Combining environmental, health, and safety features with a conductor like Screening Model for selecting green solvents for antibiotic analyses.

Extraction and chromatographic techniques for analyzing pharmaceutically active compounds necessitate large quantities of organic solvents, resulting in a high volume of hazardous waste. The concept of green solvents focuses on protecting the environment by reducing or even eliminating the use of toxic solvents. The main objective of this critical review article is to build a framework for choosing green solvents for antibiotic analyses. The article briefly discusses the chemical properties of ciprofloxacin, sulfamethoxazole, tetracycline, and trimethoprim, and the current state of methodologies for their analyses in water and wastewater. It evaluates the greenness of solvents used for antibiotic analyses and includes insights on the comparison between conventional and green solvents for the analyses. An economic and environmental health and safety analysis combined with a Conductor-like Screening Model for Real Solvent (COSMO-RS) molecular simulation technique for predicting extraction efficiency was used in the evaluation. Methyl acetate and propylene carbonate tied for the greenest solvents from an environmental and economic perspective, whereas the COSMO-RS approach suggests dimethyl sulfoxide (DMSO) as the most suitable candidate. Although DMSO ranked third environmentally and economically, after methyl acetate and propylene carbonate, it would be an ideal replacement of hazardous solvents if it could be manufactured at a lower cost. DMSO showed the highest extraction capacity, as it can interact with antibiotics through hydrophobic interaction and hydrogen bonding. This article can be used as a green solvent selection guide for developing sustainable processes for antibiotic analyses.

GenX is not always a better fluorinated organic compound than PFOA: A critical review on aqueous phase treatability by adsorption and its associated cost.

Hexafluoropropylene oxide dimer acid (GenX) has been marketed as a substitute for perfluorooctanoic acid (PFOA) to reduce environmental and health risks. GenX and PFOA have been detected in various natural water sources, and adsorption is recognized as a typical treatment process for PFOA removal. In this paper, comparisons of GenX and PFOA adsorption are evaluated, including adsorption potential, adsorption mechanisms, and associated costs. A detailed literature review suggests that anion-exchange resins are more effective in removing GenX than activated carbon. GenX removal efficiency through activated carbon (30%) is lower than that of PFOA (80-95%), while GenX and PFOA removal efficiencies by anion exchange resins are similar (99%). Unconventional adsorbents, such as ionic fluorogels and covalent organic frameworks can effectively remove GenX from water. The review reveals that GenX adsorption is more challenging, requiring almost 4 times the treatment cost of its predecessor, PFOA. Annual operation and maintenance costs for GenX adsorption (initial concentration of GenX and PFOA = 0.2 µg.L-1) by GAC for treating 10,000 m3 per day is almost US$1,000,000 per year, but only around US$240,000 per year for PFOA. Desorption of GenX in the presence of PFOA highlights GenX's inferior treatability by adsorption. It is believed that GenX is a more environmentally friendly compound than PFOA, but this environmental friendliness comes with the price.

Iron turning waste: Low cost and sustainable permeable reactive barrier media for remediating dieldrin, endrin, DDT and lindane in groundwater.

The feasibility and effectiveness of iron turning waste as low cost and sustainable permeable reactive barrier (PRB) media for remediating dieldrin, endrin, dichlorodiphenyltrichloroethane (DDT), and lindane individually (batch system) and combined (continuous flow column) in water were investigated. After 10 min of reaction in a batch system, removal of endrin, dieldrin, and DDT was higher (86-91 %) than lindane (41 %) using 1 g of iron turning waste in 200 mL of pesticide solution (20 µg/L for each pesticide). Among the studied pesticides, only lindane removal decreased substantially in the presence of nitrate (37 %) and magnesium (18 %). Acidic water environment (pH = 4) favored the pesticide removal than neutral and basic environments. For the column experiments, sand alone as PRB media was ineffective for remediating the pesticides in water. When only iron turning was used, the removal efficiencies of lindane, endrin, and dieldrin were 83-88 % and remained stable during 60 min of the experiments. DDT removal was less than other pesticides (58 %). Sandwiching the iron turning waste media between two sand layers improved DDT removal (79 %) as well as limited the iron content below a permissible level in product water. In a long-term PRB column performance evaluation, iron turning waste (150 g) removed all pesticides in water (initial concentration of each pesticide = 2 µg/L) effectively (≥94 %) at a hydraulic retention time of 1.6 h. Iron turning waste, which was mainly in the form of zerovalent iron (Fe0), was oxidized to ferrous (Fe2+) and ferric (Fe3+) iron during its reaction with pesticides, and electrons donated by Fe0 and Fe2+ were responsible for complete dechlorination of all the pesticides. Therefore, it can be used as inexpensive and sustainable PRB media for groundwater remediation especially in developing countries where groundwater contamination with pesticides is more prevalent.

Virgin (Fe0) and microbially regenerated (Fe2+) iron turning waste for treating chlorinated pesticides in water.

This work investigated the applicability of iron turning waste as filtration media for treating mixture of organochlorine pesticides (OCPs) in water and the ability of non-pathogenic bacterium Shewanella oneidensis to regenerate the exhausted iron turning waste for reuse. In batch experiments, 1.5 × 104 mg/L of iron turning waste efficiently removed (≥85%) five out of six pesticides in 200 mL of water (20 µg/L for each pesticide) in 10 min. Increasing the iron dose from 2.5 × 103 to 1.5 × 104 mg/L enhanced the removal of heptachlor, endosulfan, dieldrin, and endrin by 5.7, 13.2, 23.3, and 39.4%, respectively, whereas lindane and dichlorodiphenyltrichloroethane removal was comparable when using 2.5 × 103 and 1.5 × 104 mg/L of iron. Better pesticide removal (except lindane) was achieved when the initial concentration of each pesticide was higher (20 µg/L versus 1 µg/L) in the solution. Acidic pH favored OCPs (except endosulfan) removal. S. oneidensis efficiently reduced 80 ± 5% of dissolved ferric iron (Fe3+) to ferrous iron (Fe2+) in 72 h. Microbially regenerated Fe2+ iron removed all six OCPs in water efficiently (52-91%) and at similar levels as provided by virgin iron turning (38-100%). Lindane, endosulfan, and dieldrin removal increased 4-fold using S. oneidensis regenerated iron compared to exhausted iron.

Iron turning waste media for treating Endosulfan and Heptachlor contaminated water.

This study explored the application of iron turning waste for the degradation of heptachlor and endosulfan. In batch experiments, 2.5 g of iron turning waste efficiently removed 96% of heptachlor and 85% of endosulfan in 200 mL of water (20 µg/L for each pesticide) in ten minutes. By increasing the iron turning dose from 1 g to 2.5 g, pseudo second order removal rates of heptachlor and endosulfan increased 1.5-fold and 1.37-fold, respectively. Among the minerals in groundwater, calcium and potassium lowered heptachlor removal (8-10%), whereas their effect on endosulfan removal was minimal. Endosulfan removal increased 16%, when water pH was raised from 4 to 10. The effect of water pH on heptachlor removal was minimal. The removal of heptachlor and endosulfan dropped to 55% and 46%, respectively, when the initial concentration was 1 µg/L. In a continuous flow system, iron turning worked better in combination with sand media. Water flow rate (5-15 mL/min) had a limited effect on the removal of both pesticides (initial concentration of 2 µg/L) which increased with increasing iron turning dose (100-150 g) for endosulfan. Heptachlor removal remained stable (100%) regardless of the iron turning amount (100-150 g) used in a filtration column. Iron turning based filter completely removed heptachlor throughout the filtration period (600 h), whereas endosulfan removal dropped from 100% to 88-90% after 300 h. Endosulfan and heptachlor were degraded into nonanal and heptanal, respectively. Iron turning waste was characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) before and after its reactions with both pesticides. XRD and XPS analyses revealed that virgin iron turning waste consisted of zerovalent iron (Fe0) and iron oxides, and Fe0 was transformed to magnetite (Fe3O4) after reacting with both pesticides. Based on detected degradation by-products, the removal mechanism and degradation pathways for both pesticides were elucidated.

Correlation studies on nitrogen for sunflower crop across the agroclimatic variability.

Nitrogen (N) fertilizer is an important yield limiting factor for sunflower production. The correlation between yield components and growth parameters of three sunflower hybrids (Hysun-33, Hysun-38, Pioneer-64A93) were studied with five N rates (0, 60, 120, 180, 240 kg ha(-1)) at three different experimental sites during the two consecutive growing seasons 2008 and 2009. The results revealed that total dry matter (TDM) production and grain yield were positively and linearly associated with leaf area index (LAI), leaf area duration (LAD), and crop growth rate (CGR) at all three sites of the experiments. The significant association of yield with growth components indicated that the humid climate was most suitable for sunflower production. Furthermore, the association of these components can be successfully used to predict the grain yield under diverse climatic conditions. The application of N at increased rate of 180 kg ha(-1) resulted in maximum yield as compared to standard rate (120 kg ha(-1)) at all the experimental sites. In this way, N application rate was significantly correlated with growth and development of sunflower under a variety of climatic conditions. Keeping in view such relationship, the N dose can be optimized for sunflower crop in a particular region to maximize the productivity. Multilocation trails help to predict the input rates precisely while taking climatic variations into account also. In the long run, results of this study provides basis for sustainable sunflower production under changing climate.