Global NEST Journal

Anthracene and phenanthrene belong to a group of persistent environmental contaminants called PAHs. Evaluation of the structure of two selected PAHs i.e. anthracene and phenanthrene on their resistance to destruction by UV-activated PDS was the aim of this study. The authors focused on two aspects of this problem: - the role of the so-called ‘bay-region’, in the structure of phenanthrene, during PDS/UV oxidation - formation of substituted forms of these PAHs in the absence and presence of three nitrogen-containing compounds i.e. ammonia and nitrite or nitrate ions. Even though phenanthrene and anthracene have the same molecular formula, the difference in their ring assessment influences their degradability. Considering all the results, in all the cases anthracene was degraded faster and/or had a higher degradation rate. That proves phenanthrene to be more stable and resistant for degradation however comparison of PDS/UV systems vs. UV– irradiation alone confirms that the addition of PDS accelerates the degradation of anthracene and phenanthrene. Comparison of PDS/UV with the addition of three different nitrogen-containing compounds showed a significant difference between anthracene and phenanthrene. In the experiments with phenanthrene were observed additional peaks with an absorption maximum between 230-240 cm-1 which is characteristic of the nitro-group. Based on their absorption maximum and the addition of nitrogen-containing compounds, emerging by-products are assumed to be nitro-derivatives of phenanthrene. The results of GC/MS analysis suggest the possibility of formation of many compounds which can be formed from phenanthrene and are embedded on its skeleton. These analyzes also suggest the rearrangement of phenanthrene’s aromatic rings and formation new compounds.

In Gilgit-Baltistan, urbanization, transportation, unplanned small-scale industry, kitchen waste, inorganic fertilizers, pesticides, insecticides, and weedicides contribute to agricultural field contamination, creating severe health risks. This study aims to determine the health risks caused by heavy metals found in various indigenous fresh fruits. To this end, we first assessed heavy metals concentration using well-established experimental procedures. In addition, a survey of male and female responde nts in the Gilgit District of Pakistan was conducted to determine the daily intake pattern. Finally, we used the Fuzzy-TOPSIS technique to calculate each indigenous fresh fruit's health risk and synergetic performance score. Results show the concentration order of heavy metals in indigenous fresh fruits, such as, Mn >Pb>Cu>Cr>Ni>Cd. For both males and females, the order of estimated daily intake (EDI) was Mn>Pb>Cu>Cr>Ni>Cd. Males estimated daily intake of Mn was highest in apricots, whereas females' EDI of Cd was lowest in apples. For females, the sequence was cherry>apricot>pear>apple>grape, while for men it was apricot>cherry>pear>apple>grape. Individual cancer risks varied from 1.513E-03 to 1.066E-01, with cherries posing the highest risk for males and grapes posing the lowest risk for females. Non-carcinogenic risks in fruits were cherry>apricot>pear>apple>grape for females and apricot>cherry>pear>apple>grape for males, whereas carcinogenic risks exhibited cherry>apricot>pear>apple>grape for both males and females. Although the estimated daily consumption of Mn and Pb exceeded the WHO standards, the heavy metals were below permissible levels. The Health Index (HI) revealed a ranking of cherry>apricot>pear>apple>grape for females and apricot>cherry>pear>apple>grape for males. According to the ranking, the cumulative cancer risk for both males and females followed the order of cherry>apricot>pear>apple>grape. The fuzzy-TOPSIS results were consistent with the experiment, and it was established that a regular intake could synergistically cause cancer. The study's findings can support policymakers and administrators in improving food safety standards to ensure fruit quality.

We propose a simple method for synthesising Poly(azomethine), ZnO, TiO2, poly(azomethine)/TiO2, and poly(azomethine)/ZnO nanocomposites using an ultrasonication process, as well as the use of these nanomaterials for photocatalytic degradation of organic dyes (Methylene blue (MB), malachite green (MG), Bismarck brown (BB), alizarin red S (ARS), and (MO). Our findings show that precise control and optimization of ambient factors in the presence of natural sunlight can result in efficient tailoring of poly(azomethine)/TiO2 (PNT) and poly(azomethine)/ZnO (PNZ) nanocomposites. Compared to Poly(azomethine), ZnO, TiO catalysts, the PNT and PNZ composites exhibit better photocatalytic activity for MB, MG, BB, ARS, MO degradation, which could be attributed to the formation of special catalytically active structures on the nanocomposite surface. The synthesized PNT and PNZ composites had the maximum catalytic activity under circumstances of 500 mg photocatalyst dose, 5 h of sunlight exposure and 10 ppm dye concentrations. Under ideal conditions, MB degrades at a rate of 97 % after 5 h of sunlight exposure. The composites demonstrated selective dye degradation and have greater photocatalytic effectiveness for cationic dyes. This research could lead to the simple development of a high photocatalysts for the rapid removal of ecologically harmful dyes from aqueous solutions.

Biochar was synthesized from Kappaphycus alvarezii reject (KR) remove the anionic azo dye, Acid Red 88 from wastewater. In this study, biochar was experimented in both batch and column adsorption studies. Batch adsorption studies were performed at varying temperature (25 – 40 °C), dosage (1 – 10 g), pH (4 – 10), time (30 – 90 min) and dye concentration (25 – 125 mg/L) respectively. From the batch adsorption studies, it was seen that maximum removal efficiency was 87.64% at 75ppm, dosage of 4 g/L, time of 60 min and pH 7 respectively. The batch adsorption experiment best fitted to Freundlich isotherm model with Pseudo-second-order kinetics indicating the adsorption to follow chemisorption mechanism process along with multilayer adsorption onto biochar’s uneven adsorption sites. It was clear from this study, that Kappaphycus alvarezii reject has the potential to serve as economical biochar as it can be utilized as an adsorbent for the efficient removal of colorants from wastewater.