An integrated method to produce fermented liquid feed and biologically modified biochar as cadmium adsorbents using corn stalks

Effective adsorptive removal of Pb2+ ions from aqueous solution using functionalized agri-waste biosorbent: New green mediation via Seidlitzia rosmarinus extract

Currently, the use of natural adsorbent for the elimination of pollutants, such as heavy metals, from water has been extensively investigated. However, the low adsorption capacity of these natural adsorbents has led researchers towards the use of synthetic surfactants, which themselves can become environmental pollutants. In this research, an investigation was conducted to examine the impact of a surfactant obtained from the Seidlitzia rosmarinus plant on the adsorption properties of Pumpkin seed shell (PSS), a natural adsorbent. As a result, a modified version of PSS, known as functionalized Pumpkin seed shell (FPSS), was developed, and the effect of these two adsorbents on the elimination of Pb2+ has been investigated. FESEM, EDS, FTIR, and BET analyses were conducted to get detailed information of the adsorbent. Additionally, the effects of contact time, dosage of the adsorbent, pH of the solution, and temperature on the adsorbent were studied. The experimental data was fitted using Langmuir, Freundlich, Temkin, and Jovanovic isotherms. The PSS adsorbent was fitted best with the Langmuir isotherm, showing an adsorption capacity of 160.80 mg g-1, while the FPSS adsorbent was fitted with the Jovanovic isotherm, exhibiting an adsorption capacity of 553.57 mg g-1. Furthermore, kinetic modeling results indicated that the data for these adsorbents follow pseudo-second-order kinetic. Finally, the impact of coexisting ions and reusability was examined, with the FPSS adsorbent outperforming PSS. Therefore, the investigation of all these aspects demonstrated that the use of this natural surfactant significantly improves the performance of the adsorbent.

Pore size and organic carbon of biochar limit the carbon sequestration potential of Bacillus cereus SR

Carbon-fixing functional strain-loaded biochar may have significant potential in carbon sequestration given the global warming situation. The carbon-fixing functional strain Bacillus cereus SR was loaded onto rice straw biochar pyrolyzed at different temperatures with the anticipation of clarifying the carbon sequestration performance of this strain on biochar and the interaction effects with biochar. During the culture period, the content of dissolved organic carbon (DOC), easily oxidizable organic carbon, and microbial biomass carbon in biochar changed. This finding indicated that B. cereus SR utilized organic carbon for survival and enhanced carbon sequestration on biochar to increase organic carbon, manifested by changes in CO2 emissions and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) enzyme activity. Linear regression analysis showed that the strain was likely to consume DOC on 300 °C biochar, although the Rubisco enzyme activity was higher. In contrast, the strain had a higher carbon sequestration potential on 500 °C biochar. Correlation analysis showed that Rubisco enzyme activity was controlled by the physical structure of the biochar. Our results highlight the differences in the survival mode and carbon sequestration potential of B. cereus SR on biochar pyrolyzed at different temperatures.

Effect of lignocellulosic corn stalk on mechanical, physical, and thermal properties of injection moulded low density polyethylene composites: An approach towards a circular economy

Escalating concern over global warming, which is mostly associated with deforestation, has led to the development of new classes of materials that can replace wood and better utilise natural resources. Presently, waste is a significant factor in recycling. In this regard, one of the leading contributors to waste is agricultural waste, which includes dried branches, leaves of trees, plants, and other organic materials. In the current study, waste from corn agriculture was utilised as a potential reinforcement for the fabrication of corn stalk-low density polyethylene (CS-LDPE) composites via an injection moulding technique at 170 °C. The different parameters were assessed to develop composites using CS, including physico-chemical, macromolecular, mineralogical, elemental, and morphological analysis. The amount of corn stalk (CS) was varied from 10 to 50 wt% with respect to the polymer. The mechanical, physical and thermal performance of the composites was examined. The density and water absorption of the composites were found to remain within the ranges of 1.00-1.11 g/cm3 and 0.22-1.01 %, respectively, whereas these parameters increased as the proportion of CS increased. The thermal conductivity decreases with the addition of CS from 0.36964 ± 0.020 to 0.22388 ± 0.002 W/mK. It was observed that adding CS to the composites increased their tensile and flexural properties, but decreased their impact strength. The maximum flexural strength of 14.40 ± 1.558 MPa, flexural modulus of 752.53 ± 180.409 MPa, tensile strength of 10.49 ± 0.946 MPa and tensile modulus of 539.79 ± 91.044 MPa were observed with a 50 % CS content. The results suggest that these materials have considerable potential to serve as a cost-effective substitute for the conventional lignocellulosic fillers in the manufacturing of wood-plastic composites.

Facile construction of ZIF-94/PAN nanofiber by electrospinning for the removal of Co(II) from wastewater

This study aimed to synthesize a novel nanofiber adsorbent based on metal-organic frameworks (MOFs), ZIF-94-PAN, by incorporating ZIF-94 into polyacrylonitrile (PAN) through electrospinning. The investigation of the adsorption characteristics of ZIF-94-PAN for cobalt ions was undertaken, yielding findings that suggest an optimum ZIF-94 loading content within the ZIF-94-PAN composite of 8%. The adsorption experiments revealed that, under pH 8.3 and 298 K, ZIF-94-PAN-8% attained cobalt ion equilibrium adsorption (139.08 mg/g). Additionally, the adsorption kinetics of cobalt ions exhibited conformity with the pseudo-second-order model, whereas adherence to the Freundlich isotherm model indicated a non-homogeneous, endothermic process. XPS analysis unveiled that the adsorption mechanism was characterized by the coordination of nitrogen and oxygen atoms within ZIF-94-PAN with cobalt ions. This study effectively addressed the challenges of separating and recovering MOFs adsorbents by fabricating them as nanofibers. The remarkable adsorption performance and stability of the ZIF-94-PAN nanofibers highlight their potential for removing cobalt-contaminated wastewater.

Characteristics and reduction assessment of GHG emissions from crop residue open burning in China under the targets of carbon peak and carbon neutrality

Driven by the goal of carbon peak and carbon neutrality, greenhouse gas (GHG) emissions from the crop residue open burning (CROB) in China cannot be ignored. In this study, we have established a high-resolution (0.05° × 0.05°) GHG emissions inventory (including CO2, CH4, and N2O) of CROB from 2012 to 2021 in China based on the VIIRS data and official statistics. To improve the results accuracy, we compared the two commonly used bases for grid allocation, fire counts (FC) and fire radiative power (FRP), in the construction of high-resolution inventory. In 2012, GHG emissions are overestimated by 599 t CO2e per grid on average in 24,577 grids, and underestimated by 1096 t CO2e per grid on average in 13,546 grids based on FC compared to FRP. Then, we characterized the spatial and temporal distribution of GHG emissions from CROB by using the FRP-based method. From 2012 to 2021, total GHG emissions from CROB in China have decreased by 31.2 %, of which the East and South-Central China contributed 22.51 and 9.12 Tg CO2e of GHG reductions, while the Northeast China contributed 10.73 Tg CO2e of GHG growth, respectively. In addition, GHG emissions from CROB on the time scale are mainly concentrated in April, June, and October, with variations between years and regions influenced by the policy, climate, and farmers' perceptions. Finally, we assessed the GHG emission reductions from CROB under different scenarios in the future. By 2060, GHG emissions would be significantly reduced by 57.3 %-77.9 % compared to 2021 under effective control measures. We believe the results will be of great significance for GHG policy formulation and emission reduction potential assessment.

Integrated Hemicellulose Extraction and Papermaking Fiber Production from Agro-Waste Biomass

The present study deals with the valorization of corn stalks in an integrated processing strategy targeting two products: extracted hemicelluloses (HC) and papermaking fibers. Preliminary trials were conducted to assess the individual or the combined effects of biomass treatment on the quality of the obtained hemicelluloses and papermaking fibers. Depending on the hot alkaline extraction (HAE) conditions, the extracted HC had a xylan content between 44-63%. The xylan removal yield ranged between 19-35%. The recovery of HC from the extraction liquor and final black liquor was significantly affected by process conditions. The experimental approach continued with the study of HAE conditions on the obtained paper's mechanical properties. The optimization approach considered conserving paper strength properties while achieving an equilibrium with the highest possible HC extraction yield. The optimal values are sodium hydroxide concentration (1%), process time (33 min), and temperature (100 °C). The xylan content in the separated HC sample was ~55%. An extended extraction of HC from the resulting pulp under hot alkaline conditions with 5% NaOH was performed to prove the HC influence on paper strength. The xylan content in HC samples was 65%. The consequence of xylan content reduction in pulp leads to 30-50% mechanical strength loss.

Qualitative and quantitative analysis for Cd2+ removal mechanisms by biochar composites from co-pyrolysis of corn straw and fly ash

Removal of heavy metals (e.g., Cd) from contaminated water using waste-converted adsorbents is promising, but the efficiency still needs to be improved. Here, we prepared a functional biochar composite as novel Cd adsorbents by co-pyrolysis of two typical solid wastes, i.e., agricultural corn straw and industrial fly ash. The adsorption behavior and mechanism were investigated using batch and column adsorption experiments and modern characterization techniques. Results showed that alkali-modified fly ash (AMFA) was loaded onto the surface of the corn straw biochar as some fine particle forms, with quartz (SiO₂) and silicate being the main mineral phases on the surface. The maximum sorption capacity fitted by Langmuir model for functionalized biochar composite (FBC700) was up to 137.1 mg g^-1, which was 7.7 times higher than that of the original corn straw biochar (BC700). Spectroscopic analysis revealed that adsorption mechanisms of Cd onto the FBC700 included mainly precipitation and ion exchange, with complexation and Cd-π interaction also contributing. The AMFA could effectively improve the mineral precipitation with Cd. The adsorption columns filled with FBC700 exhibited a longer breakthrough time than that filled with BC700. The adsorption capacity calculated by Thomas model for FBC700 was also approximately 6.0 times higher than that for BC700, showing that FBC700 was more suited to practical applications. This study provided a novel perspective for recycling solid wastes and treating Cd-contaminated water.

In vivo cadmium-assisted dilute acid pretreatment of the phytoremediation sweet sorghum for enzymatic hydrolysis and cadmium enrichment

Phytoremediation with energy crops is considered an integrated technology that provides both environment and energy benefits. Herein, the sweet sorghum cultivated on Cd-contaminated farmland (1.21 mg/kg of Cd in the soil) showed promising phytoremediation potential, and the approach for utilizing sorghum stalks was explored. Sweet sorghum bagasse with Cd contamination was pretreated with dilute acid in order to improve enzymatic saccharification and achieve Cd recovery, resulting in harmless and value-added utilization. After pretreatment, hemicelluloses were dramatically degraded, and the lignocellulosic structures were partially deconstructed with xylan removal up to 98.1%. Under the optimal condition (0.75% H₂SO₄), the highest total sugar yield was 0.48 g/g of raw bagasse; and nearly 98% of Cd was enriched in the liquid phase. Compared with normal biomass, Cd reduced the biomass recalcitrance and further facilitated the deconstruction of biomass under super dilute acid conditions. This work provided an example for the subsequent valorization of Cd-containing biomass and Cd recovery, which will greatly facilitate the development of phytoremediation of heavy metal contaminated soil.

Pyrolysis characteristics, kinetics, and biochar of fermented pine sawdust-based waste

The objective of current study is to explore the energy recovery potential of fermentation residues. In this perspective, pyrolysis characteristics, kinetics, and modified biochar derived from pine sawdust after fermentation (FPD) were determined, and comparison was established with pine sawdust (PD). The variation range of comprehensive pyrolysis index (CPI) values of FPD was found 6.51 × 10^-7-16.38 × 10^-7%²·min^-2·°C^-3, significantly higher than that of untreated samples determined under the same experimental conditions. The average activation energy of FPD was 367.95 kJ/mol, 389.45 kJ/mol, and 346.55 kJ/mol calculated by Flynn-Wall-Ozawa (FWO) method, Kissinger-Akahira-Sonuse (KAS), and Starink method respectively, and importantly, these values are much higher than those of PD. Additionally, fermentation could enhance the adsorption capacity for methylene blue of biochar from 0.76 mg/g to 1.6 mg/g due to the abundant surface functional groups and three-dimensional internal pore structure. The adsorption pattern of fermented pine wood shifted from chemisorption dominated to the synergetic adsorption of surface functional groups adsorption and intragranular filling. These results show that FPD has favorable pyrolytic properties, and the derived biochar has adsorption properties, which is the basis for designing pyrolysis process and reusing fermentation residues. HIGHLIGHTS: The FPD has higher values of CPI and activation energy than the PD. FPD-derived biochar has higher adsorption capacity than PD-derived biochar. The fermentation improves the pyrolysis performance. The fermentation enhances adsorption capacity due to unique structure of biochar.

Efficient Remediation of Cadmium Contamination in Soil by Functionalized Biochar: Recent Advances, Challenges, and Future Prospects

Heavy metal pollution in soil seriously harms human health and animal and plant growth. Among them, cadmium pollution is one of the most serious issues. As a promising remediation material for cadmium pollution in soil, functionalized biochar has attracted wide attention in the last decade. This paper summarizes the preparation technology of biochar, the existing forms of heavy metals in soil, the remediation mechanism of biochar for remediating cadmium contamination in soil, and the factors affecting the remediation process, and discusses the latest research advances of functionalized biochar for remediating cadmium contamination in soil. Finally, the challenges encountered by the implementation of biochar for remediating Cd contamination in soil are summarized, and the prospects in this field are highlighted for its expected industrial large-scale implementation.

Production of a bio-magnetic adsorbent via co-pyrolysis of pine wood waste and red mud

The efficient reduction of accumulated waste biomass and red mud by converting them into a value-added magnetic adsorbent is both difficult and tempting in terms of sustainability. This study focused on investigating the reaction mechanism of co-pyrolysis of different biomasses, including pine wood, cellulose, and lignin, with red mud at 500, 650, and 800 °C, and the comprehensive characterizations of the produced bio-magnetic particles. The performance of biomass and red mud based magnetic adsorbents is also evaluated, and their primary adsorption mechanisms for organic pollutants are revealed by using different organic model compounds. The samples produced at 800 °C showed the best performance. For example, the sample prepared using red mud and pine wood at 800 °C showed the highest adsorption capacity of ibuprofen, which was 21.01 mg/g at ∼pH 4.5, indicating strong π stacking interactions as the dominant adsorption mechanism. When compared to lignin-rich biomass, adsorbents composed of cellulose-rich biomass showed greater adsorption efficacy. The findings show that co-pyrolysis of biomass with red mud can reduce waste while also producing a flexible adsorbent that is magnetically separable and effective at absorbing different organic contaminants from water.

Modified Biochars and Their Effects on Soil Quality: A Review

Biochar (BC) has attracted attention due to its impacts on soil quality by enhancing soil fertility, carbon storage and contaminants immobilization. BC also induces changes in microbial community structure and enhances crop productivity in long term scenarios compared to many other organic amendments. However, information related to the role of modified BCs in altering the soil quality is still scarce. BC can be modified by using physical, chemical and microbial methods. Modified BC can change the functional groups, pore size, pore structure, surface area and chemical properties of soil, which plays a key role in changing the soil quality. The addition of modified BCs as soil amendment increased soil CEC (cation exchange capacity), EC (electron conductivity), pH, organic matter, hydraulic conductivity, soil porosity, infiltration rate, microbial activities (enzymes and community), nutrient profile and gas exchange properties, but it varies according to the soil structure and pervading environmental conditions. This study provides a basis for effective practical approaches to modifying BCs for improving soil quality.

The ion-imprinted oyster shell material for targeted removal of Cd(II) from aqueous solution

In order to realize the sustainable utilization of waste oyster shell and develop a targeted removal technology for cadmium. A novel ion-imprinted oyster shell material (IIOS) was prepared by surface imprinting technique. The prepared samples were characterized by scanning electron microscope, Fourier infrared spectrometer, X-ray diffractometer, thermogravimetric analysis and N₂ adsorption-desorption. The adsorption performances of IIOS for Cd(II) from aqueous solution were studied by the single factor sequential batch, kinetics, isotherms, selectivity and recycling experiments. The characterization researches showed that IIOS was successfully prepared. The adsorption experiments indicated that the adsorption process reached equilibrium within 240 min; the maximum adsorption capacity was up to 69.1 mg g^-1 with the initial Cd(II) concentration of 75 mg L^-1 at pH 5; the adsorption process fitted well to the pseudo-second-order model and the Langmuir isotherm model, which revealed the chemisorption characteristic of Cd(II). Moreover, IIOS exhibited a good targeted adsorption of Cd(II) in several binary competition systems owing to the present of these imprinted cavities. The recycling experiment showed that the targeted removal ratio of IIOS for Cd(II) remained above 80% after used six times. The results of this study indicated that it is a promising prospect for waste oyster shell used as IIOS to dispose heavy metals in wastewater.

Effects of fermented feed on growth performance, nutrient metabolism and cecal microflora of broilers

Objective

To investigate the effects of enzyme-bacteria co fermentated feed on broilers, the basal diet was pretreated by microbial enzyme co fermentation, and then different proportions of basal diet were replaced to study its effects on growth performance, nutrient metabolism and cecal microflora of broilers.

Methods

Four hundred and eighty 1-day-old broilers were randomly divided into 6 groups. The control group was fed with basal diet, and groups 1 to 4 were treated with fermented feed at 10%, 15%, 20% and 25% of the basal diet, and group 5 was treated with fermented wet feed instead of 10% of the basal diet, named BF, 10% DFF, 15% DFF, 20% DFF, 25% DFF, and 10% WFF, respectively. The trial period was 42 days.

Results

The results showed that the average daily feed intake and average daily gain of 10%DFF, 15%DFF and 10%WFF groups were significantly higher than those of the control group at 22-42 days and 1-42 days (P<0.05). Except for 10%DFF group, Firmicutes of all treatment were higher than that of control group. The Bacteroides of each treatment group were lower than that of the control group (P>0.05). At the same time, the nutrient apparent metabolic rate and cecal microbial abundance of each treatment group had an increasing trend (P>0.05).

Conclusion

In conclusion, the feed fermented by enzyme and bacteria had a potential promoting effect on the growth performance and nutrient digestibility of broilers.