Physicochemical methods for disinfection of contaminated surfaces - a way to control infectious diseases.

This paper represents the reviews of recent advancements in different physicochemical methods for disinfecting contaminated surfaces, which are considered to be responsible for transmitting different bacterial, viral, and fungal infectious diseases. Surface disinfection can be achieved by applying chemicals, UV-based processes, ionization radiation (gamma-ray, X-ray and electron beam), application of self-disinfecting surfaces, no-touch room disinfection methods, and robotic disinfection methods for built-in settings. Application of different chemicals, such as alcohols, hydrogen peroxide, peracetic acid, quaternary ammonium salts, phenol, and iodine solution, are common and economical. However, the process is time-consuming and less efficient. The use of UVC light (wavelength: 200-280 nm, generated by low vapor mercury lamps or pulse xenon light) has gained much attention for disinfecting fomites worldwide. In recent times, the combination of UV and H2O2, based on the principle of the advanced oxidation process, has been applied for disinfecting inanimate surfaces. The process is very efficient and faster than chemical and UV processes. Heavy metals like copper, silver, zinc, and other metals can inactivate microbes and are used for surface modification to produce self-disinfecting surfaces and used in healthcare facilities. In combination with UVB (280-315 nm) and UVA (315-400 nm), titanium oxide has been utilized for disinfecting contaminated surfaces. Ionization radiation, one of the advanced methods, can be used in disinfecting medical devices and drugs. Post-COVID-19 pandemic, the no-touch and robotic disinfection methods utilizing chemicals or UVC lights have received much importance in built-in settings. Among these methods, surface disinfection by applying chemicals by fogging/vaporization and UV radiation methods has been widely reported in the literature compared to other methods. Supplementary Information: The online version contains supplementary material available at 10.1007/s40201-024-00893-2.

Determination of antimicrobial concentration and associated risk in water sources in West Bengal state of India.

The presence of antimicrobials in wastewater (WW), surface water (SW), groundwater (GW), and even in potable water from treatment plants has been reported from many countries. Their presence in the water sources is causing the rise and spread of antimicrobial resistance (AMR), thereby threatening our public health, global economy, and development. This necessitates the constant monitoring of these compounds along with the evaluation of their associated risk to aquatic organisms. In this study, GW, WW, and SW samples from different parts of West Bengal (India) were analyzed using the SPE-HPLC-DAD method for detecting two frequently used fluoroquinolones (ciprofloxacin, CIP and ofloxacin, OFL). The highest concentration of CIP and OFL was 5.75 µg/L (GW) and 17.84 µg/L (WW), respectively. The antimicrobial activity was determined against Escherichia coli and Staphylococcus aureus isolates from WW against CIP, which showed that Escherichia coli and Staphylococcus aureus had developed ~ 69 and ~ 12 times resistance compared to their respective pure strains. The risk assessment showed that CIP poses an insignificant threat to fish and Daphnia (RQ < 1) but a significant threat to green algae and Microcystis aeruginosa (RQ> > 1). OFL concentration also poses a great threat to all the organisms for which the assessment was made (RQ> > 1). Moreover, risk assessment in terms of AMR showed that the present level of these antimicrobials in different water sources could cause the development of resistance among the microbial community (RQ > 1). These results emphasize the need for constant monitoring of pharmaceutical compounds, especially antimicrobials, to be kept under check.

As(V) removal using biochar produced from an agricultural waste and prediction of removal efficiency using multiple regression analysis.

Arsenic contamination in drinking water is a matter of concern for many countries. An efficient and low-cost solution for this hazard is essentially needed on urgent basis. Therefore, in this study, banana pith (an agricultural waste) was used for biochar production and later it was modified with iron and applied for arsenic adsorption from aqueous solution. Produced biochar was characterized for proximate, ultimate, and surface analyses. Interestingly, after iron impregnation, the surface area of biochar increased (31.59 m2/g) by nearly 8 times. Morphological analysis showed that iron particles firmly held within the pores after impregnation. Arsenate (As(V)) adsorption behavior of iron-impregnated banana pith biochar was evaluated through a batch study by considering various parameters like dose, concentration, pH, temperature, and competing anions. Compared to impregnated biochar, raw biomass and its biochar showed a lesser affinity for arsenate in aqueous solution. The adsorption isotherm of As(V) on banana pith biochar was covered in the temperature range of 298 to 318 K, and kinetic data of adsorption was experimentally generated at 298 K. Langmuir model for the sorption isotherms and pseudo-second-order kinetic model for the sorption kinetics represented the experimental data. The thermodynamic study showed negative Gibb's free energy (- 46.88 kJ/mol at 298 K, - 48.58 kJ/mol at 308 K, - 50.73 kJ/mol at 318 K) that suggested spontaneity of the adsorption process. Negative enthalpy (ΔH° = - 10.55 kJ/mol) showed exothermic nature of adsorption of arsenic, while negative entropy (ΔS° = 0.123 kJ/mol.K) suggested enthalpy-driven adsorption process. Mechanism of arsenic adsorption onto iron-impregnated banana pith biochar has also been discussed in detail. Based on the experimental observation, a predictive model for arsenate removal has been developed in this study. The findings of the present study elucidated that iron-impregnated banana pith biochar can be used as a low-cost adsorbing material for As(V) from aqueous solutions.

Effect of operating conditions and interfering substances on photochemical degradation of a cationic surfactant.

This work investigates the degradation kinetics of a recalcitrant organic pollutant, cetyltrimethylammonium bromide (CTAB), using direct UV and UV-H2O2 advanced oxidation processes. Direct photolysis at 253.7 nm showed only 55% degradation up to fluence dose of 40.65 J/cm2 for an initial CTAB concentration of 100 mg/L. The apparent fluence-based pseudo-first-order rate constant and quantum yield were 2.29(±0.325) × 10-5 cm2/mJ and 0.305(±0.043) mol/Einstein, respectively. In case of UV-H2O2, >99% degradation was observed up to a fluence dose of 0.79 J/cm2. The rate constant was ∼200 times higher compared to direct photolysis, which was due to hydroxyl radical generation in the UV-H2O2 process. The second-order hydroxyl radical rate constant for CTAB was found to be 1.59(±0.18) × 109 M-1 s-1. The effects of H2O2 dose, initial CTAB concentration and relevant water quality parameters (pH, alkalinity and nitrate concentrations) were studied; all of these influenced the rate constants. CTAB degradation was also examined in the municipal wastewater matrix. It is concluded that UV-H2O2 represents an efficient treatment process for CTAB in environmental matrices.

Characterization of Sweetmeat Waste and Its Suitability for Sorption of As(III) in Aqueous Media.

Presence of arsenic in effluents from mining, mineral processing, and metal plating industries pose a serious health hazard to human beings. In this research, suitability of cheap sweetmeat waste (SMW), which is sweet industry byproduct, was investigated for the treatment of As(III). The physicochemical properties of the sorbent were characterized. The SEM images revealed highly heterogeneous sorbent surface. XRD analysis showed the presence of different polysaccharides mainly containing hydroxyl functional group. FTIR analysis was also performed to confirm the functional groups present in the sorbent. Batch experiments were conducted for kinetic analysis, effect of initial As(III) concentration, sorbent dose, electrolytes, pH, and temperature in order to understand sorption behavior. Presence of electrolyte, solution pH, and temperature were found to affect the performance of the sorbent. The sorption followed pseudo-second order reaction and Langmuir isotherm model best. The studies revealed SMW to be an efficient media for removal of As(III) from aqueous environment.

Organoarsenicals in poultry litter: detection, fate, and toxicity.

Arsenic contamination in groundwater has endangered the health and safety of millions of people around the world. One less studied mechanism for arsenic introduction into the environment is the use of organoarsenicals in animal feed. Four organoarsenicals are commonly employed as feed additives: arsanilic acid, carbarsone, nitarsone, and roxarsone. Organoarsenicals are composed of a phenylarsonic acid molecule with substituted functional groups. This review documents the use of organoarsenicals in the poultry industry, reports analytical methods available for quantifying organic arsenic, discusses the fate and transport of organoarsenicals in environmental systems, and identifies toxicological concerns associated with these chemicals. In reviewing the literature on organoarsenicals, several research needs were highlighted: advanced analytical instrumentation that allows for identification and quantification of organoarsenical degradation products; a greater research emphasis on arsanilic acid, carbarsone, and nitarsone; identification of degradation pathways, products, and kinetics; and testing/development of agricultural wastewater and solid treatment technologies for organoarsenical-laden waste.

UV irradiation and UV-H2O2 advanced oxidation of the roxarsone and nitarsone organoarsenicals.

Roxarsone (ROX) and nitarsone (NIT) are used as additives in animal feeding operations and have been detected in animal manure, agricultural retention ponds, and adjacent surface waters. This work investigates treatment of organoarsenicals using UV-based treatment processes, namely UV irradiation at 253.7 nm and the UV-H2O2 advanced oxidation process. The apparent molar absorptivity was mapped for ROX and NIT across pH and wavelength. For UV irradiation at 253.7 nm, the fluence-based pseudo-first order rate constant (kp(')) and effective quantum yield (Φ) for ROX were 8.10-29.7 × 10(-5) cm(2)/mJ and 2.34-8.37 × 10(-3) mol/E, respectively; the corresponding constants were slightly lower for NIT. The observed rate constants are higher during advanced oxidation (e.g., kp,ROX(')=3.92(±0.19)-217(±48) × 10(-4) cm(2)/mJ). Second order rate constants for organoarsenical transformation by hydroxyl radicals were determined to be 3.40(±0.45) × 10(9) and 8.28(±0.49) × 10(8) M(-1)s(-1) for ROX and NIT, respectively. Solution pH and nitrate concentration did not significantly impact ROX transformation during advanced oxidation; however, bicarbonate and dissolved organic matter from chicken litter reduced ROX transformation through hydroxyl radical scavenging. Inorganic arsenic was the predominant transformation product of ROX during UV-H2O2 treatment.

Modeling and fixed bed column adsorption of As(V) on laterite soil.

Laterite soil, an abundant locally available natural adsorbent, has been evaluated for As(V) removal from aqueous solutions in column mode operation. The column studies were conducted using columns of 10, 20, 30 cm bed depth with 2 cm internal diameter. Initial As(V) concentration was 0.5 mg/L and flow rate was 7.75 mL/min. Bohart and Adams sorption model was employed for the determination of different parameters like height of exchange zone, adsorption rate, time required for exchange zone to move, and the adsorption capacity. Effect of flow rate and initial concentration was studied. The adsorption capacity of the laterite soil for 0.5 mg/L of As(V) was found to be 62.32 mg/L, and the adsorption rate constant was 1.0911 L/mg h for the minimum bed depth of 8.47 cm. The column was designed by the BDST model. Freundlich isotherm model was used to compare the theoretical and experimental breakthrough profile in the dynamic process. The bed saturation obtained was 36-80%. Regeneration of the exhausted column was possible with 1M NaOH.

Sorption kinetics of arsenic on laterite soil in aqueous medium.

The efficiency of a locally available laterite soil in removing both arsenite and arsenate from aqueous medium by adsorption was evaluated. It was observed that in batch experiment conducted at 0.5 mg/L initial concentration of arsenic, laterite soil could remove up to 98% of arsenite and 95% of arsenate under optimized conditions. The kinetic profiles under various conditions were developed. Both arsenite and arsenate removal followed pseudo--second order reaction kinetic model. Pore and film diffusion coefficients were determined from the half-time equation and film diffusion appeared to be the rate-limiting. This was further supported by multiple interruption tests.

Removal kinetics and mechanism for crystal violet uptake by surfactant-modified alumina.

Sodium dodecyl sulfate (SDS), an anionic surfactant (AS) was used for the surface modification of neutral alumina. Micelle-like structures are formed on the surface of alumina, which was used for the removal of crystal violet (CV), a well-known cationic dye from aquatic environment. This process is called adsolubilization. The surfactant-modified alumina (SMA) was found to be very efficient showing >99% CV removal from a 200 ppm CV bearing solution with only 6 g/L of adsorbent dose. The kinetic studies showed that 60 minutes' shaking time was sufficient to achieve the equilibrium. The reaction kinetics data were analysed using four reaction kinetic models, viz., first-order reaction model, pseudo-first-order reaction model, second-order reaction model and pseudo-second-order reaction model, and it was found that the removal of CV followed the pseudo-second order reaction model. It was found that neither film diffusion nor pore diffusion was rate limiting for this process. Isotherm studies showed that Langmuir isotherm fitted more accurately compared to Freundlich isotherm. To test whether the removal of CV was possible from real water using SMA, the experiments were conducted using CV spiked distilled water and synthetic wastewater. It was interesting to note that the removal efficiency was better for wastewater as compared to that of distilled water.

Adsorption of anionic surfactant on alumina and reuse of the surfactant-modified alumina for the removal of crystal violet from aquatic environment.

The adsorption characteristics of sodium dodecyl sulfate (SDS), an anionic surfactant on neutral alumina were studied in detail. Alumina was found to be an efficient adsorbent for SDS and could be used for the removal of SDS from its highly concentrated (several thousand ppm) solution. The equilibrium time found was 2 h. Though the removal efficiency was low (approximately 65%) at neutral pH, but in slightly acidic condition and in the presence of NaCl the efficiency could be increased dramatically (up to >98%). The adsorption isotherm study showed distinct four regions. The effects of various other parameters such as adsorbent dose, time, and the presence of different ions (Cl-, NO3-, SO4(2-), and Fe3+), and nonionic surfactant on the SDS adsorption were also studied. It was observed that the adsorption capacity was increased due to the presence of these ions in general. After the adsorption of SDS on alumina, the surfactant-modified alumina (SMA) was used for the removal of crystal violet (CV), a well-known cationic dye from aquatic environment. The kinetic studies showed that 1 h shaking time was sufficient to achieve the equilibrium. The removal of CV followed the second order kinetics. Studies were conducted to see the effects of adsorbent dose and initial CV concentration on the removal of CV using SMA. The pH was maintained at 6.7+/-0.1. SMA was found to be very efficient, and approximately 99% efficiency could be achieved under optimised conditions for the removal of CV when present even at a high concentration (200 ppm). To test whether the removal of CV was possible from real water using SMA, the adsorption study was conducted using CV spiked samples using distilled water, tap water, and synthetically prepared wastewater. It was interesting to note that the removal efficiency was even better for tap water and much better for wastewater when compared to that using distilled water. Desorption of both SDS and CV from the SMA surface was possible using 1 M sodium hydroxide solutions.