Design of a sustainable system for wastewater treatment and generation of biofuels based on the biomass of the aquatic plant Eichhornia Crassipes.

Colombia's continuous contamination of water resources and the low alternatives to produce biofuels have affected the fulfillment of the objectives of sustainable development, deteriorating the environment and affecting the economic productivity of this country. Due to this reality, projects on environmental and economic sustainability, phytoremediation, and the production of biofuels such as ethanol and hydrogen were combined. The objective of this article was to design and develop a sustainable system for wastewater treatment and the generation of biofuels based on the biomass of the aquatic plant Eichhornia crassipes. A system that simulates an artificial wetland with live E. crassipes plants was designed and developed, removing organic matter contaminants; subsequently, and continuing the sustainability project, bioreactors were designed, adapted, and started up to produce bioethanol and biohydrogen with the hydrolyzed biomass used in the phytoremediation process, generating around 12 g/L of bioethanol and around 81 ml H2/g. The proposed research strategy suggests combining two sustainable methods, bioremediation and biofuel production, to preserve the natural beauty of water systems and their surroundings.

Alien emergent aquatic plants develop better ciprofloxacin tolerance and metabolic capacity than one native submerged species.

Antibiotic pollution and biological invasion pose significant risks to freshwater biodiversity and ecosystem health. However, few studies have compared the ecological adaptability and ciprofloxacin (CIPR) degradation potential between alien and native macrophytes. We examined growth, physiological response, and CIPR accumulation, translocation and metabolic abilities of two alien plants (Eichhornia crassipes and Myriophyllum aquaticum) and one native submerged species (Vallisneria natans) exposed to CIPR at 0, 1 and 10 mg/L. We found that E. crassipes and M. aquaticum's growth were unaffected by CIPR while V. natans was significantly hindered under the 10 mg/L treatment. CIPR significantly decreased the maximal quantum yield of PSII, actual quantum yield of PSII and relative electron transfer rate in E. crassipes and V. natans but didn't impact these photosynthetic characteristics in M. aquaticum. All the plants can accumulate, translocate and metabolize CIPR. M. aquaticum and E. crassipes in the 10 mg/L treatment group showed greater CIPR accumulation potential than V. natans indicated by higher CIPR contents in their roots. The oxidative cleavage of the piperazine ring acts as a key pathway for these aquatic plants to metabolize CIPR and the metabolites mainly distributed in plant roots. M. aquaticum and E. crassipes showed a higher production of CIPR metabolites compared to V. natans, with M. aquaticum exhibiting the strongest CIPR metabolic ability, as indicated by the most extensive structural breakdown of CIPR and the largest number of potential metabolic pathways. Taken together, alien species outperformed the native species in ecological adaptability, CIPR accumulation and metabolic capacity. These findings may shed light on the successful invasion mechanisms of alien aquatic species under antibiotic pressure and highlight the potential ecological impacts of alien species, particularly M. aquaticum. Additionally, the interaction of antibiotic contamination and invasion might further challenge the native submerged macrophytes and pose greater risks to freshwater ecosystems.

Sorption capacity of Eichhornia crassipes (Mart.) Solms for zinc removal from electroplating industry wastewater.

Various industrial operations in the dye, fertilizer, pesticide, battery, mining, and chemical industries have been associated with releasing heavy metals in wastewater, such as lead, zinc, copper, arsenic, cadmium, chromium, nickel, and mercury. These metals are dangerous to aquatic life as well as to humans, who may consume them directly or indirectly. Therefore, before being released into open water and land resources, it is necessary to minimize the concentration of toxic ions below the discharge limit. This study used Eichhornia crassipes (Mart.) Solms to remove zinc from wastewater from the electroplating industry in a constructed wetland. Experimental investigations were conducted for removing zinc ions from electroplating industry wastewater using various process parameters such as nutrient dosages, dilution ratios, potential of hydrogen ions, biomasses, and contact times. The outcome of this study revealed that the maximum zinc removal percentage in electroplating industrial wastewater was found for the optimum nutrient dosages of 60 g, dilution ratios of 10, potential hydrogen ion levels of 8, and biomass amounts of 100 g. The maximum zinc removal by Eichhornia crassipes (Mart.) Solms was found to be 88.3 ± 0.6 and 93.4 ± 0.4% at the optimum parameter values for the electroplating industry wastewater and the aqueous solution, respectively, against the optimum contact time of 22 days. This study suggests using this phytoremediation technology to remove all pollutants from industrial wastewater in general, not just wastewater from the electroplating industry.

Silane and fluorine free facile hydrophobicization of water hyacinth biomass for oil-water separations.

As the adverse effects of using plastics and perfluorinated alkyl substances become more apparent, there is a growing need for sustainable hydrophobic products. Cellulose and its derivatives are the most abundant and widely used polymers, and cellulose-based products have great potential in industries where plastics and other hydrophobic polymers are used, such as stain-resistant fabrics, food packaging, and oil-water separation applications. In this study, we extracted cellulose from water hyacinth (WH) biomass, known for its negative environmental impact, and converted it into hydrophobic cellulose. This addresses the issue of managing WH waste and creating an environmentally friendly hydrophobic material. Initially, aldehyde groups were introduced through oxidation with periodate, followed by direct octadecyl amine (ODA) grafting onto dialdehyde cellulose (DAC) via a Schiff base condensation. The resulting ODA modified cellulose (ODA-C) was dispersed in ethanol and used to coat various materials, including cotton fabric, cellulose filter paper, and packaging paper. The modified materials showed excellent hydrophobicity as measured by their water contact angles (WCAs), and the application of the coating was demonstrated for oil-water separation, stain-resistant hydrophobic fabric, and paper-based packaging materials. FTIR, XRD, and WCA analysis confirmed the successful modification of cellulose. A high separation efficiency of 99% was achieved for diesel/water separation using modified filter paper (MoFP), under gravity. On application of the coating, cotton fabric became hydrophobic and resisted staining from dye, and paper-based packaging materials became more robust by becoming water-resistant. Overall, the facile synthesis, low cost, high efficiency, and use of environmentally friendly sustainable materials make this a promising strategy for hydrophobically modifying surfaces for a wide range of applications while reducing the menace of water hyacinth.

Removal of perfluoroalkyl acids (PFAAs) from aqueous solution by water hyacinth (Eichhornia crassipes): Uptake, accumulation, and translocation.

Although Eichhornia crassipes, commonly known as water hyacinth, has been widely used in wastewater treatment, further investigations are still needed to explore the removal efficiency of perfluoroalkyl acids (PFAAs) from the aqueous environment using this floating aquatic plant. In this study, a hydroponic experiment was conducted to assess accumulation, bioconcentration factors (BCFs), translocation factors (TFs), and removal rates of eight PFAAs by water hyacinth. The obtained results indicated that all PFAAs, including five perfluoroalkyl carboxylic acids (PFCAs) with chain lengths C4-C8 and three perfluoroalkyl sulfonic acids (PFSAs) with C4, C6, and C8, were readily accumulated in water hyacinth. Throughout the duration of the experiment, there was a noticeable increase in PFAA concentrations and BCF values for different plant parts. For the root, PFAAs with more carbon numbers showed a higher uptake than the shorter homologues, with PFSAs being more readily accumulated compared to PFCAs with the same carbon number in the molecules. In contrast, the levels of long-chain PFAAs were comparatively lower than those of short-chain substances in the stem and leaf. Notably, PFAAs with less carbon numbers, like PFPeA, PFBA, and PFBS, showed a remarkable translocation from the root to the stem and leaf with TFs >1. For the whole plant, no significant correlation was found between BCFs and organic carbon-water partition coefficients (Koc), octanol-water partition coefficients (Kow), membrane-water distribution coefficients (Dmw), or protein-water distribution coefficients (Dpw). The removal rates of PFAAs ranged from 40.3 to 63.5 % throughout the three weeks of the experiment while the removal efficiencies varied from 48.9 % for PFHxS to 82.6 % for PFPeA in the last week.

Assembly and comparative analysis of the first complete mitochondrial genome of the invasive water hyacinth, Eichhornia crassipes.

Eichhornia crassipes is an aquatic plant in tropical and subtropical regions, renowned for its notorious invasive tendencies. In this study, we assembled the complete mitogenome of E. crassipes into a single circle molecule of 397,361 bp. The mitogenome has 58 unique genes, including 37 protein-coding genes (PCGs), 18 tRNA genes, three rRNA genes, and 47 % GC content. Sixteen (6.93 %) homologous fragments, ranging from 31 bp to 8548 bp, were identified, indicating the transfer of genetic material from chloroplasts to mitochondria. In addition, we detected positive selection in six PCGs (ccmB, ccmC, ccmFC, nad3, nad4 and sdh4), along with the identification of 782 RNA editing sites across 37 mt-PCGs. These findings suggest a potential contribution to the robust adaptation of this invasive plant to the stressful environment. Lastly, we inferred that phylogenetic conflicts of E. crassipes between the plastome and mitogenome may be attributed to the difference in nucleotide substitution rates between the two organelle genomes. In conclusion, our study provided vital genomic resources for further understanding the invasive mechanism of this species and exploring the dynamic evolution of mitogenomes within the monocot clade.

Detoxification of water hyacinth hydrolysate mediated by exopolysaccharide-based hydrogel enhances hydrogen and methane production.

In this study, the exopolysaccharide from cyanobacteria was used for detoxification of acid hydrolysate of water hyacinth biomass. Exopolysaccharide-hydrogel showed phenolics and furans removal of 86 % and 97 %, respectively, with sugar recovery of 98.3 %. The fermentation of detoxified acid hydrolysate was integrated with that of pretreated biomass subjected to enzymatic saccharification derived from commercial cellulose (ESF) or from microbe (MSF). The maximum hydrogen production of 69.2 mL/g-VS was obtained in MSF, which is 1.2- and 1.6-fold higher than ESF and undetoxified acid hydrolysate, respectively. Additionally, the methane production of 12.6 mL/g-VS by mixed methanogenic consortia was obtained using the spent liquor containing volatile fatty acids. This enhanced hydrogen and methane production in subsequent microbial processes is mainly attributed to the selective removal of inhibitors in combination with an integrated carbohydrate utilization.

A reference genome of Commelinales provides insights into the commelinids evolution and global spread of water hyacinth (Pontederia crassipes).

Commelinales belongs to the commelinids clade, which also comprises Poales that includes the most important monocot species, such as rice, wheat, and maize. No reference genome of Commelinales is currently available. Water hyacinth (Pontederia crassipes or Eichhornia crassipes), a member of Commelinales, is one of the devastating aquatic weeds, although it is also grown as an ornamental and medical plant. Here, we present a chromosome-scale reference genome of the tetraploid water hyacinth with a total length of 1.22 Gb (over 95% of the estimated size) across 8 pseudochromosome pairs. With the representative genomes, we reconstructed a phylogeny of the commelinids, which supported Zingiberales and Commelinales being sister lineages of Arecales and shed lights on the controversial relationship of the orders. We also reconstructed ancestral karyotypes of the commelinids clade and confirmed the ancient commelinids genome having 8 chromosomes but not 5 as previously reported. Gene family analysis revealed contraction of disease-resistance genes during polyploidization of water hyacinth, likely a result of fitness requirement for its role as a weed. Genetic diversity analysis using 9 water hyacinth lines from 3 continents (South America, Asia, and Europe) revealed very closely related nuclear genomes and almost identical chloroplast genomes of the materials, as well as provided clues about the global dispersal of water hyacinth. The genomic resources of P. crassipes reported here contribute a crucial missing link of the commelinids species and offer novel insights into their phylogeny.

Combination of alkaline biodiesel-derived crude glycerol pretreated corn stover with dilute acid pretreated water hyacinth for highly-efficient single cell oil production by oleaginous yeast Cutaneotrichosporon oleaginosum.

Single cell oil (SCO) prepared from biodiesel-derived crude glycerol (BCG) and lignocellulosic biomass (LCB) via oleaginous yeasts is an intriguing alternative precursor of biodiesel. Here, a novel strategy combining alkaline BCG pretreated corn stover and dilute acid pretreated water hyacinth for SCO overproduction was developed. The mixed pretreatment liquors (MPLs) were naturally neutralized and adjusted to a proper carbon-to-nitrogen ratio beneficial for SCO overproduction by Cutaneotrichosporon oleaginosum. The toxicity of inhibitors was relieved by dilution detoxification. The enzymatic hydrolysate of solid fractions was suitable for SCO production either separately or simultaneously with MPLs. Fed-batch fermentation of the MPLs resulted in high cell mass, SCO content, and SCO titer of 80.7 g/L, 75.7 %, and 61.1 g/L, respectively. The fatty acid profiles of SCOs implied high-quality biodiesel characteristics. This study offers a novel BCG&LCB-to-SCO route integrating BCG-based pretreatment and BCG/LCB hydrolysates co-utilization, which provides a cost-effective technical route for micro-biodiesel production.

Biodiesel production potential of Eichhornia crassipes (Mart.) Solms: comparison of collection sites and different alcohol transesterifications.

Renewable resources have stood out as raw materials in producing biofuels. This study aimed to evaluate the parameters of alcohol transesterification (ethanol and methanol) and localization of collection of aquatic macrophyte Eichhornia crassipes (Mart.) Solms in the production of biodiesel by in situ transesterification. E. crassipes was collected in Dourados and Corumbá (Brazil) municipalities. The fatty acid ester composition of the biodiesel was characterized and quantified by gas chromatography. The biodiesel properties were estimated using the BiodieselAnalyzer© program prediction. The ethyl transesterification resulted in higher yields, but the localization of collection was the most relevant parameter in biodiesel production according to the Permutation Multivariate Analysis of Variance. The simulation and comparison of the physical-chemical properties of E. crassipes biodiesel and BD 100 (commercial biodiesel) were promising for commercial application.

Efficient degradation of antibiotic wastewater by biochar derived from water hyacinth stems via periodate activation: pyridinic N and carbon structures improved the electron transfer process.

Biochar-activated periodate (PI) is a promising technology toward antibiotic wastewater purification. However, the mechanism of pyrolysis temperature on PI activation efficiency by biochar has not yet been revealed. Herein, this work selected water hyacinth stems as raw materials to prepare biochar with different pyrolysis temperatures (400, 500, 600, and 700 °C), and applied it to degrade tetracycline (TC) wastewater through PI activation. The results show that biochar with a pyrolysis temperature of 700 °C (BC-700) possesses the best TC degradation performance (∼100% within 30 min). Besides, the degradation of TC by BC-700 is less interfered by coexisting anions and water matrix, and exhibits good reusability. Quenching experiments and open circuit voltage tests verified that IO3•, 1O2, and reactive complex BC-PI* are active species involved in TC degradation. In addition, by constructing the relationship between biochar surface properties and degradation rate kobs, it was revealed that the dominant role of pyridinic N in PI adsorption and formation of reactive complexes as well as the promotion of sp2-hybridized carbon in the electron transfer process. This work provides novel insights into the application of biochar in antibiotic wastewater treatment via PI activation.

Insights of phytoremediation mechanisms for viruses based on in-vitro, in-vivo and in-silico assessments of selected herbal plants.

Waterborne pathogenic viruses present unrelenting challenges to the global health and wastewater treatment industry. Phytoremediation offers promising solutions for wastewater treatment through plant-based technologies. This study investigated antiviral mechanisms in-vivo using bacteriophages MS2 and T4 as surrogates for effective herbs screened in-vitro from three embryophytes (Ocimum basilicum, Mentha sp., Plectranthus amboinicus), two macrophytes (Eichhornia crassipes, Pistia stratiotes) and a perennial grass (Cyperus rotundas). In-silico virtual screening predicted antiviral phytochemicals for further antiviral potency assessment. Results suggested in-vitro antiviral activities of embryophytes and macrophytes were higher (43-62%) than grass (21-26%). O. basilicum (OB, 57-62%) and P. stratiotes (PS, 59-60%) exhibited the highest antiviral activities. In-vivo tests showed notable virus reduction (>60%) in culture solution, attributed to rhizofiltration (66-74%) and phytoinactivation/phytodegradation (63-84%). In-silico analysis identified rutin as a primary antiviral phytochemical for MS2 (-9.7 kcal/mol) and T4 (-10.9 kcal/mol), correlating with dose-response inactivation (∼58-62%). In-vivo tests suggested additional phytocompounds may contribute to viral inactivation, presenting new opportunities for herb-based wastewater treatment solutions. Consequently, this study not only demonstrates the antiviral capabilities of OB and PS but also introduces an innovative approach for addressing viral contaminants in water.

Removal of enrofloxacin using Eichhornia crassipes in microcosm wetlands.

The global consumption of antibiotics leads to their possible occurrence in the environment. In this context, nature-based solutions (NBS) can be used to sustainably manage and restore natural and modified ecosystems. In this work, we studied the efficiency of the NBS free-water surface wetlands (FWSWs) using Eichhornia crassipes in microcosm for enrofloxacin removal. We also explored the behavior of enrofloxacin in the system, its accumulation and distribution in plant tissues, the detoxification mechanisms, and the possible effects on plant growth. Enrofloxacin was initially taken up by E. crassipes (first 100 h). Notably, it accumulated in the sediment at the end of the experimental time. Removal rates above 94% were obtained in systems with sediment and sediment + E. crassipes. In addition, enrofloxacin was found in leaves, petioles, and roots (8.8-23.6 µg, 11-78.3 µg, and 10.2-70.7 µg, respectively). Furthermore, enrofloxacin, the main degradation product (ciprofloxacin), and other degradation products were quantified in the tissues and chlorosis was observed on days 5 and 9. Finally, the degradation products of enrofloxacin were analyzed, and four possible metabolic pathways of enrofloxacin in E. crassipes were described.

Uptake mechanism, translocation, and transformation of organophosphate esters in water hyacinth (Eichhornia crassipes): A hydroponic study.

Owing to their dominant wastewater origin, bioavailability, and toxicity, the occurrence and behavior of organophosphate esters (OPEs) in aquatic systems have attracted considerable attention over the past two decades. Aquatic plants can accumulate and metabolize OPEs in water, thereby playing an important role in their behavior and fate in waterbodies. However, their uptake, translocation and transformation mechanisms in plants remain incompletely characterized. We investigated the accumulation and transformation of OPEs in water hyacinth (Eichhornia crassipes) through a series of hydroponic experiments using three representative OPEs, tris(2-chloroethyl) phosphate (TCEP), tris(2-butoxyethyl) phosphate (TBEP), and triphenyl phosphate (TPP). These OPEs can not only be adsorbed onto and enter plant roots via passive diffusion pathways, which are facilitated by anion channels and/or aquaporins, but also can return to the solution when concentration gradients exist. After entry, hydrophilic TCEP showed a dominant distribution in the cell sap, strong acropetal transportability, and rapid translocation rate, whereas hydrophobic TPP was mostly retained in the root cell wall and therefore demonstrated weak acropetal transportability; TBEP with moderate hydrophilicity remained in the middle. All these OPEs can be transformed into diesters, which presented higher proportions in the cell sap and therefore have stronger acropetal transferability than their parent OPEs. TCEP exhibits the lowest biodegradability, followed by TPP and TBEP. These OPEs exerted apparent effects on plant growth, photosynthesis, and the diversity and composition of the rhizosphere microbial community.

Microbes-assisted phytoremediation of lead and petroleum hydrocarbons contaminated water by water hyacinth.

An experiment was carried out to explore the impact of petroleum hydrocarbons (PHs)-degrading microbial consortium (MC) on phytoremediation ability and growth of water hyacinth (WH) plants in water contaminated with lead (Pb) and PHs. Buckets (12-L capacity) were filled with water and WH plants, PHs (2,400 mg L-1) and Pb (10 mg L-1) in respective buckets. Plants were harvested after 30 days of transplanting and results showed that PHs and Pb substantially reduced the agronomic (up to 62%) and physiological (up to 49%) attributes of WH plants. However, the application of MC resulted in a substantial increase in growth (38%) and physiology (22%) of WH plants over uninoculated contaminated control. The WH + MC were able to accumulate 93% Pb and degrade/accumulate 72% of PHs as compared to initial concentration. Furthermore, combined use of WH plants and MC in co-contamination of PHs and Pb, reduced Pb and PHs contents in water by 74% and 68%, respectively, than that of initially applied concentration. Our findings suggest that the WH in combination with PHs-degrading MC could be a suitable nature-based water remediation technology for organic and inorganic contaminants and in future it can be used for decontamination of mix pollutants from water bodies.

Phytoremediation by aquatic macrophytes is a promising technique for the cleanup of environmental toxins from wastewater. To our knowledge, this is the first study reporting the integrated use of water hyacinth (WH) plants and a newly developed multi-trait microbial consortium for the simultaneous remediation of organic (i.e., petroleum hydrocarbons) and inorganic (i.e., lead) pollutants from the contaminated water. Findings of this study provide the basic but important information on the combined use of WH and microbes for remediation of mix pollution from water bodies.

Dual phytoremediation and biochar production by Eichhornia crassipes in hydroponic system receiving different 1,4-dioxane dosages.

This study focuses on applying phytoremediation as a low-effective and simple process to treat wastewater laden with 1,4 dioxane (DIOX). A floating macrophyte (Eichhornia crassipes) was cultivated under hydroponic conditions (relative humidity 50-67%, photoperiod cycle 18:6 h light/dark, and 28-33 °C) and subjected to different DIOX loads between 0.0 (control) and 11.5 mg/g fresh mass (FM). The aquatic plant achieved DIOX and chemical oxygen demand (COD) removal efficiencies of 76-96% and 67-94%, respectively, within 15 days. E. crassipes could tolerate elevated DIOX-associated stresses until a dose of 8.2 mg DIOX/g, which highly influenced the oxidative defense system. Malondialdehyde (MDA) content, hydrogen peroxide (H2O2), and total phenolic compounds (TPC) increased by 7.3, 8.4, and 4.5-times, respectively, in response to operating the phytoremediation unit at a DIOX load of 11.5 mg/g. The associated succulent value, proteins, chlorophyll-a, chlorophyll-b, and pigments dropped by 39.6%, 45.8%, 51.5%, 80.8%, and 55.5%, respectively. The suggested removal mechanism of DIOX by E. crassipes could be uptake followed by phytovolatilization, whereas direct photodegradation from sunlight contributed to about 19.36% of the total DIOX removal efficiencies. Recycling the exhausted E. crassipes for biochar production was a cost-efficient strategy, making the payback period of the phytoremediation project equals to 6.96 yr.

Eichhornia crassipes could be used in phytoremediation of 1,4 dioxane (DIOX)-laden water at DIOX load< 8.2 mg/g FM. E. crassipes removed 77­97% DIOX via uptake and phytovolatilization. Recycling exhausted-plant to produce biochar was cost-efficient with 7 yr-payback period.

Screening and signifying the uranium remediation level of Alternanthera philoxeroides and Eichhornia crassipes from aquatic medium.

Uranium is causing a hazardous impact on the human population throughout the globe. Different methods of remediation have been documented but the approach of phytoremediation has been praised throughout the globe. The bioaccumulation of uranium especially as a hyper-accumulator, has been documented in limited plant species. Therefore the current studies were conducted to elaborate on the overall U accumulation, biochemical and photochemical reactions in Alternanthera philoxeroides and Eichhornia crassipes to different concentrations of Uranium. The results showed that the accumulation of U in A.philoxeroides is higher; followed by E.crassipes; with maximum amounts of roots accumulation. Overall A.philoxeroides and E.crassipes accumulate as much as 948.88 mg/kg and 801.87 mg/kg on a dry weight basis. The biochemical results showed that Superoxide dismutase (SOD) decreased in the leaves and stem of A.philoxeroides; whereas an increase has been seen in E.crassipes in response to all treatments. peroxidase (POD) and Catalase (CAT) showed irregular response to all treatments; where the main increase was observed at T3 (120 µmol/L) and 72 h up to 138 µ/g-FW (POD) and 178 µ/g-FW (CAT) in A.philoxeroides and 1870 µ/g-FW (POD) and 73 µ/g-FW (CAT) in E.crassipes, respectively. The correlation coefficient between the fluorescence ratio Fv/Fm and the concentrations of U-treatment was significantly negative. It is concluded from the results that Uranium halted the biochemical and photochemical reaction but the plants resisted its impact while accumulating a good amount of uranium which is a good prospect for future interventions for the in-situ remediation of uranium-affected sites.

Water hyacinth derived hierarchical porous biochar absorbent: Ideal peroxydisulfate activator for efficient phenol degradation via an electron-transfer pathway.

In this paper, a facile hydrothermal pretreatment and molten salt activation route was presented for preparing a self-doped porous biochar (HMBC) from a nitrogenous biomass precursor of water hyacinth. With an ultrahigh specific surface area (2240 m2 g-1), well-developed hierarchical porous structure, created internal structural defects and doped surface functionalities, HMBC exhibited an excellent adsorption performance and catalytic activity for phenol removal via peroxydisulfate (PDS) activation. Specifically, the porous structure promoted the adsorption of PDS on HMBC, forming a highly active HMBC/PDS* complex and thereby increasing the oxidation potential of the system. Meanwhile, the carbon defective structure, graphitic N and CO groups enhanced the electron transfer process, favoring the HMBC/PDS system to catalyze phenol oxidation via an electron transfer dominated pathway. Thus, the system degraded phenol effectively with an ultralow activation energy of 4.9 kJ mol-1 and a remarkable oxidant utilization efficiency of 8.2 mol mol-oxidant-1 h-1 g-1. More importantly, the system exhibited excellent resistance to water quality and good adaptability for decontaminating different organic pollutants with satisfactory mineralization efficiency. This study offers valuable insights into the rational designing of a low-cost biochar catalyst for efficient PDS activation towards organic wastewater remediation.

Trends on adsorption of lead (Pb) using water hyacinth: Bibliometric evaluation of Scopus database.

Heavy metals (Cd, Ni, Zn, Cu, Cr, and Pb) are widely recognized as being hazardous to human health and environmentally deleterious. Therefore water hyacinth is used as a greener adsorption material. This study is a bibliometric analysis of research developments on the adsorption of lead (Pb) using water hyacinth (1995-2023). The data was retrieved from the Scopus database and analyzed using VOSviewer software to determine the relationship between keywords from each published document. The results of this research was divided into three parts: 1) publication output, 2) global research, and 3) keyword research. From the data obtained, it was found that there has been an increasing research trend of adsorption of lead using water hyacinth, although it is not significant and fluctuating. Overall, this study can be used by researchers to quantitatively assess trends and future directions of this research topic.

Entrapment behaviours of trivalent and hexavalent chromium from aqueous medium using edible alkali-derived activated carbon of Eichhornia crassipes (water hyacinth).

The study examines the adsorption capabilities of an environmentally friendly activated carbon derived from a novel activating agent, i.e., an edible alkali prepared from black gram plant ash, for the removal of Cr(III) and Cr(VI) ions from an aqueous environment. The results of the systematic research show impressive removal efficiencies of 95.12% for Cr(III) ions and 99.6% for Cr(VI) ions. The kinetics and equilibrium data of the adsorption process confirm to the pseudo-second-order kinetics and Freundlich isotherm model. The thermodynamic analysis reveals the adsorption process as feasible and spontaneous across the temperature range of 298-313 K. The mechanism entails electrostatic attraction and adsorption of Cr(III) and Cr(VI) ions on oppositely charged surfaces and the participation of oxygen-containing functional groups on WHAC-BGA surface in the reduction of Cr(VI) to Cr(III). This study provides valuable insights for optimizing strategies to combat chromium contamination in water sources, offering a sustainable solution with the potential for real-world application.