The green synthesis of magnesium oxide nanocomposite-based solid phase for the extraction of arsenic, cadmium, and lead from drinking water.

Solid-phase extraction (SPE) has attracted the attention of scientists because it can increase the selectivity and sensitivity measurements of analytes. Therefore, this study is designed to synthesise magnesium oxide nanoparticles (D-MgO-NPs) by an eco-friendly method using biogenic sources Duranta erecta followed by fabricating its chitosan-based polymeric composite (D-MgO-NC) for the SPE of heavy metals (HMs), i.e., arsenic (As), cadmium (Cd), and lead (Pb) from drinking water. Various analytical techniques were used for the surface characterization of D-MgO-NPs and D-MgO-NC. FTIR findings confirmed the formation of D-MgO-NC based on MgO association with the -OH/-NH2 of the chitosan. D-MgO-NC showed the smallest size of particles with rough surface morphology, followed by the crystalline cubic structure of MgO in its nanoparticle and composites. The synthesised D-MgO-NC was used as an adsorbent for the SPE of HMs from contaminated water, followed by their detection by atomic absorption spectrometry. Various experimental parameters, including pH, flow rate, the concentration of HMs, eluent composition, and volume, were optimised for the preconcentration of HMs. The limits of detection for As, Cd, and Pb of the proposed D-MgO-NC-based SPE method were found to be 0.008, 0.006, and 0.012 µm L-1, respectively. The proposed method has an enrichment factor and relative standard deviation of >200 and <5.0%, respectively. The synthesised D-MgO-NC-based SPE method was successfully applied for the quantitative detection of As, Cd, and Pb in groundwater samples, which were found in the range of 18.3 to 15.2, 3.20 to 2.49, and 8.20 to 6.40 µg L-1, respectively.

Biosynthesis and Analytical Characterization of Iron Oxide Nanobiocomposite for In-Depth Adsorption Strategy for the Removal of Toxic Metals from Drinking Water.

The biosynthesis of the iron oxide nanoparticles was done using Ixoro coccinea leaf extract, followed by the fabrication of iron oxide nanobiocomposites (I-Fe3O4-NBC) using chitosan biopolymer. Furthermore, the synthesized I-Fe3O4-NPs and I-Fe3O4-NBC were characterized, and I-Fe3O4-NBC was applied to remove toxic metals (TMs: Cd, Ni, and Pb) from water. The characterization study confirmed that the nanostructure, porous, rough, crystalline structure, and different functional groups of chitosan and I-Fe3O4-NPs in I-Fe3O4-NBCs showed their feasibility for the application as excellent adsorbents for quantitative removal of TMs. The batch mode strategy as feasibility testing was done to optimize different adsorption parameters (pH, concentrations of TMs, dose of I-Fe3O4-NBC, contact time, and temperature) for maximum removal of TMs from water by Fe3O4-NBC. The maximum adsorption capacities using nanocomposites for Cd, Ni, and Pb were 66.0, 60.0, and 66.4 mg g-1, respectively. The adsorption process follows the Freundlich isotherm model by I-Fe3O4-NBC to remove Cd and Ni, while the Pb may be adsorption followed by multilayer surface coverage. The proposed adsorption process was best fitted to follow pseudo-second-order kinetics and showed an exothermic, favorable, and spontaneous nature. In addition, the I-Fe3O4-NBC was applied to adsorption TMs from surface water (%recovery > 95%). Thus, it can be concluded that the proposed nanocomposite is most efficient in removing TMs from drinking water up to recommended permissible limit.

Risk Assessment of Macronutrients and Minerals by Processed, Street, and Restaurant Traditional Pakistani Foods: a Case Study.

The current work is aimed to assess the impact of macronutrient and mineral contents in food products of packaged food, restaurant food, and street food in Hyderabad. The estimated daily intake of macronutrients and minerals, followed by the toxic risk assessment of microminerals by consuming studied food dishes, was also conducted. The collected products were freeze-dried and standard procedures for measuring macronutrients were followed. At the same time, the acid digestion method was used to prepare the solution for detecting minerals by atomic absorption spectrometry. The resulting data indicated that all the food dishes supplied 134-454 kcals/100 g. The chicken/meat and pulse food dishes of all three categories were enriched with protein except bhindi masala. All the food dishes have a massive variation in fat contents and differ based on the used quantity of hydrogenated oil during their preparations. A significant difference in the macro- and microminerals in studied food products was observed. However, all food dishes are a good supplementary source of fundamental nutrients, supplying the recommended daily allowances for adults. The estimated hazardous index (Ih) of microminerals in some street and restaurant food products (based on a survey) showed possible toxicity risk, especially for the workers of automechanic workshops (Ih > 1.00). Thus, it is concluded that the contaminated (cheap) raw materials and unhygienic conditions for preparing street and restaurant foods and hawking places (atmospheric pollution) are the significant sources of micromineral contamination.