Removal of chlorhexidine digluconate from aqueous solution by heterogenous photocatalysis using sunlight-driven Ni-doped TiO₂ material

Astha Singh,Brijesh Kumar Mishra 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.1

Photoactive Ni-TiO₂ was synthesized through green hydrothermal method with preferential photocatalytic performance in visible and solar light for synthetic and formulated wastewater treatment. Incorporation of this transition metal into TiO₂ was examined by XRD, FTIR, UV–visible DRS, XPS, SEM-EDS and HRTEM analysis. According to the Langmuir–Hinshelwood model, the photodegradation of the chlorhexidine digluconate under solar (R²=0.986) and simulated visible light (R²=0.982), follows a pseudo-first-order kinetics. The interaction of operational fractions, such as S/C ratio, irradiation time, and pH of the reaction mixture, were evaluated using the RSM. Although complete mineralization of CHD was not achieved using Ni-TiO₂ under visible light, but the parent compound was mineralized to some extent, as demonstrated by TOC reduction (85.71%-synthetic wastewater and 61.17%-formulated wastewater), UV<SUB>254</SUB> (89.91% synthetic wastewater and 55.39%-formulated wastewater) and UV<SUB>280</SUB> (68.23%-synthetic wastewater and 68.23%-formulated wastewater) absorbance variations. Based on the identified transformed products, the possible degradation pathway was proposed and bacterial susceptibility test on Bacillus cereus DPAML065 was performed to evaluate the toxicity of oxidation intermediates. Comparative studies about energy consumption and removal efficiency during simulated visible light/Ni-TiO₂ and sunlight/ Ni-TiO₂ mediated treatment system for formulated wastewater revealed that sunlight/ Ni-TiO₂ mediated treatment system was high energy efficient (1.67 kWhKg<SUP>-1</SUP>) system.

Assessment of kinetics behavior of electrocoagulation process for the removal of suspended solids and metals from synthetic water

Hariraj Singh,Brijesh Kumar Mishra 대한환경공학회 2017 Environmental Engineering Research Vol.22 No.2

Globalization, industrialization, mining, and uncontrolled population growth have fostered a shortage of potable water. Therefore, it has become imperative to understand an effective and reasonable water purification technique. A renewed interest in electrocoagulation (EC) has been spurred by the search for reliable, cost-effective, water-treatment processes. This paper has elucidated a technical approach for getting rid of heavy metals and total suspended solids (TSS) from synthetic water using an aluminum electrode. The effect of operational parameters, such as current density, inter-electrode distance, operating time, and pH, were studied and evaluated for maximum efficiency. This study corroborates the correlation between current density and removal efficiency. Neutral pH and a low electrode gap have been found to aid the efficacy of the EC setup. The outcome indicates that a maximum TSS removal efficiency of 76.6% occurred at a current density of 5.3 mA/cm² during a contact time of 30 min. In the case of heavy metals remediation, 40 min of process time exhibited extremely reduced rates of 99%, 59.2%, and 82.1%, for Cu, Cr, and Zn, respectively. Moreover, kinetic study has also demonstrated that pollutants removal follows first-and second-order model with current density and EC time being dependent.

Level of Organochlorine Pesticide in Prediabetic and Newly Diagnosed Diabetes Mellitus Patients with Varying Degree of Glucose Intolerance and Insulin Resistance among North Indian Population

Shipra Tyagi,Brijesh Kumar Mishra,Tusha Sharma,Neha Tawar,Abdul Jamil Urfi,Basu Dev Banerjee,Sri Venkata Madhu 대한당뇨병학회 2021 Diabetes and Metabolism Journal Vol.45 No.4

Background Organochlorine pesticides (OCPs) exposure may induce an endocrine disruption which may lead to the risk of developing diabetes through alteration and disturbance of glucose metabolism, insulin resistance, and destruction of β-cells. The present study determines the recent trend of OCPs residue in blood samples and their association with the known risk factors responsible for developing the risk of diabetes among the North Indian population. Methods Blood sample of 300 patients (100 each of normal glucose tolerance [NGT], prediabetes and newly detected diabetes mellitus [DM]) between the age group of 30 to 70 years were collected. OCPs residue in whole blood samples was analyzed by using gas chromatography equipped with a 63Ni selective electron capture detector. Results Significantly higher levels of β-hexachlorocyclohexane (HCH), dieldrin, and p,p’-dichloro-diphenyl-dichloroethylene (DDE) were found in the prediabetes and newly detected DM groups as compared to NGT group. Insulin resistance showed to be significantly positive correlation with β-HCH and dieldrin. Also, fasting and postprandial glucose levels were significantly positively correlated with levels of β-HCH, dieldrin, and p,p’-DDE. Further, when OCPs level was adjusted for age and body mass index (BMI), it was found that β-HCH, dieldrin, and p,p’-DDE levels in blood increases the risk of diabetes by 2.70, 2.83, and 2.55 times respectively. Moreover, when we adjust OCPs level based on BMI categories (BMI <23, ≥23, and ≤25, and >25 kg/m2); β-HCH and p,p’-DDE showed a significant risk of developing newly detected DM with BMI >25 and ≥23 and ≤25 kg/m2. Conclusion The OCPs level present in the environment may be responsible for biological, metabolic, and endocrine disruptions within the human body which may increase the risk of developing newly detected DM. Hence, OCPs exposure can play a crucial role in the etiology of diabetes.

Removal of chlorhexidine digluconate from aqueous solution by heterogenous photocatalysis using sunlight-driven Ni-doped TiO2 material

Astha Singh,Brijesh Kumar Mishra 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.1

Photoactive Ni-TiO2 was synthesized through green hydrothermal method with preferential photocatalytic performance in visible and solar light for synthetic and formulated wastewater treatment. Incorporation of this transition metal into TiO2 was examined by XRD, FTIR, UV–visible DRS, XPS, SEM-EDS and HRTEM analysis. According to the Langmuir–Hinshelwood model, the photodegradation of the chlorhexidine digluconate under solar (R2=0.986) and simulated visible light (R2=0.982), follows a pseudo-first-order kinetics. The interaction of operational fractions, such as S/C ratio, irradiation time, and pH of the reaction mixture, were evaluated using the RSM. Although complete mineralization of CHD was not achieved using Ni-TiO2 under visible light, but the parent compound was mineralized to some extent, as demonstrated by TOC reduction (85.71%-synthetic wastewater and 61.17%-formulated wastewater), UV254 (89.91% synthetic wastewater and 55.39%-formulated wastewater) and UV280 (68.23%-synthetic wastewater and 68.23%-formulated wastewater) absorbance variations. Based on the identified transformed products, the possible degradation pathway was proposed and bacterial susceptibility test on Bacillus cereus DPAML065 was performed to evaluate the toxicity of oxidation intermediates. Comparative studies about energy consumption and removal efficiency during simulated visible light/Ni-TiO2 and sunlight/Ni-TiO2 mediated treatment system for formulated wastewater revealed that sunlight/Ni-TiO2 mediated treatment system was high energy efficient (1.67 kWhKg−1) system.

Augmentation of the coagulation activity of alum using a porous bio-flocculant for the remediation of trihalomethanes-generating hydrophobic natural organic matter

Bramha Gupta,Tanwi Priya,Brijesh Kumar Mishra 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.3

Conventional coagulation techniques have shown inefficacy for the removal of DBPs precursor i.e. hydrophobic NOM. The present study has used a bio-flocculant named Ficus benghalensis to enhance the coagulation activity of alum for the removal of hydrophobic NOM. The coagulation activity of the augmented treatment (Alum-F. benghalensis) system was validated using spectroscopic analysis. The augmented system had shown an increment in DOC and A254 removal by ~30% and ~16%, respectively. ASI and A272 had shown a continual decrease (from 0.12 to 0.08 and 0.46 to 0.23, respectively) for the augmented system. Chlorine demand was found lesser for the augmented system (1.4 ㎎/L) compared to alum (1.55 ㎎/L) only. The augmented system had shown a drastic reduction (from 0.1459 to 0.0638) in the value of (-ΔA272), which is directly related to the reduction in THMFP. The combined effects of sweep coagulation and charge neutralization were the responsible mechanisms for the augmented coagulation system. The noteworthy anti-bacterial activity of F. benghalensis was observed due to the presence of silver, copper, and traces of chlorine in its structure. Thus, the proposed augmented coagulation system can be used to remove the hydrophobic NOM from the water.

Adsorption of chlorhexidine digluconate on acid modified flyash : Kinetics, isotherms and influencing factors

Astha Singh,Sonalika Sonal,Rohit Kumar,Brijesh Kumar Mishra 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.2

Chlorhexidine digluconate (CHD) in the aquatic environment causes irreversible change to microbes, making them resistant to biodegradation, which needs remediation other than biological process. Adsorption study was performed for the removal of CHD on fly ash (FA) as a function of pH and ionic strength. Experimental result has been validated by characterization using Scanning electron microscopy, Fourier Transform-Infrared Spectroscopy and Brunauer-Emmett-Teller. CHD adsorption with FA showed an increasing trend with an increase in pH. Variation in pH proved to be an influential parameter for the surface charge of adsorbent and the degree of ionization of the CHD molecules. The adsorption capacity of CHD decreased from 23.60 mg g-1 to 1.13 mg g-1, when ionic strength increased from to M. The adsorption isotherms were simulated well by the Freundlich isotherm model having R2 = 0.98. The Lagergren’s model was incorporated to predict the system kinetics, while the mechanistic study was better explained by pseudo-second order for FA. On the basis of operational conditions and cost-effectiveness FA was found to be more economical as an adsorbent for the adsorption of CHD.