, mineral content of bamboo charcoal itself, the application of drinking water and its mechanism of action are rarely reported. In this paper, bamboo charcoal from different site conditions, locations and bamboo ages was prepared by orthogonal product method of L9(34)*L4(23) in a mechanical carbonization furnace under the carbonization conditions of 650 C/750 C and reaction time of 3 h/5 H. The physical and chemical properties of ash, volatile matter, fixed carbon, density, specific surface area and dissolved pH value and the content of trace elements were tested and analyzed respectively according to the relevant national standards by ICP-AES, ICP-AES and other instruments. Several groups of bamboo charcoal with metal content were tested in drinking water, including the ratio of boiled charcoal to water, boiling time, cycle times, water quality, boiling water immersion and room temperature impregnation, and the optimum process for bamboo charcoal drinking water was obtained. The changes of functional groups, microstructure and crystal structure of bamboo charcoal before and after boiling were characterized and analyzed by powder X-ray diffraction. The application mechanism of bamboo charcoal in drinking water was preliminarily explored. Water is mainly affected by the solubility of major elements and the amount of dissolved tar, but the content of heavy metals in bamboo charcoal has little effect, and the heavy metals in bamboo charcoal can hardly dissolve into water. (1) Under the experimental conditions, the carbonization process and raw material conditions and their interaction have different degrees of influence on ash, volatile matter and fixed carbon of bamboo charcoal, and the wool without operation. The density of bamboo charcoal was between 0.367 and 0.705 g.cm-3, which was mainly related to the selection of bamboo parts. The specific surface area of bamboo slices is larger at 750 C/3 H. The pH value of bamboo charcoal is between 7.02 and 9.57, which is alkaline and suitable for drinking water. (2) The contents of As, Pb, Cd, K, Ca, Na, Mg, P and S in Phyllostachys pubescens var. pubescens var. pubescens var. pubescens var. pubescens var. pubescens var. pubescens var. pubescens var. pubescens var. pubescens var. pubescens var. pubescen The content of As, Pb, Cd and the total content of major elements of Phyllostachys pubescens decreased to a certain extent after carbonization, and the interaction between carbonization process and raw material conditions and their interactions. The content of As, Pb and Cd in the base of the bamboo is higher than that in the base of the bamboo. 3. Bamboo charcoal is used for tap water boiling, brewing or impregnating, continuous boiling or circulating boiling, for ultra-pure water, mineral water and tap water boiling, and for drinking water. The contents of major elements in tap water and tar increased significantly after bamboo charcoal boiling water or boiling water was brewed. The optimum ratio of charcoal boiling water to boiling water was 1:75. The bamboo charcoal should be immersed in drinking water at room temperature for 3 hours before drinking; the boiling time should not exceed 30 minutes as far as possible. Elements and a small amount of tar, thereby increasing the color and turbidity of water quality, but little impact, to meet the sanitary standards of drinking water GB 5749-2006; at the same time, bamboo charcoal boiled water can adsorb residual chlorine in tap water. (4) Fourier transform infrared spectroscopy analysis of bamboo charcoal boiled water before and after functional groups showed that there may be alcohols or phenols in the association of - OH, it in the water. Under acidic condition, the acidic functional group positive ions such as - OH2 + were formed by interaction with H + in the solution to form biochemical adsorption; boiling water had little effect on the chemical structure of bamboo charcoal. Many cracks were found in the pores of bamboo charcoal before and after boiling. These cracks may be the mesopores and micropores in the pore structure of bamboo charcoal and play a major role in physical adsorption. The physical and chemical properties of bamboo charcoal and the content of trace elements and the application test of drinking water were analyzed comprehensively. Quality water and tap water can be boiled water, boiling water and soaking at room temperature. The ratio of charcoal to water is 1:75, boiling time of boiling water is not more than 30 minutes, boiling water is recycled more than 4 times, and drinking before soaking at room temperature for 3 hours is preferred.
【学位授予单位】：浙江农林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.11

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