Organic pollutants are widespread and a known problem for the environment. p-nitrophenol (PNP) is one such pollutant found in effluents from various industries involved with pesticides, pharmaceuticals, petrochemicals, plastic, paper, and other materials. The objective of this research was to prepare and test organically modified clays using four different surfactants and to evaluate the removal efficiency of PNP from aqueous solutions. Organically modified clays have attracted great interest due to their wide applications in industry and environmental protection as sorbents for organic pollutants. Two natural smectite-dominated clay types from outcrops in Latvia and Lithuania as well as industrially manufactured montmorillonite (Mt) clay were modified using different nonionic (4-methylmorpholine N-oxide (NMO) and dimethyldodecylamine N-oxide (DDAO)) and cationic (benzyltrimethyl ammonium chloride (BTMAC) and dodecyltrimethyl ammonium chloride (DTAC)) surfactants. Modified clay materials were characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and the Brunauer-Emmett-Teller method (BET) for surface area analysis. Sorption of PNP was investigated under various conditions, e.g. surfactant loading, initial PNP concentration, contact time, and pH. The novelty of the present study was to prepare innovative organo-sorbents based on manufactured as well as natural clay samples using cationic surfactants and nonconventional nonionic surfactants as modifiers. The sorption data combined with FTIR and XRD supplementary results suggests that nonionic organo-clay (Mt-DDAO_2) is the most effective sorbent and may serve as a low-toxicity immobilizer of pollutants such as phenols.

中文翻译：

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用于去除对硝基苯酚的表面活性剂改性粘土吸附剂

有机污染物分布广泛，是众所周知的环境问题。对硝基苯酚 (PNP) 是一种此类污染物，存在于涉及杀虫剂、制药、石化、塑料、造纸和其他材料的各个行业的废水中。本研究的目的是使用四种不同的表面活性剂制备和测试有机改性粘土，并评估从水溶液中去除 PNP 的效率。有机改性粘土作为有机污染物的吸附剂，在工业和环境保护中的广泛应用引起了人们的极大兴趣。使用不同的非离子（4-甲基吗啉 N-氧化物 (NMO) 和二甲基十二烷胺 N-氧化物 (DDAO)）和阳离子（苄基三甲基氯化铵 (BTMAC) 和十二烷基三甲基氯化铵 (DTAC)) 表面活性剂。改性粘土材料通过傅里叶变换红外 (FTIR) 光谱、X 射线衍射 (XRD)、扫描电子显微镜 (SEM) 和用于表面积分析的 Brunauer-Emmett-Teller 方法 (BET) 进行表征。在各种条件下研究了 PNP 的吸附，例如表面活性剂负载、初始 PNP 浓度、接触时间和 pH 值。本研究的新颖之处在于使用阳离子表面活性剂和非常规非离子表面活性剂作为改性剂，基于人造和天然粘土样品制备创新的有机吸附剂。吸附数据结合 FTIR 和 XRD 补充结果表明，非离子有机粘土 (Mt-DDAO_2) 是最有效的吸附剂，可作为苯酚等污染物的低毒固定剂。