Lignin rich solid residues after saccharification during the production of ethanol from lignocellulosic substrates are major concern during past times. These solid residues left after the saccharification of Coir pith and Bit fiber waste are pyrolysed at 350 oC to yield biochar, which has been characterized and its potential for removal of Malachite Green, a dye present in the effluents from coir product manufacturing units are studied. FTIR and XRD spectra revealed the diverse functional groups present on the surface of biochar. SEM images showed the porous structure of the biochar. A maximum dye removal efficiency of 99.5% was achieved using Coir Pith Biochar (1 %) within 24 hours of treatment at a dye concentration of 100 mg/l. The removal efficiency was 99.4 % using Bit Fiber Biochar (0.8 %) in the same treatment period. The efficiency of removal was enhanced on adjusting the pH to 4 at which the dye removal of 99.6 % and 99.7 % was achieved using Bit fiber biochar and Coir pith biochar respectively. The residence time was significantly reduced to 2 and 4 hours respectively for bit fiber and coir pith biochar at pH 4 and hence the produced biochars are cost effective adsorbents for removal of dyeing effluents in wastewater. The adsorption fits into pseudo-second order kinetics and is well described by langmuir isotherm model. This would also facilitate the sustainable use of spent solid substrates left after lignocellulosic ethanol production in a more economical way.

In order to investigate the effectiveness of diagnostic ratios in polycyclic aromatic hydrocarbon (PAH) source discrimination, semi-open pyrolysis experiments have been performed on an organic-rich, immature shale from the Winnipegosis Formation in southeastern Saskatchewan, Western Canada Sedimentary Basin. The concentrations and distributions of PAHs in expelled oils and residual extracts change drastically with increasing pyrolysis temperatures. The difficulty and inconsistency commonly encountered by using diagnostic ratios for PAH source identification in environmental samples seem to be rooted in the great variation of the diagnostic ratios themselves under different formation temperatures. No single diagnostic ratio allows a simple segregation of PAHs into petrogenic or pyrogenic sources. Some diagnostic ratios such as anthracene/phenanthrene and benz[a]anthracene/chrysene compound pairs are mostly effective for low-temperature pyrolysis, whereas indeno[1,2,3-cd]pyrene/benzo[ghi]perylene, aromatic hydrocarbon ring number distribution and degree of alkylation are mainly valid for high-temperature pyrolysis. The diagnostic ratios based on fluoranthene/pyrene, benzo[bk]fluoranthene/benz[a]pyrene compound pairs enjoy limited validity over a narrow pyrolysis range, whereas parameters derived from aromatic hydrocarbon ring number distribution, degree of alkylation and 1,7-/(2,6- + 1,7-dimentylphenanthrene) may be undistinguishable between petrogenesis and low-temperature pyrolysis. The apparent temperature-related variability must be taken into account when using the diagnostic ratios for source identification purposes. Multiple molecular markers need to be carefully selected to confirm the results obtained with PAH diagnostic ratios. Mechanical use of diagnostic ratios most likely leads to misinterpretation of environmental samples.

Chicken poultry industry produces a vast amount of feather waste and is often disposed into landfills, creating environmental pollution. Therefore, we explored the valorization of chicken feather waste into lipids and keratinous sludge biomass. This study demonstrates the successful utilization of keratinous sludge biomass as a unique precursor for the facile preparation of novel keratinous sludge biomass-derived carbon-based molybdenum oxide (KSC@MoO₃) nanocomposite material using two-step (hydrothermal and co-pyrolysis) processes. The surface morphology and electrochemical properties of as-prepared nanocomposite material were analyzed using HR-SEM, XRD, XPS, and cyclic voltammetric techniques. KSC@MoO₃ nanocomposite exhibited prominent electrocatalytic behavior to simultaneously determine hydroquinone (HQ) and catechol (CC) in environmental waters. The as-prepared electrochemical sensor showed excellent performance towards the detection of HQ and CC with broad concentration ranges between 0.5–176.5 μM (HQ and CC), and the detection limits achieved were 0.063 μM (HQ) and 0.059 μM (CC). Furthermore, the developed modified electrode has exhibited excellent stability and reproducibility and was also applied to analyze HQ and CC in environmental water samples. Results revealed that chicken feather waste valorization could result in sustainable biomass conversion into a high-value nanomaterial to develop a cost-effective electrochemical environmental monitoring sensor and lipids for biofuel.

Garden pruning waste is becoming a problem that intensifies the garbage siege. It is of great significance to purify polluted water using biochar prepared from garden pruning waste. Herein, the interaction mechanism between BPS and oriental plane tree biochar (TBC) with different surface functional groups was investigated by adsorption experiments, spectroscopic analysis and theoretical calculations. Adsorption kinetics and isotherm of BPS on TBC can be satisfactorily fitted into pseudo-second-order kinetic and Langmuir models, respectively. A rapid adsorption kinetic toward BPS was achieved by TBC in 15 min. As compared with TBC prepared at low temperature (300 °C) (LTBC), the maximum adsorption capacity of TBC prepared at high temperature (600 °C) (HTBC) can be significantly improved from 46.7 mg g⁻¹ to 72.9 mg g⁻¹. Besides, the microstructure and surface functional groups of HTBC were characterized using SEM, BET-N₂, and XPS analysis. According to density functional theory (DFT) theoretical calculations, the higher adsorption energy of HTBC for BPS was mainly attributed to π-π interaction rather than hydrogen bonding, which was further supported by the analysis of FTIR and Raman spectra as well as the adsorption thermodynamic parameters. These findings suggested that by improving π-π interaction through high pyrolysis temperature, BPS could be removed and adsorbed by biochar with high efficacy, cost-efficiency, easy availability, and carbon-negative in nature, contributing to global carbon neutrality.

Soil polycyclic aromatic hydrocarbons (PAHs) generated from industrial processes are highly spatially heterologous, with limited quantitative studies on their main influencing factors. The present study evaluated the soil PAHs in three types of industrial parks (a petrochemical industrial park, a brominated flame retardant manufacturing park, and an e-waste dismantling park) and their surroundings. The total concentrations of 16 PAHs in the parks were 340–2.43 × 10³, 26.2–2.63 × 10³, and 394–2.01 × 10⁴ ng/g, which were significantly higher than those in the surrounding areas by 1–2 orders of magnitude, respectively. The highest soil PAH contamination was observed in the e-waste dismantling park. Nap can be considered as characteristic pollutant in the petrochemical industrial park, while Phe in the flame retardant manufacturing park and e-waste dismantling park. Low molecular weight PAHs (2–3 rings) predominated in the petrochemical industrial park (73.0%) and the surrounding area of brominated flame retardant manufacturing park (80.3%). However, high molecular weight PAHs (4–6 rings) were enriched in the other sampling sites, indicating distinct sources and determinants of soil PAHs. Source apportionment results suggested that PAHs in the parks were mainly derived from the leakage of petroleum products in the petroleum manufacturing process and pyrolysis or combustion of fossil fuels. Contrarily, the PAHs in the surrounding areas could have been derived from the historical coal combustion and traffic emissions. Source emissions, wind direction, and local topography influenced the PAH spatial distributions.

Modification of biochar by low-cost iron sources has gained increasing attention to improve pollutants removal performance and reduce production costs compared to conventional chemical modifications. While such iron sources generally have complex compositions, their effects on properties of the iron-biochar composite are not well investigated. This study produced an iron-biochar (RBC) composite from co-pyrolysis of incinerated sewage sludge ash (ISSA) and peanut shell, and examined the role of silica with widespread existence in ISSA and other low-cost iron sources on properties of the iron-biochar composite relevant to As(III)/As(V) removal. Silica was found to react with iron during the pyrolysis process at 850 °C and formed iron silicon at the expense of producing zero valent iron and Fe₃O₄ which resulted in a poorer removal efficacy for As(III) and As(V) compared to the iron-biochar (FBC) made from pure Fe₂O₃ and peanut shell. Moreover, a high leaching of reactive silica from RBC was observed which affected the formation of corrosion products of ZVI and competed with arsenic for active adsorption sites. Despite this, RBC still exhibited a maximum adsorption capacity of 17.44 and 57.56 mg/g towards As(III) and As(V) respectively at pH 3.0. Overall, this study provides an interesting insight into upcycling ISSA into useful media for sorptive removal of arsenic from aqueous solutions.

In this study, magnetic biochar (MAB) and humic acid (HA)-coated magnetic biochar produced from apple branches without and after cellulase hydrolysis (HMAB and CHMAB, respectively) were prepared and tested as adsorbents of enrofloxacin (ENR) and moxifloxacin (MFX) in aqueous solution. Compared with MAB and HMAB, novel adsorbent CHMAB possessed a superior mesoporous structure, greater graphitization degree and abundant functional groups. When antibiotic solutions ranged from 2 to 20 mg L⁻¹, the theoretical maximum adsorption capacities of CHMAB for ENR and MFX were 48.3 and 61.5 mg g⁻¹ at 35 °C with adsorbent dosage of 0.4 g L⁻¹, respectively, while those of MAB and HMAB were 39.6 and 54.4 mg g⁻¹, and 44.7 and 59.0 mg g⁻¹, respectively. The pseudo-second-order kinetic model and Langmuir model presented a better fitting to the spontaneous and endothermic adsorption process. The maximum adsorption capacity of ENR and MFX onto CHMAB was achieved at initial pH values of 5 and 8, respectively. Additionally, the adsorption capacity of ENR and MFX decreased with increasing concentrations of K⁺ and Ca²⁺ (0.02–0.1 mol L⁻¹). Synergism between the pore-filling effect, π-π electron-donor-acceptor interactions, regular and negative charge-assisted H-bonding, surface complexation, electrostatic interactions and hydrophobic interactions may dominate the adsorption process. This study demonstrated that a novel magnetic biochar composite prepared through pyrolysis of agricultural waste lignocellulose hydrolyzed by cellulase in combination with HA coating was a promising adsorbent for eliminating quinolone antibiotics from aqueous media.

Soil fumigation continues to play an important role in soil disinfection, but tools to significantly reduce emissions while providing environmental benefits (e.g., biochar) are lacking. The objective of this study was to determine the effects of biochar products on fumigant 1,3-dichloropropene (1,3-D) and chloropicrin (CP) emissions, their distribution and persistence in soil, nematode control, and potential toxicity to plants in a field trial. Treatments included three biochar products [two derived from almond shells (ASB) at either 550 or 900 °C pyrolysis temperature and one from coconut shells (CSB) at 550 °C] at 30 and 60 t ha⁻¹, a surface covering with a low permeability film (TIF), and no surface covering (control). A mixture of 1,3-D (∼65%) and CP (∼35%) was injected to ∼60 cm soil depth at a combined rate of 640 kg ha⁻¹. All biochar treatments significantly reduced emissions by 38–100% compared to the control. The ASB (900 °C) at both rates reduced emissions as effectively as the TIF (by 99–100%). Both fumigant emission reduction and residue in surface soil were positively correlated with biochar's adsorption capacity while cucumber germination rate and dry biomass were negatively correlated with residual fumigant concentrations in surface soil. This research demonstrated the potential and benefits of using biochar produced from local orchard feedstocks to control fumigant emissions. Additional research is needed to maximize the benefits of biochar on fumigant emission reductions without impacting plant growth.

The resource utilization of sewage sludge can solve its disposal issue essentially. Meanwhile the removal of diclofenac (DCF) in wastewater is an emerging environmental problem. In this study, a novel strategy of sludge utilizing via hydrothermal - peroxydisulfate (PDS) dewatering coupled pyrolysis process was proposed. The obtained sludge-derived biochar (HSC) could be as candidate to activate PDS to degrade DCF. Results indicated that exceed 90% of DCF was eliminated within 30 min in HSC-PDS/DCF ternary system under the optimized condition (0.6 mmol/L PDS and 0.5 mg/L HSC, without temperature and pH pre-adjusting). The inner mechanism of HSC-PDS/DCF system was revealed as follows: (1) Major: CO in quinones and ketone structure in HSC accelerated the degradation of DCF via non-radical pathway (electron transfer and ¹O₂). (2) Minor: Graphitic N structure accelerated the electron transfer and O₂•⁻ originated from defective sites involved into the redox. Several by-products were identified and two tentative degradation pathways of DCF (eg. dechlorination and C–N cleavage) were proposed.

Biochar modification by metal/metal oxide is promising for improving its adsorption capability for contaminants, especially the anions. However, conventional chemical modifications are complicated and costly. In this study, novel Fe/Fe oxide loaded biochars (RMBCs) were synthesized from a one-step co-pyrolysis of red mud (RM) and shaddock peel (SP), and their potential application for removing anionic azo dye (acid orange 7, AO7) from the aqueous environment was evaluated. Fe from red mud was successfully loaded onto biochars pyrolyzed at 300–800 °C, which presented from oxidation form (Fe₂O₃) to the reduction forms (FeO and Fe⁰) with increasing pyrolysis temperature. The RMBC produced at 800 °C with RM:SP mass ratio of 1:1 (RMBC800₁:₁) exhibited the best capability for AO7 removal (∼32 mg/g), attributed to both adsorption and degradation. The higher surface area of RMBC800₁:₁ and its greater affinity for AO7 led to the higher adsorption. In addition, RMBC800₁:₁-induced degradation of AO7 was another key mechanism for AO7 removal. The reduction forms of Fe (FeO or Fe⁰) in RMBC800₁:₁ may provide electrons for breaking down the azo bond in AO7 molecules and result in degradation, which is further enhanced in acid conditions due to the participation of readily release of Fe²⁺ and the available H⁺ in AO7 degradation. Furthermore, RMBC800₁:₁ can be easily separated from the treated water by using magnetic field, which significantly benefits its separation in wastewater treatment.