Chemical Engineering Department, School of Engineering, University of Mississippi, 134 Anderson Hall, Oxford, MS 38677-1848, USA.
Chemical Engineering Department, School of Engineering, University of Mississippi, 134 Anderson Hall, Oxford, MS 38677-1848, USA.
Ultrason Sonochem. 2019 Mar;51:20-30. doi: 10.1016/j.ultsonch.2018.09.015. Epub 2018 Sep 17.
The main objective of a series of our researches is to develop a novel acoustic-based method for activation of biochar. This study investigates the capability of biochar in adsorbing Ni(II) as a hazardous contaminant and aims at enhancing its adsorption capacity by the addition of extra nitrogen and most probably phosphorous and oxygen containing sites using an ultrasono-chemical modification mechanism. To reach this objective, biochar physically modified by low-frequency ultrasound waves (USB) was chemically treated by phosphoric acid (HPO) and then functionalized by urea (CO(NH)). Cavitation induced by ultrasound waves exfoliates and breaks apart the regular shape of graphitic oxide layers of biochar, cleans smooth surfaces, and increases the porosity and permeability of biochar's carbonaceous structure. These phenomena synergistically combined with urea functionalization to attach the amine groups onto the biochar surface and remarkably increased the adsorption of Ni(II). It was found that the modified biochar could remove > 99% of 100 mg Ni(II)/L in only six hours, while the raw biochar removed only 73.5% of Ni(II) in twelve hours. It should be noted that physical treatment of biochar with ultrasound energy, which can be applied at room temperature for a very short duration, followed by chemical functionalization is an economical and efficient method of biochar modification compared with traditional methods, which are usually applied in a very severe temperature (>873 K) for a long duration. Such modified biochars can help protect human health from metal-ion corrosion of degrading piping in cities with aging infrastructure.
本系列研究的主要目的是开发一种新颖的基于声学的生物炭活化方法。本研究考察了生物炭吸附 Ni(II)作为有害污染物的能力，并旨在通过添加额外的氮，可能还有磷和含氧官能团，利用超声化学改性机制来提高其吸附能力。为了实现这一目标，生物炭通过低频超声波（USB）物理改性，然后用磷酸（HPO）化学处理，再用尿素（CO(NH))功能化。超声波诱导的空化作用使生物炭的石墨氧化物层的规则形状剥落和破裂，清洁光滑表面，并增加生物炭碳质结构的孔隙率和渗透性。这些现象与尿素功能化协同作用，将胺基团附着在生物炭表面上，显著提高了 Ni(II)的吸附能力。研究发现，改性生物炭仅在六小时内就能去除超过 99%的 100mg/L Ni(II)，而原始生物炭在十二小时内仅去除了 73.5%的 Ni(II)。需要注意的是，与传统方法相比，用超声能对生物炭进行物理处理，然后进行化学功能化，是一种经济高效的生物炭改性方法，传统方法通常在非常恶劣的温度（>873 K）下长时间应用。这种改性生物炭有助于保护人类健康，防止基础设施老化的城市中金属离子腐蚀降解管道。
