In this research work, the removal of chromium(III) ion (Cr³⁺) by raw materials such as zeolite (Z) and chert (CH) was investigated. The batch method was invested, using two concentrations in chromium(III) sulphate at 21.31mg/L and at 22mg/L in nitrate nonahydrate. In order to improve the porous structure, the specific surface area and the adsorbent capacity of these natural materials, a purification technique was undertaken, namely a chemical treatment of the used natural materials (zeolite and cherts) with NaCl was carried out. Thus, the obtained raw and purified materials were characterized through chemical analysis by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and liquid nitrogen adsorption-desorption analyses by measuring the specific surface area (BET method). The results demonstrated that zeolite (Z) and chert (CH) are good adsorbents and that the purified materials have a potential adsorbent to reduce the chromium concentration for a maximum adsorbed amount (Qads) of about 2.72mg/g and 2.85mg/g, respectively for purified zeolite and chert (Z-p and CH-p) in chromium(III) nitrate and about 2.83mg/g and 2.48mg/g, respectively for purified zeolite and chert (Z-p and CH-p) in chromium(III) sulphate. These results revealed that natural zeolite and chert hold great potential to remove cationic heavy metal species from industrial wastewater. The kinetics adsorption was also examined using pseudo-first-order and pseudo-second-order kinetics models. The adsorption kinetics was best described by the pseudo-second-order.

In this work, we successfully fabricated boron nitride foams by assembling boron nitride into a 3D porous structure using freeze drying. Boron nitride was modified by Hummers method and NaOH, which results in the functionalization with OH groups. Such chemical functionalization enabled the attachment of the surfactant molecules, leading to a 3D foam structure. We found that the type of the surfactant molecules and method of freezing (in liquid nitrogen or in a deep freezer) have significant impact on the structure of the foams and consequently their absorbent properties. Fast freezing technique (with liquid nitrogen) created more stable and porous structures compared to the slow freezing technique (in a deep freezer). The best foam structures were obtained for the samples coded as h-BN-B-H-SA and h-BN-N-DA. The highest absorption capacity was found as 2014.3% for h-BN-B-H-SA. Absorption capacity results show that foams can absorb approximately 2–20 times their own weight. The method we use here is easy to apply, environmentally friendly, and can be readily scaled up for industrial use.

Nine hydrothermal carbonization process waters (PWs) of poultry litter were prepared at 180, 220, and 260 °C for 1, 4, and 8 h, respectively. They were characterized with pH, EC (electric conductivity), DOC (dissolved organic carbon), TN (total nitrogen), NH₄⁺-N, NO₃⁻-N, etc. After diluted according to TN, the PWs were supplied as liquid nitrogen fertilizers and their phytotoxic and nutrition effects on lettuce germination and growth were studied. The results showed that the PWs from short time (1 h) were with low DOC/TN and DOC/NH₄⁺-N and high NH₄⁺-N/TN. Compared with the PWs from long time 4 and 8 h, they provided more NH₄⁺-N and less DOC and resulted in lettuce with relatively high germination index (GI), dry biomass, and low antioxidant enzyme activities. Especially, the PW from 220 °C and 1 h significantly enhanced the dry weight by 196.3% relative to negative control of nitrogen deficiency. However, all the PWs led lettuce to an unhealthy condition, which decreased GI and the chlorophyll content and increased antioxidant enzyme activities. Furthermore, it was confirmed by linear regression that the ratios of DOC/TN, NH₄⁺-N/TN, and DOC/NH₄⁺-N were the determining indexes for evaluating the phytotoxicity and nutrition behavior of the PWs as liquid nitrogen fertilizers.

Imidacloprid (1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine (CAS No: 138261–41-3), neonicotinoid insecticide, and agricultural plant protectants were applied as seed and soil treatments. The aim of the present study is to determine the effects of sub-lethal imidacloprid concentrations on the histopathology and oxidative stress parameters with lipid peroxidation (LPO) to standard non-target test organism, tilapia (Oreochromis niloticus). 50 and 100 mgL⁻¹ imidacloprid concentrations were chosen for experimental groups with control group. Fish were stocked in 60 L glass aquaria, maintained in aerated and dechlorinated tap water. The mean weight and length of tilapia were 37.78 ± 2.19 g and 12.98 ± 0.22 cm, respectively. After 24 and 96 h exposure to sub-lethal imidacloprid concentrations, the fish were sacrificed; tissue samples of gill and liver were snap frozen in liquid nitrogen for oxidative stress parameters and LPO assays, fixed (buffered 10% formalin) for histopathology. After exposure to sub-lethal imidacloprid, LPO was induced in both tissues. MDA levels were increased in both tissues, while GSH levels were reduced at the high concentration of imidacloprid in the gill tissues after 96 h and both concentrations in the liver tissues (P < 0.05). There were no significant differences for antioxidant enzymes CAT, SOD and GPx between exposed and control groups (P > 0.05). Gill tissues revealed hyperaemia, epithelial lifting, fusion of secondary lamellae and telangiectasia, whereas hyperaemia, mononuclear cell infiltration vacuolization of hepatocytes and hydropic degeneration were observed in liver tissues. Imidacloprid is very toxic to the non-target species in the aquatic ecosystem even at sub-lethal concentrations.

Pesticides are one of the main sources of pollution on the planet, affecting different environments. The aim of the study was to evaluate the chronic effect of atrazine (ATZ) on brain, gill, and liver histology and the clinical signs of intoxication in Hyphessobrycon eques fish and to determine the effect on the expression of proteins related to proliferation, damage, death, and cellular stress pathways. The chronic toxicity test was performed during 30 days of exposure to ATZ. Concentrations of 0.57, 1.14, 5.74, and 11.50 mg L⁻¹ were applied and there was a control. Aquariums with a capacity of 5 L of water were used with aeration pumps containing 5 animals per replica, weighing between 1.0 ± 0.2 g per organism. At the end of the chronic toxicity tests of ATZ for H. eques, samples of the gills, brain, and liver were collected for histological analysis. The same organs were collected and stored in cryogen tubes in liquid nitrogen until the moment of extraction and then massaged mechanically for the Western-blot technique. In the histopathological analyses, the gills showed the greatest changes in relation to the other organs, such as the loss of support of the secondary lamellae, and the fish also showed a loss of swim bladder capacity. In conclusion, ATZ in the environment, in long-term exposure, can cause histological and biochemical effects, affecting the survival and proliferation of cell pathways.

The formaldehyde dehydrogenase (FADH) activity in plants is essential to the removal of airborne formaldehyde (FA) by plants. A rapid and efficient method was established to assess the FADH activity in plants by analyzing the efficiencies of the extracts of fresh and enzyme-inactivated leaves to degrade FA, with the enzyme-inactivated leaves prepared by freezing with liquid nitrogen. The efficiencies of airborne FA dissipated by different plants were evaluated through the FA fumigation experiments using four selected plants, with the results analyzed against the calculated leaf FADH activities. Fresh and enzyme-inactivated leaf extracts degraded FA to different extents. The degradative efficiencies of leaf extracts were positively related to the initial FA test levels at 6–18 mg l⁻¹. The relative plant-leaf FADH activities formed the order of Chenopodium album L. > Atenia cordifolia > Plantain > Aloe, which was in line with the observed FA dissipating efficiencies of the plants exposed to 0.72 mg m⁻³ airborne FA for 24 h. Other dominant degrading mechanisms in plant leaves resulted in higher dissipating efficiencies of Plantain over that of Atenia cordifolia when exposed to 1.56 mg m⁻³ FA for 24 h. The established method could be applied to estimate the FADH activity in plants for assessment of the plant remediation efficiency of FA in air at lower concentrations.