Removal of inorganic toxic contaminants from wastewater using sustainable biomass: A review

Optimizing hydrogen gas production from genetically modified rice straw by steam co-gasification

Future sustainability visions include clean, renewable energy from hydrogen, which can be produced, among other ways, by biomass steam gasification. This study explores strategies addressing the limitations in steam co-gasification of herbaceous biomass, using Monster-TUAT1 rice straw, a genetically modified rice plant with a taller and bigger stalk developed by Tokyo University of Agriculture and Technology (TUAT), and Giant Miscanthus, a promising energy crop, as the feedstock. Firstly, compared with the typical rice straw, the Monster TUAT1 demonstrated superior steam gasification performance with a 1.75 times higher hydrogen gas yield and 27.0 % less tar generation. With a focus on overcoming the challenges posed by high silica content in the Monster TUAT1, co-gasification of it with an energy crop of Giant Miscanthus was performed. However, even under the optimum operation condition (750 °C, steam flowrate: 0.15 g/min), the hydrogen gas yield was only 29.3 mmol/g-C with a tar yield of 27.6 %wt. and a carbon conversion efficiency of 45.9 %, which is deemed unsatisfactory for hydrogen production. Thus, strategies for enhancement were proposed, including the incorporation seaweed biochar with high alkali and alkaline earth species, calcined scallop shell powder, and alkali metal salt into the gasifier. Consequently, the introduction of 10 %wt. of calcined scallop shell resulted in an increase in H2 yield to 37.0 mmol/g-C and 24.3 % CO2 reduction. The addition of alkali metal salt led to 43.9 % increase of H2 product with a 15 %wt. tar yield. The most significant improvement occurred with the introduction of seaweed biochar at 50 %wt., increasing of the hydrogen gas yield to 62.0 mmol/g-C with 86 % of carbon conversion efficiency and tar reduction to 5.5 %. These findings demonstrate the viability of utilizing herbaceous biomass such as rice straw in conjunction with the strategic solutions of co-gasification to overcome constraints in improving hydrogen production.

Development of hybrid biomicroparticles: cellulose exposing functionalized fusion proteins

BACKGROUND

One of the leading current trends in technology is the miniaturization of devices to the microscale and nanoscale. The highly advanced approaches are based on biological systems, subjected to bioengineering using chemical, enzymatic and recombinant methods. Here we have utilised the biological affinity towards cellulose of the cellulose binding domain (CBD) fused with recombinant proteins.

RESULTS

Here we focused on fusions with 'artificial', concatemeric proteins with preprogrammed functions, constructed using DNA FACE™ technology. Such CBD fusions can be efficiently attached to micro-/nanocellulose to form functional, hybrid bionanoparticles. Microcellulose (MCC) particles were generated by a novel approach to enzymatic hydrolysis using Aspergillus sp. cellulase. The interaction between the constructs components - MCC, CBD and fused concatemeric proteins - was evaluated. Obtaining of hybrid biomicroparticles of a natural cellulose biocarrier with proteins with therapeutic properties, fused with CBD, was confirmed. Further, biological tests on the hybrid bioMCC particles confirmed the lack of their cytotoxicity on 46BR.1 N fibroblasts and human adipose derived stem cells (ASCs). The XTT analysis showed a slight inhibition of the proliferation of 46BR.1 N fibroblasts and ACSs cells stimulated with the hybrid biomicroparticles. However, in both cases no changes in the morphology of the examined cells after incubation with the hybrid biomicroparticles' MCC were detected.

CONCLUSIONS

Microcellulose display with recombinant proteins involves utilizing cellulose, a natural polymer found in plants, as a platform for presenting or displaying proteins. This approach harnesses the structural properties of cellulose to express or exhibit various recombinant proteins on its surface. It offers a novel method for protein expression, presentation, or immobilization, enabling various applications in biotechnology, biomedicine, and other fields. Microcellulose shows promise in biomedical fields for wound healing materials, drug delivery systems, tissue engineering scaffolds, and as a component in bio-sensors due to its biocompatibility and structural properties.

Hydrolyzed sewage sludge as raw bio-based material for hermetic bag production

This study aimed to assess the potential of sewage sludge, a significant residue of wastewater treatment plants (WWTPs), as a sustainable resource for producing a bio-based material for hermetic bags (BMHB), in order to reduce the dependency on petroleum-derived plastics. The approach involved the application of thermal hydrolysis to solubilize sewage sludge, and it systematically examined critical process parameters, including temperature (120-150 °C), residence time (1-4 h), and medium pH (6.6-10). Results revealed that alkaline thermal hydrolysis significantly enhanced biomolecule solubilization, particularly proteins (289 ± 1 mg/gVSSo), followed by humic-like substances (144 ± 6 mg/gVSSo) and carbohydrates (49 ± 2 mg/gVSSo). This condition also increased the presence of large-and medium-sized compounds, thereby enhancing BMHB mechanical resistance, with puncture resistance values reaching 63.7 ± 0.2 N/mm. Effective retention of UV light within the 280-400 nm range was also observed. All BMHB samples exhibited similar properties, including water vapor permeability (WVP) (∼3.9 g * mm/m2 * h * kPa), hydrophilicity (contact angles varied from 35.4° ± 0.3 to 64° ± 5), solubility (∼95%), and thermal stability (∼74% degradation at 700 °C). Notably, BMHB proved to be an eco-friendly packaging for acetamiprid, an agricultural pesticide, preventing direct human exposure to harmful substances. Testing indicated rapid pesticide release within 5 min of BMHB immersion in water, with only 5% of BMHB residues remaining after 20 min. Additionally, the application of this material in soil was considered safe, as it met regulatory limits for heavy metal content and exhibited an absence of microorganisms.

Fixed-bed column adsorption modeling using Zr biocomposites for fluoride removal

This research involved conducting continuous adsorption experiments to assess fluoride elimination from drinking water achieved by utilizing biocomposites created from the peels of oranges and apples, which were impregnated with zirconium (Zr), to form BOP-Zr and BAP-Zr, respectively. The findings from the experimental data indicate that BOP-Zr and BAP-Zr are effective biosorbents with a solid ability to remove fluoride selectively. Additionally, these biosorbents were found to be stable, as they do not release Zr into the treated water. Notably, these environmentally friendly biosorbents are derived from renewable sources and enhance the value of waste materials. The study employed various empirical models, including Bohart-Adamas, Thomas, Yoon-Nelson, BDST, Clark, Yan, and Woolborska, to elucidate the mechanisms and crucial parameters involved in fluoride adsorption within packed bed columns. The Yan model demonstrated the highest correlation among these models, indicating a chemical adsorption process with kinetics following a pseudo-second-order pattern. BOP-Zr and BAP-Zr exhibited a maximum adsorption capacity of 59.3 and 47.5 mg/g, respectively, under a flow rate of 4 mL/min and an inlet fluoride concentration of 25 mg/L. The analysis of mass transfer coefficients revealed that the primary step governing the adsorption procedure was diffusion through pores. Consequently, the study conclusively establishes that BOP-Zr and BAP-Zr biocomposites, originating from lignocellulosic biomass remains, present a practical and competitive choice for eliminating fluoride from water. These materials surpass waste materials in performance and rival more expensive options in efficiency and performance.

Gum arabic-assisted green synthesis of biocompatible MoS2 nanoparticles for methylene blue photodegradation

The current work reports the gum arabic-mediated greener synthesis of MoS2 nanoparticles (NPs) and its utilization for the solar light-assisted degradation of methylene blue. Furthermore, the safety analyses were performed on human-beneficial gut bacterium, L. delbrueckii, and human blood cells to confirm the biocompatibility of NPs synthesized. Antioxidant and antimicrobial activities were done to explore their usefulness for biological applications. Sonication and microwave treatment were used to obtain spherical 10-12 nm MoS2 NPs as characterized using high-resolution transmission electron microscopy. FT-IR characterization revealed the occurrence of gum arabic on the NPs surface. The MoS2 NPs exhibited ~ 98% MB degradation within 8 h under direct sunlight exposure. Moreover, the reusability studies have also been evaluated and free radical trapping experiments indicated that superoxide (•O2-) is the dominant active species of the reaction system. Furthermore, 98.89% MB degradation efficiency was observed within 150 min in the case of real textile industry MB effluent samples. Untreated MB inhibited the growth of L. delbrueckii on MRS agar plates, while growth was observed in the case of MoS2 NPs-treated MB samples indicating safety of current MB degradation approach. MoS2 NPs inhibited the growth of E. coli MTCC1698 and S. aureus MTCC 3160 with 26 mm and 21 mm zone of inhibition, respectively. Furthermore, MoS2 NPs have shown antioxidant properties, resulting in 82.3 ± 0.43% of DPPH scavenging activity which was comparable to ascorbic acid (81.6 ± 0.6%), a standard antioxidant molecule. The NPs have not shown any hemolytic activity at 0.0625 and 0.125 mg/mL doses to human blood proving their biocompatible nature. Gum arabic-synthesized biocompatible MoS2 NPs have good potential to treat MB released as waste from the textile industry and other biological applications.

Remediation of water tainted with noxious aspirin and fluoride ion using UiO-66-NH2 loaded peanut shell

One green adsorbent, UiO-66-NH2 modified peanut shell (c-PS-MOF), was prepared in a green synthetic route for improving the capture level of aspirin (ASP) and fluoride ion (F-). The adsorption properties of c-PS-MOF were evaluated by batch experiments and its physicochemical properties were explored by various characterization methods. The results showed that c-PS-MOF exhibited a wide range of pH applications (ASP: 2-10; F-: 3-12) and high salt resistance in the capturing processes of ASP and F-. The unit adsorption capacity of c-PS-MOF was as high as 84.7 mg·g-1 for ASP as pH = 3 and 11.2 mg·g-1 for F- under pH = 6 at 303 K from Langmuir model, respectively. When the solid-liquid ratio was 2 g·L-1, the content of ASP (C0 = 100 mg·L-1) and F- (C0 = 20 mg·L-1) in solution can be reduced to 0.48 mg·L-1 and 1.05 mg·L-1 separately. The recycling of c-PS-MOF can be realized with 5 mmol·L-1 NaOH as eluent. Analysis of simulated water samples showed that c-PS-MOF could be used to remove ASP and F- from actual water. The c-PS-MOF is promising to bind ASP and F- from rivers, lakes, etc.

Amino-functionalization of lignocellulosic biopolymer to be used as a green and sustainable adsorbent for anionic contaminant removal

In this work, natural biopolymer stemming from lignocellulosic peanut hull biomass was used as a green and low-cost adsorbent to eliminate anionic Congo red (CR) and Cr(VI) ions from aqueous sample. In order to enhance the removal performance, the lignocellulosic biopolymer was subjected to amino-modification by the graft copolymerization of (3-acrylamidopropyl) trimethylammonium chloride and N, N'-methylenebisacrylamide. The property of the prepared amino-functionalized biopolymer (AFB) was examined through FTIR, TG, SEM, particle size analysis, zeta potential determination and XPS. The adsorption efficacy of AFB for CR and Cr(VI) was tested at different pH, contact time and initial concentration. The kinetic, isotherm and thermodynamics investigations revealed that the uptakes of CR and Cr(VI) were the combination processes of chemical and physical interactions, and both endothermic in nature. The AFB exhibited good reusability without significant loss in adsorption capacity after five consecutive cycles. Mechanistic analysis indicated that the quaternary ammonium groups in AFB contributed a lot to the binding of anionic compounds through electrostatic attraction. In addition, n-π and hydrogen bonding while reduction and coordination were also responsible for the removal of CR and Cr(VI), respectively. The present study provides a favorable strategy for the removal of anionic contaminates in water by using green and sustainable lignocellulosic wastes.

Lignocellulosic Biomass as Sorbent for Fluoride Removal in Drinking Water

Water supply to millions of people worldwide is of alarmingly poor quality. Supply sources are depleting, whereas demand is increasing. Health problems associated with water consumption exceeding 1.5 mg/L of fluoride are a severe concern for the World Health Organization (WHO). Therefore, it is urgent to research and develop new technologies and innovative materials to achieve partial fluoride reduction in water intended for human consumption. The new alternative technologies must be environmentally friendly and be able to remove fluoride at the lowest possible costs. So, the use of waste from lignocellulosic biomasses provides a promising alternative to commercially inorganic-based adsorbents-published studies present bioadsorbent materials competing with conventional inorganic-based adsorbents satisfactorily. However, it is still necessary to improve the modification methods to enhance the adsorption capacity and selectivity, as well as the reuse cycles of these bioadsorbents.

Magnetite Metal-Organic Frameworks: Applications in Environmental Remediation of Heavy Metals, Organic Contaminants, and Other Pollutants

Due to the increasing environmental pollution caused by human activities, environmental remediation has become an important subject for humans and environmental safety. The quest for beneficial pathways to remove organic and inorganic contaminants has been the theme of considerable investigations in the past decade. The easy and quick separation made magnetic solid-phase extraction (MSPE) a popular method for the removal of different pollutants from the environment. Metal-organic frameworks (MOFs) are a class of porous materials best known for their ultrahigh porosity. Moreover, these materials can be easily modified with useful ligands and form various composites with varying characteristics, thus rendering them an ideal candidate as adsorbing agents for MSPE. Herein, research on MSPE, encompassing MOFs as sorbents and Fe₃O₄ as a magnetic component, is surveyed for environmental applications. Initially, assorted pollutants and their threats to human and environmental safety are introduced with a brief introduction to MOFs and MSPE. Subsequently, the deployment of magnetic MOFs (MMOFs) as sorbents for the removal of various organic and inorganic pollutants from the environment is deliberated, encompassing the outlooks and perspectives of this field.

Fabrication and characterization of magnetic nanomaterials for the removal of toxic pollutants from water environment: A review

The success of any sustainable growth represents an advancement of novel approaches and new methodologies for managing any ecological concern. Magnetic nanoparticles have gained recent interest owing to their versatile properties such as controlled size, shape, quantum and surface effect, etc, and outcome in wastewater treatment and pollutant removal. Developments have progressed in synthesizing magnetic nanoparticles with the required size, shape and morphology, surface and chemical composition. Magnetic nanoparticles are target specific and inexpensive compared to conventional treatment techniques. This review insight into the synthesis of magnetic nanoparticles using physical, chemical, and biological methods. The biological method of synthesizing magnetic nanoparticles serves to be cost-effective, green process, and eco-friendly for various applications. Characterization studies of synthesized nanoparticles using TEM, XRD, SARS, SANS, DLS, etc are discussed in detail. Magnetic nanoparticles are widely utilized in recent research for removing organic and inorganic contaminants. It was found that the magnetic nanosorption approach together with redox reactions proves to be an effective and flexible mechanism for the removal of pollutants from waste effluents.

Utilization of Phyllanthus emblica fruit stone as a Potential Biomaterial for Sustainable Remediation of Lead and Cadmium Ions from Aqueous Solutions

In the present work, an effort has been made to utilize Phyllanthus emblica (PE) fruit stone as a potential biomaterial for the sustainable remediation of noxious heavy metals viz. Pb(II) and Cd(II) from the aqueous solution using adsorption methodology. Further, to elucidate the adsorption potential of Phyllanthus emblica fruit stone (PEFS), effective parameters, such as contact time, initial metal concentration, temperature, etc., were investigated and optimized using a simple batch adsorption method. It was observed that 80% removal for both the heavy metal ions was carried out within 60 min of contact time at an optimized pH 6. Moreover, the thermodynamic parameters results indicated that the adsorption process in the present study was endothermic, spontaneous, and feasible in nature. The positive value of entropy further reflects the high adsorbent-adsorbate interaction. Thus, based on the findings obtained, it can be concluded that the biosorbent may be considered a potential material for the remediation of these noxious impurities and can further be applied or extrapolated to other impurities.