Advanced Materials for Sustainable Environmental Remediation: Terrestrial and Aquatic Environments

Advanced Materials for Sustainable Environmental Remediation: Terrestrial and Aquatic Environments presents detailed, comprehensive coverage of novel and advanced materials that can be applied to address the growing global concern of the pollution of natural resources in waters, the air and soil. It provides fundamental knowledge on available materials and treatment processes, as well as applications, including adsorptive remediation and catalytic remediation. Organized clearly by type of material, this book presents a consistent structure for each chapter, including characteristics of the materials, basic and important physicochemical features for environmental remediation applications, routes of synthesis, recent advances as remediation medias, and future perspectives.

This book offers an interdisciplinary and practical examination of available materials and processes for environmental remediation that will be valuable to environmental scientists, materials scientists, environmental chemists, and environmental engineers alike.

• Highlights a wide range of synthetic methodologies, physicochemical and engineered features of novel materials and composites/hybrids for environmental purposes
• Provides comprehensive, consolidated coverage of advanced materials for environmental remediation applications for researchers in environmental science, materials science, and industry to identify in-depth solutions to pollution
• Presents up-to-date details of advanced materials, including descriptions and characteristics that impact their applications in environmental remediation processes

• Language: English
• Publisher: Elsevier Science
• Release date: Apr 21, 2022
• ISBN: 9780323904865

Book preview

Chapter 1

Trends in advanced materials for sustainable environmental remediation

Vanish Kumara, Sherif A. Younisb,c, Kumar Vikrantb, Ki-Hyun Kimb

aNational Agri Food Biotechnology Institute (NABI), S.A.S. Nagar, Punjab, India

bDepartment of Civil and Environmental Engineering, Hanyang University, Seoul, Republic of Korea

cAnalysis and Evaluation Department, Egyptian Petroleum Research Institute (EPRI), Nasr City, Cairo, Egypt

1.1 Environmental pollution and role of materials in its remediation

As a major global problem, environmental pollution exerts significant impacts on the growth of vegetation, health of living organisms, food grain quality (e.g., increased contaminants levels), and life expectancy [1–8]. Pollutant particles are affecting all three major components of the environment, i.e., water, air, and soil. Natural and anthropogenic activities are responsible for the increased pollutant levels in the environment [9–12]. Interestingly, the environment itself can moderate increased levels of contaminants up to a certain limit through a number of processes such as photosynthesis, rain, agglomeration, and sedimentation [13–16]. However, after such pollutants exceed a certain limit, the self-regulation function of the environment decreases and cannot to balance the system efficiently [17]. In such cases, an external intervention must be provided to help repair the damage.

The best way to heal the environment is to decrease the generation of pollutants. Interestingly, use of green energy can be a suitable option to reduce pollutant levels (especially for air pollution) [18–20]. However, it cannot be used to control the nonpower–related pollution, e.g., industrial effluents. Hence, another option (which is also more realistic) is to control existing or newly generated pollutants with environment treatment options. Material-based treatment options can be used as an effective tool to revive the health of the environment due to their ease and low cost of operation, high efficiency (on the basis of types of material and pollutants), and easy regeneration. Many material-based options have been tested to recover environmental health. However, their major shortcomings are (1) limited availability of materials, (2) low pollutant removal efficiency, (3) limited regenerability, (4) risk of material leakage in the environment, and (5) toxicity associated with the material.

Several advanced materials have been tested successfully for environmental remediation. The preferable forms include metal-organic frameworks (MOFs) [21–24], oxides/hydroxides [25–28], carbonaceous materials [29–32], metal-based nanomaterials [23,33–35], clay-based materials [36–38], and aerogels/cryogels/xerogels [39–45]. These materials can reduce air/water/soil pollution via adsorption, catalysis, and/or a combination of both processes. Moreover, additional merits (e.g., abundant active sites, easy regeneration, less/no toxicity, facile synthesis, and the possibility of bulk production) increase their suitability in applications. The choice of material can be based on the target environmental component and properties of the material. In addition to removing the existing pollutants, these advanced structures can contribute to the expansion of green energy options (e.g., energy production and storage), which will be highly beneficial in reducing pollutant emissions. The introduction of strategies employed to remove pollutants using advanced materials is discussed in the next section.

1.2 Strategies for environmental remediation

To pursue exponential growth of global industry, one needs to overcome many challenges, especially shortage of natural resources, including clean freshwater and precious elements. At the same time, it is important to implement the sustainable development with the proper control on pollution and waste. Given the environmental deterioration, extensive studies have been carried out in the last decade to develop effective, durable, and economically feasible technologies to remediate environmental pollution. In terms of sustainability, solid and liquid wastes discharged into the environment contain various types (e.g., precious, rare, radioactive, and semiconductor) of metallic elements (e.g., barium, uranium, plutonium, silver, gold, platinum, molybdenum, nickel, zinc, copper, and chromium). A large portion of these elements are considered secondary or artificial resources, due to their technological utility. Hence, the recovery and separation of these metallic elements from industrial waste streams are crucial not only to minimize their cumulative toxic impacts on ecosystems but also to improve their reuse/ recycling processes based on the sustainability concepts.

To date, several in-situ and ex-situ treatment techniques have been recommended to remediate water, air, and soil pollution [46–48]. These techniques can be categorized into five groups based on remediation mechanisms: physical, thermal, chemical, electrochemical, and biological treatment strategies, as listed in Table 1.1. Likewise, there are many methods used to separate and recover valuable metallic elements from various industrial streams. These methods are divided into two groups: (1) traditional techniques (e.g., mechano-physical, pyrometallurgical, hydrometallurgical, and biometallurgical processes) and (2) advanced technologies (e.g., electrochemical, electrodialysis, supercritical fluid, ionic liquid, adsorption, ion-exchange, and membrane separation techniques) [49–51]. However, it is noticed that the use of single technology is often not sufficient to separate pure elements from waste streams and/or to treat all types of contaminants due to the complex nature of environmental systems. For example, the bioremediation strategy is deemed a cost-effective and greener approach for treating water/soil systems contaminated with organic pollutants [52]. However, this technique cannot be used for treating inorganic pollutants. The biodegradation process also can generate more mobile and toxic by-products than the original contaminants if it is not controlled (in terms of the nature of microbial strains, soil/water matrix, and ecological factors). Further, the use of hydrometallurgical processes (e.g., solvent extraction) for the separation of precious metals is unattractive due to the possible interferences of impurities in the recovery process, the low concentration of target metals in waste streams, and solvents losses. Additionally, it is not feasible to separate and recover precious metals and nutrient elements from dilute wastewater by adsorption technique such as carbon materials due to their apparent demerits (e.g., low selectivity and difficulty in elution and regeneration) [53].

Table 1.1

Selection and suitability of treatment and/or separation techniques for practical application are frequently dependent on the nature of environmental systems and contaminant types/concentrations (e.g., initial quality of feed streams; Fig. 1.1). Many integrated/hybrid abatement strategies consisting of two or more treatment process have been recommended in recent years to avoid the limitations of a single treatment method at the commercial scale, to promote remediation efficiency/selectivity toward multiple pollutants, to reduce operation costs, and to decrease secondary pollution [48,54–56]. Further, numerous porous functional materials have been synthesized and applied to enhance the removal of multiple pollutants and/or to selectively separate target elements of interest under certain conditions in the field.

Figure 1.1 Hybrid treatment techniques (primary (physicochemical), secondary (biological), and advanced tertiary processes) for effective industrial wastewater treatment.

For the efficient separation of precious metals, the use of various adsorbent materials has been proposed for their selective separation from industrial streams. For example, a tertiary-amine-type gel (DMA-PW) was synthesized by chemical modification of persimmon waste (PW) with dimethylamine (DMA) for adsorption separation of Au(III) (5.63 mol/kg), Pt(IV) (0.28 mol/kg), and Pd(II) (0.42 mol/kg) in a hydrochloric acid medium [57]. The adsorption separation mechanism was suggested to follow the formation of ion pairs of the metal chloro complex anions with the protonated DMA-PW gel. Similarly, the synthesis of hydrazono-imidazoline modified cellulose (HI-MC, as carbohydrate-based material) was reported to enhance adsorption recovery of Pt(IV) (0.311 mol/kg), Pd(II) (0.496 mol/kg), and Au(III) (0.247 mol/kg) from geological samples [58]. However, the feasibility of these adsorbent materials is debatable as they were tested only under ideal condition (e.g., media containing the target element only without any interference).

A number of techniques (e.g., ionic liquid-based split-anion solvent extraction [59,60], ion-exchange membrane (IEM) [61], and electrodialysis (ED) [62]) have been developed to improve the selective recovery of precious metal ions (e.g., Au(III), Sc(III), Rh(III), Pd(II), and Pt(IV)) from various media (compared to the adsorption recovery process). Among these techniques, the IEM is an emergent type of membrane technology for versatile applications toward the separation, recovery, and concentration of various natural resources from wastewaters, along with waste conversion processes into energy (Fig. 1.2) [61]. For instance, hybrid membrane separation technologies (e.g., reverse osmosis [RO] membrane with ultrafiltration [UF] unit) have been used successfully to recover chromium (99.9%) from tannery industry wastewater at optimum pH 6.6, flow rate 0.62 m³/h, and permeate mass flux at 23.09 g/min [63]. Recently, a supported liquid membrane (SLM, Table 1.1) method has also been employed for the recovery of particulate metals from various industrial wastewater [64–66].

Figure 1.2 The application of ion-exchange membrane for pollutants removals as well as natural resources, precious metals, energy, and pure water recovery from domestic and industrial wastewaters [61].

The integrated adsorption-photocatalytic hybrid process has also been extensively applied to exploit their combinatorial technological advantages toward enhanced removal of mixed organic/inorganic or microbial pollutants from air/water environments [67–70]. In this hybrid technique, photocatalysis can effectively degrade persistent/biodegradable organic pollutants to less harmful trace organic compounds and/or reduce toxic heavy metals under mild conditions, yielding minimal by-products (secondary pollutants) in the environment. Therefore, a hybrid adsorption-photocatalysis treatment process is recommended in a practical sense (relative to pure photocatalysis) to reduce undesirable by-products (via simultaneous adsorption from photocatalytically treated streams) and to extend treatment operation at dark conditions [69].

Many functional porous materials (e.g., carbon, zeolites, and MOF-based semiconductors and their composites [e.g., metal/metal oxides-doped carbon, zeolite, or MOFs]) are frequently employed to induce enhanced synergy of the adsorption/photocatalysis process [48,71,72]. This is due to their unique characteristics in terms of texture (large surface area and high porosity), surface reactivity/functionality, and optical/conducting properties. For composite materials, use of carbon/zeolite/MOFs supports offers three roles during the hybrid treatment: (1) potent adsorbent of pollutants on the surface-active catalytic sites, (2) promoting light-absorption and photogenerated charge transfer/separation mechanisms (i.e., increase the lifetime of electron-hole pairs), and (3) reducing agglomeration of photocatalytic materials (metal or metal oxides), thereby increasing the number of reactive sites available for catalytic reaction of pollutant degradation [67,70,72]. However, to design and upscale effective hybrid adsorbent/photocatalytic systems, use of carbon-based supports (activated carbon, biochar, and graphene) offers many advantages over MOF supporting materials in terms of operation cost, effectiveness, and stability during regeneration/reuse cycles [73–76].

Coupling traditional treatment methods (such as biological or coagulation processes) with other advanced posttreatment strategies (e.g., membrane technology and advanced oxidation processes) was useful for enhanced treatment of many industrial wastewater effluents (Fig. 1.1) [48,77]. Specifically, Gadipelly and coworkers reported that use of hybridized technologies (e.g., electrocoagulation (EC) + photocatalysis, ozonation + biological activated, aerobic + anaerobic biological membrane reactors, Fenton-oxidation + coagulation + aerobic biological degradation) is effective in treating pharmaceutical wastewater for safe disposal (relative to single treatment techniques) [77]. The treatment of petroleum wastewater (PWW) was performed effectively by coupling multiple traditional techniques in series, such as American Petroleum Institute (API) separator, coagulation-flocculation/aeration technique, activated sludge bioreactors, and sand filtration [48]. The design of hybrid/integrated treatment systems composed of traditional techniques, followed by advanced treatment strategies (like adsorption/membrane-based nanotechnologies and advanced oxidation processes) has been proposed to efficiently treat dissolved/miscible organic contaminants remaining in PWW after the traditional treatment process [48].

The hybrid membrane processes (Fig. 1.3) are also industrially applied for enhanced water purification/desalination purposes in drinking water/seawater treatment plants [78,79], oil-water separation [48,80], water disinfection [81], industrial wastewater treatment [82,83], hydrocarbon/gas separation [84,85], and enhanced precious/valuable element separation/ recovery [86,87]. For example, coupling of TiO2/CuSO4/graphene-based photocatalyst with membrane separation was proposed for effective conversion/separation of greenhouse gases (CO2) into renewable energy (e.g., methanol) [88]. A hybrid membrane-sorption system was suggested for air fractionation and purification from dust (micro and nanoscale particles) [89]. An integrated system composed of membrane and pressure swing adsorption processes was economically and technically viable for enhanced recovery of biogenic hydrogen from the gaseous stream generated during fermentation [90]. Many integrated/hybrid membrane systems were investigated for enhanced water treatment/desalination processes through coupling membrane filtration units (micro-/ultra-/nanofiltration) with other pretreatment methods (coagulation-flocculation, sand filtration, disinfection, and ion-exchange processes) in a single treatment plant [78,79].

Figure 1.3 Considerations for development of hybrid membrane processes in drinking water treatment plants [78]. TOC = total organic carbon; NF = nanofiltration; MF = microfiltration; UF = ultrafiltration; MIEX = ion-exchange resin; PAC = powdered activated carbon; NOM = natural organic matter; and COD = chemical oxygen demand.

The conventional pretreatment methods in this hybrid system are commonly utilized to reduce fouling/scaling problems during advanced membrane separation. In this case, traditional methods are used for effective removal of solid particulate matters and microbes as well as for reduction of organic content level (e.g., chemical oxygen demand and normal organic matter) and water hardness before membrane separation techniques [48,80]. However, traditional softening techniques (e.g., hot lime and pellet softening) may generate large sludge quantities. Simultaneously, the disinfection process (using ozonation and/or chlorination) could form some carcinogenic soluble by-products that are difficult to remove by traditional treatment methods. Hence, membrane filtration units are used as an advanced tool to reject and remove these by-products and other soluble emerging pollutants in the feed water streams after traditional treatment.

In summary, membrane technology is one of the fastest-growing technologies used in the actual fields for air and water purification and for effective resource recovery/separation processes (e.g., nutrients, organics, precious metals, or even chemical/electrical potential) from various media. Since the membrane is an effective means to enrich nutrients, the membrane technology can also be integrated with other chemical and/or biological methods (as integrated/hybrid membrane systems) to accelerate the separation, recovery, and concentration of target elements from wastewater [91]. The performance and economic feasibility of integrated/hybrid membrane systems for pollutant removal and/or resource recovery are greatly dependent on feed water/air quality. In this regard, many research efforts have been made to improve membrane separation performance and to mitigate fouling problems during industrial applications. For example, as membrane separation is a surface process, membrane surface engineering by incorporation of functional materials (inorganic, organic, or composites) can be an effective approach to enhance membrane performance, to reduce fouling, and to improve other parameters, such as thermal, mechanical, and physical stability [92,70,81].

1.3 Present challenges and future prospects for utilization of advanced materials in sustainable environmental remediation

Potential applications of various advanced materials toward environmental remediation have been demonstrated from numerous lab-scale studies. In many cases, advanced functional materials outperform conventional ones for specific applications. Nevertheless, practical application of advanced materials for real-world systems must be optimized for practicality. The sustainable application of advanced materials is limited by the high-cost and/or hazardous chemicals used in the synthesis (e.g., organic solvents, acids, and bases), which add to the environmental concerns [93–95]. Furthermore, large-scale production of certain advanced materials (e.g., MOFs and graphene-based materials) remains difficult and uneconomical [96,97].

Concerning catalytic remediation technologies, a significant shortcoming is generation of hazardous by-products, which can sometimes be more toxic than the parent pollutant itself [98]. Also, the high operational and maintenance costs restrict practical application of membrane reactors in many cases [99]. The inherent toxicity of nanoparticles poses a severe concern for application in real-world wastewater systems [94]. A possible solution has been proposed to develop magnetic materials (containing iron-based materials), which can be recovered through application of an external magnetic field [100,101]. Nevertheless, suitable steps need to be taken to avoid corrosion/oxidation of iron-based particles under acidic conditions [94].

A significant shortcoming of advanced materials is the lack of reliable performance data under real-world conditions. For gaseous systems, performance of advanced materials should be analyzed for near actual pollutant concentrations encountered in the real world, along with the appropriate moisture level. Similarly, for soil and aqueous matrixes, performance data for actual real-world samples should be gathered. Although real-world systems are often comprised of multicomponent pollutant systems, most studies report the performance of advanced materials against single-component pollutant systems, which are far easier to remove under practical conditions.

Future studies should focus on employing green synthesis routes for advanced materials to avoid environmental concerns [102]. Also, insights into upscaled production of such materials should be a priority [96]. A possible solution to attain sustainability could be to convert waste materials into high-performance materials (e.g., biochars and eggshell-based adsorbents/catalysts) for environmental remediation [9,103–105]. Furthermore, suitable modification of low-cost commercial materials (e.g., activated carbon, zeolite, and TiO2) can be sought to enhance the overall performance of the parent material while simultaneously maintaining low production and operational costs [95,106,107]. Reactor design also needs consideration for transitioning advanced materials from lab-scale to pilot-scale [98]. Novel materials such as micro- and nanomotors are worth considering to further enhance overall performance at reduced cost [108,109].

Conclusion

Growing concerns regarding environmental pollution and human health have led to significant research into design of high-performance environmental remediation techniques. In this regard, advanced materials (e.g., MOFs, oxide/hydroxides, carbonaceous materials, zeolites, clays, and other varieties) have been demonstrated for their high capability of efficient environmental remediation. The advanced materials can remove pollutant species from environmental systems through adsorption, catalysis, or other approaches. In this regard, the present study was designed to provide a brief introduction to applying advanced materials for environmental remediation purposes. A section was dedicated to highlight the present shortcomings and prospects of such advanced materials toward environmental remediation to help provide a roadmap for future studies. In general, active collaboration between multidisciplinary fields (e.g., chemical and environmental engineering; materials, analytical, and environmental chemistry; and life sciences) is the focus to accurately map the present challenges and to appropriately design advanced materials-based systems to achieve sustainable removal of pollutants from environmental systems.

A. Metal-organic frameworks

This section discusses metal-organic framework (MOFs) application to natural resources (water, soil, air).

Chap II: MOF-based novel adsorbents for aquatic pollutants

Chap III: MOF-based materials for gaseous adsorption

Chap III: MOF-based materials as soil amendments

Chap IV: MOFs as catalysts for advanced oxidation processes

B. Oxides/hydroxides

Chap V: Layered double hydroxides: from fundamentals to environmental applications

Chap VI: Zeolites for environmental purposes

Chap VII: Silica-based materials

Chap VII: TiO2-based photocatalysts against organics

C. Carbonaceous materials

Chap VIII: Biochar and activated carbon

Chap IX: Graphene-related materials

Chap X: Carbon quantum dots

Chap XI: Carbon nanotubes

Chap XII: Biomass-derived materials (like agricultural waste/biomass)

D. Special classes of materials

Chap XIII: Magnetic materials

Chap XIV: MXenes

Chap XV: Aerogels, cryogels, and xerogels

Chap XVI: ZIFs in adsorptive to catalytic remediation applications

Chap XVII: Synthetic and natural clay-based materials

Chap XVIII: Graphitic carbon nitride: triggering solar light-assisted decomposition of hazardous organics.

References

[1] K. Balakrishnan, S. Dey, T. Gupta, R.S. Dhaliwal, M. Brauer, A.J. Cohen, J.D. Stanaway, G. Beig, T.K. Joshi, A.N. Aggarwal, Y. Sabde, H. Sadhu, J. Frostad, K. Causey, W. Godwin, D.K. Shukla, G.A. Kumar, C.M. Varghese, P. Muraleedharan, A. Agrawal, R.M. Anjana, A. Bhansali, D. Bhardwaj, K. Burkart, K. Cercy, J.K. Chakma, S. Chowdhury, D.J. Christopher, E. Dutta, M. Furtado, S. Ghosh, A.G. Ghoshal, S.D. Glenn, R. Guleria, R. Gupta, P. Jeemon, R. Kant, S. Kant, T. Kaur, P.A. Koul, V. Krish, B. Krishna, S.L. Larson, K. Madhipatla, P.A. Mahesh, V. Mohan, S. Mukhopadhyay, P. Mutreja, N. Naik, S. Nair, G. Nguyen, C.M. Odell, J.D. Pandian, D. Prabhakaran, P. Prabhakaran, A. Roy, S. Salvi, S. Sambandam, D. Saraf, M. Sharma, A. Shrivastava, V. Singh, N. Tandon, N.J. Thomas, A. Torre, D. Xavier, G. Yadav, S. Singh, C. Shekhar, T. Vos, R. Dandona, K.S. Reddy, S.S. Lim, C.J.L. Murray, S. Venkatesh, L. Dandona. The impact of air pollution on deaths, disease burden, and life expectancy across the states of India: the Global Burden of Disease Study 2017, Lancet Planet. Health 3 (2019) e26–e39.

[2] S. Bashir, U. Ali, M. Shaaban, A.B. Gulshan, J. Iqbal, S. Khan, A. Husain, N. Ahmed, S. Mehmood, M. Kamran, H. Hu. Role of sepiolite for cadmium (Cd) polluted soil restoration and spinach growth in wastewater irrigated agricultural soil, J. Environ. Manage. 258 (2020) 110020.

[3] D.-P. Häder, A.T. Banaszak, V.E. Villafañe, M.A. Narvarte, R.A. González, E.W. Helbling. Anthropogenic pollution of aquatic ecosystems: emerging problems with global implications, Sci. Total Environ. 713 (2020) 136586.

[4] V. Kumar, K. Vaid, S.A. Bansal, K.-H. Kim. Nanomaterial-based immunosensors for ultrasensitive detection of pesticides/herbicides: current status and perspectives, Biosens. Bioelectron. 165 (2020) 112382.

[5] X. Li, L. Jin, H. Kan. Air Pollution: A Global Problem Needs Local Fixes, Nature Publishing Group, 2019.

[6] X. Luo, H. Bing, Z. Luo, Y. Wang, L. Jin. Impacts of atmospheric particulate matter pollution on environmental biogeochemistry of trace metals in soil-plant system: A review, Environ. Pollut. 255 (2019) 113138.

[7] V.É. Molnár, E. Simon, B. Tóthmérész, S. Ninsawat, S. Szabó. Air pollution induced vegetation stress – the Air Pollution Tolerance Index as a quick tool for city health evaluation, Ecol. Indic. 113 (2020) 106234.

[8] P.K. Rai. Chapter one—particulate matter and its size fractionation, in: P.K. Rai (Ed.), Biomagnetic Monitoring of Particulate Matter, Elsevier, 2016, pp. 1–13.

[9] S. Cheng, T. Chen, W. Xu, J. Huang, S. Jiang, B. Yan. Application research of biochar for the remediation of soil heavy metals contamination: a review, Molecules 25 (2020) 3167.

[10] P. Lei, K. Pan, H. Zhang, J. Bi. Pollution and risk of PAHs in surface sediments from the tributaries and their relation to anthropogenic activities, in the main urban districts of Chongqing city, southwest China, Bull. Environ. Contam. Toxicol. 103 (2019) 28–33.

[11] J.P. Vareda, A.J.M. Valente, L. Durães. Assessment of heavy metal pollution from anthropogenic activities and remediation strategies: a review, J. Environ. Manage. 246 (2019) 101–118.

[12] J. Wu, J. Lu, X. Wen, Z. Zhang, Y. Lin. Severe nitrate pollution and health risks of coastal aquifer simultaneously influenced by saltwater intrusion and intensive anthropogenic activities, Arch. Environ. Contam. Toxicol. 77 (2019) 79–87.

[13] Y. Barwise, P. Kumar. Designing vegetation barriers for urban air pollution abatement: a practical review for appropriate plant species selection, NPJ Clim. Atmos. Sci. 3 (2020) 12.

[14] A.F. Herbort, M.T. Sturm, K. Schuhen. A new approach for the agglomeration and subsequent removal of polyethylene, polypropylene, and mixtures of both from freshwater systems – a case study, Environ. Sci. Pollut. Res. 25 (2018) 15226–15234.

[15] J. Peng, Y. Huang, T. Liu, L. Jiang, Z. Xu, W. Xing, X. Feng, P. De Maeyer. Atmospheric nitrogen pollution in urban agglomeration and its impact on alpine lake-case study of Tianchi Lake, Sci. Total Environ. 688 (2019) 312–323.

[16] J.B. Shukla, A.K. Misra, S. Sundar, R. Naresh. Effect of rain on removal of a gaseous pollutant and two different particulate matters from the atmosphere of a city, Math. Comput. Modell. 48 (2008) 832–844.

[17] V.C. Pandey, V. Singh. Chapter 20—exploring the potential and opportunities of current tools for removal of hazardous materials from environments, in: V.C. Pandey, K. Bauddh (Eds.), Phytomanagement of Polluted Sites, Elsevier, 2019, pp. 501–516.

[18] J.-P. Amigues, M. Moreaux. Competing land uses and fossil fuel, and optimal energy conversion rates during the transition toward a green economy under a pollution stock constraint, J. Environ. Econ. Manage. 97 (2019) 92–115.

[19] M. Ashraf, I. Khan, M. Usman, A. Khan, S.S. Shah, A.Z. Khan, K. Saeed, M. Yaseen, M.F. Ehsan, M.N. Tahir, N. Ullah. Hematite and magnetite nanostructures for green and sustainable energy harnessing and environmental pollution control: a review, Chem. Res. Toxicol. 33 (2020) 1292–1311.

[20] Y. Guo, D.-P. Yang, M. Liu, X. Zhang, Y. Chen, J. Huang, Q. Li, R. Luque. Enhanced catalytic benzene oxidation over a novel waste-derived Ag/eggshell catalyst, J. Mater. Chem. A 7 (2019) 8832–8844.

[21] V. Kumar, S. Kumar, K.-H. Kim, D.C.W. Tsang, S.-S. Lee. Metal organic frameworks as potent treatment media for odorants and volatiles in air, Environ. Res. 168 (2019) 336–356.

[22] V. Kumar, K. Vellingiri, D. Kukkar, S. Kumar, K.-H. Kim. Recent advances and opportunities in the treatment of hydrocarbons and oils: metal-organic frameworks-based approaches, Crit. Rev. Environ. Sci. Technol. 49 (2019) 587–654.

[23] H.A. Maitlo, K.-H. Kim, V. Kumar, S. Kim, J.-W. Park. Nanomaterials-based treatment options for chromium in aqueous environments, Environ. Int. 130 (2019) 104748.

[24] K. Vikrant, Y. Qu, J.E. Szulejko, V. Kumar, K. Vellingiri, D.W. Boukhvalov, T. Kim, K.-H. Kim. Utilization of metal–organic frameworks for the adsorptive removal of an aliphatic aldehyde mixture in the gas phase, Nanoscale 12 (2020) 8330–8343.

[25] M. Chen, P. Wu, Z. Huang, J. Liu, Y. Li, N. Zhu, Z. Dang, Y. Bi. Environmental application of MgMn-layered double oxide for simultaneous efficient removal of tetracycline and Cd pollution: Performance and mechanism, J. Environ. Manage. 246 (2019) 164–173.

[26] B. Liu, K.-H. Kim, V. Kumar, S. Kim. A review of functional sorbents for adsorptive removal of arsenic ions in aqueous systems, J. Hazard. Mater. 388 (2020) 121815.

[27] Q. Yi, J. Tan, W. Liu, H. Lu, M. Xing, J. Zhang. Peroxymonosulfate activation by three-dimensional cobalt hydroxide/graphene oxide hydrogel for wastewater treatment through an automated process, Chem. Eng. J. 400 (2020) 125965.

[28] G. Zhang, X. Zhang, Y. Meng, G. Pan, Z. Ni, S. Xia. Layered double hydroxides-based photocatalysts and visible-light driven photodegradation of organic pollutants: a review, Chem. Eng. J. 392 (2020) 123684.

[29] K.-H. Kim, J.E. Szulejko, N. Raza, V. Kumar, K. Vikrant, D.C.W. Tsang, N.S. Bolan, Y.S. Ok, A. Khan. Identifying the best materials for the removal of airborne toluene based on performance metrics—a critical review, J. Cleaner Prod. 241 (2019) 118408.

[30] D. Kukkar, A. Rani, V. Kumar, S.A. Younis, M. Zhang, S.-S. Lee, D.C.W. Tsang, K.-H. Kim. Recent advances in carbon nanotube sponge–based sorption technologies for mitigation of marine oil spills, J. Colloid Interface Sci. 570 (2020) 411–422.

[31] V. Kumar, K.-H. Kim, J.-W. Park, J. Hong, S. Kumar. Graphene and its nanocomposites as a platform for environmental applications, Chem. Eng. J. 315 (2017) 210–232.

[32] K. Vikrant, D.-H. Lim, S.A. Younis, K.-H. Kim. An efficient strategy for the enhancement of adsorptivity of microporous carbons against gaseous formaldehyde: Surface modification with aminosilane adducts, Sci. Total Environ. 743 (2020) 140761.

[33] R. Fatima, M.N. Afridi, V. Kumar, J. Lee, I. Ali, K.-H. Kim, J.-O. Kim. Photocatalytic degradation performance of various types of modified TiO2 against nitrophenols in aqueous systems, J. Cleaner Prod. 231 (2019) 899–912.

[34] J. Singh, V. Kumar, S. Singh Jolly, K.-H. Kim, M. Rawat, D. Kukkar, Y.F. Tsang. Biogenic synthesis of silver nanoparticles and its photocatalytic applications for removal of organic pollutants in water, J. Ind. Eng. Chem. 80 (2019) 247–257.

[35] K. Vellingiri, K. Vikrant, V. Kumar, K.-H. Kim. Advances in thermocatalytic and photocatalytic techniques for the room/low temperature oxidative removal of formaldehyde in air, Chem. Eng. J. 399 (2020) 125759.

[36] M. El Ouardi, M. Laabd, H. Abou Oualid, Y. Brahmi, A. Abaamrane, A. Elouahli, A. Ait Addi, A. Laknifli. Efficient removal of p-nitrophenol from water using montmorillonite clay: insights into the adsorption mechanism, process optimization, and regeneration, Environ. Sci. Pollut. Res 26 (2019) 19615–19631.

[37] S. Gu, X. Kang, L. Wang, E. Lichtfouse, C. Wang. Clay mineral adsorbents for heavy metal removal from wastewater: a review, Environ. Chem. Lett. 17 (2019) 629–654.

[38] V.B. Yadav, R. Gadi, S. Kalra. Clay based nanocomposites for removal of heavy metals from water: a review, J. Environ. Manage. 232 (2019) 803–817.

[39] E. Bailón-García, E. Drwal, T. Grzybek, C. Henriques, M.F. Ribeiro. Catalysts based on carbon xerogels with high catalytic activity for the reduction of NOx at low temperatures, Catal. Today 356 (2020) 301–331.

[40] G. Bayramoglu, M.Y. Arica. Modification of epoxy groups of poly(hydroxylmethyl methacrylate-co-glycidyl methacrylate) cryogel with H3PO4 as adsorbent for removal of hazardous pollutants, Environ. Sci. Pollut. Res 27 (2020) 43340–43358.

[41] A. Bratovcic, I. Petrinic. Carbon Based Aerogels and Xerogels for Removing of Toxic Organic Compounds, Springer International Publishing, Cham, 2020, 743–749.

[42] N.P. de Moraes, R.B. Valim, R. da Silva Rocha, M.L.C.P. da Silva, T.M.B. Campos, G.P. Thim, L.A. Rodrigues. Effect of synthesis medium on structural and photocatalytic properties of ZnO/carbon xerogel composites for solar and visible light degradation of 4-chlorophenol and bisphenol A, Colloids Surf. A 584 (2020) 124034.

[43] L. Otero-González, S.V. Mikhalovsky, M. Václavíková, M.V. Trenikhin, A.B. Cundy, I.N. Savina. Novel nanostructured iron oxide cryogels for arsenic (As(III)) removal, J. Hazard. Mater. 381 (2020) 120996.

[44] H. Zhang, S. Lyu, X. Zhou, H. Gu, C. Ma, C. Wang, T. Ding, Q. Shao, H. Liu, Z. Guo. Super light 3D hierarchical nanocellulose aerogel foam with superior oil adsorption, J. Colloid Interface Sci. 536 (2019) 245–251.

[45] R. Zhang, A. Zhang, Y. Yang, Y. Cao, F. Dong, Y. Zhou. Surface modification to control the secondary pollution of photocatalytic nitric oxide removal over monolithic protonated g-C3N4/graphene oxide aerogel, J. Hazard. Mater. 397 (2020) 122822.

[46] L. Liu, W. Li, W. Song, M. Guo. Remediation techniques for heavy metal-contaminated soils: principles and applicability, Sci. Total Environ. 633 (2018) 206–219.

[47] A. Luengas, A. Barona, C. Hort, G. Gallastegui, V. Platel, A. Elias. A review of indoor air treatment technologies, Rev. Environ. Sci. Bio/Technol. 14 (2015) 499–522.

[48] S.A. Younis, H.A. Maitlo, J. Lee, K.-H. Kim. Nanotechnology-based sorption and membrane technologies for the treatment of petroleum-based pollutants in natural ecosystems and wastewater streams, Adv. Colloid Interface Sci. 275 (2020) 102071.

[49] L. Canda, T. Heput, E. Ardelean. Methods for recovering precious metals from industrial waste, IOP Conf. Series Mater. Sci. Eng. 106 (2016) 012020.

[50] Y. Ding, S. Zhang, B. Liu, H. Zheng, C.-c. Chang, C. Ekberg. Recovery of precious metals from electronic waste and spent catalysts: a review, Resour. Conserv. Recycl. 141 (2019) 284–298.

[51] M. Wang, Q. Tan, J.F. Chiang, J. Li. Recovery of rare and precious metals from urban mines—a review, Front. Environ. Sci. Eng. 11 (2017) 1.

[52] E. Okoh, Z.R. Yelebe, B. Oruabena, E.S. Nelson, O.P. Indiamaowei. Clean-up of crude oil-contaminated soils: bioremediation option, Int. J. Environ. Sci. Technol. 17 (2020) 1185–1198.

[53] R. Panda, O.S. Dinkar, M.K. Jha, D.D. Pathak. Novel approach for selective recovery of gold, copper, and iron as marketable product from industrial effluent, Gold Bull. 53 (2020) 11–18.

[54] M.V. Bagal, P.R. Gogate. Wastewater treatment using hybrid treatment schemes based on cavitation and Fenton chemistry: a review, Ultrason. Sonochem. 21 (2014) 1–14.

[55] A. Deghles, U. Kurt. Treatment of tannery wastewater by a hybrid electrocoagulation/electrodialysis process, Chem. Eng. Process. 104 (2016) 43–50.

[56] H.T. Quoc An, T. Pham Huu, T. Le Van, J.M. Cormier, A. Khacef. Application of atmospheric non thermal plasma-catalysis hybrid system for air pollution control: toluene removal, Catal. Today 176 (2011) 474–477.

[57] Y. Xiong, C.R. Adhikari, H. Kawakita, K. Ohto, K. Inoue, H. Harada. Selective recovery of precious metals by persimmon waste chemically modified with dimethylamine, Bioresour. Technol. 100 (2009) 4083–4089.

[58] M.A. Hashem, M.M. Elnagar, I.M. Kenawy, M.A. Ismail. Synthesis and application of hydrazono-imidazoline modified cellulose for selective separation of precious metals from geological samples, Carbohydr. Polym. 237 (2020) 116177.

[59] Y.Y.N. Bonggotgetsakul, R.W. Cattrall, S.D. Kolev. Recovery of gold from aqua regia digested electronic scrap using a poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) based polymer inclusion membrane (PIM) containing Cyphos® IL 104, J. Membr. Sci. 514 (2016) 274–281.

[60] V.T. Nguyen, S. Riaño, K. Binnemans. Separation of precious metals by split-anion extraction using water-saturated ionic liquids, Green Chem. 22 (2020) 8375–8388.

[61] W.-Y. Zhao, M. Zhou, B. Yan, X. Sun, Y. Liu, Y. Wang, T. Xu, Y. Zhang. Waste conversion and resource recovery from wastewater by ion exchange membranes: state-of-the-art and perspective, Ind. Eng. Chem. Res. 57 (2018) 6025–6039.

[62] C. Li, D.L. Ramasamy, M. Sillanpää, E. Repo. Separation and concentration of rare earth elements from wastewater using electrodialysis technology, Sep. Purif. Technol. 254 (2021) 117442.

[63] K. Mohammed, O. Sahu. Recovery of chromium from tannery industry waste water by membrane separation technology: health and engineering aspects, Sci. African 4 (2019) e00096.

[64] P.K. Parhi. Supported liquid membrane principle and its practices: a short review, J. Chem. 2013 (2013) 618236.

[65] M.F. San Román, E. Bringas, R. Ibañez, I. Ortiz. Liquid membrane technology: fundamentals and review of its applications, J. Chem. Technol. Biotechnol. 85 (2010) 2–10.

[66] R.N.R. Sulaiman, N. Jusoh, N. Othman, N.F.M. Noah, M.B. Rosly, H.A. Rahman. Supported liquid membrane extraction of nickel using stable composite SPEEK/PVDF support impregnated with a sustainable liquid membrane, J. Hazard. Mater. 380 (2019) 120895.

[67] E.M. El-Fawal, S.A. Younis, Y.M. Moustafa, P. Serp. Preparation of solar-enhanced AlZnO@carbon nano-substrates for remediation of textile wastewaters, J. Environ. Sci. 92 (2020) 52–68.

[68] E.M. El-Fawal, S.A. Younis, T. Zaki. Designing AgFeO2-graphene/Cu2(BTC)3 MOF heterojunction photocatalysts for enhanced treatment of pharmaceutical wastewater under sunlight, J. Photochem. Photobiol. A 401 (2020) 112746.

[69] S.A. Younis, K.-H. Kim. Heterogeneous photocatalysis scalability for environmental remediation: opportunities and challenges, Catalysts 10 (2020) 1109.

[70] X. Zhao, R. Zhang, Y. Liu, M. He, Y. Su, C. Gao, Z. Jiang. Antifouling membrane surface construction: chemistry plays a critical role, J. Membr. Sci. 551 (2018) 145–171.

[71] P. Monneyron, A. De La Guardia, M.H. Manero, E. Oliveros, M.T. Maurette, F. Benoit-Marquié. Co-treatment of industrial air streams using A.O.P. and adsorption processes, Int. J. Photoenergy 5 (2003)