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Co-pyrolysis of feedstock with varied compositions is a common practice, during which cross-interaction of volatiles from single feedstock requires particular attentions as it may affect the product properties. In this study, co-pyrolysis of swine manure and pinewood sawdust was conducted. The results proved the interaction of volatiles from pyrolysis of swine manure with pinewood sawdust and their significant impact on the evolution of pyrolysis products. The interaction effect favored the formation of bio-oil and biochar but diminished the production of gases, as the cross-interaction transformed the gaseous precursors into heavier organics. Although cross-interaction facilitated the formation of organics with π-conjugated structures, The Fourier transform ion cyclotron resonance-mass spectrometry (FT-ICR MS) characterization showed that the chemical species with large carbon number in the sawdust-derived bio-oil were transferred into the carbonaceous substance. The bio-oil from co-pyrolysis was thus lighter, and the interaction effect also inhibited the generation of nitrogenous species. The cross-interaction of volatiles made the biochar oxygen-rich and enhanced the thermal stability. Furthermore, in situ Diffuse Reflection Infrared Fourier Transform Spectra (DRIFTS) results indicated that the interaction of volatiles resulted in the formation of more functionalities like –OH, -C-H and C O on the biochar.

The burning of agricultural waste is a major cause of environmental pollution. In this study, we sought to prepare biochar from agricultural waste as a source material for the preparation of carbon nanoparticles (CNPs). Surface morphology, hydrodynamic particle size, and purity and crystallinity of CNPs were extensively investigated using transmission electron microscopy (TEM), zeta sizing, and X-ray diffraction (XRD) spectroscopy, respectively. The CNPs were subsequently immersed in a solution of potassium nitrate (KNO3) to prepare a CNPs/NK nanocomposite (CNPs loaded with nitrogen (N) and potassium (K)) as a nanocomposite fertilizer for common bean (Phaseolus vulgaris L.). The CNPs/NK nanocomposite was sprayed as a foliar fertilizer at 0, 10, 20, 30, and 40 mg L–1 on common bean plants 25 d after sowing on a farm in Shebin El-Kom, El-Monifia, Egypt. The growth, yield, and quality of common bean were investigated during two successive growing seasons (2017 and 2018). The highest seed yields of 2.04 and 2.01 t ha–1 and the highest values of growth parameters including plant height of 61.5 and 59.2 cm, number of leaves per plant of 35 and 35, number of flowers per plant of 83.3 and 82.7, and plant fresh weight of 148.7 and 152.8 g plant–1 were obtained when using the CNPs/NK nanocomposite at a concentration of 20 mg L–1 during the 2017 and 2018 growing seasons, respectively.

This study is focused on creating value addition to kitchen waste (KW) by converting it into valuable product resources via microwave pyrolysis. The effect of the following on product yields and energy efficiency were examined in this study: (i) microwave power (140–700 W), (ii) KW: susceptor ratio (20:0 to 20:20 (g/g)), and (iii) pyrolysis temperature (200–600 °C). The KW was pyrolyzed without the addition of a susceptor and char formed during pyrolysis acted as a susceptor and enhanced pyrolysis energy efficiency (78%). An increase in microwave power has significantly increased the heating rate from 4 to 85 °C/min, and KW has produced 73 wt% of bio-oil and gases even at low microwave power (140 W). An increase in pyrolysis temperature promoted thermal cracking of KW, which resulted in decreased char yields (64–27 wt%), and an increase in gas yields (12–45 wt%). Bio-oil contains a significant amount of phenolics (35–50%) and its selectivity varied significantly with the variables probed. The selectivity of furan derivatives has dramatically decreased from 45 to 20% with the increase in pyrolysis temperature. This work demonstrated the feasibility of valorization of kitchen waste into various value-added products.

Pyrolysis of walnut shells to biochar at 700 °C using N2gas was compared to one-step activation using steam/KOH under four different heating rates (10–40 °C/min). Steam biochars developed better surface area property of 342–556 m2/g compared to others (19–135 m2/g) over the same heating rates; meanwhile, increasing heating rate caused functional groups alteration and was distinct on the surface area property as about six-fold and two-fold difference from the lower to higher rates were recorded in neutral char and the steam/KOH activated biochars respectively. Increasing heating rate affected the neutral and steam biochars’ Raman intensity ratio whereas trivial influence was recorded on KOH-biochars.

Background It was an effective method and research focus to remove recalcitrant organic pollutants by advanced oxidation processes based on persulfate activation with composite material as heterogeneous catalysts. Methods Fe/N co-doped biochar (Fe/N-BC) was synthesized via one-pot calcination method with anhydrous FeCl3, melamine, and grape skin powder as precursors. Characterization results showed that biomass and melamine could anchor iron species on BC matrixes by coordination. Significant findings The Fe/N0.1-BC exhibited significant activities toward peroxymonosulfate (PMS) activation, and 20 mg/L RhB can be degraded completely in 10 min with 0.05 g/L of the material and 0.5 g/L PMS. Electron paramagnetic resonance (EPR) study and free radical quenching experiments indicated that singlet oxygen (1O2), sulfate radicals (SO4•−), and hydroxyl radicals (•OH) were the main reactive oxidizing species, and non-radical mechanism and free radical process were considered to be involved in the degradation of the pollutants. Control experiments revealed that the enhanced active sites were mainly ascribed to rich defects as well as the synergistic effect among Fe and N doping into carbon substrate. The Fe/N-BC owned the merits of environmentally friendly raw materials, easy synthesis, and high activation efficiency, exhibiting splendid prospect for environmental application.

The coexistence of nanoparticles (NPs) and environmental pollutants has become a new type of pollution, and the co-adsorption behaviors of coexisting NPs and pollutants on the coconut shell porous biochar is important to explore the environmental fate of both pollutants and NPs in complex environments. In this study, the interaction between nano-titanium dioxide (n-TiO2) and tetracycline (TC) during the adsorption process on the coconut shell biochar (CBC) was explored by adsorption experiment, the co-adsorption mechanisms of TC and n-TiO2 onto CBC were discussed by morphology and characteristics of Scanning electron microscopy, Brunauer-Emmett-Teller specific surface area, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses. The results showed that the n-TiO2 in the TC + TiO2 binary system leads to the TC adsorption decrease by 54.60% averagely. The TC in the TC + TiO2 binary system increased the n-TiO2 adsorption by 31.97% averagely but weakened the adsorption affinity of n-TiO2. Characterization analysis confirmed that, the hydrogen bonding, π-π/n-π interaction and pore filling between TC and CBC were suppressed in the TC + TiO2 binary system. The TC in the binary system enhances the n-TiO2 adsorption on the outer surface and the inner surface of CBC by surface bridging and reducing the agglomeration of n-TiO2.

The co-pyrolysis of sewage sludge and biomass is considered a promising technique for reducing the volume of sewage sludge, adding value, and decreasing the risk associated with this waste. In this study, sewage sludge and cotton stalks were pyrolyzed together with different amounts of K2CO3 to evaluate the potential of chemical activation using K2CO3 for improving the porosity of the biochar formed and immobilizing the heavy metals present in it. It was found that K2CO3 activation effectively improved the pore structure and increased the aromaticity of the biochar. Moreover, K2CO3 activation transformed the heavy metals (Cu, Zn, Pb, Ni, Cr, and Cd) into more stable forms (oxidizable and residual fractions). The activation effect became more pronounced with increasing amount of added K2CO3, eventually resulting in a significant reduction in the mobility and bioavailability of the heavy metals in the biochar. Further analysis revealed that, during the co-pyrolysis process, K2CO3 activation resulted in a reductive atmosphere, increased the alkalinity of the biochar, and led to the formation CaO, CaCO3, and aluminosilicates, which aided the immobilization of the heavy metals. K2CO3 activation also effectively reduced the leachability, and thus, the environmental risks of the heavy metals. Thus, K2CO3 activation can improve the porosity of the biochar derived from sewage sludge/cotton stalks and aid the immobilization of the heavy metals in it.

Biochar can help promote direct interspecies electron transfer (DIET) and increase methane production; the surface redox groups play a constructive role in these processes. This study attempted to improve the anaerobic digestion (AD) performance by modifying biochar with HNO3 to increase its redox activity. A comparative experimental study, raw biochar (BC0) and biochar treated with HNO3 for 6 h (BC6), were conducted to investigate the effect of HNO3 treatment on the medium temperature AD performance of food waste. Both BC0 and BC6 can enhance CH4 yield and facilitate the degradation of volatile fatty acids. The enhanced yield of CH4 was 36% for BC0 and 90% for BC6, respectively. Biochar can also enhance methanogenesis, presumably owing to direct interspecific electron transfer (DIET). Compared with BC0, BC6 had a higher redox activity and a smaller conductivity. It was supposed that BC0 mediated DIET through its conductivity, whereas BC6 accelerated DIET by surface redox groups.

Wastewater sludge drying and incineration are conventional solids handling processes that are sometimes employed in water resource reclamation facilities. However, these two processes generate byproducts, sludge drying chaff and sludge incinerator ash, which are landfilled without taking advantage of their value. To gain value from these byproducts, a new synergistic catalytic pyrolysis process using chaff and ash was investigated in this study to improve energy production (i.e. generating a high yield pyrolysis gas) and generate useful products. Ash was used as a catalyst to decrease bio-oil that is corrosive and challenging for combustion in standard equipment, while increasing pyrolysis gas yield and energy for easier energy recovery. Ash increased the pyrolysis gas yield by 50% and product energy by nearly two-fold at the highest ash loading. The bio-oil volume was greatly reduced and contained fewer constituents based on GC-MS and GC-FID analyses. The product energy shifted from bio-oil to pyrolysis gas, which is relatively clean and easier for onsite energy recovery. Ca and Fe content in ash likely plays the catalytic role.

This study investigated the effectiveness of carbon adsorbents as remediation material for sediments contaminated with heavy metals and the feasibility of utilizing diffusive gradients in thin films (DGT) as a biomimetic tool to estimate the accumulation of heavy metals in Venerupis philippinaram (Manila clam). The results showed that carbon materials had significant inhibitory effects (14.0–53.0%) on the enrichment of heavy metals in organisms and the order of increasing overall inhibitory effect was: charcoal, peat, activated carbon, and biochar. There were significant correlations (P

Microbial fuel cells (MFCs) have gained remarkable attention as a novel wastewater treatment that simultaneously generates electricity. The low activity of the oxygen reduction reaction (ORR) remains one of the most critical bottlenecks limiting the development of MFCs. To date, although research on biochar as an electrocatalyst in MFCs has made tremendous progress, further improvements are needed to make it economically practical. Recently, biochars have been considered to be ORR electrocatalysts with developmental potential. In this review, the ORR mechanism and the essential requirements of ORR catalysts in MFC applications are introduced. Moreover, the focus is to highlight the material selection, properties, and preparation of biochar electrocatalysts, as well as the evaluation and measurement of biochar electrodes. Additionally, in order to provide comprehensive information on the specific applications of biochars in the field of MFCs, their applications as electrocatalysts, are then discussed in detail, including the uses of nitrogen-doped biochar and other heteroatom-doped biochars as electrocatalysts, poisoning tests for biochar catalysts, and the cost estimation of biochar catalysts. Finally, profound insights into the current challenges and clear directions for future perspectives and research are concluded.

The advanced oxidation process (AOPs) has caused great concern in recent years. Among them, biochar has been widely studied as a catalyst for advanced oxidation process because of its low price and low environmental risk. In this study, a novel ball milling assisted KOH activation biochar (MKBC) was prepared and applied in peroxydisulfate (PDS) activation to degrade tetracycline hydrochloride (TC-H). In comparison with the oxidation (3.48%) by PDS alone and adsorption (36.19%) by MKBC alone, the removal rate of TC-H was increased to 84.15% in the MKBC/PDS system, indicating that MKBC can successfully activate PDS. Besides, the catalytic activity of the MKBC to activate PDS for the degradation of TC-H is 58.33% higher than that of pristine biochar (PBC). In addition, MKBC has outstanding stability that after three repeated experiments, the removal rate of TC-H by the MKBC/PDS system still remains 77.35%. Meanwhile, the mechanism was investigated that the singlet oxygen (1O2) seized the principal position in the degradation of TC-H in the PDS/MKBC system. This study explored a novel, solvent-free and economic method to propose this extraordinary biochar, which provided a new strategy for the future research of biochar.

To explore the effects of pretreatment methods including drying, vacuum freezing drying (VFD), pelleting, and ultrasonic vibration-assisted pelleting (UV-AP) on corn stover and biochar properties, the physicochemical and morphological changes of biomass before and after pretreatment were examined, and the effects of different pretreatment methods on biochar properties were investigated. The results showed that different pretreatment methods have a significant effect on the surface and internal structure of biochar. The highest and lowest specific surface area, micropore area, and total pore volume of biochar were 25.84 m2/g, 9.27 m2/g, 0.53 cm3/g, and 17.33 m2/g, 4.39 m2/g, 0.29 cm3/g, respectively. FTIR analysis showed that the functional group of pretreated corn stover was similar to those of biochar. Ultimate analysis indicated that both pretreatment methods and the highest treatment temperature had a significant effect on biochar compositions. The order of carbon content of biochar derived from different pretreatment methods was drying > VFD > UV-AP > pelleting. The biochar yield, enhancement factor, and energy yield were significant affected by pretreatment methods. By contrast, the biochar pH was alkaline and not significantly affected by pretreatment methods. These findings provide a reliable route to choose pretreatment methods for producing biochar with desired properties, which could be a guide for industrial application.

In this study, steam gasification and co-gasification of Japanese cedarwood and its commercial biochar were performed in a lab-scale fixed-bed reactor to investigate the feasibility for producing H2-rich syngas. Ultimate analysis, proximate analysis, Brunauer-Emmett-Teller (BET) surface area analysis, and scanning electron microscopy (SEM) were conducted to understand the changes caused by the carbonization process. The effects of gasification temperature and steam flow rate on gas production yield from the steam gasification of the individual samples were investigated at first, which showed larger gas production yield and less tar yield for the steam gasification of the commercial biochar than that of raw cedarwood, indicating that the commercial biochar obtained from the carbonization process was more beneficial for the gasification. The co-gasification of raw Japanese cedarwood and its commercial biochar with different mixing ratios was conducted at different reaction temperatures. The synergistic effect was obviously observed. Especially, the commercial biochar with the highly porous structure and high content of alkali and alkaline earth metal (AAEM) species might provide the catalytic effect on cracking and reforming of tar derived from the raw cedarwood, resulting in a larger H2 yield. However, the catalytic effect and gasification reactivity of biochar would decrease by increasing the amount of raw-cedarwood in the blends due to the coke deposition on the surface of biochar.

In this study, Samarium (Sm) modification over Mn oxide biochar (BC)-based catalysts was synthesized and the activity of low-temperature selective catalytic reduction with NH3 (LT NH3-SCR) of NO was measured. Varies in surface area and pore volume, structure, morphology, and surface chemistry of Sm-modified Mn/BC catalyst were investigated to analyze the effect of Sm on the physiochemical properties on catalyst. The Sm(0.2)-Mn/BC catalyst showed the highest NH3-SCR activity with the NO conversion of 85% at 200 °C and best N2 selectivity in a broad temperature range of 75–250 °C. Doping with Sm species, Mn4+ + Mn3+/Mnn+ and Oα/Oβ increased greatly, and the surface adsorbed oxygen were enhanced in Sm(0.2)-Mn/BC catalyst, which could promote the oxidation of NO, the NO conversion and N2 selectivity. In addition, weak and medium acid increased markedly after the Sm species added on catalysts, causing more active sites for SCR reaction. The NH3-SCR reaction of Sm(0.2)-Mn/BC catalyst followed the L-H mechanism, and the generation of intermediate –NH2, NH4+ species and the NxOy species were observed which played vital part in the LT NH3-SCR reaction.

Attaining jointly high energy density at low cost is extremely challenging for lithium-sulfur (Li-S) batteries to compete with commercially available Li ion batteries (LIB). Here we report a class of bio-derived dense self-supporting cathode with ultralow porosity of 0.4 via self-densification effect during thermal drying without mechanical compression to realize a low-cost Li-S cell with high gravimetric/volumetric energy densities. Benefiting from the great preponderances of biochar, jointly high gravimetric/volumetric energy densities of 422 Wh kg−1/446 Wh L − 1 are achieved under conditions of high mass loading (6.5 mg cm−2) and extremely lean electrolyte (2.5 μL mg−1), the corresponding costs based on sub-Ah level pouch cell are estimated to be as low as $60/kWh-$90/kWh for the initial 20 cycles via a materials-to-system analysis, which is visibly less than that in the typical commercial LIB ($100/kWh). The current study presents meaningful opportunity to develop commercially viable Li-S batteries that are competitive on a specific energy/cost basis with current state-of-the-art LIB.

The bio-wastes pyrolysis is a waste to energy strategy that converts bio-wastes into valuable products (bio-char, bio-oil) with wide use in the agri-food sector. However, limited efforts are paid to the investigation of its environmental sustainability: in this context, the study contributes the need towards the assessment of a wide range of environmental impacts for the pyrolysis process of different types of bio-wastes under different operating conditions. The study estimates the potential environmental impacts related to bio-char production from the pyrolysis of several different agro-industrial residues and different temperatures and identifies the process “hot spots”. The analysis is carried out through the life cycle assessment methodology. The functional unit for the analysis is 1 MJ of thermal energy potentially released during the complete combustion of bio-char obtained from the pyrolysis process. The study highlights that, under the examined conditions, the type of biomass affects the environmental impacts of the pyrolysis process more than the peak pyrolysis temperature. Among the biomasses tested, bio-char obtained from orange peels has the lower environmental impacts, with an average percentage difference of about 16% compared to bio-char obtained from olive tree trimmings that has the worst environmental performance. For each biomass, the impacts associated to bio-char obtained with different operational temperatures have percentage differences in general lower than 5%. A contribution analysis shows that the electricity consumed during the operational phase is responsible for the largest impacts in all the examined impact categories, followed by bio-wastes transportation. In detail, the contribution of the electricity to the total impact ranges from minimum values of about 44% (for cumulative energy demand) up to 91% (for terrestrial eutrophication), while transportation contributions range from a minimum of about 4% (for terrestrial and marine eutrophication) to 36% for mineral, fossil and renewable resource depletion. Therefore, the use of more energy efficient processes and technologies and the diffusion of distributed pyrolysis systems near farms can significantly improve the environmental performance of the system examined.

Biofuels in the form of bio-oil and biochar have been produced by microwave heating of corn stover. Different adsorbents such as silicon carbide (SiC) and activated carbon (AC) with different ratios (10%, 20%, and 30%) to corn stover are investigated with the aims of enhancing the absorption of the microwave, maximizing the yields of the desirable products i.e. bio-oil followed by biochar as well as improving their qualities. Use of both the adsorbents improved the heating performance through increase in the maximal temperature and heating rate by 170 °C and 36 °C/min respectively compared to without adsorbent. Use of AC increased the yield of bio-oil up to 45 wt% while SiC increased the gas yields up to a maximum value of 48 wt%. The better physical properties such as 37%, 5.3, 2.9 mPa s, and 1 g/mL for water content, pH, viscosity and density respectively of bio-oil were obtained when using AC as an adsorbent. Also, use of AC helped in producing bio-oils which contained higher carbon and hydrogen contents as well as high calorific value (17 MJ/kg). Similarly, use of AC increased the contents of hydrocarbons and phenols in the bio-oil up to 36% and 28% respectively with low oxygen-containing compounds (2%). Also, use of AC produced the biochar having cleanest pores that were almost free of carbon-like impurities with a higher surface area of the pore (105.2 m2/g). In addition, biochar having low ash content, high carbon content, and calorific value (28 MJ/kg) were achieved. The net energy recovery with respect to raw corn stover was calculated to be of maximum value i.e., 55% when using AC. The AC and SiC were reused for further runs of the experiments (5 times) with few changes in the heating behavior and the yields of the pyrolytic products.

Biochar is a charcoal-like substance produced by pyrolisis of organic material from agricultural and forestry wastes, that can improve soil and substrates physical and chemical properties in the field and in plant nurseries. Despite some studies showing the advantages of its use in forestry nurseries, other studies show that biochar effects on seedling growth and quality are variable, and depends on the specific properties of the biochar and the particular species response to it. The objective of this study was to evaluate, through the analysis of the substrate and plant measurements, the effect of biochar produced from Acacia mangium Willd wood residues on the production of the same species seedlings. An experiment with complete factorial design, in a completely randomized arrangement, was established, with 9 treatments resulting from the combination of A. mangium biochar (BAM) and synthetic fertilizer (FS), with 3 dose levels for BAM: 0, 40, and 80 ton • ha−1 and 3 levels for the FS: 0% 50% and 100% of common fertilizer practice in the studied region of Colombia. The quality of the seedlings was estimated using the Dickson index (DQI), which considers the size and biomass allocation of the plant. The addition of BAM + FS increased the cationic exchange capacity, nitrogen, phosphorus, organic matter and carbon in the substrate without modifying the pH or the concentrations of calcium and potassium. Foliar analysis showed an increase in these cations in BAM treatments. An increase of over 130% was found in the DQI of seedlings with BAM + FS, but an intermediate dose of both elements was required to achieve this improvement in seedling quality. Neither of the two fertilizer alternatives alone resulted in good seedling quality. EEA Balcarce Fil: Reyes Moreno, Giovanni. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt; Colombia. Fil: Fernández, María Elena. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Innovación Para la Producción Agropecuaria y el Desarrollo Sostenible; Argentina. Fil: Darghan Contreras, Enrique. Universidad Nacional de Colombia. Facultad de Ciencias Agrarias; Colombia.

The effect of foliar treatment with jasmonic acid at 0.5 mM (JA) and biochar (15 ton ha−1) as a soil amendment for the faba bean (Vicia faba L. Sakha 4) was studied under salinity conditions. Salt stress led to a significant decrease in leaf numbers, leaf areas and plants, chlorophyll content, relative water content, and yield parameters. In contrast, reactive oxygen species, the proline concentration, level of malondialdehyde, and amount of electrolyte leakage were noticeably increased during both seasons under salt levels of 1500 and 3000 ppm sodium chloride (NaCl). Also, enzyme activities (i.e., of superoxide dismutase, catalase, peroxidase, and glutathione reductase) were increased, especially under a high level of salinity stress (3000 ppm). Application of biochar, jasmonic acid, or biochar + jasmonic acid significantly reduced the catalase, superoxide dismutase, and glutathione reductase activities in salt-stressed plants to values approaching those of the control (unstressed) plants, especially under 1500 ppm of NaCl stress. Biochar and jasmonic acid treatments mitigated the damaging effects of salinity and improved the plant status as indicated by the plant height, leaf area, relative water content, and chlorophyll a and b concentrations. Moreover, biochar and jasmonic acid treatments of the salt-stressed plants enhanced plant productivity, number of flowers, number of seeds per plant, and weight of 100 seeds during two successive seasons. Overall, this study suggests that biochar or jasmonic acid treatments might be promising for mitigating the detrimental impact of salt stress on faba beans.

Phosphate is a primary plant nutrient, serving integral role in environmental stability. Excessive phosphate in water causes eutrophication; hence, phosphate ions need to be harvested from soil nutrient levels and water and used efficiently. Fe-Mg (1:2) layered double hydroxides (LDH) were chemically co-precipitated and widely dispersed on a cheap, commercial Douglas fir biochar (695 m2/g surface area and 0.26 cm3/g pore volume) byproduct from syn gas production. This hybrid multiphase LDH dispersed on biochar (LDHBC) robustly adsorbed (~5h equilibrium) phosphate from aqueous solutions in exceptional sorption capacities and no pH dependence between pH 1–11. High phosphate Langmuir sorption capacities were found for both LDH (154 to 241 mg/g) and LDH-modified biochar (117 to 1589 mg/g). LDHBC was able to provide excellent sorption performance in the presence of nine competitive anion contaminants (CO32–, AsO43−, SeO42−, NO3–, Cr2O72−, Cl−, F−, SO42−, and MoO42−) and also upon remediating natural eutrophic water samples. Regeneration was demonstrated by stripping with aqueous 1 M NaOH. No dramatic performance drop was observed over 3 sorption-stripping cycles for low concentrations (5 ppm). The adsorbents and phosphate-laden adsorbents were characterized using Elemental analysis, BET, PZC, TGA, DSC, XRD, SEM, TEM, and XPS. The primary sorption mechanism is ion-exchange from low to moderate concentrations (10–500 ppm). Chemisorption and stoichiometric phosphate compound formation were also considered at higher phosphate concentrations (>500 ppm) and at 40 °C. This work advances the state of the art for environmentally friendly phosphate reclamation. These phosphate-laden adsorbents also have potential to be used as a slow-release phosphate fertilizer.

Complex interactions based on host plant, rhizosphere microorganisms and soil microenvironment are presumed to be responsible for the suppressive properties of biochar against soil-borne diseases, although the underlying mechanisms are not well understood. This study is designed to evaluate the efficacy of biochar amendment for controlling tomato bacterial wilt caused by Ralstonia solanacearum, and to explore the interactions between biochar-induced changes in rhizosphere compound composition, the pathogen and tomato growth. The results showed that biochar amendment decreased disease incidence by 61–78% and simultaneously improved plant growth. The positive ‘biochar effect’ could be associated with enhanced microbial activity and alterations in the rhizosphere organic acid and amino acid composition. Specifically, elevated rhizosphere citric acid and lysine, but reduced salicylic acid, were induced by biochar which improved microbial activity and rendered the rhizosphere unsuitable for the development of R. solanacearum. In addition, nutrients which were either made more available by the stimulated microbial activity or supplied by the biochar could improve plant vigor and potentially enhance tomato resistance to diseases. Our findings highlight that biochar's ability to control tomato bacterial wilt could be associated with the alteration of the rhizosphere organic acid and amino acid composition, however, further research is required to verify these ‘biochar effects’ in field conditions.

The use of bioretention areas is common in urban stormwater management, but their performance varies significantly depending on rainfall characteristics and design conditions. In this study, a pilot experiment using bioretention columns with different media (commercial activated carbon and river sediment-derived biochar) investigated the influence of rainfall on bioretention performance. The results indicated that the runoff volume retention ratio (Rv), which included the runoff purified and discharged at the bottom of the column, and the runoff retained in media during rainfall event, decreased significantly with increases in the rainfall event return period (p 0.05). The addition of adsorptive material, such as activated carbon and biochar, may not be the key factor for improving nitrogen and COD removal under heavy rain that exceeds the 2-yr return period. The bioretention performance of phosphorus removal from urban stormwater runoff could be improved by replacing or adding media with high adsorption capacity, but these improvements would not be significant under heavy rain that exceeds the 2-yr return period. The results provide some reference for evaluating bioretention performance and optimizing bioretention design in the future.

Soybean residue (SR) is a main solid waste produced during the extraction of soybean oil with bulk volume. In addition to the use as vegetable protein feed, SR could also be used as feedstock for producing biofuels and carbon materials via pyrolysis. In this study, the pyrolysis behaviors of SR at varied temperatures and heating rates were investigated. The results show that the pyrolysis of the organic components in SR could reach completion even at 500 °C, due to the lower thermal stability of the organic component than that in the typical biomass. This also leads to the bio-oil with little heavy organics and also low carbon content of the resulting biochar, as the organic components decomposed to a significant extent while the charring reactions were insignificant. This leads to the biochar with low heating value and low energy yield when compared with that in the pyrolysis of typical biomass. In addition, the high content of proteins, amino acids and other nitrogen-containing nutrients make the SR derived bio-oil nitrogen-rich and a significant portion of nitrogen could also be retained in the biochar. These specialties have to be considered during their applications as either biofuels or functional carbon materials.

To explore the feasibility of converting oxy-fuel combustion flue gas into valuable syngas through char gasification process, the reactivity of three types of char (bituminous coal char, biochar, and waste char) were experimentally studied under atmospheric pressure in a fixed-bed reactor. The effects of flue gas flow rate and temperature, CO2/H2O/O2 ratio, char types on the char gasification characteristics were mainly investigated. It was found that when the flue gas temperature is 1200 °C or even higher, no matter which char is used, >90% CO2 conversion rate can be reached in line with the Boudouard equilibrium. The reactivity of biochar-H2O is relatively higher than that of waste char-H2O. Besides, 5% oxygen ratio in CO2/H2O mixture is preferred to promote the gasification reaction to some degree. It is important to balance the fixed carbon conversion rate and CO/H2 yield in syngas to decide the optimum residence time of char. Overall, it is a novel way of CO2 reduction and waste resources utilization.

A novel Egeria najas driven-biochar was activated by loading ferric chloride onto surface (FeCl3@EN-BC). The synthesized composite was evaluated for its physicochemical properties and Cr(VI) adsorption behavior and mechanism. The result of SEM showed that the modified biochar is less porous than raw Egeria najas biochar, but loaded with γ-Fe2O3 and Fe3O4 crystals. In addition, the results of FTIR, XRD and XPS also confirmed that Fe was successfully loaded on the Egeria najas biochar. Cr(VI) was efficiently removed by FeCl3@EN-BC within the pH range from 2.5–8.5. The thermodynamics parameters suggested that the adsorption processes of Cr(VI) were all spontaneous and endothermic. The overall removal mechanism was regarded as adsorption, surface complex formation, reduction and ion exchange reaction. Therefore, this modified biochar derived from Egeria najas has a potential of practical application in the removal of Cr(VI) from wastewater.

Presence of nutrients in municipal sewage water in high concentrations has raised awareness of their reuse as a vital limiting resource. With an aim to recover the nutrients in a form that can be used as a soil amendment, a novel biocompatible nanocomposite (BC-P@MNP) was fabricated using green methods. Polysaccharide induced biogenic magnetite nanoparticles (P@MNP) were immobilized onto the biochar of jackfruit peel (BC) to fabricate BC-P@MNP. Microwave irradiation employed during the fabrication of BC-P@MNP involved less energy consumption, high yields and better adsorption performance as compared to BC and other reported biochar-composites. Structural features like mesoporosity, crystallinity, magnetism, functionality and nano-sized dimension was demonstrated in BC-P@MNP. Under optimized conditions, batch studies revealed a maximum adsorption efficiency of 7.94 mg/g and 5.26 mg/g for phosphates and nitrates respectively. Thermodynamics revealed the feasibility and exothermicity of the system. The high selectivity in the presence of competing co-anions, high regeneration capacity and better separability enable BC-P@MNP to be used as advanced, economical adsorbent for wastewater applications. High nutrient recovery and biocompatibility ensured the potential of the spent adsorbent to be used as a soil amendment. Breakthrough curves obtained from fixed-bed column tests conducted on agricultural wastewater demonstrated the use of higher bed depths and lower flow rates for achieving higher phosphate removal as well as for ensuring lower unused column bed. The study demonstrated the technological advancement of a biogenic nanocomposite fabricated from green methods over other reported adsorbents for removal and recovery of nutrients from water.

Nowadays, iron ions as a ubiquitous heavy metal pollutant are gradually concerned and the convenient and quick removal of excessive iron ions in groundwater has become a major challenge for the safety of drinking water. In this study, boron-doped biochar (B-BC) was successfully prepared at various preparation conditions with the addition of boric acid. The as-prepared material has a more developed pore structure and a larger specific surface area (up to 897.97 m²/g). A series of characterization results shows that boric acid effectively activates biochar, and boron atoms are successfully doped on biochar. Compared with the ratio of raw materials, the pyrolysis temperature has a greater influence on the amount of boron doping. Based on Langmuir model, the maximum adsorption capacity of 800B-BC1:2 at 25 °C, 40 °C, 55 °C are 50.02 mg/g, 95.09 mg/g, 132.78 mg/g, respectively. Pseudo-second-order kinetic model can better describe the adsorption process, the adsorption process is mainly chemical adsorption. Chemical complexation, ions exchange, and co-precipitation may be the main mechanisms for Fe2+ removal.

Nickel sulfides are perfect anode materials for high-capacity and low-cost lithium-ion batteries (LIBs); however, with the shortcoming of polysulfide intermediate dissolution, volume expansion exceeding the limit during cycling also restricts their development. Herein, NiS/C composite materials are successfully anchored on chestnut shell fluff (CSF)-derived biochar by a glucose-auxiliary hydrothermal method along with an annealing treatment. The CSF biochar acts as an effective electron transmission channel for the rapid lithiation/delithiation of NiS and as a fixed sulfur carrier for inhibiting the dissolution of polysulfide. Glucose restrains the accumulation of NiS particles and then transforms into uniform amorphous carbon during annealing, which is more effective in buffering for rapid volume variation. Moreover, the CSF-NiS/C electrode exhibits a remarkable specific capacity of 1522.8 mAh g-1 (0.1 A g-1) and distinguished rate performance with 295 mAh g-1 capacity (3 A g-1), which are better than those of the pure NiS/C anode material displays. Researchers may be inspired by both of these reasonable design and synthesis strategies that are beneficial for the development of high-performance nickel-based sulfide anode materials for LIBs.

To understand the catalytic upgrading of bio-oil over char-based catalyst, pyrolysis of pine sawdust with various char catalysts under different reaction temperatures was performed in a fixed-bed reactor, from which the liquid product was analyzed with gas chromatography-mass spectrometry (GC/MS). The main pyrolytic liquids were ketones and acids in the non-catalytic pyrolysis run, which were mainly derived from the pyrolysis of cellulose and hemicellulose in biomass by ring opening and side chain cracking reactions, while the relative content of phenolic substances obtained from catalytic reaction at 400 °C over CO2-activated char increased from 33.79% to 78.12% with the increasing char activation time from 0.5 to 2.0 h, resulting from the formation of more multiple active sites (including surface active groups and the pore characteristics) on activated char. When the catalytic reaction temperature reached 600 °C, the quality of the bio-oil was further improved since the relative content of aromatic hydrocarbons increased from 7.30% to 21.04% at the expense of elimination of some oxygen-containing compounds (e.g., ketones, acids, aldehydes, etc). Furthermore, the content of phenol in phenolic compounds increased from 26–64% to 51–97%.

Watermelon peel residues were used to produce a new biochar by dehydration method. The new biochar has undergone two methods of chemical modification and the effect of this chemical modification on its ability to adsorb Cr(VI) ions from aqueous solution has been investigated. Three biochars, Melon-B, Melon-BO-NH2 and Melon-BO-TETA, were made from watermelon peel via dehydration with 50% sulfuric acid to give Melon-B followed by oxidation with ozone and amination using ammonium hydroxide to give Melon-BO-NH2 or Triethylenetetramine (TETA) to give Melon-BO-TETA. The prepared biochars were characterized by BET, BJH, SEM, FT-IR, TGA, DSC and EDAX analyses. The highest removal percentage of Cr(VI) ions was 69% for Melon-B, 98% for Melon-BO-NH2 and 99% for Melon-BO-TETA biochars of 100 mg·L−1 Cr(VI) ions initial concentration and 1.0 g·L−1 adsorbents dose. The unmodified biochar (Melon-B) and modified biochars (Melon-BO-NH2 and Melon-BO-TETA) had maximum adsorption capacities (Qm) of 72.46, 123.46, and 333.33 mg·g−1, respectively. The amination of biochar reduced the pore size of modified biochar, whereas the surface area was enhanced. The obtained data of isotherm models were tested using different error function equations. The Freundlich, Tempkin and Langmuir isotherm models were best fitted to the experimental data of Melon-B, Melon-BO-NH2 and Melon-BO-TETA, respectively. The adsorption rate was primarily controlled by pseudo-second–order rate model. Conclusively, the functional groups interactions are important for adsorption mechanisms and expected to control the adsorption process. The adsorption for the Melon-B, Melon-BO-NH2 and Melon-BO-TETA could be explained for acid–base interaction and hydrogen bonding interaction.

In this study, the pyrolysis of flaxseed residue (FSR), a solid waste in the production of flaxseed oil, was carried out, aiming to understand the characteristics of the pyrolysis products. Comparing with traditional biomass (such as poplar wood), the organic components in FSR are easier to be cracked, producing the bio-oil with little heavy components. The high content of proteins in FSR made the resulting bio-oil nitrogen-rich. The resulting biochar contained abundant nitrogen, as some of the N-containing organics were thermally stable even at 650 °C. The significant cracking reactions made the biochar with the relatively lower carbon content, heating value and energy yield than that from biomass. The changes of functionalities of the biochar versus increasing temperature were also characterized with in situ diffuse reflectance infrared fourier transforms spectroscopy technique. The transformation of the carbonyl and other functionalities on surface of the biochar was sensitive to the change of temperature and the increase of temperature promoted the deoxygenation and aromatization reactions.

Biochar or agrichar the carbon rich source has been appreciated globally for its versatile properties like large surface area, high level porosity, thermal stability and long shelf life. The advent of such properties and the fact that it can be obtained at low operational costs has created phenomenal applications for biochar to be used in biotechnological and agricultural industries. Availability and high cost of production of enzymes has lead immobilization to be served as fruitful technique to maintain the price efficacy. Endowing to its properties like surface availability of functional groups, being an exceptional biosorbent it is availed as potential carrier for immobilization. For better applicability, various physio-chemical tailoring strategies have been adopted to perk up the usage. The main mechanism that works for biochar immobilization is adsorption due to high surface porosity, surface area of biochar. Further aiding to perks of adsorption being simple, cost effective and economical approach that maintains structural integrity of the enzymes. In addition to this covalent binding can vanquish the demerit enzyme leeching caused by adsorption.This review centers on various methods for production of biochar, a range of tailoring mechanisms being followed, and applicative usages of biochar immobilized enzymes in diverse processes.

Development of lignin-derived carbon adsorbents with ultrahigh phosphate adsorption activity and rapid adsorption kinetics is of great importance, yet limited success has been achieved. Herein, we develop a CeO2 functionalized N-doped lignin-derived biochar (Ce@NLC) via a cooperative modification strategy for effective and fast phosphate capture. The novel modification strategy not only contributes greatly to the loading of well-dispersed CeO2 nanoparticles with a smaller size, but also significantly increases the relative concentration of Ce(III) species on Ce@NLC. Consequently, an enhanced capture capacity for phosphate (196.85 mg g−1) as well as extremely rapid adsorption kinetics were achieved in a wide operating pH range (2–10). Interestingly, Ce@NLC exhibited a strong phosphate adsorption activity at even low-concentration phosphorus-containing water. The removal efficiency and final P concentration reached 99.87% and 2.59 μg P L−1 within 1 min at the phosphate concentration of 2 mg P L−1. Experiments and characterization indicated that Ce(III) species plays a predominant role for the phosphate capture, and ligand exchange, together with electrostatic attraction, are the main adsorption mechanism. This work develops not only an efficient carbon-based adsorbent for phosphate capture, but also promotes the high-value application of industrial lignin.

The present study used soils contaminated with Fusarium oxysporum f. sp. capsici (CCS) and CCS amended with bamboo biochar (CCS + BC) to grow the pepper variety Qujiao No.1 . The physiological performance, and transcriptome and metabolome profiling in leaf (L) and fruit (F) of Qujiao No.1 were conducted. Application of biochar improved soil properties, pepper plant nutrition and increased activities of enzymes related to pest/disease resistance, leading to superior physiological performance and lesser F. wilt disease incidence than plants from CCS. Most of the differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) were involved in protein processing in endoplasmic reticulum (fruit), plant pathogen interaction (fruit), photosynthesis (leaf), phenylpropanoid biosynthesis (both tissues) and metabolic pathways (both tissues). Biochar improved plant photosynthesis, enhanced the immune system, energy production and increased stress signaling pathways . Overall, our results provide evidence of a number of pathways induced by biochar in pepper regulating its response to F. wilt disease.

With the increased awareness of reusing solid wastes for higher sustainability and the concern of water pollution associated with phosphorus over-emission, there are strong interests in developing solid waste based adsorbents for purifying phosphorus-containing wastewater. As a rich calcium resource, paper mill sludge (i.e., a major solid waste from pulping industry) can be used as phosphorus removal adsorbent after calcination. Thus, in this work, a simple and clean thermally treating route has been proposed for preparing calcium-containing biochar from paper mill sludge. The effect of the physicochemical properties of paper mill sludge and its carbonization condition on phosphorus adsorption has been analyzed. Moreover, the influence of some key adsorption parameters, e.g., biochar dosage, initial pH of solution, co-existing anions, initial phosphorus concentration and contact time has also been investigated. The results showed that the phosphorus adsorption data could be fitted well with pseudo-second-order kinetic and Langmuir isothermal models. The calculated maximum adsorption capacity of the as-prepared optimal calcium-containing biochar could reach to 68.49 mg·g−1 at 25 °C. Combined with the characterization results, it can be reasonably inferred that the adsorption process was chemisorption-dominated. Lastly, the application of this spent adsorbent in agriculture field has also been discussed. In brief, this work provided a feasible strategy for converting paper mill solid waste to an environmental functional material (i.e., calcium-rich biochar) for remediation of eutrophic water.

Waste chicken feathers are the ideal precursor for the production of low-cost N-enriched biochar. KOH-modified N-enriched biochar (KNB) containing 15.92 wt% N was successfully prepared using waste chicken feathers. The adsorption kinetics results showed that KNB had rapid Cd (2 h) and Pb (1 h) adsorption rates. The Cd and Pb adsorption capacities of KNB (the values of KF were 22.324 (Cd) and 119.654 (Pb) mg1−(1/n)·L1/n·g−1) were 7.07 and 26.52 times higher than those of the original biochar based on the adsorption isotherm results. The KNB was stable at pH 3–6 and had stronger co-adsorption capacities in double-ion systems. Based on the adsorption experiments and various characterization methods, we concluded that the primary Cd and Pb adsorption mechanisms of KNB involved electrostatic interactions, cation-π interactions, complexation, and K+ exchange. The precipitation mechanism could partially account for Pb adsorption but not for Cd adsorption. KOH modification enhanced the electronegativity of biochar and then increased the electrostatic attraction. Surface O- and N-containing functional groups were involved in Cd and Pb adsorption. Graphitic-N, oxidised-N, and O C O were the main active adsorption groups, the relative contents of which increased after KOH modification, thus increasing the Cd and Pb adsorption performance. Therefore, KNB can be used as a fast and highly efficient adsorption agent to remove Cd and Pb from wastewater containing either Cd and Pb or a combination of these two metals.

Large quantities of solid wastes are produced each year in the leather industry. The considerable wastes generated exhibit tremendous application potential in terms of renewable energy sources and functional materials. Among them, animal hair/wool wastes possess high carbon content, which can be used sustainably and efficiently by using pyrolysis. Herein, the pyrolysis process of hair/wool wastes was investigated using TG-IR and Py-GC/MS, while the pyrolysis kinetic and thermodynamic were analyzed using "model-free" methods. The results showed that the hair/wool waste pyrolysis process can be divided into three stages: dehydration, devolatilization, and carbonization. The volatile products were mainly phenols (7.42%) and heterocyclic compounds (21.26%), which can be directly used as bio-energy (bio-gases and bio-oil) or converted to other useful chemical products. The kinetic parameters (Ea and A) calculated using the Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Kissinger methods indicated the complexity of the decomposition reactions, which was also confirmed by thermodynamic (ΔH, ΔG, and ΔS) calculation. Some suggestions have also been provided for the preparation of functional biochar with heteroatoms (i.e., N, O, and S) doping. These results not only provide a guide for designing the pyrolysis of hair/wool wastes but can also help develop a potential method to convert the hair/wool wastes into bioenergy to achieve sustainable development of the leather industry.

Black soldier fly (BSF) larval bioconversion can recycle nutrients in organic wastes into larval biomass and frass. While the frass has been commonly marketed as a soil amendment, its usefulness in soilless cultivation remains largely unexplored. Growth experiments were conducted to investigate the effectiveness of surplus food-derived and okara-derived BSF larval frass as an incorporated compost, side-dress fertilizer and frass-tea drench for the cultivation of pak choi and lettuce in waste-wood derived biochar growing media. Pak choi yields from treatments with surplus food-derived frass and biochar at a 10:90 (v/v) ratio and inorganic fertilizer were comparable to those of the control which consisted of soil, peat-based compost and inorganic fertilizer. However, yields decreased with increasing frass incorporation rates owing to high salinity and potentially low oxygen conditions in the growing media. When used as a fertilizer on biochar-coir growing media, the direct application of frass as a side-dress fertilizer was 1.6-6.8 times more effective in promoting lettuce growth than the application as a frass-tea drench. Frass fertilizers derived from surplus food outperformed those derived from okara by 1.3-5.3 times. Lettuce yields were not significantly different between the treatment with surplus food-derived frass applied as a side-dress fertilizer and the control of liquid inorganic fertilizer. Variations in fertilizing potential were attributed to nutrient availability and the presence of plant growth promoting microbes in the growing media. BSF larval frass derived from food waste shows promise in partially replacing unsustainable agricultural inputs for leafy vegetable cultivation, including soil and inorganic fertilizers.

The conversion of timber industry waste to biochar was investigated, based on residues from local tropical hardwoods in Cameroon. Closed and flow reactors, loaded with few grams of the sample and fluxed with different inert gases, were used with the aim of converting these wood residues to a safe and efficient solid fuel that can be exploited by the local community for cooking purposes. The pyrolysis temperature had the highest impact on the process up to approximately 700 °C as biochar yields decreased from 87 to 23.5% while increasing the temperature. A significant concentration of carbon required temperatures greater than 500 °C for the biochar to become a good solid fuel, approaching the heating value of coal. The role of heating rate appeared marginal even in a broad range: 0.1 to 70 °C/min. The dwell time (in the range 0.5 to 5 h) at maximum temperature revealed to be of little influence on the charring which occurred mostly during the first few minutes of the isothermal phase. Thus, actual production time can be1 h/batch (up to 500 °C at 10 °C/min). Stepwise heating revealed a sequence of devolatilization reactions following their activation energies. Use of CO

This paper critically reviewed the current knowledge and challenges of rice husk biochar (RHB) production and its effects on soil properties, plant growth, immobilization of heavy metals, reduction of nutrient leaching and mitigation of greenhouse gas emissions. The characteristics of RHBs produced at various pyrolysis temperatures were discussed and compared to biochars derived from other agro- industrial wastes. RHBs produced at higher pyrolysis temperatures show lower hydrogen/carbon ratio, which suggests the presence of higher aromatic carbon compounds. The increase of pyrolysis temperature also results in production of RHBs with higher ash content, lower yield and higher surface area. RHB usually has higher silicon and ash contents and lower carbon content compared to biochars derived from other feedstocks at the same pyrolysis conditions. Although it depends on soil type, RHB application can improve soil organic carbon content, cation exchange capacity, available K concentration, bulk density and microbial activity. The effect of RHB on soil aggregation mainly depends on soil texture. The growth of different crops is also enhanced by application of RHB. RHB addition to soil can immobilize heavy metals and herbicides and reduce their bioavailability. RHB application shows a significant capacity in reduction of nitrate leaching, although its magnitude depends on the biochar application rate and soil biogeochemical characteristics. Use of RHB, especially in paddy fields, shows a promising mitigation effect on greenhouse gas (CH4, CO2 and N2O) emissions. Although RHB characteristics are also related to other factors such as pyrolysis heating rate and residence time, its performance for specific applications (e.g. carbon sequestration, pH amendment) can be manipulated by adjusting the pyrolysis temperature. More research is needed on long-term field applications of RHB to fully understand the advantages and disadvantages of RHB as a soil amendment.

Biochar supported nickel (Ni/BC) has been widely studied as a cheap and easy-to-prepare catalyst with potential applications in tar reforming during the gasification of low-rank fuels, such as brown coal and biomass. However, the role and behaviors of inherent K species, especially their interactions with Ni particles and the biochar support, are not well understood yet. In this work, three Ni/BC catalysts with varying K amount were prepared from raw, water-washed, and acid-washed biomass. They were used in steam reforming of toluene as a tar model compound to elucidate the effects of inherent K on the catalytic activity and stability. Detailed characterization indicated that K enhanced water adsorption due to its hydroscopicity and lowered the condensation and graphitization degrees of biochar, but the alteration to the electronic state of Ni was not observed. These effects together led to a temperature-dependent role of K. That is, at relatively low temperatures of 450 and 500 °C, toluene conversion was increased in the presence of K, due to the increased concentration of adsorbed water around Ni particles. By contrast, at relatively higher temperatures of 550 and 600 °C, although initial high activity was achieved, Ni/BC with K deactivated rapidly because of the accelerated consumption of the biochar support.

This study aims to assess the efficiency of two agricultural wastes as adsorbents to remove Chromium (Cr) from a wastewater sample. Chromium-containing wastewater was treated with calcined and non-calcined eggshell and biochar tea waste with the adsorption method, and the effect of contact time, pH, and adsorbent dosage were investigated to examine the efficiency. The results indicate that 120 min is sufficient for the biochar tea waste and the non-calcined eggshell to reach adsorption equilibrium, where the calcined eggshell was reached equilibrium at 30 min. The optimal pH of all adsorbents was found to be 5, which indicates the interference of H+ ions on removing metal ions at low pH. Pseudo-first order and pseudo-second-order kinetic models were studied to assess the kinetic adsorption mechanism. Results also reveal that an increasing amount of adsorbent dose improves the removal efficiency of the adsorbent. The removal rates of using 2.0 g of non-calcined eggshell, 1.5 g of calcined eggshell and 2.5 g of biochar tea waste were found to be 70.70%, 100%, and 68.2%, respectively. The results show that the adsorption can be more appropriately described by the pseudo-second-order kinetic model for the adsorption of chromium ions from the wastewater. The findings of this study suggest that using these adsorbents, industrial wastewater can be treated in a more cost-effective and simple way than other existing methods.

International audience; The present research deals with the global challenge of managing industrial sludge with respect to sustainability and circular economy principles. It focuses on raw industrial sludge (IS-R) conversion into valuable biochars that can serve as efficient adsorbents for pharmaceuticals in industrial wastewater. Three biochars were produced through sludge pyrolysis at 750 degrees C either without modification (IS-R-B), or after pre-treatment with 1 M solution of ZnCl2 (IS-ZnCl2-B) or FeCl3 (IS-FeCl3-B). Compared to the pristine biochar, the modified sludge-derived biochars (SDBs) showed improved structural, textural, and surface chemical properties. As a result, ISZnCl2-B and IS-FeCl3-B had AMX adsorption capacities of 31.9 and 32.1 mg g-1 which were 41.2% and 42.0% higher than the non-modified biochar, respectively. Moreover, both modified SDBs effectively removed AMX under various experimental conditions, including the presence of competitive ions and over a wide pH range. The AMX removal was found to be spontaneous, endothermic, and primarily controlled by chemical reactions on a monolayer system. These findings suggest that biochars generated from pyrolysis of salt-modified industrial sludge can be used as effective materials for removing pharmaceuticals from water. Therefore, this study supports the concepts of circular economy and sustainable development by offering engineering solutions.

Former gasworks sites are known to be contaminated with complex chemical mixtures that require remediation before redevelopment. Bioamendments such as biochar and spent mushroom compost (SMC) offer a green and sustainable remediation approach to help tackle this issue. However, the effectiveness of different biochar types and their interactions with the soil microbial community is still not well understood. To address this, a full factorial microcosm experiment was carried out using biochar derived from rice husk (RHB) and wheat straw (WSB) mixed with soil from a former gasworks site at varying concentrations (0%, 2.5%, and 5%), with and without SMC. The experiment aimed to evaluate the fate of contaminants including alkanes, PAHs, and metals, and their effect on the soil microbial community, as well as the implications for remediation endpoints. The results showed that the bioamendments had an average TPH reduction of 92%, with SMC and WSB-SMC having the highest degradation rates at 93%. While the bioamendments did not significantly affect the extent of TPH removal compared to the control, they did improve the degradation of high molecular weight (HMW) PAHs, particularly in RHB-SMC for EC17-20 (60%) and EC21-35 (62%) of total PAH concentration, and in WSB-SMC for HMW bioavailable PAH concentration (89%). The bioamendments also affected the partitioning and distribution of metals after 120 days of treatment, leading to decreased available phase fractions. The treatments increased microbial abundance in the soil, with Gram positives, Gram negatives, and fungi increasing by 4%, 8%, and 38%, respectively, after 120 days, particularly in SMC and mixed treatments. This was mirrored in increased microbial soil respiration. After 120 days, low metal (178 ± 5 mg/kg) and TPH (21 ± 7 mg/kg) bioavailability translated into higher EC50 (10624 ± 710 mg/L), indicating lower toxicity. There was a strong correlation between bioavailability and toxicity of TPH and metals with microbial relative abundance and activity. In summary, while green and sustainable remediation may accelerate the remediation process, monitored natural attenuation may be sufficient for site reclamation. However, this strategy, as demonstrated here, can reduce metal bioavailability, and promote the biodegradation of HMW PAHs.