Adsorption and Reduction from Modified Polypyrrole Enhance Electrokinetic Remediation of Hexavalent Chromium-Contaminated Soil

Heavy metal pollutant Cr(Ⅵ) in the environment will pose a severe threat to animal and human health. In this work, Fe3O4@PPy, Arg@PPy, and Arg/Fe3O4@PPy were prepared to enhance adsorption of Cr(Ⅵ) by doping Fe3O4 nanoparticles and amino radicals into the original PPy structure. Their characteristics were investigated by FTIR, SEM, EDS, BET analysis, and batch adsorption experiments. And they were used as permeable reaction barriers (PRB) to combine with electrokinetic remediation (EKR) to remediate Cr-contaminated soil. Adsorption experiment results showed that the maximum adsorption capacities of PPy, Fe3O4@PPy, Arg@PPy, and Arg/Fe3O4@PPy for Cr(Ⅵ) were 60.43 mg/g, 67.12 mg/g, 159.86 mg/g, and 141.50 mg/g, respectively. All of them followed the kinetic pseudo-second-order model and the Langmuir isothermal model with a monolayer adsorption behavior. In EKR/PRB system, the presence of Fe3O4@PPy, Arg@PPy, and Arg/Fe3O4@PPy obtained the higher Cr(Ⅵ) removal efficiency near the anode than that of the PPy, increasing by 74.60%, 26.04%, 68.64%, respectively. A strong electrostatic attraction between anion contaminants and protonated modified PPy and a reduction from Cr(Ⅵ) to Cr(Ⅲ) appeared in the EKR remediation process under acid conditions. This study opened up a prospect for applying modified PPy composites to treat heavy metal contaminated soil.

Review—Sensor Evaluation for Thiamethoxam Detection in Different Matrices

Thiamethoxam (3-[(2-chloro-5-thiazolyl)methyl] tetrahydro-5-methyl-N-nitro-4H-1,3,5-oxadiazin-4- imine) is a representative compound of new neonicotinoid insecticides, which can selectively act on the central nervous system of insects and is widely used to control sucking insect pests. Due to its extensive usage, high water solubility, high leaching capability, low soil adsorption, and poor biodegradability, the residues of the thiamethoxam persist in the environment with adverse effects. Therefore, it is necessary to develop analytical tools for the monitoring of thiamethoxam. An electrochemical sensor is suitable for rapid and simple analyses of pesticides, which are likely to persist at a trace level in agro-environments, including agricultural products, soil, and water. Here, the new trends in sensors development and the application for the detection of thiamethoxam in the environmental are described. The fundamental analytical performance of the electrodes is discussed. The application of these sensors for thiamethoxam monitoring in different matrices is reported.Electrochemical sensor is suitable for rapid and simple analyses of pesticides, which are likely to persist at a trace level in agro-environments, including agricultural products, soil, and water. In this review, the new trends in sensors development and the application for the detection of thiamethoxam in the environmental are described. The fundamental analytical performance of the electrodes is discussed. The application of these sensors for thiamethoxam monitoring in different matrices is reported

Lysimeter based evaporation and condensation dynamics in a Mediterranean ecosystem

The input of liquid water to terrestrial ecosystems is composed of rain and non-rainfall water input (NRWI). The latter comprises dew, fog, and adsorption of atmospheric vapor on soil particle surfaces. Although NRWIs can be relevant to support ecosystem functioning in seasonally dry ecosystems, they are understudied, being relatively small, and therefore hard to measure. In this study, we test a routine for analyzing lysimeter data specifically to determine NRWI. We apply it on one year of data from large high-precision weighing lysimeters at a semi-arid Mediterranean site and quantify that NRWIs occur for at least 3 h on 297 days (81 % of the year) with a mean diel duration of 6 hours. They reflect a pronounced seasonality as modulated by environmental conditions (i.e., temperature and net radiation). During the wet season, both dew and fog dominate NRWI, while during the dry season it is soil adsorption of atmospheric vapor. Although NRWI contributes only 7.4 % to the annual water input NRWI is the only water input to the ecosystem during 15 weeks, mainly in the dry season. Benefitting from the comprehensive set of measurements at the Majadas instrumental site, we show that our findings are in line with (i) independent model simulations forced with (near-) surface energy and moisture measurements and (ii) eddy covariance-derived latent heat flux estimates. This study shows that NRWI can be reliably quantified through high-resolution weighing lysimeters and a few additional measurements. Their main occurrence during night-time underlines the necessity to consider ecosystem water fluxes at high temporal resolution and with 24-hour coverage.

Lead and Chromium Immobilization Process Subjected to Different Freeze-Thaw Treatments in Soils of the Northeastern Qinghai-Tibet Plateau

The freeze-thaw cycle is one of the important processes that affected heavy metal behaviors in soil. However, information regarding the adsorption and desorption behavior of heavy metals in soils under different freeze-thaw conditions is relatively less. Therefore, different freeze-thaw conditions including unfrozen, 15 freeze-thaw cycles at 60% water content, and 15 freeze-thaw cycles at 100% water content were investigated. Then the adsorption and desorption behaviors of Pb and Cr in freeze-thaw soils were studied. Results showed the Pb and Cr adsorption amount mostly decreased with increasing water-soil ratio, and the soil performance of Pb and Cr adsorption at same water-soil ratios showed variation under different freeze-thaw conditions. The Pb isothermal adsorption was higher for most freeze-thaw treatments compared to the control. The soil performance of Cr isothermal adsorption showed variation under different freeze-thaw conditions. Most electrostatic binding of Pb and Cr were stronger under unfrozen and freeze-thaw conditions than unfrozen conditions. Most Pb and Cr adsorption kinetics patterns of freeze-thaw treated soils were rapid than unfrozen conditions. These results implied that freeze-thaw cycles could change the soil adsorption and desorption patterns of Pb and Cr. Therefore, further studies are urgently needed to investigate Pb and Cr immobilization mechanisms in soils during freeze-thaw cycles. Hence, these findings provided useful information on Pb and Cr immobilization process in soils that underwent freeze-thaw cycles to offer an additional insight into predicting Pb and Cr behaviors in cold and freezing environments.

Waste Footprint of Selected City Districts of Prague

The growing population, thriving economy, rapid urbanisation significantly accelerate the generation of municipal waste. Tightening conditions for waste management are a challenge for all stakeholders to comply with the law and, at the same time, motivate them to reduce waste production. The knowledge of the biosphere's assimilation capacity can quantify the environmental impact of waste in an understandable and popular form to better understand the human need to assimilate the waste produced. Utilising the waste footprint indicator and anthropogenic emissions in the form of waste are converted into soil adsorption capacity. The article compares the waste footprints of different areas of the city of Prague. It quantifies the influence of living and waste services on the waste footprints of the capital inhabitants. This article also discusses the relationship of the waste footprint with other footprints and is intended to inform future debate on trace accounting.

The Influence of ZnCl2 Activation on Macronutrient NPK Adsorption Simultaneously Using Coconut Shell Biochar for Soil Fertility Improvement

The influence of ZnCl2 activation on macronutrient Nitrogen, Phosphor, Potassium (NPK) adsorption simultaneously using Coconut Shell Biochar for soil fertility improvement has been conducted. Biochar formation is carried out at temperature up to 500 oC using variation in the concentration of ZnCl2 0,5; 1,0; 1,5; 2,0; dan 2,5 M. The biochar formed was characterized using Fourier Transform InfraRed (FTIR) spectroscopy and Surface Area Analyzer (SAA). Whereas NPK analysis has used the Indonesian standard method (SNI 7763: 2018). Based on this research, it was concluded that the greater the concentration of ZnCl2 activator, indicated that the higher intensity of the spectra of –OH and –NH2 at wave number 3400 cm-1 and 1600 cm-1. It showed that biochar activation was higher and a more active functional group was opened. Increasing the concentration of ZnCl2 activator has increased Biochar adsorption of NPK macronutrients. The optimum condition for activation of coconut shell Biochar was activation with ZnCl2 2.5 M. The addition of activated Biochar was increased soil adsorption on NPK macronutrients. Biochar addition had increased Nitrogen (N) adsorption up to 23.53%, Phosphor (P) up to 200%, and Potassium (K) up to 41.24%.