Hydrothermal Carbonization of Waste Stream for Bio-coal Production

废物流的水热碳化用于生产生物煤

• 批准号: 2299342
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2299342
• 关键词: Hydrothermal; Carbonization; Waste; Stream; Bio

In the UK around 93,000 tonnes of clothing waste, which typically contain 55% cotton and 23% polyester, are sent to landfill every year. Under the European Green Deal, polyester terephthalate (PET) manufacturers are under pressure to increase recycling rates to 30% by 2030. Therefore, this study focusses on using hydrothermal carbonisation (HTC) to produce terephthalic acid from both coloured PET and clothing waste containing dyes. The purity of terephthalic acid is important for recycling and typically needs to be over 99% without measurable colour for manufacturing recycled plastic. Therefore, the specific aim for this study is to purify terephthalic acid from coloured PET bottles and polyester-containing clothing waste and, for the latter, to produce a hydrochar co-product that can be used as a solid hydrochar.Prior to studying HTC of cloth containing cotton and polyester, it is important to understand the behaviours of pure cotton cloth. There are several previous studies on the HTC of cellulose, but none on cotton cloth. It was established that the main difference between cellulose and cotton cloth in HTC is the temperature at which aromatic carbon is produced in the hydrochar. These are 200 C and 240 C for cellulose and cotton cloth respectively. This is because of the flame retardants chemicals added during the cotton cloth manufacturing process. The impact of recycling the aqueous liquor was also investigated and it was found that this was beneficial for increasing the hydrochar yield for cotton cloth, implying that the water-soluble organics contribute to hydrochar formation through combination reactions. However, the increase in hydrochar yield was accompanied by a decrease in calorific value due to the oxygen content increasing.Although the hydrolysis of PET has been widely investigated, there are no previous reports on how dye can be removed effectively to produce colourless high purity terephthalic acid from coloured PET bottles. The study of hydrolysis of polyester cloth showed that unreacted polyester increased with the Run of recycling aqueous liquor, due to the reactant (water) reduction. The yield of recovered terephthalic acid also increased with recycling the aqueous liquor, due to less dissolving which could be related to the water-soluble organics and ethylene glycol presence. For the coloured PET bottles, hydrolysis took place with pure deionized water. After that, the filtered solid product was mixed with sodium hydroxide solution to produce disodium terephthalate solution. The activated carbon adsorption was successfully applied to treat the disodium terephthalate solution. The removal of dyes produced a whiter and brighter sample of terephthalic acid compared to a commercial standard sample and reached over 99 % purity.For the hydrothermal carbonisation of mixed cloth, the hydrochar yield increased on recycling the aqueous liquor containing any unprecipitated terephthalic acid and ethylene glycol. It is likely that the acid served as a catalyst to increase the hydrochar yield. This also reduced the oxygen content of the hydrochar leading to a higher calorific value. The study about producing high purity terephthalic acid from mixed cloth, needed one extra step to the process of removing dye from coloured polyethylene terephthalate bottles. The filtered HTC solid product needed heating without oxygen before being mixed with sodium hydroxide solution. After that, the other impurities, notably dyes, could be removed from the disodium terephthalate solution by activated carbon absorption as for the coloured PET bottles

在英国，每年约有93，000吨服装废料被送往垃圾填埋场，其中通常含有55%的棉花和23%的聚酯。根据欧洲绿色协议，聚酯对苯二甲酸酯（PET）制造商面临着到2030年将回收率提高到30%的压力。因此，本研究的重点是使用水热碳化（HTC），从有色PET和含染料的服装废料中生产对苯二甲酸。对苯二甲酸的纯度对于回收利用很重要，通常需要超过99%，而没有可测量的颜色来制造回收塑料。因此，本研究的具体目的是从有色PET瓶和含聚酯的衣物废料中纯化对苯二甲酸，并为后者生产可用作固体水热炭的水热炭副产品。在研究含棉和聚酯的布的HTC之前，重要的是要了解纯棉布的行为。以前有几个关于纤维素的HTC的研究，但没有关于棉布的。已经确定，HTC中纤维素和棉布之间的主要差异是在水热炭中产生芳族碳的温度。纤维素和棉布的温度分别为200 ℃和240 ℃.这是因为在棉布制造过程中添加了阻燃剂化学品。还研究了再循环水溶液的影响，发现这有利于提高棉布的水热炭产率，这意味着水溶性有机物有助于通过组合反应形成水热炭。然而，水热炭产率的增加伴随着热值的降低，这是由于氧含量的增加。虽然PET的水解已经被广泛研究，但如何有效地去除染料以从有色PET瓶中生产无色高纯度对苯二甲酸还没有以前的报道。对涤纶布水解的研究表明，随着水溶液循环使用次数的增加，反应物（水）减少，未反应的涤纶增多。回收的对苯二甲酸的产率也随着水溶液的再循环而增加，这是由于较少的溶解，这可能与水溶性有机物和乙二醇的存在有关。对于有色PET瓶，用纯去离子水进行水解。之后，将过滤的固体产物与氢氧化钠溶液混合以产生对苯二甲酸二钠溶液。采用活性炭吸附法成功地处理了对苯二甲酸二钠溶液。与商业标准样品相比，染料的去除产生更白和更亮的对苯二甲酸样品，并且达到超过99%的纯度。对于混合布的水热碳化，水热炭产率在循环含有任何未沉淀的对苯二甲酸和乙二醇的水性液体时增加。很可能酸用作催化剂以增加水热炭产率。这也降低了水热炭的氧含量，导致更高的热值。以混合布为原料生产高纯度对苯二甲酸的研究，在有色聚对苯二甲酸乙二酯瓶的脱色过程中增加了一个步骤。过滤的HTC固体产物在与氢氧化钠溶液混合之前需要在没有氧气的情况下加热。之后，其他杂质，特别是染料，可通过活性炭吸附从对苯二甲酸二钠溶液中除去，如有色PET瓶