Gainful utilization of stems of the pernicious weed, Ipomoea carnea, to prepare good quality carbon and its modification with aluminum oxyhydroxide (AlOOH) nanoparticles for efficient defluoridation from contaminated drinking water is discussed in this paper. Surface functional groups are enhanced by functionalization of the carbons under acid treatment which acted as anchor to the AlOOH nanoparticles. Formation of AlOOH particles over the carbon surface is confirmed from X-ray diffractometry analysis. The AlOOH–carbon nanocomposite showed higher fluoride removal capacity than the neat AlOOH nanoparticles with a maximum removal capacity in the range of 46.55–53.71 mg g⁻¹. Reaction kinetics and isotherm studies showed that fluoride adsorption is quite feasible on the adsorbent surface. The column study showed the possibility of the adsorbent for large-scale applications. The adsorbent can be regenerated by a mild treatment with 0.1 N NaOH solutions. The adsorbent is highly capable for defluoridation from synthetic as well as fluoride-contaminated natural water and, thus, can be used as an alternative for commercial defluoridation adsorbents. The use of Ipomoea carnea for defluoridation can be a way of producing low-cost adsorbent material, and the use for such purposes may also be helpful to control the weed up to a good extent.

The study revisits the position of the environmental Kuznets curve (EKC) hypothesis in India by incorporating the role of energy consumption and democratic regime in the environmental degradation function for the period 1971–2014. Employing Zivot–Andrews nonstationarity test, Bayer–Hanck cointegration test, autoregressive distributed lag (ARDL) model, and vector autoregressive model (VECM) Granger causality test, the results found the integration order of I(1) and a stable cointegration among the series. The result validates the EKC hypothesis for India and further divulges that while energy consumption increases environmental degradation both in the long run and short run; the effect of democracy in reducing environmental degradation is weak (statistically insignificant) in the long run but strong (statistically significant) in the short run. The finding from the VECM Granger causality test indicates a long-run causality between the fundamental variables and environmental degradation. Furthermore, the results of the short run show a unidirectional Granger causality running from energy consumption to environmental degradation, energy consumption to real income, and energy consumption to square of real income. Therefore, our findings suggest that energy conservation policy should be prioritized towards harnessing energy from clean sources to mitigate environmental degradation and spur economic growth.

This study examines the impact of fossil fuel consumption, nonrenewable energy consumption, population, affluence, and poverty on carbon emissions in Pakistan by using a time series data from 1972 to 2014. The study uses a flexible ecological framework known as the STIRPAT model. The Auto Regressive Distributive Lag (ARDL) Model and Error Correction Model (ECM) are used to estimate the robust results. The results show that consumption of fossil fuels, population growth, improvement in affluence level, and urbanization are contributing factors to high carbon emissions in Pakistan. The results also highlight that poverty alleviation and carbon emissions have opposite trends, this shows that the efforts to reduce poverty are stimulating the consumption of low-cost energy sources such as fossil fuels, and contributing to carbon emissions. However, results indicate that an increase in the share of renewable energy in total energy use and consumption of hydroelectric energy has the potential to reduce carbon emissions in Pakistan. The results highlight that there is a need to promote the use of renewable and hydroelectric energy. At domestic level, this will assist to meet the energy demand of the growing population and also prove helpful to reduce carbon emissions. Thus, the study recommends that a transition from fossil fuel energy to renewable and hydroelectric energy could prove an effective strategy to improve the affluence level, to alleviate poverty and effective to reduce carbon emissions in Pakistan.

This study aims to test the EKC (Environmental Kuznets Curve) hypothesis for the ten states, having the highest levels of carbon dioxide emissions in the USA, through the independent variables of real GDP, population, and renewable energy and fossil energy consumptions. To this aim, the panel estimation method with cross-sectional dependence is applied to data from 1980 to 2015. The empirical findings of the study indicate that the EKC (inverted U-shaped) hypothesis is valid only for Florida, Illinois, Michigan, New York, and Ohio. Interestingly, the negative impacts of fossil energy consumption on CO₂ emission levels in Texas are not detected statistically although this state is the leading oil-producing state. Furthermore, the positive impacts of renewable energy consumption in Florida, officially known as “Sunshine State”, are considerably low when compared with the other states.

Copper (Cu) and norfloxacin (Nor) are frequently used as feed additives for animal growth promotion, which results in a great probability of Cu²⁺ and Nor coexisting in animal excretion and in soils. Sorption of Cu²⁺ and Nor on soil organic matter (SOM) can markedly affect their environmental fate. Thus, humic acid (HA), a major fraction of SOM, was chosen to investigate the cosorption behaviors of Cu²⁺ and Nor on HA under different solution chemistry conditions (pHs, ionic strengths, and foreign ions). The addition of Nor decreased the maximum adsorption capacity (Qₘ) of Cu²⁺ and an increasing effect was observed with increasing Nor concentration. Meanwhile, the addition of Cu²⁺ also markedly inhibited the sorption of Nor on HA. The Qₘ of Cu²⁺ increased with increasing pH from 3.0 to 5.0 whether Nor was present or not, but more addition of Nor led to less increment in Qₘ of Cu²⁺ at the same pH. The Qₘ of Nor was observed at pH 4.0 without Cu²⁺, but that was found at pH 5.0 and 3.0 with the addition of 20 and 100 mg L⁻¹ Cu²⁺, respectively. The sorption of Cu²⁺ on HA decreased with increasing ionic strength and followed an order of NaH₂PO₄ > Na₂SO₄ ≈ NaNO₃ at pH 5.0 whether Nor was present or not. Additionally, the higher valence cation had a stronger inhibition effect on Cu²⁺ sorption. The competition between Cu²⁺ and Nor for sorption on HA under the same conditions indicated that the coexistence of Cu²⁺ and Nor may enhance the feasibility of their mobility and environmental risk.

In this study, aqueous extracts of Musa paradisica (banana) peels and Dolichos lablab (Indian beans) seeds were prepared and tested as natural coagulants for turbidity removal from simulated turbid water. Effects of extraction time (15, 30, and 45 min), dosage (0.2 to 1.0 mL/L), and water pH on turbidity removals by the natural coagulants were evaluated. In both cases, the extraction time of 45 min for the preparation of aqueous extract and dosage of 0.6 mL/L gave the best results in terms of turbidity removal. Natural coagulants from M. paradisica peels powder could efficiently remove turbidity (> 83%) at all tested pH values (3.0 to 12.0) with maximum turbidity removal of 98.14% at pH 11. In the case of D. lablab seeds, low turbidity removal (71–74%) was observed at pH between 5.0 and 9.0. The maximum turbidity removal (98.84%) was obtained at pH 11. The scanning electron microscopy (SEM) analysis of the settled flocs revealed that more compact flocs formed using M. paradisica peels extract than those developed using D. lablab seeds extract. The chemical analysis and Fourier transform infrared (FTIR) spectroscopy of the extracts revealed that polymeric substances (carbohydrate and proteins) having functional groups –OH, C–N, C–C, –COOH, and N–H might be responsible for the coagulation activity. The zeta potential measurements of natural coagulants revealed that the possible coagulation mechanism would be adsorption and bridging between particles. This study demonstrated the potential use of aqueous extracts of M. paradisica peels and D. lablab seeds as low-cost natural coagulants for turbidity removal.

The objective of this study is to investigate the contributions of Mikania micrantha (chinese creeper) to remediate heavy metal pollutants present in an e-waste-contaminated soil. Different proportions of e-waste soil (0%, 25%, 50%, 75%, and 100% w/w) planted with Cynodon dactylon together with the test species were prepared for testing relative seed germination (RSG), relative root growth (RRG), and germination index (GI) tests. A significant higher value of GI (77.8%) was found in M. micrantha than that of the other species when planting in 100% e-waste-contaminated soil. A significant correlation (< 0.05) was found between heavy metal concentration and germination assays in M. micrantha. A significant decrease in heavy metal concentration of the polluted soil after the experiment indicated that biomolecule development studies to determine the aggregate benefit of M. micrantha for phytoremediation remain to be studied in future.

Soils can be contaminated by pharmaceuticals. The aim of this study was to evaluate the impact of soil conditions (influencing sorption and persistence of pharmaceuticals in soils) and plant type on the root uptake of selected pharmaceuticals and their transformation in plant-soil systems. Four plants (lamb’s lettuce, spinach, arugula, radish) planted in 3 soils were irrigated for 20 days (26) with water contaminated by one of 3 pharmaceuticals (carbamazepine, atenolol, sulfamethoxazole) or their mixture. The concentrations of pharmaceuticals and their metabolites in soils and plant tissues were evaluated after the harvest. Sulfamethoxazole and atenolol dissipated rapidly from soils. The larger concentrations of both compounds and an atenolol metabolite were found in roots than in leaves. Sulfamethoxazole metabolites were below the limits of quantifications. Carbamazepine was stable in soils, easily uptaken, accumulated, and metabolized in plant leaves. The efficiency of radish and arugula (both family Brassicaceae) in metabolizing was very low contrary to the high and moderate efficiencies of lamb’s lettuce and spinach, respectively. Compounds’ transformations mostly masked the soil impact on their accumulation in plant tissues. The negative relationships were found between the carbamazepine sorption coefficients and its concentrations in roots of radish, lamb’s lettuce, and spinach.

The increase in biodiesel production has been leading to an excess amount of crude glycerol and, consequently, serious environmental issues. For this reason, electrospun chitosan-based nanofibers (CB-EN), composed by chitosan and poly(ethylene oxide) (PEO), were synthesized to apply in the biosorption of impurities from industrial glycerol. To evaluate the biosorption efficiency, the chitosan-based nanofiber was compared to other chitosan-based biosorbents (chitosan biopolymeric film and chitosan powder). The equilibrium and thermodynamic studies were successfully performed to comprehend the interaction mechanisms through the biosorption of glycerol pigments onto electrospun chitosan-based nanofibers. The temperature effect was evaluated by experimental equilibrium curves. Freundlich and BET models were used to estimate isotherm parameters. Gibbs free energy change, enthalpy change, entropy change, and isosteric heat of biosorption were quantified. The equilibrium curves showed that the highest equilibrium relative adsorption (340.7 g⁻¹) was reached at 60 °C. The BET model was the most suitable to represent the equilibrium behavior. The thermodynamic parameters indicated that the biosorption was spontaneous, exothermic, random, and energetic heterogeneous. Therefore, this work developed a green and efficient alternative to refine industrial glycerol. Graphical abstract Note: This data is mandatory. Please provide

Several parts of the world have been facing the problem of nitrite and nitrate contamination in ground and surface water. The acute toxicity of nitrite has been shown to be 10-fold higher than that of nitrate. In the present study, aminated silica carbon nanotube (ASCNT) was synthesised and tested for nitrite removal. The synergistic effects rendered by both amine and silica in ASCNT have significantly improved the nitrite removal efficiency. The IEP increased from 2.91 for pristine carbon nanotube (CNT) to 8.15 for ASCNT, and the surface area also increased from 178.86 to 548.21 m² g⁻¹. These properties have promoted ASCNT a novel adsorbent to remove nitrite. At optimum conditions of 700 ppm of nitrite concentration at pH 7 and 5 h of contact with 15 mg of adsorbent, the ASCNT achieved the maximal loading capacity of 396 mg/g (85% nitrite removal). The removal data of nitrite onto ASCNT fitted the Langmuir isotherm model better than the Freundlich isotherm model with the highest regression value of 0.98415, and also, the nonlinear analysis of kinetics data showed that the removal of nitrite followed pseudo-second-order kinetic. The positive values of both ΔS° and ΔH° suggested an endothermic reaction and an increase in randomness at the solid–liquid interface. The negative ΔG° values indicated a spontaneous adsorption process. The ASCNT was characterised using FESEM–EDX and FTIR, and the results obtained confirmed the removal of nitrite. Based on the findings, ASCNT can be considered as a novel and promising candidate for the removal of nitrite ions from wastewater.