Remediation of copper contaminated soil by char derived from used disposable baby diapers
利用废旧婴儿尿布焦炭修复铜污染土壤

摘要

由于一次性塑料消费量的增加，塑料（包括用过的一次性婴儿尿布（UDD））正成为日益严重的土壤污染物。UDD含有50%的塑料，例如高吸水性聚合物，需要100多年才能降解。本研究重点研究了热解作为一种回收方法，从UDD中生产塑料炭，评估了其作为土壤中固定污染土壤中铜的改良剂的有效性。向未受污染的土壤中添加（240 mg/kg）硫酸铜（ll）。根据UDD的热重分析，选择550°C作为热解温度。在将产生的塑料炭施用于土壤之前，对其进行了表征。在以0%（对照），1%和2.5%的比例施用塑料炭后，对受污染的土壤进行培养。培养一个月后，通过使用1M NH4OAc的单次萃取和使用0.01M CaCl2的连续萃取来测量Cu的固定化。分析了土壤pH值、电导率以及Na、Mg、K、P、Ca和N的有效性。连续萃取分析表明，用塑料炭处理的土壤中可提取的Cu浓度显著降低（p < 0.05），塑料炭对铜的固定率为86%。两种塑料炭剂量的降低都是一致的。塑料炭的性质，例如其高pH值（11.27）、灰分含量（36.68%）和电导率-EC（0.03dS/m），可能有助于提高土壤pH值并促进Cu的固定。此外，塑料炭表面存在CH、C=O、OH、NH、PH和C-Cl等功能团和羧酸类功能团，以及其高固定碳含量（48.14%），可能支持Cu的固定。此外，它在550°C时具有70 cmol+ kg-1，这些发现表明，UDD产生的塑料炭可有效用于固定污染土壤中的Cu。UDD的热解代表了一种有前途的废物管理实践，可最大限度地减少环境污染。

Abstract

Plastic, including used disposable baby diapers (UDD), is a growing soil pollutant due to increasing single-use plastic consumption. UDDs contain 50% plastic such as super absorbent polymers that take over 100 years to degrade. This study focused on pyrolysis as a recycling method to produce plastic char from UDDs, evaluating its efficacy in the soil as an amendment to immobilize the copper in contaminated soil. Uncontaminated soil was spiked (240 mg/kg) with copper (ll) sulphate. Based on the thermogravimetric analysis of UDD, 550°C was selected as the pyrolysis temperature. The plastic char produced was characterized before being applied to the soil. The contaminated soil was incubated after applying plastic char at the rates of 0% (control), 1%, and 2.5%. Immobilization of Cu was measured after one month of incubation by single extraction using 1M NH4OAc and consecutive extraction using 0.01 M CaCl2 methods. The soil pH, electrical conductivity, and availability of Na, Mg, K, P, Ca, and N were analysed. The consecutive extraction analysis revealed a significant (p<0.05) reduction in extractable Cu concentration in the soil treated with plastic char and the immobilization percentage of copper by plastic char was 86%. The decrease was uniform for both plastic char doses. The properties of plastic char, such as its high pH (11.27), ash content (36.68%), and Electrical conductivity-EC (0.03 dS/m), likely contributed to increasing soil pH and facilitating Cu immobilization. Furthermore, the presence of functional groups such as C-H, C=O, OH, N-H, P-H, and C-Cl and carboxylic acid-like functional groups on the surface of plastic char, along with its high fixed carbon content (48.14%), likely supported the immobilization of Cu. In addition, it has 70 cmol+kg-1 at 550°C. These findings indicate that plastic char derived from UDD can be effectively utilized to immobilize Cu in contaminated soil. The pyrolysis of UDD represents a promising waste management practice that minimizes environmental pollution.