Novel electrochemical ZnO/MnO2/rGO nanocomposite-based catalyst for simultaneous determination of hydroquinone and pyrocatechol.

An innovative electrochemical sensing method is introduced for dihydroxy benzene (DHB) isomers, specifically hydroquinone (HQ) and pyrocatechol (PCC), employing a zinc-oxide/manganese-oxide/reduced-graphene-oxide (ZnO/MnO2/rGO) nanocomposite (NC) as an electrode modifier material. Comprehensive characterization confirmed well-dispersed ZnO/MnO2 nanoparticles on rGO sheets. Electrochemical analysis revealed the ZnO/MnO2/rGO-NC-based modified electrode possesses low electrical resistance (126.2 Ω), high electrocatalytic activity, and rapid electron transport, attributed to the synergies between ZnO, MnO2 and rGO. The modified electrode demonstrated exceptional electrochemical performance in terms of selectivity for the simultaneous detection of HQ and PCC. Differential pulse voltammetry studies validated the proposed sensor's ability to detect HQ and PCC within linear response ranges of 0.01-115 µM and 0.03-60.53 µM, with detection limits of 0.0055 µM and 0.0053 µM, respectively. Practical validation using diverse water samples showcased excellent percent recovery of HQ and PCC using the ZnO/MnO2/rGO-based electrochemical sensor, underscoring the sensor's potential for real-world applications in environmental monitoring.

Spatial analysis and human health risk assessment of elements in ground water of District Hyderabad, Pakistan using ArcGIS and multivariate statistical analysis.

Availability of clean drinking water is a basic necessity of human population. Therefore, the current study was taken up for spatial analysis and human health risk assessment of elements in Ground water of District Hyderabad, Pakistan. Evaluation of 10 potential hazardous elements in one hundred eighteen samples of ground water from district Hyderabad, Pakistan was done to assess their natural and anthropogenic origin and possible effects on living organisms and human health. Based on statistical tools of Pearson Co-relation, Metal Clustering and Principal Component Analysis (PCA), three groups of elements were produced; First group included Mn, Fe, B and Cr, the second group contained Cu, Ni and As while third group included Pb, Cd and Zn. Higher Relative Standard Deviation (RSD) values of Cu, Ni, As, Pb, Cd and Zn showed their anthropogenic origin while Mn, Fe, B and Cr were found with lower concentration that indicated their natural origin. Histograms and box-plots of Mn, Fe, B and Cr were found to be normally distributed while these parameters were appeared abnormal for Cu, Ni, As, Pb, Cd and Zn. Risk assessment was quantified by hazard quotient (HQ) and cancer risk for both adult and child. Non-carcinogenic risks as depicted by HQs of all the 10 metal(loid)s were below the recommended HQ threshold of 1 for both child and adult. However, highest HQ was calculated for B (child 0.300 and adult 0.338) followed by the values for Mn and Ni. The potential risks of combined effect of all the 10 metal(loid)s through ingestion of groundwater was assessed using HI and calculated to be 0.694 for adult and 0.566 for child. This indicates the potential health risk of these metal(loid)s to human due to the consumption of the groundwater of district Hyderabad for drinking purpose. Considering the geometric mean for the studied area, carcinogenic risk of As through oral intake was calculated i.e. 1.50 × 10-4 and 2.62 × 10-5 for the adult and child However, this carcinogenic risk is 1.91 × 10-5 and 3.28 × 10-6 for Cd in adult and child and 1.94 × 10-3 and 3.32 × 10-4 for Cr in adult and child, respectively. Since the cancer risk 6exceeded the target risk of 1 × 10-4 for Cr i.e. 1.94 × 10-3 in adult, it can thus be considered as 'non-acceptable'. Spatial maps of elements produced by ArcGIS showed the hotspots of potential hazardous elements such as highest concentration of elements like Zn, Pb and Cd was found in urban areas while highest concentration of Cu, Ni and As was observed near Phulleli canal which passes from Hyderabad City and may contain contamination from waste material of residential area due to their anthropogenic activities.

Identification of heavy metal ions from aqueous environment through gold, Silver and Copper Nanoparticles: An excellent colorimetric approach.

Heavy metal pollution has become a severe threat to human health and the environment for many years. Their extensive release can severely damage the environment and promote the generation of many harmful diseases of public health concerns. These toxic heavy metals can cause many health problems such as brain damage, kidney failure, immune system disorder, muscle weakness, paralysis of the limbs, cardio complaint, nervous system. For many years, researchers focus on developing specific reliable analytical methods for the determination of heavy metal ions and preventing their acute toxicity to a significant extent. The modern researchers intended to utilize efficient and discerning materials, e.g. nanomaterials, especially the metal nanoparticles to detect heavy metal ions from different real sources rapidly. The metal nanoparticles have been broadly utilized as a sensing material for the colorimetric detection of toxic metal ions. The metal nanoparticles such as Gold (Au), Silver (Ag), and Copper (Cu) exhibited localized plasmon surface resonance (LPSR) properties which adds an outstanding contribution to the colorimetric sensing field. Though, the stability of metal nanoparticles was major issue to be exploited colorimetric sensing of heavy emtal ions, but from last decade different capping and stabilizing agents such as amino acids, vitmains, acids and ploymers were used to functionalize the metal surface of metal nanoparticles. These capping agents prevent the agglomeration of nanoparticles and make them more active for prolong period of time. This review covers a comprehensive work carried out for colorimetric detection of heavy metals based on metal nanoparticles from the year 2014 to onwards.

Natural and anthropogenic origin of metallic contamination and health risk assessment: A hydro-geochemical study of Sehwan Sharif, Pakistan.

Heavy metal contamination in groundwater is a serious threat to the environment and therefore its proper monitoring is a matter of great concern these days. In the present research, groundwater samples from Sehwan Sharif district Jamshoro, Pakistan were collected to estimate the concentration of various elements including potentially hazardous metals. Statistical analysis of the collected data based on Pearson co-relation metal clustering and Principal Component Analysis (PCA) divides the elements into three groups; Group I contains As, Cu, Ni, and Cd, Group II contains Mn, Fe, B, and Cr and Group III contains Pb and Zn. The elements Cu, Ni, As, Pb, Cd, and Zn found with higher RSD values demonstrate their anthropogenic origin whereas the lower concentration of Mn, Fe, B, and Cr indicate their natural origin (Tepanosyan et al., 2016). The histograms and box-plots of Mn, Fe, B and Cr were found normally distributed while abnormal for Cu, Ni, Pb, As, Cd and Zn. The HQs of these elements indicate their non-carcinogenic risks. However, results of individual metallic behavior indicate the highest HQ measured for B followed by HQs for Cu, and As. The toxic effects of investigated metal (loid)s calculated using HI were found to be 1.58 for adults and 1.35 for the child which is considered the medium chromic risk and cancer risk. About the toxicity of these heavy metals, their cancer risk was assessed on the levels of Cd, As, and Cr in groundwater. The carcinogenic risk of As was found to be 2.78 × 10-4 and 1.62 × 10-3 for child and adult, respectively. Furthermore, the values of this carcinogenic risk are 2.64 × 10-6 and 1.54 × 10-5 for Cd while 4.24 × 10-3 and 2.48 × 10-2 for Cr in child and adult, respectively. Since cancer risk exceeded the target risk of 1 × 10-4 for As and Cr in adults and children, it can thus be considered 'non-acceptable'. The Geographic Information System (GIS) based maps were prepared using Inverse Distance Weighted (IDW) interpolation which showed the Spatial distribution of all elements throughout Sehwan Sharif from different sources of environment. Spatial maps of elements produced by ArcGIS show the hotspots of potentially hazardous elements such as the highest concentration of Pb, As, Zn, Cu, Ni, and Cd were found in urban areas of Sehwan Sharif district Jamshoro, Pakistan.