Efficient stabilization of dredged sludge with high water content using an improved bio-carbonation of reactive magnesia cement method

This study proposed an improved bio-carbonation of reactive magnesia cement(RMC)method for dredged sludge stabilization using the urea pre-hydrolysis strategy.Based on unconfined compression strength(UCS),pickling-drainage,and scanning electron microscopy(SEM)tests,the effects of prehydrolysis duration(T),urease activity(UA)and curing age(CA)on the mechanical properties and microstructural characteristics of bio-carbonized samples were systematically investigated and analyzed.The results demonstrated that the proposed method could significantly enhance urea hydrolysis and RMC bio-carbonation to achieve efficient stabilization of dredged sludge with 80%high water content.A significant strength increment of up to about 1063.36 kPa was obtained for the bio-carbonized samples after just 7 d of curing,which was 2.64 times higher than that of the 28-day cured ordinary Portland cement-reinforced samples.Both elevated T and UA could notably increase urea utilization ratio and carbonate ion yield,but the resulting surge in supersaturation also affected the precipitation patterns of hydrated magnesia carbonates(HMCs),which weakened the cementation effect of HMCs on soil particles and further inhibited strength enhancement of bio-carbonized samples.The optimum formula was determined to be the case of T?24 h and UA?10 U/mL for dredged sludge stabilization.A 7-day CA was enough for bio-carbonized samples to obtain stable strength,albeit slightly affected by UA.The benefits of high efficiency and water stability presented the potential of this method in achieving dredged sludge stabilization and resource utilization.This investigation provides informative ideas and valuable insights on implementing advanced bio-geotechnical techniques to achieve efficient stabilization of soft soil,such as dredged sludge.

Lignin derived multi-doped(N, S, Cl) carbon materials as excellent electrocatalyst for oxygen reduction reaction in proton exchange membrane fuel cells

Nowadays,hierarchically macro-/meso-/microporous 3D carbon materials have been paid more attention due to their imaginative application potential in specific electrochemistry.Here,we report a dualtemplate strategy using eutectic NaCl/ZnCl2 melt as airtight and swelling agent to obtain 3D mesoporous skeleton structured carbon from renewable lignin.The prepared lignin-derived biocarbon material(LN-3-1)has a high specific surface area(1289 m^2 g^-1),a large pore volume(2.80 cm^3 g^-1),and a well-connected and stable structure.LN-3-1 exhibits extremely high activity and stability in acidic medium for oxygen reduction reaction(ORR),superior to Pt/C catalyst and most non noble-metal catalysts reported in recent literatures.The prepared carbon material was used as a cathode catalyst to assemble a H2-O2 single fuel cell,and its excellent catalytic performance has been confirmed with the maximum power density of 779 mW cm^-2,which is one of the highest power densities among non-metallic catalysts so far.Density functional theory(DFT)calculations indicate that the synergy of chlorine and nitrogen reconciles the intermediate adsorption energies,leading to an appropriate theoretical ORR onset potential.We develop a cost-effective and highly efficient method to prepare biocarbon catalyst for ORR in proton-exchange membrane fuel cells.

Preparation of nitrogen and sulfur co-doped ultrathin graphitic carbon via annealing bagasse lignin as potential electrocatalyst towards oxygen reduction reaction in alkaline and acid media

Renewable lignin used for synthesizing materials has been proven to be highly potential in specific electrochemistry.Here,we report a simple method to synthesize nitrogen and sulfur co-doped carbon nanosheets by using bagasse lignin,denoted as lignin-derived carbon(LC).By adjusting the ratio of nitrogen source and annealing temperature,we obtained the ultrathin graphitic lignin carbon(LC-4-1000)with abundant wrinkles with high surface area of 1208 m2g_1 and large pore volume of 1.40 cm3g_1.In alkaline medium,LC-4-1000 has more positive half-wave potential and nearly current density compared to commercial Pt/C for oxygen reduction reaction(ORR).More importantly,LC-4-1000 also exhibits comparable activity and superior stability for ORR in acid medium due to its high graphitic N ratio and a direct four electron pathway for ORR.This study develops a cost-effective and highly efficient method to prepare biocarbon catalyst for ORR in fuel cells.

Enhanced capacity to CO2 sorption in humid conditions with a K-doped biocarbon

Solid sorbents with enhanced capacity and selectivity towards CO2 are crucial in the design of an efficient capture process.Among the possible alternatives,K2CO3-doped activated carbons have shown high CO2 capture capacity and rapid carbonation reaction rate.In this work,a sustainable and low-cost approach is developed with a biomass-based activated carbon or biocarbon as support.The CO2 capture performance in cyclic sorption–desorption operation and the sorption kinetics have been investigated under different scenarios in a purpose-built fixed-bed set-up.Independent of the H2O concentration in the flue gas,a constant relative humidity(~20%)in the K2CO3-doped biocarbon bed promoted the carbonation reaction and boosted the CO2 sorption capacity(1.92 mmol/g at 50℃ and 14 kPa partial pressure of CO2).Carbonation is slower than physical adsorption of CO2 but wise process design could tune the operation conditions and balance capture capacity and sorption kinetics.

The Use of Eucalyptus Activated Biocarbon for Water Treatment-Adsorption Processes

A biocarbon after activation process showed the removal percentage of 92% of methylene blue in solution, the equilibrium parameter—RL value was in the interval from 0 to 1, with 46% of surface coverage degree. The Freundlich constant (n) was higher than 1 as an indication of the physical adsorption process. The Radlich-Peterson calculations obtained the higher R2 value which g constant near 1, a high similarity with Langmuir model. Temkin constant B1 was a positive indication of endothermic process. All calculations provided favorable results for the use of activated biocarbon for dye removing and possible for other organic substances.

Oxytetracycline Water Contamination Treated with Biocarbon TiO2 and Solar Photodecomposition

Reliable data of antibiotic use and environmental discharge as veterinary medicine are essential to help countries raise awareness of the appropriate use, control, and correct water release. The first approach is to change the regulatory framework based on consuming information, use policy, and discharge laws. The important research contribution is a novel water treatment process to treat, remove, and reduce antibiotic concentration in discharged water, mainly those used in the animal protein industry. The low particle biochar added during the titanium isopropoxide hydrolysis reduces the titanium dioxide (TiO2) agglomerates and promotes the adsorption surface process. Such improved catalyst material enhances the solar decomposition efficiency to 93% from original oxytetracycline with better correspondence with the Elovich kinetics, intraparticle diffusion, R-P isotherm, and Langmuir-Hinshelwood model.

Influence of particle size distribution on biocarbonation method produced microbial restoration mortar for conservation of sandstone cultural relics

Biocarbonation of reactive magnesia based on microbially induced carbonate precipitation(MICP)process is a sustainable geotechnical reinforcement technology for strength development and permeability reduction.This method can be used to produce microbial restoration mortar(MRM)for the application of stone cultural relics restoration.In this paper,the influence of particle size distribution on the strength and porosity of MRM was examined.By mixing fine and coarse sandstone powder in various proportions,nine different particle size distributions were obtained to investigate the restoration performance,including the unconfined compressive strength(UCS),porosity,and color difference.The results indicate that the well-graded particle size distribution can lead to the UCS improvement and porosity reduction of MRM.The findings also imply that adding fine sandstone powder to the coarse sandstone powder can provide extra bridging contacts within the soil matrix.These bridging contacts can be easily connected by the precipitated hydrated magnesium carbonates(HMCs)minerals,consequently resulting in more effective bonding and filling within the pore matrix.The microstructural images of MRM confirm the formation of HMCs,which exhibited a dense network structure,filling out the gap and bonding the sandstone powders.Furthermore,the microbial restoration mortar showed a high weather resistance to dry-wet cycles,acid rain,and salt attack,which is attributed to better stability and strength of HMCs than the original calcic cemented minerals in sandstone.

A pore-confined strategy for synthesizing CoFe nanoparticles in mesoporous biocarbon matrix as advanced bifunctional oxygen electrocatalyst for zinc-air battery

Designing rational transition-metal/carbon composites with highly dispersed and firmly anchored nanoparticles(NPs)to prevent agglomeration and shedding is crucial for realizing excellent electrocatalytic performances.Herein,a biomass pore-confined strategy based on mesoporous willow catkin is explored to obtain uniformly dispersed CoFe NPs in N-doped carbon nanotubes and hollow carbon fibers(CoFe@N-CNTs/HCFs).The resultant catalyst exhibits enhanced electrocatalytic performance,which affords a half-wave potential of 0.86 V(vs.RHE)with a limited current density of 6.0 mA·cm^(-2)for oxygen reduction reaction and potential of 1.67 V(vs.RHE)at 10 mA·cm^(-2)in 0.1 M KOH for oxygen evolution reaction.When applied to rechargeable zinc-air batteries,a maximum power density of 340 mW·cm^(-2)and long-term cyclic durability over 800 h are achieved.Such superior bifunctional electrocatalytic activities are ascribed to the biocarbon matrix with abundant mesopores and unobstructed hollow channels,CoFe NPs with high dispersion and controllable nanoscale and the hybrid composite with optimized electronic structure.This work presents an effective approach for constraining the size and dispersion of NPs in a low-cost biocarbon substrate,offering valuable insights for designing advanced oxygen electrocatalysts.

Micro‑Supercapacitors Based on Fungi‑Derived Biocarbon Microfibers Infused with NiMoO Nanoparticles for Biomedical and E‑Skin Applications

In various biomedical fields,noninvasive medical procedures are favored over invasive techniques,as the latter require major incisions or surgeries that cause bleeding,pain,and tissue scarring.The increased use of noninvasive biomedical equipment has created a demand for effective energy storage devices that are sufficiently compact to be used as a power source,easy to commercialize,and bio-friendly.Herein,we report the facile synthesis of nickel molybdenum oxide nanoparticle-infused biocarbon microfibers(NiMoO NPs@BCMFs)as a novel energy storage material.The microfibers were derived from the bracket fungus Laetiporus sulphureus.In a three-electrode system,the NiMoO NPs@BCMFs/nickel foam(NF)electrode delivered an areal capacity of 113µAh cm^(-2)at 1.5 mA cm^(-2),with excellent cycling stability.Its capacity retention was 104%,even after 20,000 cycles.Bare BCMFs were also synthesized from the fungal biomass to fabricate a negative BCMFs/NF electrode.This,together with the positive NiMoO NPs@BCMFs/NF electrode,was used to construct a bio-friendly(hybrid-type)micro-supercapacitor(BMSC),which exhibited maximum energy and power density values of 56µWh cm^(-2)and 11,250µW cm^(-2),respectively.When tested for its ability to power biomedical electronics,the BMSC device successfully operated an electrical muscle stimulator,inducing potential signals into a volunteer in real-time application.

Biocarbon with different microstructures derived from corn husks and their potassium storage properties

In this paper,biocarbon was prepared from corn husks as anode materials for potassium ion batteries at temperatures ranging from 700 to 1600℃.The prepared biocarbon materials have amorphous phase structure and possess larger interlayer spacing than graphite.The biocarbon exhibits enhanced graphitic degree and decreased amounts of surface defects,while the carbonization temperature gradually increases.The obtained potassium ion battery electrode at 1300℃ acquired high reversible capacity up to 216.6 mAh·g^(-1) at 0.1 A·g^(-1) after 100 cycles, and retained 128.6 mAh·g^(-1) at 1 A·g^(-1) even after500 cycles.The results indicate that the samples prepared at 1300℃ have better electrochemical performance than other samples prepared at different temperatures,which was attributed to the decisive influence of microstructure on surface-induced and intercalating potassium storage.

Walnut septum-derived hierarchical porous carbon for ultra-high-performance supercapacitors

The conversion of biomass waste into eco-nomical and high-performance energy storage devices receives significant attention.Herein,a facile and green method to prepare porous active carbon from walnut sep-tum is applied to the electrode materials of supercapacitors.The effect of chemical etching reagent(KOH)on the microstructure and specific capacitance of the porous car-bon are explored.The modified BC-2.0,with a KOH/walnut septum mass ratio of 2∶1,exhibits large specific surface area of 1003.9 m^(2)·g^(-1)with hierarchical micro-mesoporous structures.BC-2.0 reveals a superior specific capacitance of 457 F·g^(-1)at 1 A·g^(-1).The flexible sym-metric supercapacitor in gel electrolyte(KOH/PVA)exhi-bits considerable synergetic energy-power output performance.The results indicate that walnut septum is a better precursor to obtain activated carbons relative to other biomass carbon sources.The large mesoporosity after activation effectively boosts the electrochemical properties of supercapacitor.Consequently,the walnut septum has potential to be a superior electrode material for supercapacitors.