Department of Civil Engineering, National Chi Nan University, Puli, Nantou, 545301, Taiwan.
Department of Civil Engineering, National Chi Nan University, Puli, Nantou, 545301, Taiwan.
Chemosphere. 2023 Aug;333:138954. doi: 10.1016/j.chemosphere.2023.138954. Epub 2023 May 16.
Groundwater contamination by chlorinated solvents causes potential threats to water resources and human health. Therefore, it is important to develop effective technologies to remediate contaminated groundwater. This study uses biodegradable hydrophilic polymers, hydroxypropyl methylcellulose (HPMC), hydroxyethyl cellulose (HEC) and polyvinyl pyrrolidone (PVP) as binders to manufacture persulfate (PS) tablets for the sustained release of persulfate to treat trichloroethylene (TCE) in groundwater. The release time for different tablets decreases in the order: HPMC (8-15 days) > HEC (7-8 days) > PVP (2-5 days). The efficiency with which persulfate is released is: HPMC (73-79%) > HEC (60-72%) > PVP (12-31%). HPMC is the optimal binder for the manufacture of persulfate tablets and persulfate is released from a tablet of HPMC/PS ratio (wt/wt) of 4/3 for 15 days at a release rate of 1127 mg/day. HPMC/PS/biochar (BC) ratios (wt/wt/wt) between 1/1/0.02 and 1/1/0.0333 are suitable for PS/BC tablets. PS/BC tablets release persulfate for 9-11 days at release rates of 1243 to 1073 mg/day. The addition of too much biochar weakens the structure of the tablets, which results in a rapid release of persulfate. TCE is oxidized by a PS tablet with an efficiency of 85% and a PS/BC tablet eliminates more TCE, with a removal efficiency of 100%, due to oxidation and adsorption during the 15 days of reaction. Oxidation is the predominant mechanism for TCE elimination by a PS/BC tablet. The adsorption of TCE by BC fits well with the pseudo-second-order kinetics and the pseudo-first-order kinetics, which describes the removal of TCE by PS and PS/BC tablets. The results of this study show that a PS/BC tablet can be used in a permeable reactive barrier for long-term passive remediation of groundwater.
地下水受氯化溶剂污染会对水资源和人类健康造成潜在威胁。因此，开发有效的技术来修复受污染的地下水非常重要。本研究使用可生物降解的亲水性聚合物羟丙基甲基纤维素（HPMC）、羟乙基纤维素（HEC）和聚乙烯吡咯烷酮（PVP）作为粘结剂，制造过硫酸盐（PS）片剂，以实现过硫酸盐的持续释放，从而处理地下水中的三氯乙烯（TCE）。不同片剂的释放时间顺序递减：HPMC（8-15 天）>HEC（7-8 天）>PVP（2-5 天）。过硫酸盐的释放效率为：HPMC（73-79%）>HEC（60-72%）>PVP（12-31%）。HPMC 是制造过硫酸盐片剂的最佳粘结剂，HPMC/PS（质量比）为 4/3 的片剂在 15 天内以 1127mg/天的释放速率释放过硫酸盐。PS/BC（生物炭）的 HPMC/PS/BC（质量比）在 1/1/0.02 到 1/1/0.0333 之间适用于 PS/BC 片剂。PS/BC 片剂以 1243 至 1073mg/天的释放速率释放过硫酸盐，持续 9-11 天。添加过多的生物炭会削弱片剂的结构，导致过硫酸盐快速释放。PS 片剂氧化 TCE 的效率为 85%，PS/BC 片剂在 15 天的反应时间内通过氧化和吸附作用，消除更多的 TCE，去除效率达到 100%。氧化是 PS/BC 片剂去除 TCE 的主要机制。BC 对 TCE 的吸附符合准二级动力学和准一级动力学，这两种动力学描述了 PS 和 PS/BC 片剂对 TCE 的去除。本研究结果表明，PS/BC 片剂可用于可渗透反应屏障，对地下水进行长期被动修复。
