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Pilot-scale valorization of hazardous aluminum dross into γ-Al2O3 nanoadsorbent for efficient removal of fluoride
Environmental Technology & Innovation ( IF 6.7 ) Pub Date : 2021-04-20 , DOI: 10.1016/j.eti.2021.101549
Mostafa Mahinroosta , Ali Allahverdi

In this study, secondary aluminum dross as an alumina-rich resource was valorized into the gamma-aluminum oxide (γ-Al2O3) via a pilot-scale extraction system. The pilot-scale process was designed for a total γ-Al2O3 production of 5 kg/day. The extraction process included leaching, precipitation, hydroxide separation, aluminum hydroxide re-precipitation, drying and high-temperature dihydroxylation The obtained γ-Al2O3 was then characterized using XRD, XRF, BET, and FESEM. The XRD analysis disclosed the emergence of the gamma-crystalline phase with a crystallite size of 19.6nm. The XRF revealed a purity of more than 99 wt%. The BET surface area, pore volume, and mean pore size were 170 m2/g, 0.45cm 3/g, and 17.4nm, respectively. The FESEM and TEM indicated that the as-synthesized γ-Al2O3 was in the form of agglomerates, consisting of <20nm particles. The γ-Al2O3 was then used to adsorb aqueous fluoride with two different concentrations of 10 and 20 ppm. The adsorption results revealed that the amount of fluoride adsorbed by γ-Al2O3 was 16.5 mg/g when adsorbent dosage, initial fluoride concentration, pH, and equilibrium time were 1 g/l, 20 ppm, 4, and 1 h, respectively. The maximum monolayer adsorption was obtained 35.6 mg/g by Langmuir model. Investigating the influence of the adsorbent dosage indicated that the adsorbent dosage of 4 g/l resulted in 98% fluoride removal. It was found that fluoride adsorption occurred through chemisorption, and carbonate and phosphate anions had the most interference with fluoride adsorption. The regeneration experiments showed that the regenerated γ-Al2O3 can exhibit good fluoride adsorption performance, even after 8 times regeneration. 



中文翻译:

对有害铝渣进行中试评估 γ-铝2个Ø3 纳米吸附剂可有效去除氟化物

在这项研究中,将次生铝渣作为一种富含氧化铝的资源转化为γ-氧化铝(γ-Al 2 O 3)通过中试规模的提取系统。中试规模的过程是为总体设计的 γ-Al 2 O 3生产 5公斤/天。萃取过程包括浸出,沉淀,氢氧化物分离,氢氧化铝再沉淀,干燥和高温二羟基化。 γ然后使用XRD,XRF,BET和FESEM对-Al 2 O 3进行表征。XRD分析揭示了出现了具有19.6nm微晶尺寸的γ晶相。XRF显示纯度大于99重量%。BET表面积,孔体积和平均孔径为 分别为170 m 2 /g、0.45cm 3 / g和17.4nm。FESEM和TEM表明合成后的 γ-Al 2 O 3为附聚物形式,由<20nm的颗粒组成。这 γ然后,使用-Al 2 O 3吸附具有两种不同浓度的10和20 ppm的氟化物水溶液。吸附结果表明,氟的吸附量为 γ当吸附剂量,初始氟化物浓度,pH和平衡时间分别为1 g / l,20 ppm,4和1 h时,-Al 2 O 3为16.5 mg / g。通过Langmuir模型获得最大单层吸附为35.6mg / g。研究吸附剂剂量的影响表明,吸附剂剂量为4 g / l导致98%的氟化物去除。发现氟化物的吸附是通过化学吸附发生的,而碳酸根和磷酸根阴离子对氟化物的吸附影响最大。再生实验表明,再生 γ-Al 2 O 3甚至在再生8次后仍具有良好的氟化物吸附性能。 

更新日期:2021-04-20
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