Characterization of ultraviolet-modified biochar from different feedstocks for enhanced removal of hexavalent chromium from water

The Immobilization of a Cyclodipeptide Synthase Enables Biocatalysis for Cyclodipeptide Production

Cyclodipeptide synthases (CDPSs) are enzymes that use aminoacylated tRNAs as substrates to produce cyclic dipeptide natural products acting as anticancer and neuroprotective compounds. Many CDPSs, however, suffer from instability and poor recyclability, while enzyme immobilization can enhance catalyst efficiency and reuse. Here, the CDPS enzyme from Parcubacteria bacterium RAAC4_OD1_1 was immobilized using three different supports: biochar from waste materials, calcium-alginate beads, and chitosan beads. Immobilization of active PbCDPS was successful, and production of the cyclodipeptide cyclo (His-Glu) (cHE) was confirmed by HPLC-MS. Biochar from spent coffee activated with glutaraldehyde, alginate beads, and chitosan beads activated with glutaraldehyde led to a 5-fold improvement in cHE production, with the immobilized enzyme remaining active for seven consecutive cycles. Furthermore, we co-immobilized three enzymes participating in the cascade reaction yielding cHE (PbCDPS, histidyl-tRNA synthetase, and glutamyl-tRNA synthetase). The enzymatic cascade successfully produced the cyclic dipeptide, underscoring the potential of immobilizing various enzymes within a single support. Importantly, we demonstrated that tRNAs remained free in solution and were not adsorbed by the beads. We paved the way for the immobilization of enzymes that utilize tRNAs and other complex substrates, thereby expanding the range of reactions that can be exploited by using this technology.

Study on improvement of copper sulfide acid soil properties and mechanism of metal ion fixation based on Fe-biochar composite

In this study, Fe modification of bamboo biochar (BC) with ferrate was used to construct a composite soil amendment based on K2FeO4-biochar (Fe-BC) system. Based on soil culture experiments, Fe-BC combined with organic-inorganic materials at the application levels of 3%, 5% and 10% to copper sulfide contaminated acid soil was studied. Adsorption kinetics experiment was used to investigate the adsorption capacity of Fe-modified biochar to heavy metal Cu. The results showed that the pH value of bamboo biochar could be increased by 1.12 units after K2FeO4 modification. Compared with the BC, the adsorption capacity of Cu2+ increased from 190.48 to 276.12 mg/g, which was mainly reflected in single-layer surface adsorption and chemisorption. Pore diffusion, electrostatic interaction and surface interaction are the possible mechanisms of Fe-BC interaction with Cu2+ ions. And the contents of Pb, Cu and Zn in soil leaching state decreased by 59.20%, 65.88% and 57.88%, respectively, at the 10% application level of Fe-BC. In general, the composite modifier based on ferrate and biochar has a positive effect on improving the characteristics of acidic soil in copper mining area.

Advances on tailored biochar for bioremediation of antibiotics, pesticides and polycyclic aromatic hydrocarbon pollutants from aqueous and solid phases

Biochar is gaining incredible importance for remediation applications due to their attractive removal properties. Moreover, it is becoming ecofriendly, cost-effective and sustainable bioadsorbents towards replacing expensive activated carbons. Studies reveal biochar effectiveness for removal of important and potentially severe organic pollutants such as antibiotics and pesticides. Recent research advancements on biochar modification (physical, chemical and biological) opens greater opportunity to form tailored biochar with improved surface properties than their native forms for offering better removal efficiencies. Further attentions paid towards emergent new modification methods to cover broad-spectrum pollutants using tailored biochar. Current review aims to summarize recent updates upon biochar tailoring, comparative account of tailored biochars removal efficiencies with respect to their native forms and to provide in-depth discussion covering specific interactions of tailored biochars with antibiotics, polycyclic aromatic hydrocarbons (PAHs) and pesticides for their effective removals and degradation from polluted environments. Application of inducer compounds e.g., peroxymonosulfate and sodium percarbonate further improved the biochar role towards degradation of toxic organic pollutants into their less or nontoxic forms. Biochar engineered with specific metals enable them for the same role without inducer compounds. Moreover, microbial interactions with biochar not only improve the bioremediation level further but also degrade the pollutants from the environment and open up better environmental and socio-economic prospects. Application of green, cost-effective and sustainable biochar for remediation of environmentally potential organic pollutants offers economical treatment methods as well as safe environment. These benefits are inline with global trends towards developing a sustainable process for biocircular economy.

Study on the regulation mechanism of cadmium adsorption system mediated by extraneous dissolved organic matter

Adsorption of biochar on heavy metals is one of the hot spots in the application of biochar. However, the mediation of existing extraneous substances in the environment, such as dissolved organic matter (DOM), could regulate and affect the heavy metals adsorption process on biochar. In our study, we mainly focus on the regulation mechanism of modified biochar on the adsorption process of cadmium mediated by exogenous DOM. The modification significantly changed the functional groups composition on biochar, thus improving the adsorption capacity of cadmium on biochar. In the adsorption system concerned, the combination was formed between DOM and cadmium to a certain extent. The combination had a certain correlation with the influence on the adsorption capacity of cadmium onto biochar in the system.

Bioengineered biochar as smart candidate for resource recovery toward circular bio-economy: a review

Biochar's ability to mediate and facilitate microbial contamination degradation, as well as its carbon-sequestration potential, has sparked interest in recent years. The scope, possible advantages (economic and environmental), and future views are all evaluated in this review. We go over the many designed processes that are taking place and show why it is critical to look into biochar production for resource recovery and the role of bioengineered biochar in waste recycling. We concentrate on current breakthroughs in the fields of engineered biochar application techniques to systematically and sustainable technology. As a result, this paper describes the use of biomass for biochar production using various methods, as well as its use as an effective inclusion material to increase performance. The impact of biochar amendments on microbial colonisation, direct interspecies electron transfer, organic load minimization, and buffering maintenance is explored in detail. The majority of organic and inorganic (heavy metals) contaminants in the environment today are caused by human activities, such as mining and the use of chemical fertilizers and pesticides, which can be treated sustainably by using engineered biochar to promote the establishment of a sustainable engineered process by inducing the circular bioeconomy.

Recent advances in biochar engineering for soil contaminated with complex chemical mixtures: Remediation strategies and future perspectives

Heavy metal/metalloids (HMs) and polycyclic aromatic hydrocarbons (PAHs) in soil have caused serious environmental problems, compromised agriculture quality, and have detrimental effects on all forms of life including humans. There is a need to develop appropriate and effective remediation methods to resolve combined contaminated problems. Although conventional technologies exist to tackle contaminated soils, application of biochar as an effective renewable adsorbent for enhanced bioremediation is considered by many scientific researchers as a promising strategy to mitigate HM/PAH co-contaminated soils. This review aims to: (i) provide an overview of biochar preparation and its application, and (ii) critically discuss and examine the prospects of (bio)engineered biochar for enhancing HMs/PAHs co-remediation efficacy by reducing their mobility and bioavailability. The adsorption effectiveness of a biochar largely depends on the type of biomass material, carbonisation method and pyrolysis conditions. Biochar induced soil immobilise and remove metal ions via various mechanisms including electrostatic attractions, ion exchange, complexation and precipitation. PAHs remediation mechanisms are achieved via pore filling, hydrophobic effect, electrostatic attraction, hydrogen bond and partitioning. During last decade, biochar engineering (modification) via biological and chemical approaches to enhance contaminant removal efficiency has garnered greater interests. Hence, the development and application of (bio)engineered biochars in risk management, contaminant management associated with HM/PAH co-contaminated soil. In terms of (bio)engineered biochar, we review the prospects of amalgamating biochar with hydrogel, digestate and bioaugmentation to produce biochar composites.

Effects of UV-modified biochar derived from phytoremediation residue on Cd bioavailability and uptake in Coriandrum sativum L. in a Cd-contaminated soil

Biochar has been applied widely as an amendment in the remediation of contaminated soil to immobilize the heavy metals. However, the role of ultraviolet (UV) irradiation modified biochar derived from the residues of phytoremediation plants in the contaminated soil not investigated yet. In this study, the UV-modified biochars were obtained from Brassica napus L. and Lolium perenne L. by pyrolysis at 600 °C. They were applied in a pot experiment to investigate their effect on Cd bioavailability and uptake in Coriandrum sativum L. in a Cd-contaminated soil at four addition rate (0%, 0.2%, 0.4%, and 0.6%). The results showed that the Cd was effectively stabilized in the biochar with environmentally acceptable leaching toxicity. The specific surface area and carboxyl functional group of biochar were greatly increased after UV modification. The application of biochar progressively increased the soil pH and electrical conductivity (EC). Furthermore, the CaCl₂-extractable Cd was significantly reduced by 18.4-51.4% with biochar amendments. The concentration of Cd in shoots and roots was significantly reduced by biochars. In conclusion, the UV-modified biochar obtained from phytoremediation residue could effectively deal with hazardous waste and repair Cd-contaminated soil.