Aqueous carbofuran removal using slow pyrolyzed sugarcane bagasse biochar: equilibrium and fixed-bed studies

The adsorption effects of biochar on carbofuran in water and the mixture toxicity of biochar-carbofuran in rats

Carbofuran, a widely used carbamate insecticide, is frequently detected in water. In this study, a high-performance adsorbent (WAB4) for carbofuran was obtained from laboratory-synthesized biochars. The maximum adsorption of carbofuran by WAB4 reaches 113.7 mg/g approximately. The adsorption of carbofuran by biochar was a multi-molecular layer and the adsorption process conforms to the pseudo-second-order kinetic model (R2 = 0.9984) and Freundlich isotherm model (R2 = 0.99). Importantly, an in vivo rat model was used to assess the combined toxicological effects of biochar-carbofuran complexes. The toxicity of the complexes (LD50 > 12 mg/kg) is lower than that of carbofuran (LD50 = 7.9 mg/kg) alone. The damage of biochar-carbofuran complex on rat liver and lung is significantly less than that of carbofuran. The Cmax and bioavailability of carbofuran were found to be reduced by 64% and 68%, respectively, when biochar was present, by UPLC-MS/MS analysis of carbofuran in rat plasma. Furthermore, it was confirmed that the biochar-carbofuran complex is relatively stable in the gastrointestinal tract, by performing a carbofuran release assay in artificial gastrointestinal fluids in vitro. Collectively, biochar is a bio-friendly material for the removal of carbofuran from water.

Sequestration of chromium(vi) and nickel(ii) heavy metals from unhygienic water via sustainable and innovative magnetic nanotechnology

In a stride towards sustainable solutions, this research endeavors to address the critical issue of water pollution via heavy metals by coupling the power of magnetic nanotechnology, in combination with a green chemistry approach, to eliminate two noxious inorganic pollutants: chromium(vi) and nickel(ii) from aqueous environments. The synthesis of magnetite (Fe3O4) nanoparticles was achieved using ferric chloride hexahydrate (FeCl3·6H2O) as a precursor, with the assistance of Ziziphus mauritiana Lam. leaves extract, known for its remarkable salt-reducing properties. A range of bio-adsorbents, derived from corncob biomass, corncob pyrolyzed biochar, and magnetite/corncob biochar nanocomposite (NC), were engineered for their eco-friendly and biocompatible characteristics. Extensive parametric optimizations, including variations in pH, contact time, dose rate, and concentration, were carried out to gain insights into the adsorption behavior and capacity of these bioadsorbents concerning Cr(vi) and Ni(ii). Equilibrium and kinetic studies were undertaken to comprehensively understand the adsorption dynamics. In the case of Ni(ii), the Freundlich isotherm model provided a satisfactory fit for all bio-adsorbents, demonstrating R2 values of 0.91, 0.95, and 0.96 for BM, BC, and NC, respectively. Furthermore, the pseudo 1st order model emerged as the most suitable fit for Cr(vi) sequestration in corncob BM with an R2 value of 0.98, while pseudo 2nd order models were robustly fitted for BC and NC, yielding R2 values of 0.88 and 0.99, respectively. The magnetite/corncob nanocomposite outperformed other bioadsorbents in removing heavy metals from wastewater due to its environmental friendliness, larger surface area, reusability, and cost-effectiveness at an industrial scale.

Adsorptive removal of dimethyl phthalate using peanut shell-derived biochar from aqueous solutions: equilibrium, kinetics, and mechanistic studies

Rise in polymer industry and extensive use of their products leads to leaching of phthalate esters and distributed into the different matrices of the environment. This chemical group has the potential to hamper the life of living organisms and ecosystem. Thus, it is essential to develop cost-effective adsorbents capable of removing these harmful compounds from the environment. In this work, peanut hull-derived biochar was taken as the adsorbent, and DMP was selected as the model pollutant or adsorbates. The biochars of different properties were produced at three pyrolysis temperatures (i.e., 450, 550, and 650 °C) to check how temperature affected the adsorbent properties and adsorption performance. Consequently, the performance of biochars for DMP adsorption was thoroughly studied by the combination of experiments and compared with commercial activated carbon (CAC). All the adsorbents are meticulously characterized using various analytical techniques and used for adsorption DMP from aqueous solutions. The results suggested that adsorption was favoring chemisorption with multi-layered adsorption as adsorption kinetics and isotherm are in good alignment with pseudo-second-order kinetics and Freundlich isotherm, respectively. Further, thermodynamic study revealed DMP adsorption on adsorbent is physically spontaneous and endothermic. The removal efficiency order of four adsorbent was as follows: BC650 > CAC > BC550 > BC450 with maximum efficiency of 98.8% for BC650 followed by 98.6% for CAC at optimum conditions. And as it is a short carbon chain PAE, dominant mechanisms of adsorption for DMP onto porous biochar were H-bonding, π-π EDA interactions, and diffusion within the pore spaces. Therefore, this study can provide strategies for the synthesis of biochar for effectively removing DMP from aqueous solution.

Rapid and efficient removal of multiple aqueous pesticides by one-step construction boric acid modified biochar

Tricyclazole, propiconazole, imidacloprid, and thiamethoxam are commonly used pesticides in paddy fields. It is necessary and practical to remove pesticides from the water environment because the low utilization rate of pesticides will produce residues in the water environment. It is known that there are few studies on the preparation of biochar adsorption pesticides by the walnut shell and few studies on the removal of tricyclazole and propiconazole. Based on this, this paper used the walnut shell as raw material and boric acid as an activator to prepare biochar by the one-step method. The boric acid modified walnut shell biochar (WAB4) with a specific surface area of 640.6 m2 g-1, exhibited the high adsorption capacity of all four pesticides (>70%) at pH 3-9. The adsorption capacities of tricyclazole, propiconazole, imidacloprid, and thiamethoxam were 171.67, 112.27, 156.40, and 137.46 mg g-1, respectively. The adsorption kinetics fitted the pseudo-second-order kinetic model and the adsorption isotherm curves conformed to the Freundlich isotherm model. The adsorption of pesticides by WAB4 was associated with hydrogen bonding, pore filling, hydrophobic effects, and π-π interactions. More significantly, WAB4 has excellent adsorption capacity compared to other adsorbents for real water samples. Finally, walnut shell biochar has no significant acute toxicity to Daphnia magna. This work shows that walnut shell-based biochar has a good effect on the removal of pesticides at a wide range of pH and is economical and safe, providing a new idea for the removal of pesticides in water.

Effective Usage of Biochar and Microorganisms for the Removal of Heavy Metal Ions and Pesticides

The bioremediation of heavy metal ions and pesticides is both cost-effective and environmentally friendly. Microbial remediation is considered superior to conventional abiotic remediation processes, due to its cost-effectiveness, decrement of biological and chemical sludge, selectivity toward specific metal ions, and high removal efficiency in dilute effluents. Immobilization technology using biochar as a carrier is one important approach for advancing microbial remediation. This article provides an overview of biochar-based materials, including their design and production strategies, physicochemical properties, and applications as adsorbents and support for microorganisms. Microorganisms that can cope with the various heavy metal ions and/or pesticides that enter the environment are also outlined in this review. Pesticide and heavy metal bioremediation can be influenced by microbial activity, pollutant bioavailability, and environmental factors, such as pH and temperature. Furthermore, by elucidating the interaction mechanisms, this paper summarizes the microbe-mediated remediation of heavy metals and pesticides. In this review, we also compile and discuss those works focusing on the study of various bioremediation strategies utilizing biochar and microorganisms and how the immobilized bacteria on biochar contribute to the improvement of bioremediation strategies. There is also a summary of the sources and harmful effects of pesticides and heavy metals. Finally, based on the research described above, this study outlines the future scope of this field.

Remarkable Separation of Carbofuran Pesticide from Aqueous Solution Using Free Metal Ion Variation on Aluminum-Based Metal-Organic Framework

The alarming increase in pesticide residues poses a major threat to aquatic and natural habitats. Therefore, it has become essential to design extremely operationally and economically advantageous systems for the removal of carbofuran pesticides from wastewater. Here, an aluminum-based metal-organic framework (MOF), MIL-53-NH2, and its modified forms, MIL-53-NH-ph, MIL-53-NH-ph-Fe, MIL-53-NH-ph-Zn, and MIL-53-NH-ph-Cu, have been successfully synthesized. Full characterization using IR, 1HNMR, XRD, and SEM was carried out. The prepared MOFs have been utilized as effective adsorbents for carbofuran in aqueous solutions. The various factors affecting the adsorption process (pH, time, and adsorbate concentration) were also investigated. Spectroscopic approaches were used to investigate the adsorption mechanisms. A mixture of π-π stacking contact, coordination bonding, and hydrogen bond formation can be connected to the current process. The adsorption of carbofuran from aqueous solutions was best described by pseudo-second-order kinetics and Langmuir equilibrium isotherm models. MIL-53-NH2, MIL-53-NH-Ph, MIL-53-NH-Ph-Fe, MIL-53-NH-Ph-Zn, and MIL-53-NH-Ph-Cu demonstrated adsorption capacities of 367.8, 462.1, 662.94, 717.6, and 978.6 mg g−1, respectively.

Gamma-Ray-Induced Structural Transformation of GQDs towards the Improvement of Their Optical Properties, Monitoring of Selected Toxic Compounds, and Photo-Induced Effects on Bacterial Strains

Structural modification of different carbon-based nanomaterials is often necessary to improve their morphology and optical properties, particularly the incorporation of N-atoms in graphene quantum dots (GQDs). Here, a clean, simple, one-step, and eco-friendly method for N-doping of GQDs using gamma irradiation is reported. GQDs were irradiated in the presence of the different ethylenediamine (EDA) amounts (1 g, 5 g, and 10 g) and the highest % of N was detected in the presence of 10 g. N-doped GQDs emitted strong, blue photoluminescence (PL). Photoluminescence quantum yield was increased from 1.45, as obtained for non-irradiated dots, to 7.24% for those irradiated in the presence of 1 g of EDA. Modified GQDs were investigated as a PL probe for the detection of insecticide Carbofuran (2,2-Dimethyl-2,3-dihydro-1-benzofuran-7-yl methylcarbamate) and herbicide Amitrole (3-amino-1,2,4-triazole). The limit of detection was 5.4 μmol L^-1 for Carbofuran. For the first time, Amitrole was detected by GQDs in a turn-off/turn-on mechanism using Pd(II) ions as a quenching agent. First, Pd(II) ions were quenched (turn-off) PL of GQDs, while after Amitrole addition, PL was recovered linearly with Amitrole concentration (turn-on). LOD was 2.03 μmol L^-1. These results suggest that modified GQDs can be used as an efficient new material for Carbofuran and Amitrole detection. Furthermore, the phototoxicity of dots was investigated on both Gram-positive and Gram-negative bacterial strains. When bacterial cells were exposed to different GQD concentrations and illuminated with light of 470 nm wavelength, the toxic effects were not observed.

Nutrients enriched biochar production through Co-Pyrolysis of poultry litter with banana peduncle and phosphogypsum waste

Poultry litter (PL) utilisation has been widely studied for production of phosphorus (P) rich biochars. Recent research documented co-pyrolysis of PL with nutrient rich chemical additives like rock phosphate, phosphoric acid and magnesium (Mg) salts for production of P-Mg enriched biochar with improved P use efficiency. However, research is highly scarce on utilisation of waste materials for production of PL biochar enriched in P, potassium (K) and sulphur (S). In this context, present work investigated co-pyrolysis (700°C, 10°C/min, 1h residence time) of PL with banana peduncle (BP) and phosphogypsum (PG) in different w/w ratios (1:1:1, 1:2:1, 1:3:1) of BP-PL-PG for production of K-P-S enriched biochars composites. These biochars mainly showed variations in their K-P-S contents. The K (5.1%) and S (11.35%) enrichment was relatively higher in BP-PL-PG (1:1:1) biochar than PL biochar (K-3.70% and S-0.96%). However, P content was higher in PL biochar (4.48%) and was reduced in biochar composites. The P contents were 3.84, 2.84, and 2.44% in BP-PL-PG (1:3:1), BP-PL-PG (1:2:1) and BP-PL-PG (1:1:1) composites respectively. In biochars, P was present predominantly as Ca-Mg bound form. Furthermore, best fit of second order kinetic model indicated slow-release behaviour of P from biochars and composites. These results highlight the scope of co-pyrolysis of PL with selected wastes for production of multi-nutrients enriched biochars with improved nutrient availability for soil application.

A Review of the Removal of Dyestuffs from Effluents onto Biochar

The study provides a review of various applications of biomass-derived biochars, waste-derived biochars, and modified biochars as adsorbent materials for removing dyestuff from process effluents. Processing significant amounts of dye effluent discharges into receiving waters can supply major benefits to countries which are affected by the water crisis and anticipated future stress in many areas in the world. When compared to most conventional adsorbents, biochars can provide an economically attractive solution. In comparison to many other textile effluent treatment processes, adsorption technology provides an economic, easily managed, and highly effective treatment option. Several tabulated data values are provided that summarize the main characteristics of various biochar adsorbents according to their ability to remove dyestuffs from wastewaters.

Ciprofloxacin and acetaminophen sorption onto banana peel biochars: Environmental and process parameter influences

Environmental (pH, temperature ionic strength, cations, anions) and process (pyrolysis temperature, particle size, adsorbent dosage, initial concentration) parameters were evaluated for ciprofloxacin and acetaminophen sorption onto a series of sustainable banana peel biochars. Ciprofloxacin and acetaminophen were chosen as model pharmaceuticals for removal owing to their worldwide presence in aquatic systems. After pyrolytic preparation from 450 to 750 °C, the biochars were qualitatively and quantitatively characterized by physicochemical, morphological, mineralogical and elemental analyses. Batch sorption studies were employed to evaluate the pH effects from 2 to 10, biochar pyrolysis temperatures (450, 550, 650, and 750 °C), particle sizes (30-50, 50-100, 100-150 BSS mesh), adsorbent dosages (0.5, 1.0, 2.0 g/L), adsorbate concentrations (0.5-200 ppm) and uptake temperatures (10, 25, 40 °C) on sorption efficiency. Maximum pharmaceutical sorption is achieved by the biochar prepared at 750 °C. Sorption rate increased with decrease in biochar particle size from 30 to 50 to 100-150 BSS mesh. Relationships between biochar properties and their sorptive potential showed positive correlations with surface area, total pore volume, %C, %ash and C/N molar ratios. Sorption data was modelled using different isotherm models and both kinetic and thermodynamic equations. Maximum Langmuir capacities of ciprofloxacin and acetaminophen on BPBC750 were 23.3 and 40.8 mg/g at 10 °C; 21.0 and 49.93 mg/g at 25 °C and 20.42 and 57.3 mg/g at 45 °C, respectively. Langmuir isotherm fittings and thermodynamic parameters confirmed the exothermic sorption (for ciprofloxacin) and endothermic sorption (for acetaminophen). The role of ionic strength, cations and anions on pharmaceuticals sorption were evaluated. H-bonding, π-π-interactions and pore diffusion were major contributors to pharmaceutical sorption.

Preparation of biochar by mango peel and its adsorption characteristics of Cd(ii) in solution

Biochars were prepared by pyrolyzing mango peel waste at 300, 400, 500, 600 and 700 °C. Various characterizations were carried out to explore the effect of pyrolysis temperature on the biochars. The data indicated that the physical and chemical properties of biochar such as pH, element ratio, specific surface area and functional groups changed with the increase of pyrolysis temperature. The yield and contents of hydrogen, nitrogen and oxygen decreased, while contents of the ash and carbon, pH and specific surface area of the biochars increased. In addition, the molar ratios of H/C, O/C and (O + N)/C decreased. In this study, batch adsorption experiments for Cd(ii) adsorption were performed with initial Cd(ii) concentrations of 10-300 mg L-1, contact times of 0-2880 min, various pH (2-8) and biochar dose (1-20 g L-1). Langmuir isotherm and pseudo-second-order kinetics models were better fits than other models, suggesting the dominant adsorption of mango peel biochars is via monolayer adsorption. Biochar derived at 500 °C was found to have the highest adsorption capacity of 13.28 mg g-1 among all biochars and the adsorption efficiency was still 67.7% of the initial adsorption capacity after desorption for 4 times. Based on adsorption kinetics and isotherm analysis in combination with EDS, FTIR and XRD analysis, it was concluded that cation exchange, complexation with surface functional groups and precipitation with minerals were the dominant mechanisms responsible for Cd adsorption by mango peel biochar. The study suggested that mango peel can be recycled to biochars and can be used as a low-cost adsorbent for Cd(ii) removal from wastewater.

Batch and Continuous Fixed-Bed Lead Removal Using Himalayan Pine Needle Biochar: Isotherm and Kinetic Studies

Pine needle litter in Himalayan forests leads to forest fires, ground water recharge inhibition, soil acidification and contamination, and stops the growth of grass and plants. This study provides a possible solution for pine needle litter problem by converting it to biochar. Pine needle litter lying on the ground for approximately a month was collected from the Himalayan region. The pine needle litter biochars were generated using slow pyrolysis (residence time, 30 min; heating rate, 10 °C/min) at 350, 450, 550, 650, and 750 °C. Finally, pine needle litter biochar prepared at 550 °C (PNBC550) was selected for sorptive removal of aqueous lead both in batch and column studies. The PNBC550 was characterized for proximate and elemental compositions, crystallinity, surface area, morphology, and functional groups. A BET surface area of 230.9 m2/g was obtained for PNBC550. Batch sorption studies were carried out to study (1) the adsorption versus pH studies (at pH 2 to 7), (2) isotherms (at 10, 25, and 35 °C) to evaluate the temperature effect on the sorption efficiency, and (3) kinetics to reveal the effect of time, adsorbent dose, and initial concentration on the reaction rate. Increasing pyrolysis temperature raised lead sorption up to 550 °C. Lead adsorption increased considerably as pH rose from 2 to a maximum adsorption around pH 5 and above. The sorption data were fitted using different isotherm models and kinetic equations. The Langmuir adsorption capacity increased from 22.93 mg/g at 10 °C to 40.43 mg/g at 35 °C, showing that adsorption was endothermic. Fixed-bed studies were conducted at room temperature with an initial lead concentration of 7.85 mg/L and 4.0 g of PNBC550 at initial pH 5.0 and a flow rate of 3 mL/min. Desorption studies conducted under the same experimental conditions found about 90-93% lead recovery. Development of high-efficiency biochars for lead remediation provides a sustainable solution for the Himalayan pine needle litter problem. The biochars also possess the possible potential for aqueous removal of other metal cations.