Environmental Technology Division, Council of Scientific & Industrial Research-Central Leather Research Institute, Adyar, Chennai, 600 020 Tamil Nadu, India.
Environ Sci Pollut Res Int. 2013 Jan;20(1):533-42. doi: 10.1007/s11356-012-0911-3. Epub 2012 May 5.
Ammonium ions are one of the most encountered nitrogen species in polluted water bodies. High level of ammonium ion in aqueous solution imparts unpleasant taste and odor problems, which can interfere with the life of aquatics and human population when discharged. Many chemical methods are developed and being used for removal of ammonium ion from aqueous solution. Among various techniques, adsorption was found to be the most feasible and environmentally friendly with the use of natural-activated adsorbents. Hence, in this study, coconut shell-activated carbon (CSAC) was prepared and used for the removal of ammonium ion by adsorption techniques. Ammonium chloride (analytical grade) was purchased from Merck Chemicals for adsorption studies. The CSAC was used to adsorb ammonium ions under stirring at 100 rpm, using orbital shaker in batch experiments. The concentration of ammonium ion was estimated by ammonia distillate, using a Buchi distillation unit. The influence of process parameters such as pH, temperature, and contact time was studied for adsorption of ammonium ion, and kinetic, isotherm models were validated to understand the mechanism of adsorption of ammonium ion by CSAC. Thermodynamic properties such as ∆G, ∆H, and ∆S were determined for the ammonium adsorption, using van't Hoff equation. Further, the adsorption of ammonium ion was confirmed through instrumental analyses such as SEM, XRD, and FTIR. The optimum conditions for the effective adsorption of ammonium ion onto CSAC were found to be pH 9.0, temperature 283 K, and contact time 120 min. The experimental data was best followed by pseudosecond order equation, and the adsorption isotherm model obeyed the Freundlich isotherm. This explains the ammonium ion adsorption onto CSAC which was a multilayer adsorption with intraparticle diffusion. Negative enthalpy confirmed that this adsorption process was exothermic. The instrumental analyses confirmed the adsorption of ammonium ion onto CSAC.
铵离子是受污染水体中最常见的氮物种之一。高浓度的铵离子会在水溶液中产生不良的味道和气味问题，如果排放到水中，会干扰水生生物和人类的生活。许多化学方法被开发并用于从水溶液中去除铵离子。在各种技术中，吸附被发现是最可行和最环保的，使用天然活化吸附剂。因此，在这项研究中，我们制备了椰子壳活性炭（CSAC），并通过吸附技术将其用于去除铵离子。氯化铵（分析纯）购自默克化学品公司，用于吸附研究。CSAC 用于在搅拌下吸附铵离子，搅拌速度为 100rpm，使用轨道振荡器进行批处理实验。使用 Buchi 蒸馏装置通过氨蒸馏来估计铵离子的浓度。研究了 pH 值、温度和接触时间等工艺参数对铵离子吸附的影响，并验证了动力学和等温线模型，以了解 CSAC 吸附铵离子的机制。使用 van't Hoff 方程确定了铵吸附的热力学性质，如 ∆G、∆H 和 ∆S。进一步通过 SEM、XRD 和 FTIR 等仪器分析确认了铵离子的吸附。发现 CSAC 有效吸附铵离子的最佳条件为 pH 值 9.0、温度 283K 和接触时间 120min。实验数据最符合伪二级方程，吸附等温线模型符合 Freundlich 等温线。这解释了铵离子在 CSAC 上的吸附，这是一种多层吸附，伴有颗粒内扩散。负焓证实了该吸附过程是放热的。仪器分析证实了铵离子在 CSAC 上的吸附。
