Mercury Adsorption And Liberation Study

Author : Nur Shadia
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (143 download)

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Download or read book Mercury Adsorption on Biosorbents and an Analytical Method to Determine Ionic Mercury Using SP-ICPMS written by Nur Shadia and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Researching efficient removal techniques is essential due to the toxicity of heavy metals, even at low concentrations, and their pervasiveness in a variety of environmental settings. According to WHO, Mercury is one of the most dangerous pollutants for human health. It causes severe damage to the ecosystem and other living beings. But because of its favorable physical-chemical properties, it has been widely used in the industrial activities. Unfortunately, several rivers and aquifers are getting contaminated by this hazardous chemical and inevitably putting importance on how to solve this problem. Most importantly a cost effective and environmentally friendly methods are needed to get a sustainable solution to this contamination. In the first phase of this study, mercury treatment from aqueous solution using two bio-sorbents were investigated. Pinecones and pecan shells were chosen as bio-sorbents because of their natural abundance and cost-free availability. To the best of my knowledge, though some of the studies has been performed to remove some heavy metals by utilizing these two agricultural waste materials, none of the previous study investigated this two-potential bio-sorbents for removing mercury from water solutions. In addition, there is a chance that metals and other ions will coexist in the environment, which is a complicated situation where there would be a competition among the ions for active sites on the sorbent surface. This study presents the effective removal of inorganic divalent mercury (Hg2+) at a trace level concentration through adsorption on the grounded pinecones (PC), pecan shells (PS) and chemically, by acid and base, modified pinecones, and pecan shells. To evaluate the surface chemistry and reactivity of the bio-sorbents, and presence of functional groups various analyses were performed, including determining the point of zero charge (pHpzc) and conducting FTIR analysis. Several factors that could influence adsorption efficiency, including pH, adsorbent dosage, ionic strength, contact time and metal concentration were examined. Results indicated that the chemical modification led to changes in mercury removal by the bio-sorbents, possibly attributed to the change in surface area, porosity, and functional groups. The adsorption efficiency for both bio-sorbents increased as modified by acid. For 1 mg/mL of bio-sorbent dose the Hg2+ removal efficiency was found 80% and 90% for PC and PS, respectively, while increased to 92% and 95% for acid modified pinecone (APC) and acid modified pecan shells (APS) at room temperature and optimum pH condition. However, the base activated PC and PS were found to be less effective than the unmodified materials. Furthermore, all of the materials tested found to be following the Freundlich's adsorption isotherm in aqueous solutions. In the second phase of this study, the focus was on developing a method to monitor very low concentration of Hg2+ in the environment. Studies indicate that ionic mercury can be readily converted to organic mercury through methylation, and as organic mercury builds up in the food chain, it is very harmful to human health even at a low level. Thus, to provide appropriate protection, the US Environmental Protection Agency (USEPA) has set the maximum contamination level of mercury in drinking water at 2.0 ppb. As a result, it becomes very crucial to invent a very sensitive and selective approach for monitoring the ultra-low concentration of Hg2+ in the environment. This study aims to create an incredibly sensitive assay for the detection and quantification of Hg2+ using the single-particle inductively coupled plasma mass spectrometry (spICP-MS). The well-known thymine (T)- Hg2+ -T complex forms when AuNPs modified with single-stranded DNA are exposed to Hg2+ and this formation causes AuNPs to aggregate. By determining the overall reduction in the number of identified AuNPs or NP aggregates the degree of aggregation can be quantified. This spICP-MS-based approach has been reported to obtain a substantially lower detection limit of 0.031 part-per-trillion (155 fM) and a larger (10,000-fold) linear range up to 1 ppb when compared to most other Hg assays that use the similar principle of aggregation-dispersion with DNA modified AuNPs. Besides, this approach showed low interference from the sample matrix. Considering the aforementioned advantages, this study focuses on quantifying aqueous Hg2+ using single stranded DNA-gold nanoparticles conjugates with the help of single-particle inductively coupled plasma mass spectrometry (spICP-MS).