An integrated approach for the characterization of groundwater quality using multivariate statistical techniques and spatial analysis

ABSTRACT. Ground water accessed via wells in areas of Tiruvallur district of the southern Indian state of Tamil Nadu has been a subject to increase sea-water intrusion. The present study highlights the potable water crisis in the northern district evaluated using GIS-assisted determination of water quality parameters across fifty sampling sites. The most informative parameters evaluated within this study were TDS, EC, TH, Na+, Mg2+, Ca2+, Cl- and SO42- while parameters such as pH, CO32-, etc. had limited correlated significance to water quality. The total dissolved solids (TDS) and electrical conductivity (EC) determined in the study area indicated significantly elevated levels across the sampling sites. Weighted arithmetical indexing (WAI) of the water quality parameters indicated 30 out of 50 water sources meet the tolerance limits for both drinking and irrigation. Based on BIS standards, only 13 sites met acceptable limits for safe drinking water. Principal component analysis and piper plot analysis revealed a significant involvement of Mg2+, Na+, Cl- and SO42- in the impairment of water quality, particularly in the coastal zones. Spatial hydro-chemical profiles developed in this study reveal ‘hot-spots’ of sea-water tainted water sources, and the hydro-chemical dominance of alkali earth components. Altogether, the study findings indicate a widening water crisis on top of over-exploited water resources and discuss possible factors and remedial steps in addressing the situation.   KEY WORDS: Ground water, Principal component analysis, Piper Plot, Water quality index, Irrigation suitability   Bull. Chem. Soc. Ethiop. 2022, 36(2), 241-260.                                                           DOI: https://dx.doi.org/10.4314/bcse.v36i2.1                                                       &nbsp

Synthesis and characterization of SiO₂-Chitosan supported AgNPs and its catalytic application for reduction of malachite green

546-552Designing novel nanocatalysts for the reduction of water borne dyes is a topic of recent research interest. A new composite, SiO2-chitosan supported AgNPs (3-11%), has been synthesized and characterized through FT-IR, XRD, BET and SEM. The catalytic activity of the composites has been investigated through reduction of malachite green as a model reaction in the presence of NaBH4. The reduction is rapid and followed pseudo first order kinetics. Increase of pH increased the rate of reduction compared to low pH, as at a low pH, NaBH4 decomposed directly and rapidly. An increase in NaBH4 content also increased the rate. The results indicate that the reduction can also be extended to other water borne reducible contaminants

Carboxyl-tailed ionic liquid promoted aqueous dispersion of multi-walled carbon nanotubes

The present work reports the dispersion of multiwalled carbon nanotubes (MWCNTs) in water using a short chain carboxyl-tailed ionic liquid (IL), 1-carboxymethyl-3-methyl imidazolium tetrafluoroborate ([cmmim][BF4]), as an IL-based hydrophilic surfactant, instead of long-chain hydrophobic ILs. MWCNTs can be dispersed effectively in the aqueous solution of [cmmim][BF4] due to their molecular structure, including one imidazolium ring head group and one carboxyl group with fewer hydrophobic chains. The resulting MWCNT suspensions are stable for more than a month, and no precipitation is observed. The transmission electron microscopy results showed that the structural integrity of MWCNTs did not deteriorate because of their dispersal in water. Ultraviolet–visible–near infrared spectral studies confirm the presence of IL molecules onto the surface of the MWCNTs. X-Ray photoelectron spectroscopy and Fourier transform Raman studies confirmed the cation–π or π–π interactions between the MWCNTs and IL molecules, which makes the suspension of MWCNTs more stable. </jats:p

An integrated approach for the characterization of groundwater quality using multivariate statistical techniques and spatial analysis

ABSTRACT. Ground water accessed via wells in areas of Tiruvallur district of the southern Indian state of Tamil Nadu has been a subject to increase sea-water intrusion. The present study highlights the potable water crisis in the northern district evaluated using GIS-assisted determination of water quality parameters across fifty sampling sites. The most informative parameters evaluated within this study were TDS, EC, TH, Na+, Mg2+, Ca2+, Cl- and SO42- while parameters such as pH, CO32-, etc. had limited correlated significance to water quality. The total dissolved solids (TDS) and electrical conductivity (EC) determined in the study area indicated significantly elevated levels across the sampling sites. Weighted arithmetical indexing (WAI) of the water quality parameters indicated 30 out of 50 water sources meet the tolerance limits for both drinking and irrigation. Based on BIS standards, only 13 sites met acceptable limits for safe drinking water. Principal component analysis and piper plot analysis revealed a significant involvement of Mg2+, Na+, Cl- and SO42- in the impairment of water quality, particularly in the coastal zones. Spatial hydro-chemical profiles developed in this study reveal ‘hot-spots’ of sea-water tainted water sources, and the hydro-chemical dominance of alkali earth components. Altogether, the study findings indicate a widening water crisis on top of over-exploited water resources and discuss possible factors and remedial steps in addressing the situation.&#x0D;  &#x0D; KEY WORDS: Ground water, Principal component analysis, Piper Plot, Water quality index, Irrigation suitability&#x0D;  &#x0D; Bull. Chem. Soc. Ethiop. 2022, 36(2), 241-260.                                                          &#x0D; DOI: https://dx.doi.org/10.4314/bcse.v36i2.1                                                        </jats:p

Organo Modified Multi-Walled Carbon Nanotube Reinforced Pyridine Core Polybenzoxazine (MWCNT/PBZ) Nanocomposites

A new series of multi-walled carbon nanotube reinforced polybenzoxazine (MWCNT/PBZ) nanocomposites was successfully designed and developed. Three different maleimido terminal benzoxazine monomers (MI-BZs) were synthesized using N-(4-hydroxyphenyl) maleimide (HPM) and formaldehyde solution through Mannich condensation reaction and were characterized by FT-IR and NMR spectroscopy. Varying weight percentages (0 wt.%, 0.5 wt.%, 1.0 wt.% and 1.5 wt.%) of glycidyl-MWCNT were then incorporated into benzoxazine matrices to prepare MWCNT/PBZ nanocomposites. The nanocomposites having higher weight percentage of MWCNT were found to possess excellent thermal properties than those of neat PBZs. The developed nanocomposites exhibited better flame retardancy and higher dielectric constant. The optical properties ascertained from the UV-Vis absorption bands at the region of 300–350 nm and strong fluorescent emissions were observed in the wavelength range of 300–550 nm from Photoluminescence analysis. The intensity of characteristic diffraction peaks corresponding to g-MWCNT confirmed the reinforcement of MWCNT in the benzoxazine matrices, which indicated the successful formation of nanocomposites. The morphological studies ascertain the compatibility and uniform dispersion of MWCNT in the PBZ network. </jats:p