Mechanistic insights of 2,4-D sorption onto biochar: Influence of feedstock materials and biochar properties

Objective of this study was to investigate the mechanisms of 2,4-Dichlorophynoxy acetic acid (2,4-D) sorption on biochar in aqueous solutions. Sorption isotherm, kinetics, and desorption experiments were performed to identify the role of biochars' feedstock and production conditions on 2,4-D sorption. Biochars were prepared from various green wastes (tea, burcucumber, and hardwood) at two pyrolytic temperatures (400 and 700°C). The tea waste biochar produced at 700°C was further activated with steam under a controlled flow. The sorption of 2,4-D was strongly dependent on the biochar properties such as specific surface area, surface functional groups, and microporosity. The steam activated biochar produced from tea waste showed the highest (58.8mgg -1 ) 2,4-D sorption capacity, which was attributed to the high specific surface area (576m 2 g -1 ). The mechanism of 2,4-D removal from aqueous solution by biochar is mainly attributed to the formation of heterogeneous sorption sites due to the steam activation

Biomass-derived activated carbons for the removal of pharmaceutical mircopollutants from wastewater: A review

Biomass-derived activated carbons (biochars) have attracted great attention due to their excellent physicochemical properties such as high specific area, large pore volume, well-defined microporous structure and tunable surface chemistry. Although pharmaceuticals are an emerging class of micropollutants in wastewater through the sewerage disposal by pharmaceutical factories, hospitals and households, only a few recent studies have reviewed the adsorption and removal of pharmaceuticals from wastewater by biochars and they lack the systematic insights into total adsorption process from biochars preparation to adsorption mechanism. This paper aims to provide a comprehensive review on recent publications and to propose future research directions. The effects of lignocellulosic biomass as well as the pyrolysis, activation and modification conditions on the physicochemical properties of biochars and their adsorption capacities are discussed. The adsorption kinetics and isotherms of different pharmaceuticals onto various biochars are analyzed based on commonly used models. Finally, the potential adsorption mechanisms of pharmaceuticals by biochars are summarized

Engineered biochar – A sustainable solution for the removal of antibiotics from water

Antibiotic contamination and the spread of antimicrobial resistant bacteria are global environmental issues. Given the growing consumption of antibiotics, it is crucial to reduce their presence in the environment. Adsorption is one of the most efficient methods for removing contaminants from water and wastewater. For this process to be effective, it is of key importance to identify adsorption mechanisms that allow an efficient and selective adsorbent to be chosen. Carbon-based materials (including activated carbon, biochar and black carbon) are typically used for the adsorptive removal of antibiotics. To enhance the efficiency of adsorption of pharmaceuticals, engineered biochars (physically, chemically and biologically modified biochar) and their composites have attracted increasing interests. Biochar-based sorbents can be produced from various feedstocks, including waste products. The use of “green”, low cost or sustainable biochar for contaminant sorption yields economic and environmental benefits. Moreover, this is in line with global trends in creating a circular economy and sustainable development. This paper collates the most recent data on the consumption of antibiotics, their related environmental contamination, and their removal using biochar-based materials. Special attention is paid to the newly emerging approaches of biochar modification and biochar composites in relation to the antibiotic removal from water. © 2020 Elsevier B.V

Biochar-plant interaction and detoxification strategies under abiotic stresses for achieving agricultural sustainability: A critical review

The unpredictable climatic perturbations, the expanding industrial and mining sectors, excessive agrochemicals, greater reliance on wastewater usage in cultivation, and landfill leachates, are collectively causing land degradation and affecting cultivation, thereby reducing food production globally. Biochar can generally mitigate the unfavourable effects brought about by climatic perturbations (drought, waterlogging) and degraded soils to sustain crop production. It can also reduce the bioavailability and phytotoxicity of pollutants in contaminated soils via the immobilization of inorganic and/or organic contaminants, commonly through surface complexation, electrostatic attraction, ion exchange, adsorption, and co-precipitation. When biochar is applied to soil, it typically neutralizes soil acidity, enhances cation exchange capacity, water holding capacity, soil aeration, and microbial activity. Thus, biochar has been was widely used as an amendment to ameliorate crop abiotic/biotic stress. This review discusses the effects of biochar addition under certain unfavourable conditions (salinity, drought, flooding and heavy metal stress) to improve plant resilience undergoing these perturbations. Biochar applied with other stimulants like compost, humic acid, phytohormones, microbes and nanoparticles could be synergistic in some situation to enhance plant resilience and survivorship in especially saline, waterlogged and arid conditions. Overall, biochar can provide an effective and low-cost solution, especially in nutrient-poor and highly degraded soils to sustain plant cultivation

Enrofloxacin and Sulfamethoxazole Sorption on Carbonized Leonardite: Kinetics, Isotherms, Influential Effects, and Antibacterial Activity toward \u3ci\u3eS. aureus\u3c/i\u3e ATCC 25923

Excessive antibiotic use in veterinary applications has resulted in water contamination and potentially poses a serious threat to aquatic environments and human health. The objective of the current study was to quantify carbonized leonardite (cLND) adsorption capabilities to remove sulfamethoxazole (SMX)- and enrofloxacin (ENR)-contaminated water and to determine the microbial activity of ENR residuals on cLND following adsorption. The cLND samples prepared at 450oC and 850oC (cLND450 and cLND550, respectively) were evaluated for structural and physical characteristics and adsorption capabilities based on adsorption kinetics and isotherm studies. The low pyrolysis temperature of cLND resulted in a heterogeneous surface that was abundant in both hydrophobic and hydrophilic functional groups. SMX and ENR adsorption were best described using a pseudo-second-order rate expression. The SMX and ENR adsorption equilibrium data on cLND450 and cLND550 revealed their better compliance with a Langmuir isotherm than with four other models based on 2.3-fold higher values of qmENR than qmSMX. Under the presence of the environmental interference, the electrostatic interaction was the main contributing factor to the adsorption capability. Microbial activity experiments based on the growth of Staphylococcus aureus ATCC 25923 revealed that cLND could successfully adsorb and subsequently retain the adsorbed antibiotic on the cLND surface. This study demonstrated the potential of cLND550 as a suitable low-cost adsorbent for the highly efficient removal of antibiotics from water

Adsorptive desluphursation of diesel fuel on unprocessed amarula (sclerocarya birrea) wastes or synthesized activated carbons from biomass wastes

Diesel fuel has been found to contain highly concentrated organo-sulphur compounds which have bad impact economically, environmentally, and health-wise. Adsorptive desulphurization (ADS) is one of the promising processes which are carried out under atmospheric conditions. Amarula (Sclerocarya birrea) waste biomass from the production plant of Amarula liqueur, was utilized as a low-cost adsorbent and as a source of synthesized activated carbon for reducing sulphur content in diesel fuel. The performance of gasification char (waste from syngas production) was also compared with Amarula shells waste biochar. The Amarula wastes Biomass: fruit, seed, and shell waste were used as adsorbents to reduce the content of sulphur in dibenzothiophene model diesel fuel. The results showed that raw Amarula Shells (AmSh) waste had the highest adsorption efficiency as compared to Amarula seeds (AmSe) and fruit (AmWa) wastes. The effect of adsorption temperature revealed that the sorption is more favourable at room temperatures. The selected Amarula shell wastes showed that as the adsorbent quantity increases, the sorption efficiency also increases. The three Amarula wastes biomass were processed to synthesise activated carbons (ACs) using pyrolysis, and then steam activation at 800 °C for 45 min. The adsorption efficiency of DBT in model diesel fuel was found to improve on Amarula wastes ACs with the order of AmShAC-ST > AmSeAC-ST > AmWaAC-ST. The effect of steam residence time on selected Amarula shell wastes biomass revealed that the desulphurization efficiency of DBT increased outstandingly with increased steam residence time. The AmShAC-ST produced at 90 min steam resident time reduced the highest content of DBT within 30 min. The gasification chars from a down draft gasifier (DG) and a plasma gasifier (PG) were utilized for adsorption of DBT in model diesel fuel. The Algae biochar (ALGC-DGBC) was from gasification of Algae binder mixed with coal- fines in a down-draft gasifier. The Wood-DGBC was a waste product from wood pellets gasifier in a down-draft gassier, the Wood-PGBC was a by-product from Plasma gasification of wood pellets. These chars were able to reduce sulphur content in DBT model diesel fuel with Amarula shells biochar (AmShBC) being the best performer as compared to other chars. The KOH and steam were used as activating agents on biochar to improve their performance. The results showed that the gasification chars treated with the steam agent had a higher desulphurization efficiency of DBT than the ones treated with KOH agent. The desulphurisation efficiency trend: AmShBC-ACST > Wood-PGBC-ACST > Wood-DGBC-ACST > ALGC-DGBC-ACST was achieved for steam activation. In the contrary, for KOH/BC the trend was in the order of Wood-DGBC-KOH > Wood- PGBC-KOH > AmShBC-KOH > ALGC-DGBC-KOH, but with lower ADS efficiency values as compared to steam/BC. Pseudo-second-order was found to be the best fit kinetic model on experimental data. While Langmuir isotherm was found to be a better fit as compared to Freundlich isotherm for both processed and unprocessed Amarula wastes biomass. Thermodynamic studies were carried out to determine the spontaneity of the adsorption of DBT on Amarula wastes adsorbents. Qualitative analysis was carried out by techniques such as TGA, XRD, FESEM, TEM, BET and FTIR. The raw Amarula waste biomass had more O-functional groups as compared to their biochar and activated carbons. After thermal/steam activation of biomass, the micropores and mesopores were increased. This was concluded as the reason for improved desulphurisation efficiency of diesel fuel. The selected AmShAC-ST produced at 90 min steam residence time had increased mesopores and less micropores with a BET surface area of 1 194 m2/g and the highest pore volume of 0.98 cm3/g. On the other side, the gasification chars were found to have more micropores than mesopores. The ACs from KOH activation had less mesopores than the ACs from steam activation. Therefore, the above desulphurization’s data was found to contribute to the design of a small-scale adsorptive desulphurization plant for diesel fuel.School of EngineeringM. Tech. (Chemical Engineering

Surface-modified biochar in a bioretention system for Escherichia coli removal from stormwater

Bioretention systems have been recommended as one of the best management practices for low impact development for water recycling/reuse systems. Although improvement of the stormwater quality has been reported regarding pollutants eliminations such as suspended solids and heavy metals, a substantial removal of indicator bacteria is required for possible non-potable reuse. This study investigated the efficiency of wood biochar with H2SO4-, H3PO4-, KOH-, and amino-modifications for E. coli removal from synthetic stormwater under intermittent flow. The H2SO4-modified biochar showed a specific surface area of 234.7 m(2) g(-1) (approximately double the area of original biochar), whereas a substantial reduction in surface area was found with amino-modified biochar. The E. coli removal (initial concentration of 0.3-3.2 × 10(6) CFU mL(-1)) by modified biochars as filter media was very promising with, for example, over 98% removal efficiency in the first 20 pore volumes of stormwater infiltration and over 92% removal by the end of the second infiltration cycle. Only a small portion of E. coli attached on the modified biochars (<0.3%, except KOH- and amino-modified biochars) was remobilized during the drainage phase of intermittent flow. The high removal capacity and stability against drainage were attributed to the high surface area, porous structure, and surface characteristics (e.g. hydrophobicity and O-containing functional groups) of the biochars. Thus, the H2SO4-modified biochar appeared to give the best treatment performance

A critical review on production, modification and utilization of biochar

There has been an increased interest in the production of sustainable biochar in the past years, as biochar shows versatile physicochemical properties and, can have a wide applicability in diverse fields. Comprehensive studies have been made to characterize biochar produced from various biomass materials, using different production technologies and under different process conditions. However, research is still lacking in correlating biochar properties needed for certain applications with (i) feedstock, (ii) biochar production processes and conditions and (iii) biochar upgrading and modification strategies. To produce biochar with desired properties, there is a great need to establish and clarify such correlations, which can guide the selection of feedstock, tuning and optimization of the production process and more efficient utilization of biochar. On the other hand, further elucidation of these correlations is also important for biochar-stakeholder and end-users for predicting physiochemical properties of biochar from certain feedstock and production conditions, assessing potential effects of biochar utilization and clearly address needs towards biochar critical properties. This review summarizes a wide range of literature on the impact of feedstocks and production processes and reactions conditions on the biochar properties and the most important biochar properties required for the different potential applications. Based on collected data, recommendations are provided for mapping out biochar production for different biochar applications. Knowledge gaps and perspectives for future research have also been identified regarding the characterization and production of biochar.acceptedVersio

Biomass-based carbon materials for CO2 capture:A review

Carbon capture and sequestration technologies are essential to reduce CO2 emissions which are responsible for global warming. Carbon-based materials can play an important role in the reduction of CO2 emissions. These materials are normally produced from biomass through technologies such as pyrolysis and hydrothermal carbonization. The type of biomass feedstock and biomass conversion conditions can significantly affect the textual properties and surface chemistry of the carbon materials. Various modification methods such as material activation or N-doping can improve the properties of carbon materials to obtain better CO2 capture effects. This review summarizes recently reported research in the areas of using biomass-based materials for CO2 capture. The technologies of biomass conversion to carbon materials and modification of the carbon materials are critically analyzed. Meanwhile, the mechanisms of the CO2 capture process and research of different modification carbon materials for CO2 capture are also discussed. Finally, potential future research directions are suggested to promote carbon capture using biomass-based materials