Saini Saraswati, Katnoria Jatinder Kaur, Kaur Inderpreet
1Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar, Punjab - 143005 India.
2Department of Chemistry, Centre for Advanced Studies, Guru Nanak Dev University, Amritsar, Punjab - 143005 India.
J Environ Health Sci Eng. 2019 Feb 9;17(1):259-272. doi: 10.1007/s40201-019-00345-2. eCollection 2019 Jun.
Release of cadmium, a non-essential and highly toxic heavy metal, into aquatic ecosystem through discharge of effluents from various industries such as electroplating, photographic, steel/iron production and tanneries, is of considerable environmental conern at global level. Hence, it is essential to develop economic methods to remove cadmium from industrial effluents before their discharge into water bodies. The aim of present study was to explore the efficiency of Nitrilotriacetic acid (NTA) for the surface modification of charcoal powder (DCP) and application of both unmodified DCP and NTA modified DCP (NTA-MDCP) as adsorbents to remove cadmium (II) ions from aqueous solution. Isotherms, thermodynamic and kinetic studies were carried out to describe the adsorption behavior of both adsorbents for the removal of Cd(II) ions. Maximum adsorption capacity calculated from Langmuir isotherm was found to be higher for NTA-MDCP (166.66 mg/g) as compared to DCP (142.85 mg/g) which may be attributed to the complex formation (1:1 & 2:1) between NTA on the surface of adsorbent and Cd(II) ions in the solution at optimum conditions: pH = 6, temperature = 25 °C, adsorbent dose = 2 g/l and contact time = 2 h. Thermodynamic studies confirmed endothermic as well as spontaneous nature of adsorption process and kinetic investigation revealed that the adsorption process followed pseudo second-order for both DCP and NTA-MDCP. Physical characterization of both adsorbents before and after adsorption was studied using Scanning Electron Microscope, Brunauer-Emmett-Teller surface analyzer, Energy Dispersion X-ray Spectrometer, CHNS analyzer and X-Ray diffractometer which confirmed the adsorption of cadmium(II) ions. Further, the desorption studies for regeneration of adsorbents were successfully carried out using two eluents viz., 1 M sulfuric acid and 0.5% calcium chloride. The present study revealed that NTA-MDCP could be used as an effective adsorbent for the removal of cadmium(II) ions from aqueous solution.
镉是一种非必需且剧毒的重金属，通过电镀、摄影、钢铁生产和制革等各类行业的废水排放进入水生生态系统，这在全球范围内引起了相当大的环境关注。因此，开发经济的方法在工业废水排放到水体之前去除其中的镉至关重要。本研究的目的是探索次氮基三乙酸（NTA）对炭粉（DCP）进行表面改性的效率，以及未改性的DCP和NTA改性的DCP（NTA-MDCP）作为吸附剂从水溶液中去除镉（II）离子的应用。进行了等温线、热力学和动力学研究以描述两种吸附剂对去除Cd（II）离子的吸附行为。由朗缪尔等温线计算得出，NTA-MDCP（166.66 mg/g）的最大吸附容量高于DCP（142.85 mg/g），这可能归因于在最佳条件（pH = 6、温度 = 25°C、吸附剂剂量 = 2 g/l、接触时间 = 2 h）下，吸附剂表面的NTA与溶液中的Cd（II）离子形成了络合物（1:1和2:1）。热力学研究证实了吸附过程的吸热以及自发性质，动力学研究表明DCP和NTA-MDCP的吸附过程均遵循准二级动力学。使用扫描电子显微镜、布鲁诺尔-埃米特-泰勒表面分析仪、能量色散X射线光谱仪、CHNS分析仪和X射线衍射仪对吸附前后两种吸附剂进行了物理表征，证实了镉（II）离子的吸附。此外，使用两种洗脱剂即1 M硫酸和0.5%氯化钙成功进行了吸附剂再生的解吸研究。本研究表明，NTA-MDCP可作为从水溶液中去除镉（II）离子的有效吸附剂。
