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 this study Pinecones and pecan shells were chosen because of its abundance in nature and they are completely free of cost to get. 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 cites on the sorbent surface. This study presents the effective removal of Hg2+ at a trace level concentration through adsorption on the grounded pinecones (PC), pecan shells (PS) and Chemically modified pinecones (PC), and pecan shells (PS). The FTIR analysis showed the functional group present in each specimen and pHPZC of each sample was determined to understand the surface chemistry and reactivity of the materials. Chemical modification might result in the increased surface area, porosity, functional groups as compared to the unmodified samples. The factors affecting adsorption efficiency were pH, adsorbent dosage, ionic strength, contact time and metal concentration. The Hg2+ removal efficiency in aqueous solution was found 90-92% for PS and APC, 92-95% for APS, and 80-85% for PC at room temperature with 1 mg/mL dose and pH their optimum pH condition. However, for unmodified PC and PS, the adsorption efficiency was less for all situation as compared to the acid modified PC and PS. The base activated PC and PS were found to be less effective than even the unmodified materials. Thus, results indicate that modification of PC and PS with Nitric acid (HNO3) increases metal adsorption efficiency as compared to unmodified samples. Furthermore, all of the materials tested found to be following the Freundlich's adsorption isotherm in aqueous solutions. Besides, 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 (EPA) 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 low concentration of Hg2+ in the environment. This study aims to create an incredibly sensitive assay for the detection and quantification of Hg2+ (aq) 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+ (aq) 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 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).

[pt] Devido a grande poluição do meio ambiente, diferentes estratégias devem ser tomadas para remediação ambiental. Dentre as diversas estratégias, é possível citar adsorção de cátions metálicos de soluções aquosas, adsorção de fármacos, utilização e armazanamento de energia verde. Dito isso, o presente estudo relata a utilização das estratégias mencionadas. Portanto, foi utilizada nanofibras de celulose oxidada via TEMPO (2,2,6,6-tetrametil-piperidinil-N-oxil), TCNF, para a remoção de cátions de ferro, zinco e cobalto. Sua capacidade adsortiva para a remoção de ferro e zinco puros apresentou valores de 5902 e 5633 Miligrama por grama−1 , respectivamente. Quando ferro e zinco removidos de uma mesma solução, a capacidade adsortiva de TCNF foi de 5852 e 5622 Miligrama por grama−1 . Para a adsorção de cobalto, sua concentração reduziu de 50 grama por litro−1 para 8,3 grama por litro−1 . Posteriormente, as amostras de TCNF impregnadas com metais foram levadas para calcinação, com objetivo de produção de óxidos nanoestruturados. Em temperaturas a partir de 300 graus C, fases de hematita são identificadas e a partir de 400 graus C fases de zincita e franklinita são identificadas por ajustes de Rietveld nos difratogramas obtidos. Adicionalmente, quando calcinadas em atmosfera inerte, é possível observar o surgimento de óxidos. Além disso, todas as morfologias foram analisadas via MET e MEV, e podem ser comparadas a um nanocoral com espessuras entre 20 e 30 nm. Então, as amotras de ferrita de zinco foram aplicadas em adsorção de tetraciclina, com capacidade adsortiva de 18 miligrama por grama−1 e também como capacitor, atingindo um valor de capacitância de 2031 Farad por grama−1 . A amostra contendo ferrita de cobalto foi utilizada como catalisador para extração de H2 de borohidreto e a quantidade de gás hidrogênio extraída girou em torno de 476,4 Litros de hidrogênio produzido por grama de borohidreto de sódio por grama de catalisador. A energia de ativação para a reação foi calculada em torno de 57 Quilojoules por mol−1 . Portanto, a inovadora rota de síntese de óxidos nanoetruturados aparenta ser promissora. / [en] Due to significant environmental pollution, different strategies require to be implemented for environmental remediation. Among the different approaches, it is possible to cite the adsorption of metallic cations from aqueous solutions, adsorption of pharmaceuticals, and the use and storage of green energy. With this in mind, the present study reports the use of the mentioned strategies. Thus, oxidized cellulose nanofibers, produced via TEMPO (2,2,6,6-tetramethyl-piperidinyl-N-oxyl), TCNF, were used for the removal of iron, zinc, and cobalt cations from aqueous solution. Their adsorptive capacity for the removal of pure iron and zinc was 5902 and 5633 Milligram per gram−1 , respectively. When iron and zinc were removed from the same solution, the adsorptive capacity of TCNF was 5852 and 5622 Milligram per gram−1 , respectively. For cobalt adsorption, its concentration decreased from 50 gram per liter−1 to 8.3 gram per liter−1 . Subsequently, the TCNF samples impregnated with metals were subjected to calcination to produce nanostructured oxides. At temperatures above 300 C degrees, hematite phases were identified, and at 400 C degrees, zincite and franklinite phases were identified through Rietveld refinements of the obtained diffractograms. Additionally, when calcined in an inert atmosphere, the appearance of oxides was observed. Moreover, all morphologies were analyzed via TEM and SEM, resembling a nanocoral with thicknesses between 20 and 30 nm. The zinc ferrite samples were applied to tetracycline adsorption with an adsorptive capacity of 18 miligram per gram−1 and also as a capacitor, achieving a capacitance value of 2031 Farad per gram−1 . The cobalt ferrite sample was used as a catalyst for hydrogen extraction from borohydride, and the amount of extracted H2 was around 476.4 liters of hydrogen produced per gram of sodium borohydride per gram of catalyst. The activation energy for the reaction was calculated to be approximately 57 Kilojoules per mole−1 . Therefore, the innovative route for the synthesis of nanostructured oxides appears to be promising.

<p>To improve the adsorption capacity of polyacrylonitrile (PAN) fibres, hydrophilic amidoxime fibres were prepared by subsequent conversion of the cyano groups to an amidoxime group by reacting with hydroxylamine at 80&deg / C at an optimum amidoximation time of 2 hrs. The amidoxime fibre was hydrolyzed/alkali treated in a solution of sodium hydroxide to enhance or improve the adsorption properties. This was followed by characterization of the amidoxime and hydrolyzed fibres using Scanning electron microscopy (SEM) / Fourier transform Infrared Spectroscopy (FTIR) and exchange capacity (cationic and anionic). SEM showed that the hydrolysis process made the surface of Amidoxime fibre rougher than that of Polyacrylonitrile fibre. FTIR revealed that the hydrolyzed Amidoxime fibres contained conjugated imine (-C=N-) sequences. Functionalization enhanced the sorption of amidoxime fibres by an increase of 20 % in the cationic exchange capacity. This was achieved by the part conversion of the cyano groups into the carboxylic acid groups. The fibres showed faster kinetics largely due the available exchange sites on the surface of the fibres hence the equilibration was achieved much quicker.</p>

<p>To improve the adsorption capacity of polyacrylonitrile (PAN) fibres, hydrophilic amidoxime fibres were prepared by subsequent conversion of the cyano groups to an amidoxime group by reacting with hydroxylamine at 80&deg / C at an optimum amidoximation time of 2 hrs. The amidoxime fibre was hydrolyzed/alkali treated in a solution of sodium hydroxide to enhance or improve the adsorption properties. This was followed by characterization of the amidoxime and hydrolyzed fibres using Scanning electron microscopy (SEM) / Fourier transform Infrared Spectroscopy (FTIR) and exchange capacity (cationic and anionic). SEM showed that the hydrolysis process made the surface of Amidoxime fibre rougher than that of Polyacrylonitrile fibre. FTIR revealed that the hydrolyzed Amidoxime fibres contained conjugated imine (-C=N-) sequences. Functionalization enhanced the sorption of amidoxime fibres by an increase of 20 % in the cationic exchange capacity. This was achieved by the part conversion of the cyano groups into the carboxylic acid groups. The fibres showed faster kinetics largely due the available exchange sites on the surface of the fibres hence the equilibration was achieved much quicker.</p>

Magister Scientiae - MSc / To improve the adsorption capacity of polyacrylonitrile (PAN) fibres, hydrophilic amidoxime fibres were prepared by subsequent conversion of the cyano groups to an amidoxime group by reacting with hydroxylamine at 80°C at an optimum amidoximation time of 2 hrs. The amidoxime fibre was hydrolyzed/alkali treated in a solution of sodium hydroxide to enhance or improve the adsorption properties. This was followed by characterization of the amidoxime and hydrolyzed fibres using Scanning electron microscopy (SEM); Fourier transform Infrared Spectroscopy (FTIR) and exchange capacity (cationic and anionic). SEM showed that the hydrolysis process made the surface of Amidoxime fibre rougher than that of Polyacrylonitrile fibre. FTIR revealed that the hydrolyzed Amidoxime fibres contained conjugated imine (-C=N-) sequences. Functionalization enhanced the sorption of amidoxime fibres by an increase of 20 % in the cationic exchange capacity. This was achieved by the part conversion of the cyano groups into the carboxylic acid groups. The fibres showed faster kinetics largely due the available exchange sites on the surface of the fibres hence the equilibration was achieved much quicker. / South Africa

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