Wastewater Purification Research Articles

Mushroom residue derived magnetic hydrochar for antimony removal from wastewater: Mechanisms insights and practicality assessment

The magnetic mushroom residue hydrochar (MMRH) was synthesized using mushroom waste and K2FeO4, and then applied for antimony (Sb) removal from wastewater. The maximum adsorption capacity of Sb(III) and Sb(V) by MMRH reached 636.9 and 814.3 mg/g, respectively. According to characterizations, the existence of K+ in MMRH significantly increased the ion exchange of Sb species. Further, the Fenton-like reactions could generate additional •OH species to effectively oxidize Sb(III) into Sb(V), while other mechanisms including complexation, co-precipitation, and physical adsorption were also comprehensively investigated. The practicality of this MMRH was also assessed by recycling and column experiments. This study is expected to offer novel perspectives on mushroom residue reutilization and Sb-polluted wastewater purification for a greener environment.

Insights into the enhanced oxidation of organic micropollutants by single-atom Cu catalyst activated peroxydisulfate: Valence-dominated nonradical pathway

Herein, we anchored Cu atoms with four N atoms into waste adsorbent-based biochar (SACu30@NC) containing both Cu(I) and Cu(II) to explore the role of different Cu valences for PDS activation mechanism. The atomic Cu was identified as the active site, and Cu(III) and electron shuttle process dominated organics degradation in SACu30@NC/PDS system. Therein, Cu(I) preferred to activate the adsorbed PDS to produce Cu(III) (Cu(I)N4-PDS→Cu(II)N4-SO4•-→Cu(III)N4-SO42-), whereas PDS adsorbed on Cu(II) surface was more likely to extract electrons from organic pollutants directly. Benefiting from non-radical process, SACu30@NC exhibited selective and anti-interference performance for organic pollutants in complex matrixes. The promising catalytic activity of SACu30@NC (BPA=50 mg/L, 100% within 180 min) with low Cu leaching (<0.1 mg/L) in continuous-flow experiments further revealed the potential of SACu30@NC for practical applications. This work provides new insights into the PDS activation mechanism by single-atom Cu catalysts and develops an efficient approach for practical wastewater purification.

Fabricating mesoporous titanium nanocomposites with high adsorption and photolysis performance by using rice husk ash as a renewable support source

Rice husk (RH) is a valuable and renewable source of bioenergy. Once RH has been burned to produce thermal energy, RH ash (RHA) remains, and this ash can be used as a sustainable resource to improve the circular economy. In this study, we used RHA as a silicon source to fabricate RH-SBA-15. Incipient wetness impregnation was then employed to directly incorporate TiO2 nanocrystals into the mesopores of the RH-SBA-15. XRD and TEM confirmed the successful integration of TiO2 into the framework of RH-SBA-15, with the hexagonal array and ordered mesostructure of RH-SBA-15 being unchanged. FTIR and XPS revealed the formation of Ti–O–Si bonds on the surface of RH-SBA-15, which enhanced the activity of TiO2. The pore volume and surface area of TiO2/RH-SBA-15 were 0.292–0.604 cm3/g and 170–366 m2/g. Photocatalytic tests were conducted to examine the catalysts used in the degradation of Reactive Blue 4 (RB4). The results indicated that TiO2/RH-SBA-15 exhibited 63% higher catalytic efficiency than that did bare TiO2. The surface adsorption of RH-SBA-15 and the high photolytic activity of TiO2 resulted in an improvement in RB4 degradation. The photoactivity increased with decreasing solution pH and calcination temperature and increasing catalyst mass. A TiO2 ratio of 25% resulted in the highest photoactivity, yielding a composite that completely eliminated RB4 within 5 h. The catalyst composites had high stability and photoactivity after four cycles. Overall, the method used in this study for fabricating mesoporous photocatalysts from recycled RHA is valuable for bio-waste disposal and wastewater purification.

Mechanism of Cr(VI) removal by polyphenols-rich bacterial cellulose gel produced from fermented wine pomace

Hexavalent chromium (Cr(VI)) is still a common contaminant in water. In this work, we studied the Cr(VI) adsorption by polyphenol-rich bacterial cellulose(BC) gel, synthesized by the Komagataeibacter rhaeticus K15 using wine pomace. The results showed that the equilibrium removal capacity was 473.09 ± 1.41 mg g−1 (dry weight). The quasi-second-order kinetics model and the Langmuir removal isotherm model was the most suitable for describing the Cr(VI) removal process. Toxic Cr(VI) was converted to the low toxic Cr(III) during the removal process via the reduction of Cr(VI) to Cr(III) by polyphenols released into the solution by the BC gel. The FTIR, XRD, XPS, SEM-EDX results indicated the physical adsorption on the surface of BC and the reduction reaction between polyphenol groups and Cr(VI) is the critical mechanism of Cr(VI) removal by BC. The finding of this study demonstrates that polyphenols-rich BC gel produced from wine pomace has a superior feature for future Cr(VI)-wastewater purification.

Urchin-like CO2-responsive magnetic microspheres for highly efficient organic dye removal

CO2-responsive materials have emerged as promising adsorbents for the remediation of refractory organic dyes-contaminated wastewater without the formation of byproducts or causing secondary pollution. However, realizing the simultaneous adsorption−separation or complete removal of both anionic and cationic dyes, as well as achieving deeper insights into their adsorption mechanism, still remains a challenge for most reported CO2-responsive materials. Herein, a novel type of urchin-like CO2-responsive Fe3O4 microspheres (U-Fe3O4 @P) has been successfully fabricated to enable ultrafast, selective, and reversible adsorption of anionic dyes by utilizing CO2 as a triggering gas. Meanwhile, the CO2-responsive U-Fe3O4 @P microspheres exhibit the capability to initiate Fenton degradation of non-adsorbable cationic dyes. Our findings reveal exceptionally rapid adsorption equilibrium, achieved within a mere 5 min, and an outstanding maximum adsorption capacity of 561.2 mg g−1 for anionic dye methyl orange upon CO2 stimulation. Moreover, 99.8% of cationic dye methylene blue can be effectively degraded through the Fenton reaction. Furthermore, the long-term unresolved interaction mechanism of organic dyes with CO2-responsive materials is deciphered through a comprehensive experimental and theoretical study by density functional theory. This work provides a novel paradigm and guidance for designing next-generation eco-friendly CO2-responsive materials for highly efficient purification of complex dye-contaminated wastewater in environmental engineering.

The Potential of Bentonite as a Low-cost Adsorbent for the Removal of Heavy Metal Ions from Multicomponent Aqueous Systems of the Galvanic Industry

Waste water in the galvanic process contains high concentrations of heavy metals that pose a direct danger to humans and the environment. Conventional methods for their removal are quite expensive and generate a large amount of waste. The development of new and improvement of existing methods for the removal of heavy metals from galvanic wastewater are the subject of many studies. Compared to other purification methods, the adsorption is becoming an increasingly popular method of wastewater purification, especially if the adsorbent is cheap, easily available and does not require any other treatment before use. Therefore, the aim of the work was to investigate the possibility of using natural bentonite for the removal of heavy metal ions from multi-component water systems of the galvanic industry. For this purpose, the physico-chemical characterization of natural bentonite was performed, and then the influence of pH value, time and temperature on the adsorption efficiency was examined. The results of adsorption showed that natural bentonite can be used as an adsorbent for the removal of heavy metal ions from waste galvanic waters, and that at pH 5 it achieves the maximum removal efficiency for Cu(II):Cr(III):Ni(II) ions in the percentage ratio 100 : 99.990 : 99.998. The results showed that the highest removal efficiency for Cu (II) ions was achieved in the first 10 minutes, and 20 minutes for Cr (III) and Ni (II) ions. The maximum efficiency of Cu (II) removal was achieved at all temperatures, while for Cr (III) 99.99% and Ni (II) 100% maximum efficiency was achieved at 35°C, which indicates that the adsorption process is endothermic. The experimental results of the adsorption of Cu (II) metal ions are in good agreement with the Langmuir and Freundlich theoretical models, while for Cr (III) and Ni (II) ions they are in better agreement with the Langmuir adsorption model.

Molten salt synthesis of MXene-derived hierarchical titanate for effective strontium removal

The removal and recovery of radioactive Sr(II) from wastewater and seawater has been of great concern due to the negative environmental impacts of nuclear energy development and the potential risk of nuclear accidents. Herein, a facile molten salt synthesis strategy was developed to systematically investigated the reaction of different types of MXenes with nitrates. Among the products, K+ intercalated hierarchical titanate nanostructures (K-HTNs) obtained from the direct chemical transformation of multilayered Ti3C2Tx exhibited unique layered structures, good physicochemical properties, and outstanding adsorption performance for Sr(II). The maximum adsorption capacity of Sr(II) by K-HTNs reached 204 mg·g−1 at ambient temperature, and the good regeneration and reusability of the titanate was also demonstrated. K-HTNs showed preferential selectivity for Sr(II) in different environmental media containing competing ions, and the removal efficiency of Sr(II) in real seawater was as high as 93.3 %. The removal mechanism was elaborated to be the exchange of Sr2+ with K+/H+ in the interlayers of K-HTNs, and the adsorbed Sr(II) had a strong interaction with Ti−O− termination on the titanate surface. Benefiting from the merits of rapid and scalable synthesis and excellent adsorption performance, MXene-derived K-HTNs have broad application prospects for the purification of 90Sr-contaminated wastewater and seawater.

Biomass-based renewable, eco-friendly nanofiber membrane: Large-scale fabrication and application in PM0.3 capture and oily wastewater purification

Biomass-based poly (trimethylene 2,5-furandicarboxylate) (PTF) was synthesized by the simple and low-cost direct esterification method. The high number-average molecular weight (Mn) of about 39.6 kDa was achieved for PTF with a polydispersity index (PDI) of 2.0, which was suitable for spinning. The electrospun PTF nanofiber membranes were fabricated firstly and displayed adjustable diameters, excellent mechanical properties (lifting 550 g weight, foldability) and large-scale preparation potential (area of 100 cm × 50 cm). More impressively, high initial surface potential (13.5 kV) was found for the electrospun in-suit electret membranes, which facilitated the capture of ultrafine PM particles. Subsequently, the PTF membrane showed exceptional particle capture capability with a filtration performance of 99.96 %, low pressure drops of 78 Pa, and a satisfactory quality factor of 0.1 Pa−1. PTF filters also demonstrated long-term service capability for purifying high PM2.5 concentration smoke (15 cycles, 55 min), and could be flexibly introduced into various practical scenarios. Additionally, based on the selective oil/water wettability of PTF membranes, which showed outstanding separation effects of oily wastewater(＞99.88 %, 15 cycles). Therefore, the development and application of the PTF nanofibers provided a sustainable alternative for separation/purification and various fields in the future.

Understanding the synergistic interactions between photo-Fenton and photocatalytic reactions in hemin-anchored SnO2

Sensitization of wide-gap metal oxides by the porphyrins has been promising to utilize the major fraction of solar light for photocatalytic reactions. In this context, rutile-SnO2 was anchored with hemin complex and their performance was evaluated for the 4-nitro phenol (4-NP) degradation under UV/visible light. Driven by the significant interactions between -COOH and surface -OH functional groups of hemin and SnO2 respectively, a new linkage O=CO-Sn was formed at the interface, which was vital for charge carrier transfer between them. Both X-ray diffraction studies and scanning electron microscope analysis confirmed that the surface hemin adsorption did not alter the crystal structure and the morphology of pristine SnO2. The light absorption properties revealed a red shift in the optical response of the composite, which facilitated the photocatalytic reactions to operate under visible light. The electrochemical and photoluminescence measurements collectively attested to the enhanced charge carrier separation in the composite compared to pure SnO2. The synergism arising from the photo-Fenton and photocatalytic reactions was derived from the cyclic reactions of Fe(II)/Fe(III) and oxidation of hydroxyl radicals by the valence band holes of SnO2 with H2O2 under UV light. In contrast, the sensitization process resulted in electron transfer from the excited state of hemin to the conduction band (CB) of SnO2 under visible light. Such distinct mechanistic pathways by the metal oxide-porphyrin composite would be promising for wastewater purification under UV–visible light region in near future.

Insight into heterogeneous photo-Fenton degradation of naphthol by natural magnetite: Redundancy analysis and toxicity assessment

Magnetite is a ubiquitous iron mineral in nature and its iron ions are usually isomorphically substituted by Ti and V cations, which shows a high ability for degradation of organic contaminants via the photo-Fenton process. However, numerous reports pay more attention to the activity of synthetic magnetite rather than natural magnetite. Here, three types of natural magnetite (HG01, HG02, and GCL01) with different Ti and V contents were investigated from the perspective of the difference in structural property, catalytic activity, H2O2 decomposition, and reactive oxygen species generation. Structural characterization exhibited that the purity of natural magnetite obeyed the order: GCL01 > HG02 > HG01. HG01 contained the highest Ti content in the form of ilmenite, followed by HG02 and GCL01. Moreover, HG01 yielded the highest photo-Fenton catalytic activity with 99.5 % of naphthol degradation and 96.0 % of H2O2 decomposition after 60 min reaction. The superior activity of HG01 was attributed to the relatively high Ti and V content as demonstrated by redundancy analysis. Mechanistic investigation implied that the Ti and V in the octahedral sites of the magnetite surface can accelerate the electron transfer from Fe(III) to Fe(II), resulting in higher Fenton activity. Besides, ilmenite in HG01 enhanced naphthol degradation because H2O2 accelerated the separation of photoelectron-holes pairs to promote O2− production. Furthermore, as revealed by gas chromatography-mass spectrometry and the toxicity of identified products predicted by the ECOSAR model, the toxicity of naphthol can effectively reduce accompanied by the harmless products generated. The high reusability, low iron ions residual in water, harmless end products, and easily recycled with magnetic separation suggest that natural magnetite has a promising application prospect for wastewater purification.

Green synthesis of lichenan-decorated silver nanoparticles for catalytic hydrogenation of organic dyes and bacterial disinfection

Developing an eco-friendly and efficient homogeneous catalyst for treating complex wastewater containing toxic organic pollutants and bacteria is in significant demand. Herein, ultra-small Ag nanoparticles (NPs)-loaded random coil lichenan nanocomposite (L-AgNP) was prepared through a low-cost and green one-step in-situ reduction strategy using lichenan as the reducing agent. The random coil of lichenan acted as a micro-reactor to disperse and stabilize AgNPs via the Ag-O bonding interaction. In the participation of NaBH4, L-AgNP nanocomposite could achieve greater catalytic efficiency for catalyzing reduction of 4-nitrophenol (∼120 s, 34.34 × 10−3 s−1) with the smaller size of AgNPs or the higher content of Ag. The nanocatalyst also exhibited outstanding catalytic efficiency for congo red, rhodamine B, methylene blue, and methyl orange. The L-AgNP could be easily recycled through ethanol precipitation and continuously reused for ten cycles with a tiny loss of conversion rate. Furthermore, L-AgNP also displayed favorable antibacterial activity, inhibiting the growth of Escherichia coli and Staphylococcus aureus with more than 98 % disinfection ratio. This work provides a green strategy to develop polysaccharide-based multifunctional homogeneous catalysts focusing on wastewater purification.

Merits of bamboo utilization in earth preservation, water, and wastewater treatment: A mini review

This paper reviews the positive attributes and challenges of bamboo usage in carbon absorption, water, and wastewater purification. Bamboo can serve as a habitat for a variety of creatures and supports a diversified ecology. Bamboo roots can cast a fibrous net into the ground to prevent soil erosion and degradation. As the water passes through this woven mesh, the bamboo roots act as a filter, drawing toxins and other contaminants out of the water. Bamboo can treat wastewater effectively in free-water surface, horizontal flow, and vertical flow constructed wetlands. Bamboo charcoal has exceptional filtering properties for cleaner drinking water and better air quality. Additionally, bamboo can be used to form cellulose-based membranes. Bamboo is a renewable resource for creating paper, furniture, and building materials. Bamboo has various benefits. Thus, bamboo forests offer opportunities for rural communities to thrive economically

In-situ polymerization of PANI nanocone array on PEN nanofibrous membranes for solar-driven interfacial evaporation

Solar-driven interfacial evaporation (SDIE) holds great potential for desalination, but it also poses challenges to application performance. Herein, a novel polyaniline (PANI) modified polyarylene ether nitrile (PEN) electrospun nanofibrous membranes (PANI@PEN) was developed by introducing PDA and CTAB, which increased the polymerization amount of PANI and controlled its morphology by sequential in-situ polymerization, aiming to enhance its SDIE comprehensive performance. This unique structure can generate multiple diffuse reflections under sunlight, resulting in the highest water evaporation rate of the nanofibrous membrane at 1.822 kg m−2 h−1, while evaporation rate at 1.527 kg m−2 h−1 for a 3.5 wt% sodium chloride solution. Due to the good flexibility of PEN polymer substrate, the obtained membranes can be easily arched, showcasing an interesting ability to collect salt through salt deposition. Meanwhile, PEN also provides a robust skeleton, endowed PANI@PENs with corrosion-resistant, capable of desalination in acidic media, purifying heavy metal ion solutions through evaporation, as well as good mechanical properties for reusability. The study potentially provides a strategy for utilizing dopamine and CTAB loaded on high-performance polymer nanofibrous membranes and the convenient in-situ polymerization to generate advanced photothermal PANI. This strategy paves a way to enable high-performance engineering polymer, PEN, with solar-thermal evaporation capabilities, further opening its potential applications in seawater desalination and industrial wastewater purification.

The Application of Textile Materials in Interfacial Solar Steam Generation for Water Purification and Desalination.

The global increase in population, the phenomenon of climate change, the issue of water pollution and contamination, and the inadequate management of water resources all exert heightened strain on freshwater reserves. The potential utilization of the interfacial solar steam generation (ISSG) system, which utilizes photothermal conversion to generate heat on material surfaces for wastewater purification and desalination purposes, has been successfully demonstrated. Textile-material-based ISSG devices, including (woven, nonwoven, and knitted) fabrics and electrospinning membranes, exhibit distinct properties such as a rough surface texture, high porosity, significant surface area, exceptional flexibility, and robust mechanical strength. These characteristics, combined with their affordability, accessibility, and economic viability for widespread implementation, make them extremely attractive for applications in SSG. In this review, a comprehensive analysis of the emerging concepts, advancements, and applications of textile materials, such as woven, nonwoven, and knitted fabrics and electrospun membranes, in ISSG for wastewater purification and desalination is presented. We also emphasize significant obstacles and potential prospects in both theoretical investigations and real-world implementations, aiming to contribute to future advancements in the domain of textile-material-based interfacial evaporation in wastewater purification and desalination. Furthermore, the drawbacks and the challenges of ISSG systems are also highlighted.

Equilibrium and optimization of water-heat transfer in natural cellulose-based hybrid hydrogel for efficient solar desalination

Solar interfacial evaporation for seawater desalination and wastewater purification is considered a promising strategy to alleviate the water scarcity crisis. Currently, the ways to improve evaporators usually revolve around iteration of photothermal materials (enhancing heat generation) or macrostructural remodeling (altering water transport rate), but these means have limitations and do not achieve simultaneous and precise regulation of water-heat utilization. Herein, a simple hydrothermal method is used to synthesize natural cellulose-based hybridized hydrogels, exhibiting a high evaporation efficiency (97.67%) and a full range of water purification capabilities, including antimicrobial, anti-salt accumulation, and degradation of organic dyes. Significantly, the enhancement mechanism of the energy-mass utilization of this evaporator can be explained from two aspects. Firstly, the hybridization of natural cellulose and inorganic carbon materials can supplement a large number of hydrophilic functional groups, thus fully activating the water molecules and reducing the evaporation energy consumption. Furthermore, the COMSOL simulation is used to clarify the distribution of water and heat, and by adjusting the height of the hydrogel, the balance of water-heat transfer is cleverly achieved with the maximization of energy utilization. Overall, the optimization idea of water-heat transfer provides a new direction for future evaporator design and a fresh opportunity for the improvement of energy-mass management model.

Chitosan synergizes with bismuth-based metal-organic frameworks to construct double S-type heterojunctions for enhancing photocatalytic antimicrobial activity

In recent years, photocatalytic technology has been introduced to develop a new kind antimicrobial agents fighting antibiotic abusing and related drug resistance. The efforts have focused on non-precious metal photocatalysts along with green additives. In the present work, a novel bis-S heterojunctions based on the coupling of polysaccharide (CS) and bismuth-based MOF (CAU-17) s synthesized through a two-step method involving amidation reaction under mild conditions. The as prepared photocatalyst literally extended the light response to the near-infrared region. Owing to its double S-type heterostructure, the lifetime of the photocarriers is significantly prolonged and the redox capacity are enhanced. As a result, the as prepared photocatalyst indicated inhibition up to 99.9 % under 20 min of light exposure against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria as well as drug-resistant bacteria (MRSA). The outstanding photocatalytic performance is attributed to the effective charge separation and migration due to the unique double S heterostructure. Such a double S heterostructure was confirmed through transient photocurrent response, electrochemical impedance spectroscopy tests and electron spin resonance measurements. The present work provides a basis for the simple synthesis of high-performance heterojunction photocatalytic inhibitors, which extends the application of CAU-17 in environmental disinfection and wastewater purification.

Interfacial Solar Evaporation: From Fundamental Research to Applications.

In the last decade, interfacial solar steam generation (ISSG), powered by natural sunlight garnered significant attention due to its great potential for low-cost and environmentally friendly clean water production in alignment with the global decarbonization efforts. This review aims to share the knowledge and engage with a broader readership about the current progress of ISSG technology and the facing challenges to promote further advancements toward practical applications. The first part of this review assesses the current strategies for enhancing the energy efficiency of ISSG systems, including optimizing light absorption, reducing energy losses, harvesting additional energy, and lowering evaporation enthalpy. Subsequently, the current challenges faced by ISSG technologies, notably salt accumulation and bio-fouling issues in practical applications, are elucidated and contemporary methods are discussed to overcome these challenges. In the end, potential applications of ISSG, ranging from initial seawater desalination and industrial wastewater purification to power generation, sterilization, soil remediation, and innovative concept of solar sea farm, are introduced, highlighting the promising potential of ISSG technology in contributing to sustainable and environmentally conscious practices. Based on the review and in-depth understanding of these aspects, the future research focuses are proposed to address potential issues in both fundamental research and practical applications.

Novel solar-induced wastewater purification materials originated from ore tailing solid waste

Ore tailings (OT) are solid waste produced as a by-product of the mining industry, posing serious environmental challenges. Ensuring the low-carbon and environmentally friendly development of mineral raw materials, enhancing the reclamation, reuse and recycling rate of raw materials in the full lifecycle, presents a significant challenge. To achieve high-value utilization of OT and solve the problem of clean water supply, a novel solar evaporation wastewater purification material was developed using modified ore tailing/acrylate composite photothermal coating. The photothermal functional modified ore tailings (OT@PDA@CB) were fabricated by grafting carbon black (CB) and polydopamine (PDA) onto the OT surface through the physical adhesion of active chemical groups, synergistically enhancing broadband light absorption ability of OT@PDA@CB/acrylate coating. UV–Vis-NIR spectra showed increased absorption in visible and near-infrared (NIR) light. Surface temperature of OT@PDA@CB/acrylate coating under 1200 W/m−2 illumination increased to 65.6 °C compared with 52.6 °C of OT/acrylate coating due to increased light absorption, resulting in an evaporation rate of 0.89 kg·m−2·h−1 within 1 h. The solar evaporation efficiency for OT@PDA@CB evaporator was 48.3%, which was 192.7% higher than that in blank acrylate sample. The obtained OT@PDA@CB/acrylate composite photothermal coating demonstrated versatile abilities for desalination, heavy-metal purification and organic contaminant removal. This work offers a straightforward approach for high-value utilization of inexpensive mineral solid wastes and green solar-induced wastewater purification technique.

Natural pyrite-stimulative periodate activation: efficiency and mechanism study.

Natural pyrite (NP) is an alternative catalyst for wastewater purification via advanced oxidation processes (AOPs). However, the activation performance and mechanism of periodate (PI) by NP have not yet been revealed. Herein, this work examines the activation performance of NP towards PI and its application in the degradation of antibiotic wastewater. Interestingly, 95.69% of chlortetracycline (CTC) was degraded by NP within 20min via PI activation. Besides, NP shows effective degradation of various pollutants such as rhodamine B (65.81%), sulfamethoxazole (89.04%), and sodium butylxanthate (99.77%) within 20min. The active species quenching experiment suggested that the active species , , 1O2 and the active complex of PI bonded with NP surface participated in CTC degradation. In addition, Fe(II) on NP surface is the main active site for PI activation, while Sn2- species accelerates the reduction of Fe(III) to Fe(II) and promotes sustained PI activation. This work provides new ideas for the application of NP in environmental pollution control.

Mechanochemical activation of silicon photothermal material for efficient interfacial solar desalination and wastewater purification

Solar steam generation (SSG) has emerged as a sustainable solution for addressing water scarcity, and ongoing research has resulted in the development of various photothermal materials that demonstrate exceptional light-absorption capabilities and overall performance. This study presents mechanochemically activated silicon (Si60), which exhibits a high photon-to-heat conversion efficiency for SSG, as an advanced and superior photothermal material. When exposed to simulated sunlight conditions (AM1.5G, 100 mW cm−2), the Si60-coated photothermal membrane demonstrated an impressive evaporation rate of 2.2 kg m−2 h−1 and a high SSG efficiency of 107.9 %. Our investigation revealed that Si60 possessed a minute particle size (∼1.2 µm), nano-scale cracks, and reduced Si-O bond percentage owing to mechanochemical activation (60 h). In addition, it exhibited low thermal conductivity (∼0.33 W m−1 K−1), hydrophilic characteristics, and high photon-to-heat conversion efficiency (∼56.4 %). These characteristics collectively enhanced SSG performance. Moreover, we examined the practical application of the Si60 photothermal membrane in seawater desalination and wastewater purification. Inductively coupled plasma mass spectroscopy (ICP-MS) analysis revealed that the ion concentrations in the collected water were considerably lower than the standards set by the World Health Organization (WHO) in both cases. In addition, we evaluated the SSG performance of a large-area Si60 membrane under natural sunlight conditions. The results demonstrated robust evaporation capabilities of approximately 11 kg m−2 day−1, even under low average solar intensity (0.61 sun). This study underscores the profound impact of mechanochemical activation on bulk silicon, enhancing its photothermal properties and potentially facilitating the development of high-performance desalination systems on a large scale.