Vimal Vineet, Patel Manvendra, Mohan Dinesh
School of Environmental Sciences, Jawaharlal Nehru University New Delhi 110067 India
RSC Adv. 2019 Aug 23;9(45):26338-26350. doi: 10.1039/c9ra01628g. eCollection 2019 Aug 19.
Herein, biochar was produced by the slow pyrolysis of sugarcane bagasse at 500 °C in absence of oxygen. The resulting sugarcane bagasse biochar (SB500) was characterized and used for aqueous carbofuran sorptive removal. Batch carbofuran sorption studies were accomplished to ascertain the influence of solution pH, contact time, temperature (25, 35 and 45 °C) and adsorbate/adsorbent concentration. SB500 adsorbed more carbofuran at low pH values and less carbofuran at high pH values. The necessary sorption equilibrium, kinetic and thermodynamic parameters were determined. The equilibrium isotherm data were fitted to the Freundlich, Langmuir and Temkin models. The Langmuir equation best fitted the experimental sorption data. The maximum Langmuir adsorption capacity of 18.9 mg g was obtained at pH 6.0 and 45 °C. The enthalpy change (Δ°), entropy change (Δ°) and Gibbs free energy (Δ°) were evaluated. The fixed-bed carbofuran sorption studies were carried out using the optimum parameters determined the batch studies. The necessary fixed-bed design parameters were obtained. Carbofuran desorption and SB500 regeneration were successfully achieved. About 96% of the total carbofuran was successfully desorbed from the exhausted biochar using 20 mL ethanol in 10 mL increments. Moreover, a possible carbofuran adsorption mechanism has been proposed. A number of interactions including (1) hydrogen bonding of the protonated and neutral carbofuran to biochar, (2) carbofuran sorption onto biochar π-π electron donor-acceptor interactions and (3) carbofuran diffusion into the biochar pores were considered to explain the sorption mechanism. The batch and fixed-bed sorption results demonstrate that the sugarcane bagasse biochar (SB500) can be effectively used for the sustainable removal and recovery of carbofuran from water.
在此，通过在500°C无氧条件下对甘蔗渣进行慢速热解制备生物炭。对所得甘蔗渣生物炭（SB500）进行表征，并用于水中呋喃丹的吸附去除。进行了呋喃丹批量吸附研究，以确定溶液pH值、接触时间、温度（25、35和45°C）以及吸附质/吸附剂浓度的影响。SB500在低pH值下吸附更多的呋喃丹，在高pH值下吸附较少的呋喃丹。测定了必要的吸附平衡、动力学和热力学参数。将平衡等温线数据拟合到Freundlich、Langmuir和Temkin模型。Langmuir方程最适合实验吸附数据。在pH 6.0和45°C下获得的最大Langmuir吸附容量为18.9 mg/g。评估了焓变（Δ°）、熵变（Δ°）和吉布斯自由能（Δ°）。使用批量研究确定的最佳参数进行了固定床呋喃丹吸附研究。获得了必要的固定床设计参数。成功实现了呋喃丹的解吸和SB500的再生。使用20 mL乙醇，每次以10 mL递增，约96%的总呋喃丹从耗尽的生物炭中成功解吸。此外，还提出了一种可能的呋喃丹吸附机制。考虑了多种相互作用，包括（1）质子化和中性呋喃丹与生物炭的氢键作用，（2）呋喃丹通过π-π电子供体-受体相互作用吸附到生物炭上，以及（3）呋喃丹扩散到生物炭孔隙中，以解释吸附机制。批量和固定床吸附结果表明，甘蔗渣生物炭（SB500）可有效用于从水中可持续去除和回收呋喃丹。
