Instituto de Pesquisas Energéticas e Nucleares, Comissão Nacional de Energia Nuclear, Av. Professor Lineu Prestes, 2242 - 05508-000, São Paulo, Brazil.
Depto. de Engenharia Química da Escola Politécnica, Universidade de São Paulo, Rua do Lago, 250 - 05508-080, São Paulo, Brazil.
Environ Pollut. 2021 Mar 1;272:116022. doi: 10.1016/j.envpol.2020.116022. Epub 2020 Nov 10.
The main aim of this study was to evaluate options for addressing two pressing challenges related to environmental quality and circular economy stemming from wastage or underutilization of abundant biomass residue resources and contamination of water by industrial effluents. In this study we focused on residues (endocarp) from Macaúba palm (Acrocomia aculeata) used for oil production, its conversion to activated biochar, and its potential use in uranium (U) removal from aqueous solutions. Batch adsorption experiments showed a much higher uranyl ions (U(VI)) removal efficiency of activated biochar compared to untreated biochar. As a result of activation, an increase in removal efficiency from 80.5% (untreated biochar) to 99.2% (after activation) was observed for a 5 mg L initial U(VI) concentration solution adjusted to pH 3 using a 10 g L adsorbent dosage. The BET surface area increased from 0.83 to 643 m g with activation. Surface topography of the activated biochar showed a very characteristic morphology with high porosity. Activation significantly affected chemical surface of the biochar. FTIR analysis indicated that U(VI) was removed by physisorption from the aqueous solution. The adsorbed U(VI) was detected by micro X-ray fluorescence technique. Adsorption isotherms were employed to represent the results of the U adsorption onto the activated biochar. An estimation of the best fit was performed by calculating different deviation equations, also called error functions. The Redlich-Peterson isotherm model was the most appropriate for fitting the experimental data, suggesting heterogeneity of adsorption sites with different affinities for uranium setting up as a hybrid adsorption. These results demonstrated that physical activation significantly increases the adsorption capacity of macauba endocarp-derived biochar for uranium in aqueous solutions, and therefore open up a potential new application for this type of waste-derived biochar.
本研究的主要目的是评估与环境质量和循环经济相关的两个紧迫挑战的解决方案，这些挑战源于丰富的生物质残余资源的浪费或未充分利用以及工业废水对水的污染。在本研究中，我们专注于用于生产油的 Macaúba 棕榈（Acrocomia aculeata）的残余物（内果皮），将其转化为活性生物炭，并将其潜在用于从水溶液中去除铀（U）。批量吸附实验表明，与未处理的生物炭相比，活性生物炭对铀酰离子（U（VI））的去除效率更高。由于活化，观察到对于初始 U（VI）浓度为 5 mg L 的溶液，在调整 pH 值至 3 时，使用 10 g L 的吸附剂剂量，从 80.5%（未处理的生物炭）到 99.2%（活化后）的去除效率提高。BET 表面积从 0.83 增加到 643 m2 g-1。活化后的生物炭的表面形貌显示出非常特征的高孔隙率形态。活化显著影响生物炭的化学表面。FTIR 分析表明，U（VI）通过从水溶液中物理吸附而被去除。通过微 X 射线荧光技术检测到吸附的 U（VI）。吸附等温线用于表示 U 吸附到活性生物炭上的结果。通过计算不同的偏差方程（也称为误差函数）来进行最佳拟合的估计。Redlich-Peterson 等温模型最适合拟合实验数据，表明吸附位点具有不同的铀亲和力，形成混合吸附，从而具有异质性。这些结果表明，物理活化显著提高了源自 Macaúba 内果皮的生物炭在水溶液中对铀的吸附能力，因此为这种源自废物的生物炭开辟了新的潜在应用。
