Applications of engineered biochar in remediation of heavy metal(loid)s pollution from wastewater: Current perspectives toward sustainable development goals.

Environmental pollution of heavy metal(loid)s (HMs) caused adverse impacts, has become one of the emerging concerns and challenges worldwide. Metal(loid)s can pose significant threats to living organisms even when present in trace levels within environmental matrices. Extended exposure to these substances can lead to adverse health consequences in humans. Removing HM-contaminated water and moving toward sustainable development goals (SDGs) is critical. In this mission, biochar has recently gained attention in the environmental sector as a green and alternative material for wastewater removal. This work provides a comprehensive analysis of the remediation of typical HMs by biochars, associated with an understanding of remediation mechanisms, and gives practical solutions for ecologically sustainable. Applying engineered biochar in various fields, especially with nanoscale biochar-aided wastewater treatment approaches, can eliminate hazardous metal(loid) contaminants, highlighting an environmentally friendly and low-cost method. Surface modification of engineered biochar with nanomaterials is a potential strategy that positively influences its sorption capacity to remove contaminants. The research findings highlighted the biochars' ability to adsorb HM ions based on increased specific surface area (SSA), heightened porosity, and forming inner-sphere complexes with oxygen-rich groups. Utilizing biochar modification emerged as a viable approach for addressing lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), and chromium (Cr) pollution in aqueous environments. Most biochars investigated demonstrated a removal efficiency >90 % (Cd, As, Hg) and can reach an impressive 99 % (Pb and Cr). Furthermore, biochar and advanced engineered applications are also considered alternative solutions based on the circular economy.

A review on sterilization methods of environmental decontamination to prevent the coronavirus SARS-CoV-2 (COVID-19 virus): A new challenge towards eco-friendly solutions.

In recent years, the COVID-19 pandemic is currently wreaking havoc on the planet. SARS-CoV-2, the Severe Acute Respiratory Syndrome Coronavirus, is the current term for this outbreak. Reports about this novel coronavirus have been presented since the pandemic's breakout, and they have demonstrated that it transmits rapidly from person to person, primarily by droplets in the air. Findings have illustrated that SARS-CoV-2 can survive on surfaces from hours to days. Therefore, it is essential to find practical solutions to reduce the virus's impact on human health and the environment. This work evaluated common sterilization methods that can decontaminate the environment and items. The goal is that healthcare facilities, disease prevention organizations, and local communities can overcome the new challenge of finding eco-friendly solutions. Further, a foundation of information encompassing various sterilization procedures and highlighting their limits to choose the most appropriate method to stop disease-causing viruses in the new context has been presented. The findings of this crucial investigation contribute to gaining insight into the comprehensive sterilization approaches against the coronavirus for human health protection and sustainable environmental development.

Occurrence, fate, and potential risk of pharmaceutical pollutants in agriculture: Challenges and environmentally friendly solutions.

In recent years, pharmaceutical active compounds (PhACs) have attained global prevalence. The behavior of PhACs in agricultural soils is complex and depends on several factors, such as the nature of the compounds and their physicochemical characteristics, which affect their fate and potential threats to human health, ecosystems, and the environment. The detection of residual pharmaceutical content is possible in both agricultural soils and environmental matrices. PhACs are commonly found in agricultural soil, with concentrations varying significantly, ranging from as low as 0.048 ng g-1 to as high as 1420.76 mg kg-1. The distribution and persistence of PhACs in agriculture can lead to the leaching of these toxic pollutants into surface water, groundwater, and vegetables/plants, resulting in human health risks and environmental pollution. Biological degradation or bioremediation plays a critical role in environmental protection and efficiently eliminates contamination by hydrolytic and/or photochemical reactions. Membrane bioreactors (MBRs) have been investigated as the most recent approach for the treatment of emerging persistent micropollutants, including PhACs, from wastewater sources. MBR- based technologies have proven to be effective in eliminating pharmaceutical compounds, achieving removal rates of up to 100%. This remarkable outcome is primarily facilitated by the processes of biodegradation and metabolization. In addition, phytoremediation (i.e., constructed wetlands), microalgae-based technologies, and composting can be highly efficient in remediating PhACs in the environment. The exploration of key mechanisms involved in pharmaceutical degradation has revealed a range of approaches, such as phytoextraction, phytostabilization, phytoaccumulation, enhanced rhizosphere biodegradation, and phytovolatilization. The well-known advanced/tertiary removal of sustainable sorption by biochar, activated carbon, chitosan, etc. has high potential and yields excellent quality effluents. Adsorbents developed from agricultural by-products have been recognized to eliminate pharmaceutical compounds and are cost-effective and eco-friendly. However, to reduce the potentially harmful impacts of PhACs, it is necessary to focus on advanced technologies combined with tertiary processes that have low cost, high efficiency, and are energy-saving to remove these emerging pollutants for sustainable development.

Facile preparation of porphyrin@g-C3N4/Ag nanocomposite for improved photocatalytic degradation of organic dyes in aqueous solution.

In the quest of improving the photocatalytic efficiency of photocatalysts, the combination of two and more semiconductors recently has garnered significant attention among scientists in the field. The doping of conductive metals is also an effective pathway to improve photocatalytic performance by avoiding electron/hole pair recombination and enhancing photon energy absorption. This work presented a design and fabrication of porphyrin@g-C3N4/Ag nanocomposite using acid-base neutralization-induced self-assembly approach from monomeric porphyrin and g-C3N4/Ag material. g-C3N4/Ag material was synthesized by a green reductant of Cleistocalyx operculatus leaf extract. Electron scanning microscopy (SEM), X-ray diffraction (XRD), FT-IR spectroscopy, and UV-vis spectrometer were utilized to analyse the properties of the prepared materials. The prepared porphyrin@g-C3N4/Ag nanocomposite showed well integration of porphyrin nanostructures on the g-C3N4/Ag's surface, in which porphyrin nanofiber was of the diameter in nanoscales and the length of several micrometers, and Ag NPs had an average particle size of less than 20 nm. The photocatalytic behavior of the resultant nanocomposite was tested for the degradation of Rhodamine B dye, which exhibited a remarkable RhB photodegrading percentage. The possible mechanism for photocatalysis of the porphyrin@g-C3N4/Ag nanocomposite toward Rhodamine B dye was also proposed and discussed.

Recent advances and applicable flexibility potential of electrochemical processes for wastewater treatment.

This study examined >140 relevant publications from the last few years (2018-2021). In this study, classification was reviewed depending on the operation's progress. Electrocoagulation (EC), electrooxidation (EO), electroflotation (EF), electrodialysis (ED), and electro-Fenton (EFN) processes have received considerable attention. The type of action (individual or hybrid) for each electrochemical procedure was evaluated, and statistical analysis was performed to compare them as a new manner of reviewing cited papers providing a massive amount of information efficiently to the readers. Individual or hybrid operation progress of the electrochemical techniques is critical issues. Their design, operation, and maintenance costs vary depending on the in-situ conditions, as evidenced by surveyed articles and statistical analyses. This work also examines the variables affecting the elimination efficacy, such as the applied current, reaction time, pH, type of electrolyte, initial pollutant concentration, and energy consumption. In addition, owing to its efficacy in removing toxins, the hybrid activity showed a good percentage among the studies reviewed. The promise of each wastewater treatment technology depends on the type of contamination. In some cases, EO requires additives to oxidise the pollutants. EF and EFN eliminated lightweight organic pollutants. ED has been used to treat saline water. Compared to other methods, EC has been extensively employed to remove a wide variety of contaminants.

Kinetic study on methylene blue removal from aqueous solution using UV/chlorine process and its combination with other advanced oxidation processes.

This study investigated the kinetic degradation of methylene blue (MB) by a UV/chlorine process and its combination with other advanced oxidation processes. The ∙OH and reactive chlorine species (RCS: Cl∙, ClO∙, etc.) were the primary reactive species, which accounted for 56.7% and 37.6% of MB degradation at pH 7, respectively. The second-order rate constant of Cl∙ towards MB was calculated to be 2.8 × 109 M-1 s-1. When the pH increased from 3 to 7, kMB by ∙OH increased from 0.15 to 0.21 min-1 before being reduced to 0.11 min-1 at pH 11. kMB by RCS continuously reduced from 0.16 to 0.13 min-1 when the pH was increased to 11. Humic acid (HA), Br-, and Cl- inhibited the degradation with kMB in the order: kMB (in HA) < kMB (in Br-) < kMB (in Cl-). HCO3- increased kMB from 0.37 to 0.48 min-1. The experimental and modeling methods fit well, indicating the effectiveness of using Kintecus® in predicting concentrations of free radicals in complex water matrices. TOC removal was achieved at 60% after 30 min in a control process and it was strongly inhibited by the presence of HA, with 22% removal achieved at 5 mgc L-1 HA. UV/chlorine/electrochemical oxidation (UV/chlorine/EO) significantly improves kMB from 0.37 to 0.94 min-1 at a high current (240 mA), while UV/chlorine/H2O2 decreased kMB at a low concentration of 0.01 mM H2O2 (kMB decreased by 6.1%). The results indicate that the energy cost for UV irradiation was the main cost in MB treatment in both UV/chlorine and UV/persulfate (UV/PS) processes, accounting for 91% and 84%, respectively.

Can electrocoagulation technology be integrated with wastewater treatment systems to improve treatment efficiency?

Considerable amounts of domestic and industrial wastewater that should be treated before reuse are discharged into the environment annually. Electrocoagulation is an electrochemical technology in which electrical current is conducted through electrodes, it is mainly used to remove several types of wastewater pollutants, such as dyes, toxic materials, oil content, chemical oxygen demand, and salinity, individually or in combination with other processes. Electrocoagulation technology used in hybrid systems along with other technologies for wastewater treatment are reviewed in this work, and the articles reviewed herein were published from 2018 to 2021. Electrocoagulation is widely employed in integrated systems with other electrochemical technologies or conventional methods for effective removal of different pollutants with less cost and sometimes over shorter durations of operation. It has also been observed that the hybrid effects besides increasing the removal efficiency can overcome the disadvantages of using electrocoagulation alone, such as less sludge formation, high cost of operation and increased life of the used electrodes, and stable flux of water with longer periods of operation. More than 20 types of other technologies have been combined efficiently with electrocoagulation.

Green synthesis of a photocatalyst Ag/TiO2 nanocomposite using Cleistocalyx operculatus leaf extract for degradation of organic dyes.

Green synthesis has emerged as a sustainable approach for the fabrication of nanomaterials in the last few decades. Leaf extracts have been considered low-cost and highly efficient reactants for the synthesis of nanoparticles. In this study, an aqueous extract of Cleistocalyx operculatus leaves was employed as a reductant to synthesize Ag/TiO2 nanocomposites. The morphology, structure, and interface interaction of the Ag/TiO2 nanocomposites were investigated by (i) X-ray diffraction (XRD) to determine the crystallinity, (ii) scanning electron microscopy (SEM) to determine the morphologies, (iii) energy dispersive X-ray spectroscopy (EDX) to determine the elemental composition and distribution, and (iv) diffuse reflectance spectroscopy (DRS) to understand the optical properties. The results showed that Ag nanoparticles (AgNPs) with particle sizes of 20-40 nm homogeneously covered the surface of the TiO2 nanoparticles. The green-synthesized Ag/TiO2 nanocomposite also exhibited an excellent photodegradation ability for Rhodamine B with a removal percentage up to 91.4% after 180 min of photocatalytic reaction.

Developing a new approach for design support of subsurface constructed wetland using machine learning algorithms.

Knowing the effluent quality of treatment systems in advance to enable the design of treatment systems that comply with environmental standards is a realistic strategy. This study aims to develop machine learning - based predictive models for designing the subsurface constructed wetlands (SCW). Data from the SCW literature during the period of 2009-2020 included 618 sets and 10 features. Five algorithms namely, Random forest, Classification and Regression trees, Support vector machines, K-nearest neighbors, and Cubist were compared to determine an optimal algorithm. All nine input features including the influent concentrations, C:N ratio, hydraulic loading rate, height, aeration, flow type, feeding, and filter type were confirmed as relevant features for the predictive algorithms. The comparative result revealed that Cubist is the best algorithm with the lowest RMSE (7.77 and 21.77 mg.L-1 for NH4-N and COD, respectively) corresponding to 84% of the variance in the effluents explained. The coefficient of determination of the Cubist algorithm obtained for NH4-N and COD prediction from the test data were 0.92 and 0.93, respectively. Five case studies of the application of SCW design were also exercised and verified by the prediction model. Finally, a fully developed Cubist algorithm-based design tool for SCW was proposed.

Novel pure α-, ß-, and mixed-phase α/ß-Bi2O3 photocatalysts for enhanced organic dye degradation under both visible light and solar irradiation.

Combining the pure α- and ß-phases of bismuth oxide enhances its photocatalytic activity under both visible and solar irradiation. α-Bi2O3, ß-Bi2O3, and α/ß-Bi2O3 were synthesized by a solvothermal calcination method. The structural, optical, and morphological properties of the as-synthesized catalysts were analyzed using XRD, UV-DRS, XPS, SEM, TEM, and PL. The bandgaps of α/ß-Bi2O3, α-Bi2O3, and ß-Bi2O3 were calculated to be 2.59, 2.73, and 2.34 eV, respectively. The photocatalytic activities of the catalysts under visible and solar irradiation were examined by the degradation of carcinogenic reactive blue 198 and reactive black 5 dyes. The kinetic plots of the degradation reactions followed pseudo-first-order kinetics. α/ß-Bi2O3 exhibited higher photocatalytic activity (∼99%) than α-Bi2O3 and ß-Bi2O3 under visible and solar irradiation. The TOC and COD results confirmed the maximum degradation ability of α/ß-Bi2O3, and the decolorization percentage remained above 90%, even after five cycles under visible irradiation. The photocatalytic dye degradation mechanism employed by α/ß-Bi2O3 was proposed based on active species trapping experiments.

Generation patterns and consumer behavior of single-use plastic towards plastic-free university campuses.

This study was conducted to estimate the generation of single-use plastics (SUPs) and elucidate consumer behavior towards a plastic-free university. The results show that the consumption rate of plastic bottles was the highest at 1.39 g per student per day (g.s-1.d-1), followed by plastic cups (0.20 g s-1.d-1), and plastic bags (0.14 g s-1.d-1). Approximately 94.41% of students were highly aware of the negative impacts of SUPs. More than four-fifths of the students (82.32%) assumed that they were responsible for the SUP pollution issue, whereas 59.52% considered SUP reduction (or lack thereof) by individuals, governments, and producers/businesses be important factors. Approximately 19.03% of the students supported implementing a high fine, one-tenth agreed for a total ban on SUPs, while nearly one-fifth believed reducing SUP consumption was unnecessary. Strategies for plastic-free universities was initiated by establishing the goal of "plastic-free university" and implementing integrated actions including a ban (plastic cups and bags) awareness-raising, and suitable alternatives.

Polyethylene over magnetite-multiwalled carbon nanotubes for kerosene removal from water.

In this study, a nano-adsorbent was prepared for kerosene removal from water. Multiwalled carbon nanotubes (MWCNTs) were functionalized with concentrated HNO3 (nitric acid). Subsequently, Fe3O4 (magnetite) nanoparticles were deposited on the MWCNTs to prepare a magnetite/MWCNTs (Fe-MWCNTs) nanocomposite. Then, polyethylene was added to the Fe-MWCNTs to fabricate a polyethylene/magnetite/MWCNTs (PE/Fe-MWCNTs) novel nanocomposite. The nano-adsorbent was characterized using BET, FTIR, Raman, XRD, TEM, and SEM. A kerosene-water model mixture was used for adsorption tests. Several parameters: adsorption time, adsorbent dose, solution pH, solution temperature, and kerosene concentration in the kerosene-water model mixture, were analyzed during adsorption experiments. After each batch experiment, kerosene concentration was determined using high-performance liquid chromatography (HPLC). Magnetic field was used to remove the adsorbent after each experiment. The kerosene adsorption capacity and removal efficiency of the PE/Fe-MWCNTs nanocomposite (3560 mg/g and 71.2 %, respectively) were higher than those of Fe-MWCNTs, ox-MWCNTs, and fresh MWCNTs (3154 mg/g and 63.1 %, 2204 mg/g and 44.0 %, and 2092 mg/g and 41.8 %, respectively). Kerosene adsorption followed a pseudo-second-order kinetic model (R2 = 0.999) and the Langmuir isotherm model, suggesting that adsorption was uniform and homogenous process.

Sustainable carbonaceous biochar adsorbents derived from agro-wastes and invasive plants for cation dye adsorption from water.

This study investigated methyl orange (MO) dye adsorption using three biochars produced from agro-waste and invasive plants; the latter consisted of wattle bark (BA), mimosa (BM), and coffee husks (BC). BC had the lowest specific surface area (2.62 m2/g) compared to BA (393.15 m2/g) and BM (285.53 m2/g). The adsorption efficiency of MO was stable at pH 2-7 (95%-96%), whilst it had reduced stability at pH 7-12. Between 0 and 30 min, MO adsorption efficiency was >82%, and at 120 min, representative adsorption equilibrium had occurred. The maximum adsorption capacity of the biochars was 12.3 mg/g. The underlying adsorption mechanisms of the three biochars were governed by electrostatic adsorption and pore diffusion. There was an abundance of active sites for adsorption in BA and BM, while chemical adsorption appeared to be more vital for BC, as it contained more functional groups on its surface. The highest MO adsorption efficiency occurred with BM. BC was not recommended for MO removal, as it was observed to stain the water when a dose exceeding 5.0 g/L was utilized.

Effects of radiation and role of plants in radioprotection: A critical review.

Radiation can be lethal at high doses, whereas controlled doses are useful in medical applications. Other applications include power generation, agriculture sterilization, nuclear weapons, and archeology. Radiation damages genetic material, which is reflected in genotoxicity and can cause hereditary damage. In the medical field, it is essential to avoid the harmful effects of radiation. Radiation countermeasures and the need for radioprotective agents have been explored in recent years. Considering plants that evolve in radiative conditions, their ability to protect organisms against radiation has been studied and demonstrated. Crude extracts, fractioned extracts, isolated phytocompounds, and plant polysaccharides from various plants have been used in radioprotection studies, and their efficiency has been proven in various in vitro and in vivo experimental models. It is important to identify the mechanism of action to develop a potent plant-based radioprotective agent. To identify this protective mechanism, it is necessary to understand the damage caused by radiation in biological systems. This review intends to discuss the effects of ionizing radiation on biological systems and evaluate plant-based radioprotectants that have tested thus far as well as their mechanism of action in protecting against the toxic effects of radiation. From the review, the mechanism of radioprotection exhibited by the plant-based products could be understood. Meanwhile, we strongly suggest that the potential products identified so far should undergo clinical trials for critically evaluating their effects and for developing an ideal and compatible radioprotectant with no side-effects.

Scalable Fabrication of Modified Graphene Nanoplatelets as an Effective Additive for Engine Lubricant Oil.

The use of nano-additives is widely recognized as a cheap and effective pathway to improve the performance of lubrication by minimizing the energy loss from friction and wear, especially in diesel engines. In this work, a simple and scalable protocol was proposed to fabricate a graphene additive to improve the engine lubricant oil. Graphene nanoplates (GNPs) were obtained by a one-step chemical exfoliation of natural graphite and were successfully modified with a surfactant and an organic compound to obtain a modified GNP additive, that can be facilely dispersed in lubricant oil. The GNPs and modified GNP additive were characterized using scanning electron microscopy, X-ray diffraction, atomic force microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The prepared GNPs had wrinkled and crumpled structures with a diameter of 10-30 µm and a thickness of less than 15 nm. After modification, the GNP surfaces were uniformly covered with the organic compound. The addition of the modified GNP additive to the engine lubricant oil significantly enhanced the friction and antiwear performance. The highest reduction of 35% was determined for the wear scar diameter with a GNP additive concentration of approximately 0.05%. The mechanism for lubrication enhancement by graphene additives was also briefly discussed.

Two-step system consisting of novel vertical flow and free water surface constructed wetland for effective sewage treatment and reuse.

This study developed a unique system by combining the novel vertical flow (NVF) using expanded clay (ExC) and free flow surface constructed wetland (FWS) for dormitory sewage purification and reuse. The NVF tank consisted of filter layers of ExC, sandy soil, sand, and gravel. The FWS consisted of sandy soil substrate and was installed after the NVF. Colocasia esculenta and Dracaena sanderiana was planted in NVF and FWS, respectively. The treatment system was operated and tested for more than 21 weeks by increasing the hydraulic loading rate (HLR) from 0.02 m/d to 0.12 m/d. The results demonstrated that effluents in the system changed proportionally to the HLRs, except for nitrate nitrogen. Furthermore, the maximum removal efficiencies for TSS, BOD5, NH4-N, and Tcol were 76 ± 13%, 74 ± 11%, 90 ± 3%, and 59 ± 18% (0.37 ± 0.19 log10MPN/100 mL), respectively. At HLRs of 0.04-0.06 m/d, the treatment system satisfied the limits of agriculture irrigation.

A hybrid constructed wetland for organic-material and nutrient removal from sewage: Process performance and multi-kinetic models.

A pilot-scale hybrid constructed wetland with vertical flow and horizontal flow in series was constructed and used to investigate organic material and nutrient removal rate constants for wastewater treatment and establish a practical predictive model for use. For this purpose, the performance of multiple parameters was statistically evaluated during the process and predictive models were suggested. The measurement of the kinetic rate constant was based on the use of the first-order derivation and Monod kinetic derivation (Monod) paired with a plug flow reactor (PFR) and a continuously stirred tank reactor (CSTR). Both the Lindeman, Merenda, and Gold (LMG) analysis and Bayesian model averaging (BMA) method were employed for identifying the relative importance of variables and their optimal multiple regression (MR). The results showed that the first-order-PFR (M2) model did not fit the data (P > 0.05, and R2 < 0.5), whereas the first-order-CSTR (M1) model for the chemical oxygen demand (CODCr) and Monod-CSTR (M3) model for the CODCr and ammonium nitrogen (NH4-N) showed a high correlation with the experimental data (R2 > 0.5). The pollutant removal rates in the case of M1 were 0.19 m/d (CODCr) and those for M3 were 25.2 g/m2∙d for CODCr and 2.63 g/m2∙d for NH4-N. By applying a multi-variable linear regression method, the optimal empirical models were established for predicting the final effluent concentration of five days' biochemical oxygen demand (BOD5) and NH4-N. In general, the hydraulic loading rate was considered an important variable having a high value of relative importance, which appeared in all the optimal predictive models.