Herein, a walnut shell as a biosorbent was applied to remove petroleum compounds from the water medium. The characterization analyses of the walnut shells showed the macro-mesopore structure of the walnut shells, a specific surface area of 26 m2/g, and the presence of various functional groups (-OH, -COOH, -C = O). The CCD design showed that the walnut shell can remove 84.43% of petroleum compounds at pH = 3 (the optimum pH), adsorbent dosage: 2 g/L, and initial concentration of petroleum compounds: 550 mg/L. The study of kinetics and adsorption equilibrium indicated matching the experimental data with the pseudo-second-order kinetic model and Freundlich equilibrium isotherm, respectively. The maximum adsorption ability of walnut shell was 3038.29 mg/g at 45 °C. The ability to regenerate and reuse the walnut shell was investigated in 6 cycles, and the results showed a 21% decrease in adsorption ability after 6 cycles. The obtained data showed that the walnut shells could be a promising adsorbent with high adsorption ability toward petroleum components. Also, the walnut shell is a regenerable adsorbent, low-cost, and environmentally friendly, and can be effective in successive cycles. Therefore, this biosorbent can have a superb influence on wastewater treatment technology and possible applications at an industrial scale.

Calotropis procera fibres have been proposed for free-phase diesel removal in case of spillage into groundwater. For this, characterizations were carried out using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FEG-SEM), wettability and contact angle measurements. Sorption oil capacity, kinetic, isothermal and recycling behaviour were evaluated. For initial optimization of the oil sorption capacity, an experimental design (DOE) was applied, with the optimized condition being 60 g L-1 of diesel in water and 0.01 g of fibre. Then, the results clearly indicated that the fibres have a hydrophobic and oleophilic character, quickly reaching more than 71.43 g g-1 of diesel sorption, according to the adjustment (R² > 0.99) of the pseudo-second order and Langmuir models, governed by absorption mechanisms. It should also be noted that at the end of 8 reuse cycles, the fibre presented a total accumulated sorption capacity of about 252.6 g g-1 of diesel. Furthermore, a laboratory-scale experiment was carried out to remove diesel from groundwater in gas station areas, the fibre removed 98.55% to 99.97% of removal efficiencies were achieved of the free phase over time. Therefore, the material demonstrates excellent characteristics for removing diesel spills in groundwater due to its fast, high and stable removal capacity.

Biochar is a carbon-rich, sponge-like material with intricate functionalities, making it suitable for various environmental remediation applications, including water treatment, soil amendment and, additives in construction materials, anaerobic digesters, and electrodes, among others. Its easy adaptability and low cost make it particularly attractive. This review highlights a range of biochar and surface-modified biochar exhibiting high uptake and degradation efficiencies for a broad spectrum of contaminants, including humic acid, disinfection by-products (DBPs), radioactive materials, dyes, heavy metals, antibiotics, microplastics, pathogens, Per- and polyfluoroalkyl substances (PFAS), and cytotoxins. The study provides a detailed discussion on different classes of pollutants and their removal mechanisms using biochar, covering processes like physical and chemical adsorption, electrostatic interactions, π-π interactions, hydrogen bonding, as well as surface complexation, chelation, among others. This review article stands out for its comprehensive exploration of biochar's effectiveness in removing a wide range of emerging contaminants, as well as recent advancements in the removal of conventional pollutants like heavy metals and antibiotics.

Miscanthus x giganteus phytoremediation of soil contaminated with petroleum was assessed in this study. A method of soil sample preparation for determining the total content of petroleum products by infrared spectrophotometry has been developed. It is a one-stage extraction method with minimal use of carbon tetrachloride as an extractant. This soil sample preparation method was environmentally friendly and cost-effective, as it required a significantly lower amount of extractant (15-30 ml of tetrachloromethane) compared to the commonly used threefold extraction method, which uses up to 150 ml of extractant. The extraction degree of petroleum products (PP) was determined to be from 81.78 % to 94.22 % after two days of extraction using the additive method of determining PP. It was observed that the presence of different fertilizer additives in the soil samples led to a reduction in the determined PP content in the following series: "without fertilizer" - "Biochar" additive - "Biohumus" additive. These results were compared with reference samples that did not involve the use of Miscanthus x giganteus. Furthermore, the main thermolysis stages of petroleum products sorbed by the soil matrix and the thermal behavior of an artificial soil sample spiked with PP were examined. Detailed interpretation of thermograms of laboratory soil samples was conducted at various phytoremediation stages.

While the industrial sectors have recently focused on producing bioplastic materials, the utilization of edible feedstocks and the generation of wastes and byproducts during the bioplastic synthesis process might delay achieving the environmental sustainability strategy. To overcome these limitations related to bioplastic industrialization, this study focuses on synthesizing bioplastics from waste sources, followed by recycling its end-of-life (e.g., spent and exhausted) material into biochar. Sweet potato peel waste, banana pseudo-stems, and cooking oil waste were used to extract starch, cellulose, and glycerol (a plasticizer) involved in bioplastic manufacturing, respectively. It was found that the cellulose content of 30% w w-1 in bioplastic maintained the best physicochemical, mechanical, and biodegradability properties, recommending a high applicability for food packaging. The exhausted bioplastic was then pyrolyzed to maintain a biochar yield of 32.60 ± 0.89%, avoiding the risk of secondary pollution from waste material disposal. This biochar was utilized to treat wastewater generated from the bioplastic synthesis process, showing the optimum adsorption factors of biochar dosage = 3.81 g L-1, time = 102 min, and solution pH = 7.81. The combined bioplastic production, waste pyrolysis, and wastewater treatment scheme could earn profits from biomaterial sales, carbon credit, and pollution reduction shadow price, maintaining a 6.78-year payback period and a 12.09% internal rate of return. This integrated framework depicted better contributions to the mid-point/end-point life cycle assessment impact categories than the only bioplastic production scenario. This study contributed towards achieving several sustainable development goals (SDGs), including SDG#3: human health protection, SDG#6: wastewater treatment, and SDG#12: waste recycling.

The unremitting pollution of our environment induced by crude oil spillage and drilling site accidents has jeopardized every living species in the biological ecosystem. Removing heavy crude oil constituents with the help of traditional and mainstream oil sorbents because of their ingrained raised viscosities is a strenuous venture. Lighter distillates of crude oil, like condensate, do not aggregate with tremulous shine on the aquatic surface nor settle at the bottom sediment of the water bodies like the heavier components do with time. Fabricating optimally designed materials capable of capturing, degrading, or removing toxic chemical constituents of this fossil fuel is critical in this modern era. This review comprehensively discusses the evolution of scientific technologies developed to separate these constituents from land and aquatic bodies. We provide an overview of the latest physical and chemical strategies and prevalent biological remediation schemes for removing these pollutants from soils and water for environmental protection. The article highlights the urgency of preventing oil spill accidents, whose anticipation is challenging to harness. A spectrum of advanced functional methodologies is also discussed to adequately treat discharged hydrocarbon contaminants, establish public safety, and pave the path to enhancing the circular economy metrics linked with oil industries.

Lignocellulosic waste generation and their improper disposal has accelerated the problems associated with increased greenhouse gas emissions and associated environmental pollution. Constructive ways to manage and mitigate the pollution associated with lignocellulosic waste has propelled the research on biochar production using lignocellulose-based substrates. The sustainability of various biochar production technologies in employing lignocellulosic biomass as feedstock for biochar production not only aids in the lignocellulosic biomass valorization but also helps in carbon neutralization and carbon utilization. Functionalization of biochar through various physicochemical methods helps in improving their functional properties majorly by reducing the size of the biochar particles to nanoscale and modifying their surface properties. The usage of engineered biochar as nano adsorbents for environmental applications like dye absorption, removal of organic pollutants and endocrine disrupting compounds from wastewater has been the thrust areas of research in the past few decades. This review presents a comprehensive outlook on the up-to-date research findings related to the production and engineering of biochar from lignocellulosic biomass and their applications in environmental remediation especially with respect to wastewater treatment. Further a detailed discussion on various biochar activation methods and the future scope of biochar research is presented in this review work.

Accidental diesel spills can occur in marine environments such as harbors, leading to adverse effects on the environmental compartment and humans. This study proposes the surgical mask as an affordable and sustainable adsorbent for the remediation of diesel-contaminated seawater to cope with the polymeric waste generated monthly in hospital facilities. This approach can also be helpful considering a possible future pandemic, alleviating the pressure on the waste management system by avoiding improper mask incineration and landfilling, as instead occurred during the previous COVID-19. Batch adsorption-desorption experiments revealed a complete diesel removal from seawater after 120 min with the intact laceless mask, which showed an adsorption capacity of up to 3.43 g/g. The adsorption curve was better predicted via Weber and Morris's kinetic (R2 = 0.876) and, in general, with Temkin isotherm (R2 = 0.965-0.996) probably due to the occurrence of chemisorption with intraparticle diffusion as one of the rates-determining steps. A hysteresis index of 0.23-0.36 was obtained from the desorption isotherms, suggesting that diesel adsorption onto surgical masks was faster than the desorption mechanism. Also, the effect of pH, ionic strength and temperature on diesel adsorption was examined. The results from the reusability tests indicated that the surgical mask can be regenerated for 5 consecutive cycles while decreasing the adsorption capacity by only approximately 11%.

Anthracene belongs to the polycyclic aromatic hydrocarbon (PAH) consisting of benzene rings, unusually highly stable through more π-electrons and localized π-bond in entire rings. Aqueous-phase anthracene adsorption using carbon-based materials such as biochar is ineffective. In this paper, carbon dots (CDs) derived from the acid treatment of coconut shell biochar (CDs/MCSB) decorated with chitosan (CS) are successfully synthesized and applied for anthracene removal from aqueous solutions. The h-CDs/MCSB exhibited fast adsorption of anthracene with significant sorption capacity (Qmax = 49.26 mg g-1) with 95 % removal efficiency at 60 min. The study suggested chemisorption dominated monolayer anthracene adsorption onto h-CDs/MCSB, where a significant role was played by ion-exchange. Density Functional Theory (DFT) suggested the anthracene adsorption was dominated by the electrostatic interactions and delocalized electron, induced by higher polarizability of functional groups on the surface of hybrid CDs/MCSB assisted by chitosan (h-CDs/MCSB). In addition, the aromatic structure of CDs/MCSB and high polarizability of functional groups provided the strong interactions between benzene rings of anthracene and hybrid adsorbent-assisted multiple π-bond through delocalized π-bond and polarization-induced H-bond interactions. The presence of carboxylic and sulfonic groups on the CDs/MCSB surface also contributed to the effective adsorption of anthracene was confirmed by the fluorescence spectra. The results showed that the hybrid adsorbent was an effective material for removing PAHs, usually difficult to remove from water owing to the presence of benzene rings in their structures. Further, consistency in the DFT results suggested the outstanding binding capacity with the anthracene molecules with h-CDs/MCSB.

Bioremediation is a sustainable and pollution-free technology for crude oil-contaminated soil. However, most studies are limited to the remediation of shallow crude oil-contaminated soil, while ignoring the deeper soil. Here, a high-efficiency composite microbial agent MAB-1 was provided containing Bacillus (naphthalene and pyrene), Acinetobacter (cyclohexane), and Microbacterium (xylene) to be synergism degradation of crude oil components combined with other treatments. According to the crude oil degradation rate, the up-layer (63.64%), middle-layer (50.84%), and underlying-layer (54.21%) crude oil-contaminated soil are suitable for bioaugmentation (BA), biostimulation (BS), and biostimulation+bioventing (BS+BV), respectively. Combined with GC-MS and carbon number distribution analysis, under the optimal biotreatment, the degradation rates of 2-ring and 3-ring PAHs in layers soil were about 70% and 45%, respectively, and the medium and long-chain alkanes were reduced during the remediation. More importantly, the relative abundance of bacteria associated with crude oil degradation increased in each layer after the optimal treatment, such as Microbacterium (2.10-14%), Bacillus (2.56-12.1%), and Acinetobacter (0.95-12.15%) in the up-layer soil; Rhodococcus (1.5-6.9%) in the middle-layer soil; and Pseudomonas (3-5.4%) and Rhodococcus (1.3-13.2%) in the underlying-layer soil. Our evaluation results demonstrated that crude oil removal can be accelerated by adopting appropriate bioremediation approach for different depths of soil, providing a new perspective for the remediation of actual crude oil-contaminated sites.

Considerable amount of produced water discharged by the oil industry contributes to an environmental imbalance due to the presence of several components potentially harmful to the ecosystem. We investigated the factors influencing the adsorption capacity of Zinc Imidazolate Framework-8 (ZIF-8) in finite bath systems for crude oil removal from petroleum extraction in synthetic produced water. ZIF-8, experimentally obtained by solvothermal method, was characterized by XRD, FTIR, TGA, BET and its point of zero charge (pHpcz) was determined. Synthesized material showed high crystallinity, with surface area equal to 1558 m2 g-1 and thermal stability equivalent to 400 °C. Adsorption tests revealed, based on the Sips model, that the process takes place in a heterogeneous system. Additionally, intraparticle diffusion model exhibited multilinearity characteristics during adsorption process. Thermodynamic investigation demonstrated that adsorption process is spontaneous and exothermic, indicating a physisorption phenomenon. These properties enable the use of ZIF-8 in oil adsorption, which presented an adsorption capacity equal to 452.9 mg g-1. Adsorption mechanism was based on hydrophobic interactions, through apolar groups present on ZIF-8 structure and oil hydrocarbons, and electrostatic interactions, through the difference in charges between positive surface of adsorbent and negatively charged oil droplets.

Few studies tried to explore the mitigation effect and underlying mechanisms of biochar and their complex for negative allelopathy from invasive plants, which may provide a new way in the invasive plant management. Herein, an invasive plant (Solidago canadensis)-derived biochar (IBC) and its composite with hydroxyapatite (HAP/IBC) were synthesized by high temperature pyrolysis, and characterized by scanning electron microscopy, energy dispersion spectrometer, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Then, both the batch adsorption and pot experiments were conducted to compare the removal effects of kaempferol-3-O-β-D-glucoside (C21 H20 O11 , kaempf), an allelochemical from S. canadensis, on IBC and HAP/IBC, respectively. HAP/IBC showed a stronger affinity for kaempf than IBC due to its higher specific surface area, more functional groups (P-O, P-O-P, PO4 3- ), stronger crystallization [Ca3 (PO4 )2 ]. The maximum kaempf adsorption capacity on HAP/IBC was six times higher than on IBC (10.482 mg/g > 1.709 mg/g) via π-π interactions, functional groups, and metal complexation. The kaempf adsorption process could be fitted best by both pseudo-second-order kinetic and Langmuir isotherm models. Furthermore, HAP/IBC addition into soils could enhance and even recover the germination rate and/or seedling growth of tomato inhibited by negative allelopathy from the invasive S. canadensis. These results indicate that the composite of HAP/IBC could more effectively mitigate the allelopathy from S. canadensis than IBC, which may be a potential efficient approach to control the invasive plant and improve invaded soils.

Phenoxyacetic acid herbicides are widely used in agriculture for controlling weeds. These organic compounds are persistent and recalcitrant, often contaminating water and soil. Therefore, we studied five pristine biochars (BCs), and southern yellow pine (SYP) based self-activated carbon (SAC) for the adsorptive removal of 2,4-Dichlorophenoxyacetic acid (2,4-D) herbicide. Among the tested adsorbents, SYP-SAC-15 demonstrated higher (>90%) 2,4-D removal from water. The SYP-SAC-15 was produced using a facile and green route where the biomass pyrolysis gases worked as activating agents creating a highly porous structure with a surface area of 1499.79 m2/g. Different adsorption kinetics and isotherm models were assessed for 2,4-D adsorption on SYP-SAC-15, where the data fitted best to pseudo-second order (R2 > 0.999) and Langmuir (R2 > 0.991) models, respectively. Consequently, the adsorption process was mainly dominated by the chemisorption mechanism with monolayer coverage of SYP-SAC-15 surface with 2,4-D molecules. At the optimum pH of 2, the maximum 2,4-D adsorption capacity of SYP-SAC-15 reached 471.70 mg/g. Furthermore, an increase in the water salinity demonstrated a positive influence on 2,4-D adsorption, whereas humic acid (HA) showed a negative impact on 2,4-D adsorption. The regeneration ability of SYP-SAC-15 showed excellent performance by retaining 71.09% adsorption capability at the seventh adsorption-desorption cycle. Based on the operating pH, surface area, spectroscopic data, kinetics, and isotherm modeling, the adsorption mechanism was speculated. The 2,4-D adsorption on SYP-SAC-15 was mainly governed by pore filling, electrostatic interactions, hydrogen bonding, hydrophobic and π-π interactions.

Adsorption serves as an effective way to collect (remove) contaminants from aqueous solution. In the present study, a novel floating adsorbent was designed through surface modification of a layered alkali silicate (octosilicate) using a silane coupling reagent (chlorodimethyl[3-(2,3,4,5,6-pentafluorophenyl)propyl]silane) to collect metal ions from water. By conducting the grafting by solvent-free mechanochemical reaction at room temperature, the external surface of octosilicate was modified to be hydrophobic while preserving the ion exchange capability in the interlayer space. Characterizations of XRD, IR, SEM, TGA, 29Si MAS NMR, and 19F MAS NMR confirmed the successful grafting at the external surface of octosilicate particles. The modified silicate demonstrated buoyancy at the air-water interface, facilitating the concentration of methylene blue, Ni2+, and Pb2+ from aqueous solutions. The adsorbed amounts of metal ions on the floating adsorbent were greater than those reported for the common nonfloating adsorbents (zeolites, clays, and clay minerals).

The development of new materials that have a high capacity to remove pollutants in water-based media is becoming increasingly important because of the serious contamination of water and the negative impact on biodiversity and public health. The presence of glyphosate in water, the most widely used herbicide worldwide, has triggered alerts owing to the collateral effects it may cause on human health. The main objective of the present study was to investigate the potential of the hybrid material MIL-53(Al)@RH for the adsorption of glyphosate in aqueous solution. The material was obtained following the methodology of MIL-53(Al) synthesis in the presence of hydrolyzed rice husk assisted by microwave. Batch adsorption experiments were carried out to evaluate the adsorbent dosage, pH₀ solution effect, contact time, adsorbate concentration, and temperature effect. The results demonstrated that a maximum adsorption capacity of 296.95 mg g^-1, at pH₀ 4 with a ratio of 0.04 g MIL-53(Al)@RH/50 mL of solution, was achieved in 30 min. The Avrami and pseudo-second order models appropriately described the adsorption kinetics and the equilibrium by Langmuir and Sips models. The enthalpy changes (ΔH°) determined propose an endothermic reaction governed by chemisorption, corroborating the kinetic and equilibrium settings. Hydrogen bonds, π*-π interactions, and complexation between the metal centers of MIL-53(Al) and the anionic groups of glyphosate were postulated to be involved as adsorption mechanisms. Finally, for practical application, MIL-53(Al)@RH was packed in a column for a fixed-bed test which revealed that the hybrid can remove glyphosate with an adsorption capacity of 76.304 mg L^-1, utilizing 90% of the bed.

Most traditional oil spill clean-up techniques are still laboratory based and are expensive and fairly ineffective. This study investigated the capacity of biochars derived from bio-energy industries in oil spill remediation with a pilot-testing. Three different biochars from bio-energy industries, Embilipitya (EBC), Mahiyanganaya (MBC), and Cinnamon Wood Biochar (CWBC) were assessed for the removal of Heavy Fuel Oil (HFO) at three dosages (10, 25, and 50 g L^-1). Pilot-scale experiment was conducted with 100 g of biochars separately in the oil slick of X-Press Pearl shipwreck. All adsorbents exhibited rapid oil removal (within 30 min). Isotherm data were well explained by Sips isotherm model (R² > 0.98). The pilot-scale experiment resulted oil removal for CWBC, EBC and MBC as 0.62, 1.12, and 0.67 g kg^-1 respectively, even in rough sea conditions with a limited contact time (>5 min) indicates biochar's capacity in oil spill remediation as a cost-effective material.

The current water crisis necessitates the development of new materials for wastewater treatment. A variety of nanomaterials are continuously being investigated for their potential as adsorbents for environmental remediation. Researchers intend to develop a low-cost, simple, and sustainable material that can cater to removal of pollutants. Biochar derived from biowaste is a potential candidate for the existing problem of water pollution. The review focuses on the various aspects of biochar, such as its sources, preparation methods, mechanism, applications for wastewater treatment, and its regeneration. Compared with other adsorbents, biochar is considered as an environmentally friendly, sustainable, and cost-effective substitute for waste management, climate protection, soil improvement, wastewater treatment, etc. The special properties of biochar such as porosity, surface area, surface charge, and functional groups can be easily modified by various chemical methods, resulting in improved adsorption properties. Therefore, in view of the increasing environmental pollution and the problems encountered by researchers in treating pollutants, biochar is of great importance. This review also highlights the challenges and prospective areas that can be explored and studied in more detail in the future.

Oil leakage incidentally occurs and leads to environmental disasters. Because of their porous and hydrophobic characteristics, graphene sponges are often studied as an oil adsorbent to repair oil spills at sea. Graphene materials are very expensive, and their biological toxicity has been given serious concerns; however, the easier preparation and eco-friendly, biomass-derived porous carbon materials can be used as an alternative to graphene materials. In this study, we prepared a porous carbon sponge (PCS) for oil and organic solvent removal by carbonizing white-rot fungus Phanerochaete chrysosporium, a fast-growing microorganism for the production of lignin-degrading enzymes and the environmental remediation. P. chrysosporium fungus balls were converted into black PCS by carbonization at high temperatures, where PCS was light (density of 56 g/L), hydrophobic (contact angle of 115°) and porous. According to the results of BET and XPS analysis, the surface area of PCS was 14.43 m²/g, and the carbon in PCS is mainly sp² carbon. PCS could adsorb pure oils and organic solvents within seconds. The adsorption capacities of PCS were 20.7 g/g for gasoline, 30.1 g/g for peanut oil, 27.7 g/g for toluene, 18.5 g/g for dodecane, 32.5 g/g for chloroform, 27.1 g/g for tetrahydrofuran, 23.7 g/g for acetone and 13.7 g/g for ethanol. According to the reusability study, there was no obvious capacity loss after recycling up to 10 cycles. Our results indicated that white-rot fungi could be adopted as a cheap carbon resource for oil and organic solvent removal.

In this study, crayfish shell biochar (CSB) was modified by introducing vitamin C (VC) with abundant surface functional groups. CSB was impregnated with VC at different ratios and its capacity to adsorb tetracycline (TC) from water was analyzed. The physicochemical properties of CSB were determined by N₂ adsorption-desorption isotherm analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. The effects of various factors on adsorption such as the pH, TC concentration, time, and salt ion concentrations were also investigated. Based on the chemical structure of VC, VC can provide CSB with more oxygen-containing functional groups such as hydroxyl groups. The results showed that the CSB modified with VC (CSB-VC) exhibited excellent adsorption of TC, and CSB-VC₂ with an impregnation ratio of 2 (gVC/gCSB) had the greatest adsorption performance (saturated adsorption capacity, Q_m = 293.36 mg/g), whereas the adsorption performance of CSB alone was about 50% lower (Q_m = 172.16 mg/g). The optimal impregnation ratio VC improved the adsorption performance of CSB after modification to 70.4% of the original. Hydrogen bonding, p-p conjugation, pi-pi electron donor-acceptor effect, and π-π interactions were identified as the main adsorption mechanisms. CSB-VC₂ was highly effective over a wide range of pH values and at high ion concentrations. Experiments demonstrated the effective regeneration of the adsorbent after multiple cycles, thereby indicating its excellent reusability. It should be noted that the adsorption capacity was good under different water quality conditions, and thus it should exhibit stable adsorption performance under complex water environment conditions.

Porous carbons are excellent sorbents for removing organic pollutants. Green conversion of biowaste into advanced porous carbons is crucial for industrialized production and practical applications, which, however, have rarely been investigated. This study develops a coassisted carbonization method for the preparation of porous carbons with the environmentally friendly agents HCOOK and (HCOO)₂Ca for the first time. The bamboo waste-derived hydrochar was transformed into oxygen-doped porous carbons, which displayed a large surface area and pore volume, abundant oxygen content, graphene structure and many surface functional groups. These properties contributed to the extremely high sorption of large quantities of diethyl phthalate, which reached 761 mg g^-1. Surface adsorption, including pore filling, hydrogen bonding, and π-π stacking, rather than partitioning, was the main sorption process. Therefore, this study provides a sustainable and promising route for the preparation of porous carbons that can be applied in the efficient removal of organic pollutants.

This contribution aims to demonstrate the scope of new hybrids between biomass and metal-organic frameworks (MOF@biomass) used in the adsorption process of pollutants. After a brief presentation of the use of the main series of MOFs as efficient adsorbents for different types of pollutants, the limitations of these structures related to particle size and hydrodynamic problems during their application are highlighted. Lignocellulosic biomasses are also recognized as an alternative adsorbent, mainly due to their high natural abundance and their low environmental impact during and after their application. The limited capacity of bioadsorbents becomes important in this research. Consequently, the largest amount of information existing in the last ten years on MOF-Biomass functionalization as a hybrid and improvement technology for adsorption processes is compiled, analyzed, compared and contrasted. So far, there is no evidence of works that exploit the concept of functionalization of adsorbents of different nature to give rise to new hybrid materials. Through this review it was found that the hybrids obtained show a higher adsorption capacity (Qe) compared to their precursors, due to the increase of organic functional groups provided by the biomass. Thus, for heavy metals, dyes, Arsenium anions and other organic and pharmaceutical compounds, there are increases in Qe of about 100 mg g^-1. The possibility of the new hybrid being studied for desorption and reuse processes is also raised, resulting in a new line of research that is attractive for the industry from an economic and environmental point of view. The functionalization methods and techniques used in the studies cited in this article are outlined. In conclusion, this research brings a new horizon of study in the field of adsorption and mentions the main future challenges related to new sustainable applications.

In this work, engineered biochar decorated layered double hydroxides and cellulose nanocrystals (B-CuFe-CNC) biocomposites were synthesized by the facile ultrasonicated-co-precipitation technique. The biocomposite was investigated for purification of Eriochrome Black T (EBT) dye from water. The characterization results showed that the presence of CNC in biochar-layered double hydroxides resulted in a two-dimensional rod-like structure with excellent crystallinity, improved surface functionalities, and provides an attractive platform for the enhanced adsorption of azo anionic dye molecules. The adsorption system was appropriately demonstrated by the BBD-RSM (R² > 0.994). The biocomposite exhibited higher EBT adsorption in the acidic pH range (2-5) due to strong electrostatic and chemical interactions. The kinetic and isotherm results were well demonstrated by pseudo-second order, Freundlich, and Redlich Peterson models. The maximum adsorption capacity of biocomposite was 876.2 mg/g achieved within 45 min. The spectroscopic analyses imply that the high removal of EBT by biocomposite is mainly governed by electrostatic attraction, hydrogen bonding, and chemical/metal complexation mechanisms. The biocomposite maintained high EBT removal after six successive adsorption cycles and excellent dye adsorption in the different water matrices. The results suggest that tailoring biochar properties with layered double hydroxide and CNC is a promising way for the enhanced removal of dye contaminants from wastewater.

The existing study deals with adsorptive removal of the endocrine-disrupting chemical bisphenol-A and toxic azo dye solvent black-3 from single and binary solutions. These two chemicals are commonly used as an additive in the synthetic plastic industries. Among the tested twenty pristine and modified biochars, the pristine pinecone biochar produced at 750 °C revealed greater bisphenol-A removal. Simulation of the experimental data obtained for bisphenol-A and dye removal from the single-component solution offered a best-fit to Elovich (R² > 0.98) and pseudo-second-order (R² > 0.99) kinetic models, respectively. Whereas for the bisphenol-A + dye removal from binary solution, the values for bisphenol-A adsorption were best suited to Elovich (R² > 0.98), while pseudo-second-order (R² > 0.99) for dye removal. Similarly, the two-compartment model also demonstrated better values (R² > 0.92) for bisphenol-A and dye removal from single and binary solutions with greater F_fast values (except for bisphenol-A in binary solution). The Langmuir isotherm model demonstrated the highest regression coefficient values (R² > 0.99) for bisphenol-A and dye removal with the highest adsorption capacity of 38.387 mg g^-1 and 346.856 mg g^-1, correspondingly. Besides, the co-existence of humic acid revealed a positive impact on bisphenol-A removal, while the dye removal rate was slightly hindered in presence of humic acid. The absorption process showed monolayer coverage of biochar surface with contaminants using a chemisorption mechanism with fast reactions between functional groups on the adsorbate and adsorbent. Whereas the adsorption mechanism was primarily controlled by hydrogen bonding, hydrophobic and π-π electron-donor-acceptor interactions as confirmed by FTIR, XPS, and pH investigations.

Petrochemicals are important hydrocarbons, which are one of the major concerns when accidently escaped into the environment. On one hand, these cause soil and fresh water pollution on land due to their seepage and leakage from automobile and petrochemical industries. On the other hand, oil spills occur during the transport of crude oil or refined petroleum products in the oceans around the world. These hydrocarbon and petrochemical spills have not only posed a hazard to the environment and marine life, but also linked to numerous ailments like cancers and neural disorders. Therefore, it is very important to remove or degrade these pollutants before their hazardous effects deteriorate the environment. There are varieties of mechanical and chemical methods for removing hydrocarbons from polluted areas, but they are all ineffective and expensive. Bioremediation techniques provide an economical and eco-friendly mechanism for removing petrochemical and hydrocarbon residues from the affected sites. Bioremediation refers to the complete mineralization or transformation of complex organic pollutants into the simplest compounds by biological agents such as bacteria, fungi, etc. Many indigenous microbes present in nature are capable of detoxification of various hydrocarbons and their contaminants. This review presents an updated overview of recent advancements in various technologies used in the degradation and bioremediation of petroleum hydrocarbons, providing useful insights to manage such problems in an eco-friendly manner.

Biochar is a stable carbon-rich product loaded with upgraded properties obtained by thermal cracking of biomasses in an oxygen-free atmosphere. The pristine biochar is further modified to produce engineered biochar via various physical, mechanical, and chemical methods. The hasty advancement in engineered biochar synthesis via different technologies and their application in the field of energy and environment is a topical issue that required an up-to-date review. Therefore, this review deals with comprehensive and recent mechanistic approaches of engineered biochar synthesis and its further application in the field of energy and the environment. Synthesis and activation of engineered biochar via various methods has been deliberated in brief. Furthermore, this review systematically covered the impacts of engineered biochar amendment in the composting process, anaerobic digestion (AD), soil microbial community encouragement, and their enzymatic activities. Finally, this review provided a glimpse of the knowledge gaps and challenges associated with application of engineered biochar in various fields, which needs urgent attention in future research.

Quantum dots (QDs) are getting special attention due to their commendable optical properties and applications. Conventional metal-based QDs have toxicity and non-biodegradability issues, thus it becomes necessary to search for renewable precursor molecules for QDs synthesis. In recent years, biomass-based carbon rich QDs (CQDs) have been introduced which are mainly synthesised via carbonization (pyrolysis and hydrothermal treatment). These CQDs offered higher photostability, biocompatibility, low-toxicity, and easy tunability for physicochemical properties. Exceptional optical properties become a point of attraction for its multifaceted applications in various sectors like fabrication of electrodes and solar cells, conversion of solar energy to electricity, detection of pollutants, designing biosensors, etc. In recent years, a lot of work has been done in this field. This article will summarize these advancements along in a special context to biomass-based QDs and their applications in energy and the environment.

Due to the continuous and adverse effects of microplastics on the environment, an increasing number of studies have begun to focus on their migration patterns and removal from aquatic environments. Herein, our study innovatively evaluated the ability of the capacity of ZIF-67, a novel metal-organic framework (MOF) material, to adsorb polystyrene (PS) microplastics (MPs) from aqueous solutions, aiming to explore the potential of MOF materials to remove MPs from wastewater. The adsorption ratio of PSMPs (5 mg/L, 30 mL) by ZIF-67 reached up to 92.1%, and the PSMP adsorption equilibrium was achieved within 20 min at 298 K. The adsorption of PSMPs would be favored at a pH of 8, a PSMPs solution concentration of 5 mg/L, and a temperature of 298 K. Further analyses demonstrated that hydrogen bond interactions, π-π stacking, and electrostatic interactions played a crucial role in the adsorption of PSMPs by ZIF-67 in aqueous solutions. Our findings thus provide insight into novel methods to remove MPs from acidic and weakly alkaline aquatic environments and wastewater.

Tremendous population growth and industrialization have increased energy consumption unprecedentedly. The depletion of fossil-based energy supplies necessitates the exploration of solar, geothermal, wind, hydrogen, biodiesel, etc. as a clean and renewable energy source. Most of these energy sources are intermittent, while bioelectricity, biodiesel, and biohydrogen can be produced using abundantly available organic wastes regularly. The production of various energy resources requires materials that are costly and affect the applicability at a large scale. Biomass-derived materials (biochar) are getting attention in the field of bioenergy due to their simple method of synthesis, high surface area, porosity, and availability of functional groups for easy modification. Biochar synthesis using various techniques is discussed and their use as an electrode (anodic/cathodic) in a microbial fuel cell (MFC), catalysts in transesterification, and anaerobic digestion for energy production are reviewed. Renewable energy production using biochar would be a sustainable approach to create an energy secure world.