Ammonia hydroxide and citric acid modified wheat straw-biochars: Preparation, characterization, and environmental applications.

This study presents an assessment of inorganic and organic modification of biochar on physicochemical properties, dissolved organic carbon (DOC) release, sorption efficiency towards enrofloxacin (E) and silver nanoparticles (Ag-NPs), as well as an evaluation of addition of prepared materials on hydro-physical properties and adsorption capacity of montmorillonite (M). The biochar was derived from wheat straw at 650 °C. An inorganic modification was performed using ammonia hydroxide, whereas an organic modification, using citric acid. The ammonia hydroxide and citric acid changed the biochar nature and surface chemistry by introducing amino and ester groups. The lowest DOC release was from ammonia-biochar (BCN) and the highest, from citric acid-biochar (BCC). The adsorption data were better described by pseudo-II order equation and Marczewski-Jaroniec isotherm. Results showed that BCN exhibited the highest efficiency in adsorption of E and Ag-NPs. It also improved the adsorptive abilities and saturated hydraulic conductivity of M. This provides the chemically modified biochars have an excellent potential to improve pollution removal from aqueous media and hydro-physical/sorption properties of soil sorption complex. They can be used with advantageous in environmental applications.

Chemical modification of biochars as a method to improve its surface properties and efficiency in removing xenobiotics from aqueous media.

Biochar (BC) is a carbonaceous material produced by pyrolysis of biomass, applied in various areas such as water purification, fuel production, soil amendment, etc. Many types of BC are characterized by insufficient textural parameters or poor surface chemistry, and hence by low adsorption capacity. This makes innovative chemical methods increasing BC ability to remove xenobiotics from aquatic environments highly needed. Many of them have already been described in the literature. This review presents them in detail and evaluates their effectiveness in improving textural parameters, surface chemistry, and adsorption capacity of BC.

Assessment of agricultural waste biochars for remediation of degraded water-soil environment: Dissolved organic carbon release and immobilization of impurities in one- or two-adsorbate systems.

This paper presents a method of agricultural waste management - the production of two biochars (BC) from potato and raspberry stems. It defines the potential of these materials for remediation of degraded water and soil environments. The performed study included analyses of BC physicochemistry, dissolved organic carbon (DOC) release and ability to immobilize copper (Cu), tetracycline (TC) and carboxin (CB) in one- and two-adsorbate systems. The BCs were obtained with pyrolysis at 600 °C for 30 min in a nitrogen atmosphere. Their DOC was predominantly constituted of substances with large molecular weights and high aromaticity, meaning that both BCs can be safely applied as soil additives. Potato-biochar (P-BC) had a more developed surface than raspberry-biochar (R-BC). The specific surface area (SBET) of P-BC was 122 m2/g, whilst of R-BC was 87 m2/g. As a result, the efficiency of impurity adsorption in the one-adsorbate systems was higher for P-BC (61.75% for Cu, 73.84% for TC, and 54.43% for CB). In the two-adsorbate systems, organic impurities improved the immobilization of heavy metal ions on BCs. The efficiency of Cu adsorption on P-BC when TC was present was 88.29%. Desorption of Cu from BC was highest using HCl, whilst that of TC and CB was highest using NaOH. Maximum desorption was observed in a two-adsorbate system with TC + CB (up to 63.6% for TC). These results confirmed that potato and raspberry stems can be used to produce highly effective BCs with large application potential, especially for remediation of degraded soils and polluted waters.

Effect of Biochar Modification by Vitamin C, Hydrogen Peroxide or Silver Nanoparticles on Its Physicochemistry and Tetracycline Removal.

Chemical modification of biochars can improve their adsorption capacity relative to antibiotics, posing a serious threat to the environment. Therefore, this research is aimed at the treatment of sunflower husk biochar (BC) by vitamin C, hydrogen peroxide or silver nanoparticles and the impact of this procedure on the biochar porosity, surface chemistry, and ability to remove tetracycline (TC). During the study, BC was produced by pyrolysis of sunflower husks at 650 °C. All solids were characterized using potentiometric titration, nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, etc. The experimental adsorption data was described by kinetics equations: pseudo-first order, pseudo-second order, and particle internal diffusion (IPD) models as well as by isotherms of Langmuir, Langmuir-Freundlich, and Redlich-Peterson. The obtained results indicated that the biochar upgraded by vitamin C (BCV) had the highest ability to attract antibiotic molecules and, as a result, the TC adsorption on its surface was the largest. Furthermore, the TC desorption from this material was minimal. The measured TC adsorbed amounts for the modified BCs were as follows: 47.75% (7.47 mg/g) for BCV, 37.35% (8.41 mg/g)-for biochar treated by hydrogen peroxide (BCH), and 42.04% (9.55 mg/g) for biochar modified by silver nanoparticles (BCA). The lowest adsorption level was noted for non-modified biochar, i.e., 34.17% (6.83 mg/g). Based on the presented results it can be stated that the upgraded biochars had a good potential to improve the tetracycline removal from aqueous media, e.g., groundwater.

How chrysanthemum (Chrysanthemum × grandiflorum) 'Palisade White' deals with long-term salt stress.

Salinity is a serious problem in the cultivation of ornamental plants. Chrysanthemum (Chrysanthemum × grandiflorum) 'Palisade White' was evaluated in order to examine its responses to long-term salt stress. Plants were grown in substrate supplemented with NaCl doses (g dm-3 of substrate) 0, 0.44, 0.96, 1.47, 1.98, 2.48 and 2.99. The initial electrical conductivity (EC) of the substrates was 0.3, 0.9, 1.4, 1.9, 2.6, 3.1 and 3.9 dS m-1, respectively. Plant growth, relative water content (RWC), Na, Cl, K, N and P concentrations, membrane injury (MI), chlorophyll and proline levels, as well as gas exchange parameters in leaves of chrysanthemum were determined. A dose-dependent significant reduction of growth and minor decrease of leaf RWC were observed. Foliar Na and Cl concentrations increased with the highest NaCl dose up to 6-fold. However, the concentration of K increased by about 14 %, N by about 5 % but P decreased by about 23 %. Membrane injury was rather low (11 %) even at the highest NaCl dose. Statistically significant decreases of stomatal conductance (20 %), transpiration rate (32 %) and photosynthesis (25 %) were already observed at the lowest NaCl dose and about 40 % decrease of all these parameters with the highest dose. A significant reduction in the intercellular CO2 concentration occurred at the lower NaCl doses and no changes with the highest dose. These results show that in plants grown with the highest NaCl dose, non-stomatal limitation of photosynthesis may occur. According to Maas and Hoffman tolerance assessment (1977) chrysanthemum 'Palisade White' may be considered as moderately sensitive to salt stress in terms of growth inhibition. However, it is able to cope with long-term salt stress without any signs of damage, such as chlorophyll depletion, leaf browning or necrotic spots probably due to maintenance of K homeostasis and proline accumulation, which alleviate the toxic effect of chloride.

Immobilization mechanism of Cd2+/HCrO4-/CrO42- ions and carboxin on montmorillonite modified with Rhizobium leguminosarum bv. trifolii exopolysaccharide.

The modification of clay minerals by exopolysaccharides (EPSs) may significantly increase their adsorption capacity. Therefore, this study focused on the impact of the EPS synthesised by the soil bacterium Rhizobium leguminosarum bv. trifolii on the adsorptive features of montmorillonite relative to two heavy metal ions (cadmium/Cd(II) and chromium/Cr(VI)) and a pesticide (carboxin). The characterization of montmorillonite was carried out using various methods: X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy. The adsorption/desorption data were modelled using theoretical equations (Langmuir-Freundlich, Redlich-Peterson, etc.). The obtained results showed that EPS promoted the accumulation of heavy metals on the clay mineral and, simultaneously, contributed to a lower degree of their desorption. This resulted from complexation between the biopolymer and the Cd(II)/Cr(VI) ions. After montmorillonite modification with 100 mg/L EPS, the maximum noted growth in Cd(II) adsorption was 26.10%, whereas it was 20.30% for Cr(VI). The adsorbed amounts of Cd(II) and Cr(VI) were then 24.24 and 14.45 mg/g, respectively. In the case of carboxin, the EPS effect on its adsorption/desorption rates was opposite - its adsorption level decreasing by 10.80%, was 0.27 mg/g. Thus, the presence of EPS-producing bacteria could reduce the bioavailability of the heavy metals, but not of the selected pesticide.

Carboxin and Diuron Adsorption Mechanism on Sunflower Husks Biochar and Goethite in the Single/Mixed Pesticide Solutions.

The study focused on the adsorption mechanism of two selected pesticides: carboxin and diuron, on goethite and biochar, which were treated as potential compounds of mixed adsorbent. The authors also prepared a simple mixture of goethite and biochar and performed adsorption measurements on this material. The adsorbents were characterized by several methods, inter alia, nitrogen adsorption/desorption, Boehm titration, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The adsorption study included kinetics and equilibrium measurements, in the solution containing one or two pesticides simultaneously. The adsorption data were fitted to selected theoretical models (e.g., Langmuir, Freudlich, Redlich-Peterson, pseudo first-order and pseudo second-order equations). Based on the obtained results, it was stated that, among all tested adsorbents, biochar had the highest adsorption capacity relative to both carboxin and diuron. It equaled 0.64 and 0.52 mg/g, respectively. Experimental data were best fitted to the pseudo second-order and Redlich-Peterson models. In the mixed systems, the adsorption levels observed on biochar, goethite and their mixture were higher for diuron and lower for carboxin, compared to those noted in the single solutions. The presented results may enable the development of new mixed adsorbent for remediation of soils polluted with pesticides.

Impact of Sinorhizobium meliloti Exopolysaccharide on Adsorption and Aggregation in the Copper(II) Ions/Supporting Electrolyte/Kaolinite System.

To obtain insight into physicochemical interactions between Cu(II) ions, kaolinite, and exopolysaccharide (EPS) synthesized by Sinorhizobium meliloti Rm 1021 soil bacteria, an adsorption, electrokinetic, and aggregation study was performed in the selected systems. The obtained data showed that supporting electrolyte type affects both EPS and Cu(II) ions adsorption. For initial Cu(II) concentration 100 mg/L, 4.36 ± 0.25 mg/g (21.80 ± 1.00%) of the ions were adsorbed in 0.001 M NaCl and 3.76 ± 0.20 mg/g (18.80 ± 1.00%) in 0.001 M CaCl2. The experimental data were best fitted to the Langmuir model as well as pseudo second-order equation. The EPS adsorbed amount on kaolinite was higher in the CaCl2 electrolyte than in NaCl one. For an initial polymer concentration of 100 mg/L, the EPS adsorbed amount was 4.69 ± 0.08 mg/g (23.45 ± 0.40%) in 0.001 M NaCl and 5.26 ± 0.15 mg/g (26.32 ± 0.75%) in 0.001 M CaCl2. In the mixed system, regardless of electrolyte type, exopolysaccharide contributed to immobilization of higher amount of copper(II) ions on the clay mineral. Also, in the samples containing heavy metal ions and exopolysaccharide simultaneously, the aggregation of kaolinite particles was the strongest. The results presented in the paper may be very helpful in soil bioremediation, especially in the development of technologies reducing the mobility of heavy metals in the environment.

Comparison of Monovalent and Divalent Ions Removal from Aqueous Solutions Using Agricultural Waste Biochars Prepared at Different Temperatures-Experimental and Model Study.

Copper (Cu) and silver (Ag) occur naturally in the environment but have toxic effects on organisms at elevated concentrations. This paper discussed the removal of Cu and Ag from aqueous solutions using biochars obtained at different pyrolysis temperatures. Three biomass sources-sunflower husks (SH), a mixture of sunflower husks and rapeseed pomace (SR) and wood waste (WW)-were pyrolyzed at 300, 400 and 500 °C. Biochars produced at 500 °C exhibited a higher specific surface area, lower variable surface charge and lower contents of surface functional groups than those obtained at 400 or 300 °C. The pseudo-second-order model and intra-particle diffusion (IPD) model well-described the Cu and Ag adsorption kinetics. The Cu adsorption was about 1.48 times slower than the Ag adsorption on the biochars obtained at 500 °C. The model of Langmuir-Freundlich well-described the equilibrium adsorption. Agricultural biochars obtained at >500 °C had a surface with a higher affinity to attract Ag than Cu and were able to remove a larger amount of heavy metals from aqueous media than those prepared at lower pyrolysis temperatures.

Purification of Aqueous Media by Biochars: Feedstock Type Effect on Silver Nanoparticles Removal.

Due to the harmful effects of nanoparticles in the environment, their effective removal from aqueous media is of great importance. This paper described the research on the silver nanoparticles (Ag-NPs) sorption on biochars obtained from different feedstock types. The sorbents were produced through pyrolysis (double-barrel method) of the vineyard (BV), paulownia tree (BP), and tobacco (BT). BV exhibited the highest specific surface area, porosity, value of variable surface charge, and content of surface acidic functional groups among the used biochars. The pseudo-second order model best described the obtained adsorption kinetics, whereas the Freundlich model accounted for the registered adsorption data. The Ag-NPs removal was highly efficient in the case of BV, especially in the nanoparticle concentration range 50-500 mg/L. Thus, this biochar can be considered as an ecofriendly, effective, low-cost organic adsorbent, potentially used in the aqueous media purification.

Effect of Dietary Phytase Supplementation on Bone and Hyaline Cartilage Development of Broilers Fed with Organically Complexed Copper in a Cu-Deficient Diet.

Tibial mechanical, chemical, and histomorphometrical traits were investigated for growing male Ross 308 broiler chickens fed diets that had copper (Cu) from organic source at a lowered level of 25% of the daily requirement (4 mg kg-1 of a premix) with or without phytase. Dietary treatments were control non-copper, non-phytase group (0 Suppl); 4 mg kg-1 Cu non-phytase group (25%Cu); and 4 mg kg-1 Cu + 500 FTU kg-1 phytase group (25%Cu + phyt). The results show that birds fed with the addition of phytase exhibited improved weight gain and final body weight and had increased serum IGF-1 and osteocalcin concentrations. The serum concentration of Cu and P did not differ between groups; however, Ca concentration decreased in the 25%Cu + phyt group when compared to the 25%Cu group. Added Cu increased bone Ca, P, Cu, and ash content in Cu-supplemented groups, but bone weight and length increased only by the addition of phytase. Bone geometry, yield, and ultimate strengths were affected by Cu and phytase addition. A decrease of the elastic stress and ultimate stress of the tibia in Cu-supplemented groups was observed. The histomorphometric analysis showed a positive effect of Cu supplementation on real bone volume and trabecular thickness in the tibia metaphyseal trabeculae; additionally, phytase increased the trabeculea number. The supplementation with Cu significantly increased the total articular cartilage and growth plate cartilage thickness; however, the changes in thickness of particular zones were dependent upon phytase addition. In summary, dietary Cu supplements given to growing broilers with Cu in their diet restricted to 25% of the daily requirement had a positive effect on bone metabolism, and phytase supplementation additionally improved cartilage development.

The effect of tannic acid on bone mechanical and geometric properties, bone density, and trabecular histomorphometry as well as the morphology of articular and growth cartilages in rats co-exposed to cadmium and lead is dose dependent.

Cadmium (Cd) and lead (Pb) are toxic elements that accumulate to the largest extent in bones. Rats were used to investigate whether tannic acid (TA; 0.5%, 1.0%, 1.5%. 2.0%, or 2.5%) would have a protective effect on the structure and properties of bones in the case of exposure to Cd and Pb (diet: 7 mg Cd/kg and 50 mg Pb/kg) for 6 weeks. The effects of administration of TA in Cd- and Pb-poisoned rats on bone characteristics and the morphology of articular and growth cartilages were determined. All the rats administered Cd and Pb had an enhanced Cd and Pb concentration in blood plasma and bone and reduced bone Ca content irrespective of the TA administration. Cd and Pb alone reduced the mechanical endurance and histomorphometric parameters of trabecular bone and the thickness of the growth plate and articular cartilage. Tannic acid improved cancellous bone parameters in the rat exposed to Cd and Pb. A diet rich in TA improved articular cartilage constituents in heavy metal-poisoned rats. These results suggest that alimentary TA supplementation can counteract in a dose-dependent manner some of the destructive changes evoked by Cd and Pb possibly by reducing the exposure.

The effect of tannic acid on the bone tissue of adult male Wistar rats exposed to cadmium and lead.

Toxic elements such as cadmium (Cd) and lead (Pb) accumulate to the largest extent in bones. Rats at the age of 12 weeks were used to check whether tannic acid (TA) at the concentration of 0.5%, 1.0%, 1.5%. 2.0% or 2.5% would have a protective effect on the structure and properties of bones in the case of exposure to Cd and Pb (diet: 7mg Cd/kg and 50mg Pb/kg) for 12 weeks. The effects of administration of TA in Cd- and Pb-poisoned rats on bone mechanical and geometric properties, trabecular histomorphometry as well as the morphology of articular and growth cartilages were determined. All the rats co-exposured to Cd and Pb had enhanced heavy metals concentration in blood plasma and bone and reduced bone Ca content irrespective of the tannic acid administration. Heave metals given to adult rats did not influence the morphology and geometry of the femur, but reduced the mechanical endurance and histomorphometric parameters of trabecular bone irrespective of the treatment. A diet rich in TA improved articular cartilage and growth plate constituents in heavy metal-poisoned rats, as indicated by the measurement of the thickness of particular zones. It seems that a use of alimentary TA supplementation in adult rats can counteract, in a dose-dependent manner, only some of the destructive changes evoked by Cd and Pb excess.

The Influence of the Dietary Cu-Glycine Complex on the Histomorphology of Cancellous Bone, Articular Cartilage, and Growth Plate as well as Bone Mechanical and Geometric Parameters Is Dose Dependent.

Copper (Cu) is required for all basic biochemical and physiological processes. The objective of this study was to compare the effect of two different chemical forms (sulfates and glycinate chelates also below the recommended dose) of Cu administered to adult rats on the biomechanical and morphometric properties of femur. Male rats at the age of 12 weeks were used in the 12-week experiment. The control diet provided the required Cu level from sulfate (S-Cu), and the other diets were supplemented with Cu-glycine complex. The Cu-Gly-treatment, irrespective of its concentration, did not influence the bone mass and length. The Cu-Gly-treatment in 100 and 75% of daily demand increased mechanical endurance. The Cu-Gly-treatment (regardless of its concentration) increased the real bone volume in epiphysis and decreased the total thickness and zone I of the articular cartilage compared to the control group supplemented with S-Cu. The Cu-Gly-treatment enhanced the content of proteoglycans (except the OG50 group). Dietary Cu given to adult rats in the Cu-Gly complex covering the daily demand in 75% exerted a positive effect on bone metabolism and appeared to be the most effective among the investigated doses of the organic form.

Alteration in bone geometric and mechanical properties, histomorphometrical parameters of trabecular bone, articular cartilage, and growth plate in adolescent rats after chronic co-exposure to cadmium and lead in the case of supplementation with green, black, red and white tea.

Adolescent male Wistar rats were used to check whether regular consumption of black, red, white, or green tea would have a protective effect on femur development during 12-week exposure to Cd and Pb (7mg Cd and 50mg Pb in 1kg of the diet). The animals were randomly divided (n=12) into a positive control (without Cd, Pb and teas), a negative control group (Cd and Pb), and groups supplemented additionally with green (GT), black (BT), red (RT), and white tea (WT). Heavy metals reduced the geometric and densitometric parameters and the total thickness of articular cartilage irrespective of tea administration and influenced mechanical endurance, growth plate thickness, and trabecular histomorphometry depending on the tea type. It is difficult to indicate which tea has the best protective effects on bone and hyaline cartilage against heavy metal action.