Zainal Zainor Syahira, Hoo Pengyong, Ahmad Abdul Latif, Abdullah Ahmad Zuhairi, Ng Qihwa, Shuit Siewhoong, Enche Ab Rahim Siti Kartini, Andas Jeyashelly
Faculty of Chemical Engineering & Technology, Universiti Malaysia Perlis, 02600 Arau, Perlis, Malaysia.
Centre of Excellence for Frontier Materials Research (CFMR), Universiti Malaysia Perlis, 02600 Arau, Perlis, Malaysia.
Heliyon. 2024 Feb 16;10(4):e26591. doi: 10.1016/j.heliyon.2024.e26591. eCollection 2024 Feb 29.
Driven by the urgent need for a solution to tackle the surge of rice husk (RH) and waste frying oil (WFO) waste accumulation at a global scale, this report highlights the use of calcium silicates (CS) extracted from acid-pre-treated rice husk ash (RHA) for free fatty acid (FFA) removal from WFO as conventional RHA shows limited FFA adsorption performance. A novel alkaline earth silicate extraction method from acid-pre-treated RHA was outlined. The structural and behavioural attributes of the synthesised CS were identified through BET, SEM-EDS, and XRD analyses and compared to those of RHA. Notable morphology and structural modification were determined, including reducing specific surface areas, mitigating from amorphous to crystalline structure with regular geometric forms, and detecting Si--Ca functional groups exclusive to CS adsorbents. A comparison study showed superior lauric acid (LA) adsorption performance by CS absorbents over acid-pre-treated RHA, with a significant increase from 0.0831 ± 0.0004 mmol LA/g to 2.5808 ± 0.0011 mmol LA/g after 60 min. Recognised as the best-performing CS adsorbent, CS-1.0 was used for further investigations on the effect of dosage, LA concentration, and temperature for efficient LA adsorption, with up to 100% LA removal and 5.6712 ± 0.0016 mmol LA/g adsorption capacity. The adsorption isotherm and kinetic studies showed LA adsorption onto CS-1.0 followed Freundlich isotherm with K = 0.0598 mmol L g & Q = 3.1696 mmol g and intraparticle diffusion model with k = 0.1250 mmol g min & C = 0.9625 mmol g, indicating rapid initial adsorption and involvement of carboxylate end of LA and the calcium ions on the CS-1.0 in the rate-limiting step. The high equilibrium adsorption capacity and LA adsorption rate indicated that the proposed CS-1.0 adsorbent has excellent potential to recover FFA from WFO effectively.
在全球范围内迫切需要解决稻壳（RH）和废弃煎炸油（WFO）废弃物堆积激增问题的推动下，本报告强调了使用从酸预处理稻壳灰（RHA）中提取的硅酸钙（CS）来去除WFO中的游离脂肪酸（FFA），因为传统的RHA显示出有限的FFA吸附性能。概述了一种从酸预处理RHA中提取碱土硅酸盐的新方法。通过BET、SEM-EDS和XRD分析确定了合成的CS的结构和行为属性，并与RHA的进行了比较。确定了显著的形态和结构变化，包括比表面积减小、从无定形结构转变为具有规则几何形状的晶体结构，以及检测到CS吸附剂特有的Si-Ca官能团。一项比较研究表明，CS吸附剂对月桂酸（LA）的吸附性能优于酸预处理的RHA，60分钟后从0.0831±0.0004 mmol LA/g显著增加到2.5808±0.0011 mmol LA/g。被认为是性能最佳的CS吸附剂的CS-1.0用于进一步研究剂量、LA浓度和温度对高效LA吸附的影响，LA去除率高达100%，吸附容量为5.6712±0.0016 mmol LA/g。吸附等温线和动力学研究表明，LA在CS-1.0上的吸附遵循Freundlich等温线，K = 0.0598 mmol L g&Q = 3.1696 mmol g，以及颗粒内扩散模型，k = 0.1250 mmol g min&C = 0.9625 mmol g，表明初始吸附迅速，且LA的羧酸末端和CS-1.0上的钙离子参与了限速步骤。高平衡吸附容量和LA吸附速率表明，所提出的CS-1.0吸附剂具有从WFO中有效回收FFA的优异潜力。
