Improved method for the formation of recycled resins from depolymerized products of waste fiber-reinforced plastics: simple and effective purification of recovered monomers by washing with water

The synthesis of recycled plastics from recovered monomeric materials obtained from the depolymerization reaction of fiber-reinforced plastics (FRP) was examined. The depolymerization reaction of FRP in the presence of N,N-dimethylaminopyridine (DMAP) smoothly yielded the corresponding monomers, which mainly consisted of dimethyl phthalates. The polymerization reaction with this monomer failed to form the corresponding unsaturated polyesters due to contamination by N-methyl-4-pyridone, a decomposition product of DMAP. An efficient purification of the recovered monomer was achieved by washing with water, and the purified monomer successfully yielded the corresponding polymers. A hardness test revealed that the polymers were as hard as the polyester made from virgin materials. The present modification provides a practical method for the preparation of recycled plastics from depolymerized plastics.     

玻璃减薄蚀刻液中氟硅酸的选择性脱除方法

光电玻璃减薄蚀刻液中氟硅酸(H2SiF6)的累积,是导致蚀刻液无法连续使用而转化为废液的主要原因。尝试对蚀刻废液中氟硅酸进行选择性脱除工艺,探索刻蚀液循环利用的有效处理方法。鉴于氟硅酸的碱金属盐具有溶解度较低的特点,研究考察了利用钠盐或钾盐为沉淀剂,将废液中的H2SiF6以氟硅酸盐的形式沉淀去除,为实现蚀刻液的循环利用提供可能。结果表明,KCl相比NaCl对H2SiF6处理效果更好,但生成的K2SiF6的结晶颗粒过细,难以自然沉降,过滤效果较差;而Na2SiF6结晶沉降特性较好,且使用NaCl为沉淀剂具有价廉易得等特点,可作为氟硅酸的理想沉淀剂。H2SiF6去除率与碱金属盐H2SiF6摩尔计量比正相关,当摩尔计量比NaCl/H2SiF6=2,H2SiF6含量10%的模拟废液,其H2SiF6去除率可达到90%以上。     

光环境污染监测分类与控制值探索

在研究分析国内外现有光污染相关技术规定的基础上,结合我国城市光污染现状,为解决我国城市光污染中危害最严重的典型问题,将我国城市光环境污染划分为玻璃幕墙眩光污染、交通道路眩光污染、居住区光污染、室外光污染源4个重点监测项目,并针对具体项目初步提出了玻璃幕墙反射眩光监测控制值、交通道路眩光监测控制值、居住区光污染监测控制值和室外光污染源监测控制值。     

利用废CRT屏玻璃为原料制备泡沫玻璃

以废阴极射线管(CRT)屏玻璃为主要原料,碳黑为起泡剂,采用粉末烧结法制备了低密度保温泡沫玻璃。通过扫描电镜(SEM)、导热系数测定仪等分析手段,研究了起泡剂的用量、发泡温度和发泡时间对泡沫玻璃泡径、密度、热学性能以及机械力学性能的影响。结果表明,在相同烧制工艺条件下,随起泡剂掺加量增加,烧制所得的泡沫玻璃密度成"V"型变化;当其掺加量为0.20%时,泡沫玻璃在密度、孔径分布以及力学性能上均达到最佳。随着发泡温度的提高和发泡时间的延长,密度会逐渐减小,泡沫玻璃的气泡会逐渐增大,以致产生连通现象。当发泡温度为820℃、发泡时间为30min时烧制的泡沫玻璃密度为0.180 g/cm3,导热系数为0.0695 W/(m.K)。     

液晶显示器玻璃基板回收工艺

利用无机溶液对废液晶显示屏的玻璃基板回收工艺作了初步的探索,根据回收处理的难易,简单地将废弃液晶显示屏分为3类:含树脂黑色矩阵膜的上层玻璃基板可以采用氢氧化钠直接浸泡处理、含铬黑矩阵膜的上层玻璃基板和下层玻璃基板可以先用氢氧化钠溶液浸泡去除偏光片,再用氢氟酸溶液浸泡处理。结果表明,利用无机溶液处理可以较快得到干净的玻璃基板,而且工艺简单、成本低。     

Compressive strength and resistance to chloride ion penetration and carbonation of recycled aggregate concrete with varying amount of fly ash and fine recycled aggregate

Construction and demolition waste has been dramatically increased in the last decade, and social and environmental concerns on the recycling have consequently been increased. Recent technology has greatly improved the recycling process for waste concrete. This study investigates the fundamental characteristics of concrete using recycled concrete aggregate (RCA) for its application to structural concrete members. The specimens used 100% coarse RCA, various replacement levels of natural aggregate with fine RCA, and several levels of fly ash addition. Compressive strength of mortar and concrete which used RCA gradually decreased as the amount of the recycled materials increased. Regardless of curing conditions and fly ash addition, the 28 days strength of the recycled aggregate concrete was greater than the design strength, 40 MPa, with a complete replacement of coarse aggregate and a replacement level of natural fine aggregate by fine RCA up to 60%. The recycled aggregate concrete achieved sufficient resistance to the chloride ion penetration. The measured carbonation depth did not indicate a clear relationship to the fine RCA replacement ratio but the recycled aggregate concrete could also attain adequate carbonation resistance. Based on the results from the experimental investigations, it is believed that the recycled aggregate concrete can be successfully applied to structural concrete members.     

Recycled crushed glass in road work applications

A comprehensive suite of geotechnical laboratory tests was undertaken on samples of recycled crushed glass produced in Victoria, Australia. Three types of recycled glass sources were tested being coarse, medium and fine sized glass. Laboratory testing results indicated that medium and fine sized recycled glass sources exhibit geotechnical behavior similar to natural aggregates. Coarse recycled glass was however found to be unsuitable for geotechnical engineering applications. Shear strength tests indicate that the fine and medium glass encompass shear strength parameters similar to that of natural sand and gravel mixtures comprising of angular particles. Environmental assessment tests indicated that the material meets the requirements of environmental protection authorities for fill material. The results were used to discuss potential usages of recycled glass as a construction material in geotechnical engineering applications particularly road works.     

利用磷渣熔制饰面玻璃

介绍了用磷渣熔饰面玻璃的试验过程。对试验中出现的工艺问题进行了探讨,并讨论经济效益进行了初步分析。     

耐蚀鳞片胶泥在脱硫烟道中的应用

本文介绍了在消化吸收国外鳞片烟道防腐内衬的基础上开发的国产鳞片胶泥材料,及其性能和应用情况。     

Leaching assessment of concrete made of recycled coarse aggregate: Physical and environmental characterisation of aggregates and hardened concrete

Each year, millions of tonnes of waste are generated worldwide, partially through the construction and demolition of buildings. Recycling the resulting waste could reduce the amount of materials that need to be manufactured. Accordingly, the present work has analysed the potential reuse of construction waste in concrete manufacturing by replacing the natural aggregate with recycled concrete coarse aggregate.However, incorporating alternative materials in concrete manufacturing may increase the pollutant potential of the product, presenting an environmental risk via ground water contamination.The present work has tested two types of concrete batches that were manufactured with different replacement percentages. The experimental procedure analyses not only the effect of the portion of recycled aggregate on the physical properties of concrete but also on the leaching behaviour as indicative of the contamination degree. Thus, parameters such as slump, density, porosity and absorption of hardened concrete, were studied. Leaching behaviour was evaluated based on the availability test performed to three aggregates (raw materials of the concrete batches) and on the diffusion test performed to all concrete.From an environmental point of view, the question of whether the cumulative amount of heavy metals that are released by diffusion reaches the availability threshold was answered. The analysis of concentration levels allowed the establishment of different groups of metals according to the observed behaviour, the analysis of the role of pH and the identification of the main release mechanisms. Finally, through a statistical analysis, physical parameters and diffusion data were interrelated. It allowed estimating the relevance of porosity, density and absorption of hardened concrete on diffusion release of the metals in study.