Adsorption of Phthalic Acid Esters by Humic Acid and Its Research Progress

Humic acid is rich in highly electronegative oxygen-containing organic functional groups,so it has high reactivity and can adsorb phthalic acid ester(PAEs)in the environment to reduce the risk of environmental pollution from PAEs.In this paper,the extraction,characterization and adsorption models of humic acid were reviewed,and the research status of adsorption of PAEs by humic acid was further summarized.Based on these,the feasibility and observable application prospect of humic acid as a cheap adsorbent were analyzed.

Interaction between uranium and humic acid(Ⅰ):Adsorption behaviors of U(Ⅵ) in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) >SHA (HA from the surface) >THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was achieved at a suitable uranium concentration (10 mg·L-1 U(Ⅵ) for SHA and THA, 20 mg·L-1 U(Ⅵ) for FHA), the adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g) ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5-6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.

土壤腐殖酸的提取及其对^(241)Am的吸附

用稀碱法从核废物填埋场的土壤中提取腐殖酸,并用此腐殖酸对241Am进行吸附实验.结果表明,当241Am初始浓度为0.26~2.7×10-7mol/L,溶液pH为2~3时,腐殖酸对241Am有明显的吸附,其吸附率达90%以上;接触时间4h基本达到平衡,241Am浓度与吸附量之间的关系符合Langmuir经验公式;0℃~40℃范围内,温度对吸附无显著影响;Fe3+、EDTA和柠檬酸根等离子或基团能使腐殖酸对241Am的吸附率显著降低,而Ca2+、PO43-和SO42-等离子或基团对吸附无明显影响;溶液中Eu3+和Nd3+的浓度为241Am的2500倍或更高时,也能使腐殖酸对241Am的吸附明显降低.

土壤腐殖酸的提取及其对U(Ⅵ)的吸附

用稀碱法从拟作为核废物填埋场的土壤中提取腐殖酸并用元素分析和红外光谱进行表征。用此腐殖酸对U（Ⅵ）进行的吸附实验结果表明：当U（Ⅵ）初始总浓度为0．84×10^-4mol／L、溶液pH为3时，5mg腐殖酸可从20mL溶液中吸附U（Ⅵ）80％以上；两相接触8h后达到动态平衡；水相U（Ⅵ）浓度与吸附量之间的关系符合Langmuir经验公式；在0～40℃范围内，温度对吸附有不大的正影响；Al^3＋、Ca^2＋、Nd^3＋、Eu^3＋、CO3^2-、柠檬酸根离子、SO4^2-和EDTA等能使该腐殖酸对U（Ⅵ）的吸附率显著降低，而K^＋、NO3^-等对吸附则无明显影响。

褐煤腐植酸的抽提及其对褐煤吸水性能的影响

褐煤腐植酸含量高,腐植酸中含有多种活性基团,在工业、农业、畜牧业等领域有多种用途。褐煤直接燃烧利用率不大,因此在开发利用褐煤资源前对其进行腐植酸抽提是一种较好的提质方式。本文采用碱浸法对褐煤进行腐植酸的抽提,研究了煤样粒度、抽提条件等因素对腐植酸抽提率的影响,以及干燥的原煤、腐植酸抽提残煤和脱灰煤的水分复吸性能。结果表明:粒度在0.2mm以下的煤样,在超声波条件下抽提腐植酸效果较好;抽提残煤水分复吸率明显高于原煤,但将抽提残煤脱灰处理后,水分复吸率有明显下降,且与原煤脱灰后吸水性能相近,说明抽提残煤的吸水性与煤的孔隙率及表面的极性官能团有关,特别是碱浸法抽提腐植酸时生成的强吸水性羧酸盐类对抽提残煤吸水性有显著影响。

垃圾渗滤液中腐植酸的提取及对Cu^(2+)吸附性能

研究了垃圾渗滤液中提取腐植酸及对Cu^(2+)的吸附性能。结果表明,低温(70℃)下提取的腐植酸HA_(LT)中含有较多的O-H、-COOH、C=O等含氧官能团;高温(160℃)下提取的腐植酸HA_(HT)中含有较多的羧基的C-O、芳烃的C-H等官能团,部分含氧官能团已脱出,组成与结构已发生发化;HA_(Cu)中含有较多的芳环的C=C、羧基的O-H与C-O、芳烃的C-H官能团,组成与结构未发生太大变化,HA_(LT)的吸附性能比HA_(HT)的吸附性能好。当Cu^(2+)初始质量浓度为1.30 mg/L时,腐植酸的优化投加量为130 mg/L。腐植酸吸附时的适宜pH为5.7~6.3。腐植酸对Cu^(2+)吸附的饱和吸附量为8.31 mg/g,此吸附过程符合Langmuir等温吸附模型。

提取腐植酸后的残渣对Cu^(2+)的吸附性能研究

研究了天祝褐煤中提取腐植酸后的残渣对Cu2+的吸附性能。结果表明,在室温(20～25℃)条件下,吸附平衡时间约为5h,吸附最佳pH为5～6,相关系数R为0.9889,特性常数n为3.449。吸附符合Freundfich吸附等温式,提取腐植酸后的残渣对Cu2+有较好的吸附性能,其吸附过程可用Ho准二级反应动力学模型描述。

垃圾渗滤液中腐植酸的提取研究

采用"NF-两级物料膜-RO"的组合工艺处理垃圾渗滤液,得到膜浓缩液,再从膜浓缩液中提取两种腐植酸样品HA(Ⅰ)、HA(Ⅱ),然后对其进行了含量分析、结构分析和吸附性能研究。结果表明,样品HA(Ⅰ)中的总腐植酸含量为73.34%,游离腐植酸含量为71.12%,样品HA(Ⅱ)中黄腐酸的含量高达13.18%。两种样品中均含有较多的羧基、羰基、羟基等含氧官能团和芳烃类物质以及少量的氯化物。在25℃搅拌的条件下,腐植酸对重金属Cu^(2+)有较好的吸附效果,吸附60 min后,Cu^(2+)的去除率已达到68.4%,且在30 min时腐植酸对Cu^(2+)的吸附就已经达到饱和,说明腐植酸对Cu^(2+)的吸附速度较快。