Adsorptive removal of anthracene from water by biochar derived amphiphilic carbon dots decorated with chitosan.

Anthracene belongs to the polycyclic aromatic hydrocarbon (PAH) consisting of benzene rings, unusually highly stable through more π-electrons and localized π-bond in entire rings. Aqueous-phase anthracene adsorption using carbon-based materials such as biochar is ineffective. In this paper, carbon dots (CDs) derived from the acid treatment of coconut shell biochar (CDs/MCSB) decorated with chitosan (CS) are successfully synthesized and applied for anthracene removal from aqueous solutions. The h-CDs/MCSB exhibited fast adsorption of anthracene with significant sorption capacity (Qmax = 49.26 mg g-1) with 95 % removal efficiency at 60 min. The study suggested chemisorption dominated monolayer anthracene adsorption onto h-CDs/MCSB, where a significant role was played by ion-exchange. Density Functional Theory (DFT) suggested the anthracene adsorption was dominated by the electrostatic interactions and delocalized electron, induced by higher polarizability of functional groups on the surface of hybrid CDs/MCSB assisted by chitosan (h-CDs/MCSB). In addition, the aromatic structure of CDs/MCSB and high polarizability of functional groups provided the strong interactions between benzene rings of anthracene and hybrid adsorbent-assisted multiple π-bond through delocalized π-bond and polarization-induced H-bond interactions. The presence of carboxylic and sulfonic groups on the CDs/MCSB surface also contributed to the effective adsorption of anthracene was confirmed by the fluorescence spectra. The results showed that the hybrid adsorbent was an effective material for removing PAHs, usually difficult to remove from water owing to the presence of benzene rings in their structures. Further, consistency in the DFT results suggested the outstanding binding capacity with the anthracene molecules with h-CDs/MCSB.

Iodide Removal by Resorcinol-Formaldehyde Carbon Aerogels.

The adsorption technique is widely used in water purification, and its efficiency can be significantly improved by target-specific adsorbent design. Research on iodine and its ion removal from water has attracted a great deal of interest due to increased concentrations in the environment and acute toxic effects, e.g., in human thyroid cells. In this work, the iodide removal performance of two high-surface-area resorcinol-formaldehyde-based carbon aerogels was studied under acidic conditions. The BET surface area was 790 m2/g (RF_ac) and 375 m2/g (RMF-GO), with a corresponding micropore ratio of 36 and 26%, respectively. Both aerogels showed outstanding adsorption capacity, exceeding the reported performance of other carbons and Ag-doped materials. Owing to its basic nature, the RMF-GO carbon aerogel showed higher I- capacity, up to 97 mg/g, than the acidic RF_ac, which reached a capacity of 82 mg/g. The surface chemistry of the aerogels also played a distinct role in the removal. In terms of kinetics, RF_ac removed 60% of the iodide ions and RMF-GO 30% within 8 h. The removal kinetics was of the first order, with a half-life of 1.94 and 1.70 h, respectively.

Green-Synthesized Silver Nanoparticle-Assisted Radiofrequency Ablation for Improved Thermal Treatment Distribution.

Thermal ablation therapy is known as an advantageous alternative to surgery allowing the treatment of multiple tumors located in hard-to-reach locations or treating patients with medical conditions that are not compatible with surgery. Appropriate heat propagation and precise control over the heat propagation is considered a weak point of thermal ablation therapy. In this work, silver nanoparticles (AgNPs) are used to improve the heat propagation properties during the thermal ablation procedure. Green-synthesized silver nanoparticles offer several attractive features, such as excellent thermal conductivity, biocompatibility, and antimicrobial activity. A distributed multiplexed fiber optic sensing system is used to monitor precisely the temperature change during nanoparticle-assisted radiofrequency ablation. An array of six MgO-based nanoparticles doped optical fibers spliced to single-mode fibers allowed us to obtain the two-dimensional thermal maps in a real time employing optical backscattering reflectometry at 2 mm resolution and 120 sensing points. The silver nanoparticles at 5, 10, and 20 mg/mL were employed to investigate their heating effects at several positions on the tissue regarding the active electrode. In addition, the pristine tissue and tissue treated with agarose solution were also tested for reference purposes. The results demonstrated that silver nanoparticles could increase the temperature during thermal therapies by propagating the heat. The highest temperature increase was obtained for 5 mg/mL silver nanoparticles introduced to the area close to the electrode with a 102% increase of the ablated area compared to the pristine tissue.

Anaerobic Membrane Bioreactors for Municipal Wastewater Treatment: A Literature Review.

Currently, there is growing scientific interest in the development of more economic, efficient and environmentally friendly municipal wastewater treatment technologies. Laboratory and pilot-scale surveys have revealed that the anaerobic membrane bioreactor (AnMBR) is a promising alternative for municipal wastewater treatment. Anaerobic membrane bioreactor technology combines the advantages of anaerobic processes and membrane technology. Membranes retain colloidal and suspended solids and provide complete solid-liquid separation. The slow-growing anaerobic microorganisms in the bioreactor degrade the soluble organic matter, producing biogas. The low amount of produced sludge and the production of biogas makes AnMBRs favorable over conventional biological treatment technologies. However, the AnMBR is not yet fully mature and challenging issues remain. This work focuses on fundamental aspects of AnMBRs in the treatment of municipal wastewater. The important parameters for AnMBR operation, such as pH, temperature, alkalinity, volatile fatty acids, organic loading rate, hydraulic retention time and solids retention time, are discussed. Moreover, through a comprehensive literature survey of recent applications from 2009 to 2021, the current state of AnMBR technology is assessed and its limitations are highlighted. Finally, the need for further laboratory, pilot- and full-scale research is addressed.

Synthetic Amphoteric Cryogels as an Antidote against Acute Heavy Metal Poisoning.

The effectiveness of an amphoteric cryogel (AAC) as an oral sorbent (enerosorbent) for the treatment of acute poisoning of small animals (rats) with heavy metals (HMs) was studied in in vivo experiments. The morphological structure of the cryogel was examined using scanning electron microscopy/energy-dispersive X-ray analysis and confocal microscopy. The use of the cryogel in the treatment of rats administered an LD50 dose of Cd(NO3)2, CsNO3, Sr(NO3)2, or HgCl2 in aqueous solution showed their high survival rate compared to the control group, which did not receive such treatment. The histological and chemical analysis of internal tissues and the biochemical analysis of the blood of the experimental animals showed the effectiveness of the cryogel in protecting the animals against the damaging effect of HMs on the organism comparable with unithiol, a chelating agent based on 2,3-dimercapto-1-propane sulfonic acid sodium salt (DMPS) approved for the treatment of acute poisoning with some heavy metals.

Measuring the level of environmental performance in insular areas, through key performed indicators, in the framework of waste strategy development.

To measure "something that is not there", is not easy and at the same time not fully understandable and perceived by the citizens. Several elements (such as, waste production, waste management cost, social attitude and behaviour, etc.) interrupt and disturb any strategy in the framework of waste management. Additionally, through the European Green Deal (EGD), Europe is trying to achieve climate neutrality by 2050, taking into account the Circular Economy Strategy (CES) and the United Nations Sustainable Development Goals (UNSDGs). A Driving Force-Pressure-State-Impact-Response (DPSIR) breakdown was applied, to establish and organize key information's on the environmental performance (E.P) taking into consideration the existing pollution, reviewing the contemporary knowledge and existing implemented waste strategies on the driving forces, pressures, states and impacts. This paper includes several key performed indicators (KPIs), in order to evaluate the E.P of an area, through hybrid approach which cover among others, the waste compositional analysis, SWOT and PESTEL analysis, waste recycling and waste accumulation index, prevention activities, awareness activities etc. The results indicate that, the selected areas implement periodic measures, but they need to put more effort to boost their citizens to participate in any proposed waste strategy. Furthermore, the results are very valuable and helpful to policy makers, consultants, scientists, competent authorities, stakeholders etc., in order to design and promote synergies and activities (mainly in Local Authorities), to reach the proposed figures that EGD, proposed in relation with the CES as well as with the SDGs.

Sustainable metropolitan areas perspectives through assessment of the existing waste management strategies.

Human activities are considered among the main producers of any kind of pollution. This paper, through a Driver-Pressure-State-Impact-Response (DPSIR) model analyses, focuses on the evaluation and assessment of the existing practices, procedures, and results obtained in order to determine whether the municipal solid waste (MSW) management implemented in three major Greek municipalities in the greater urban area of Attica, namely the municipalities of Nea Smirni, Vyronas, and Piraeus, could be considered viable and sustainable. The evaluation indicated that MSW in Greek cities have reduced over the last years, also suggesting a steady downward trend, which could be considered consistent with that of the per capita incomes in Greece due to the extended economic austerity, while at the same time the recycling indicator seems to optimize. The results are very useful for policymakers and local authorities towards taking actions related to the targets set from the circular economy strategies as well as the targets set from United Nation Development Program and the European Green Deal Strategy.

Effective photochemical treatment of a municipal solid waste landfill leachate.

This work aimed at studying the photochemical treatment of a landfill leachate using ultraviolet light, hydrogen peroxide, and ferrous or ferric ions, in a batch recycle photoreactor. The effect of inorganic carbon presence, pH, initial H2O2 amount (0-9990 mg L-1) as well as Fe(II) (200-600 ppm) and Fe(III) (300-700 ppm) concentrations on the total carbon removal and color change was studied. Prior to the photochemical treatment, a pretreatment process was applied; inorganic nitrogen and inorganic carbon were removed by means of air stripping and initial pH regulation, respectively. The leachate sent subsequently for photochemical treatment was free of inorganic carbon and contained only organic carbon with concentration 1200±100 mg L-1 at pH 5.1-5.3. The most favorable concentrations of H2O2 and ferric ions for carbon removal were 6660 mg L-1 and 400 ppm, respectively. Adjusting the initial pH value in the range of 2.2-5.3 had a significant effect on the organic carbon removal. The photo-Fenton-like process was more advantageous than the photo-Fenton one for leachate treatment. By applying the most favorable operating conditions, 88.7% removal of total organic carbon, 100% removal of total inorganic carbon, 96.5% removal of total nitrogen, and 98.2% color removal were achieved.

Distributed 2D temperature sensing during nanoparticles assisted laser ablation by means of high-scattering fiber sensors.

The high demand in effective and minimally invasive cancer treatments, namely thermal ablation, leads to the demand for real-time multi-dimensional thermometry to evaluate the treatment effectiveness, which can be also assisted by the use of nanoparticles. We report the results of 20-nm gold and magnetic iron oxide nanoparticles-assisted laser ablation on a porcine liver phantom. The experimental set-up consisting of high-scattering nanoparticle-doped fibers was operated by means of a scattering-level multiplexing arrangement and interrogated via optical backscattered reflectometry, together with a solid-state laser diode operating at 980 nm. The multiplexed 2-dimensional fiber arrangement based on nanoparticle-doped fibers allowed an accurate superficial thermal map detected in real-time.

Surface Interactions and Mechanisms Study on the Removal of Iodide from Water by Use of Natural Zeolite-Based Silver Nanocomposites.

In this work a natural zeolite was modified with silver following two different methods to derive Ag2O and Ag0 nanocomposites. The materials were fully characterized and the results showed that both materials were decorated with nanoparticles of size of 5-25 nm. The natural and modified zeolites were used for the removal of iodide from aqueous solutions of initial concentration of 30-1400 ppm. Natural zeolite showed no affinity for iodide while silver forms were very efficient reaching a capacity of up to 132 mg/g. Post-adsorption characterizations showed that AgI was formed on the surface of the modified zeolites and the amount of iodide removed was higher than expected based on the silver content. A combination of experimental data and characterizations indicate that the excess iodide is most probably related to negatively charged AgI colloids and Ag-I complexes forming in the solution as well as on the surface of the modified zeolites.

Behaviour of Aquaporin Forward Osmosis Flat Sheet Membranes during the Concentration of Calcium-Containing Liquids.

This study aims to examine the scaling and performance of flat sheet aquaporin FO membranes in the presence of calcium salts. Experiments showed that the application of calcium sulphate (CaSO4) resulted in an 8%-78% decline in the water flux. An increase in the cross-flow velocity from 3 to 12 cm/s reduced the decline in the flux by 16%. The deposition of salt crystals on the membrane surface led to the alteration in the membrane's intrinsic properties. Microscopy, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and X-Ray fluorescence (XRF) analyses confirmed measurements of the zeta potential and contact angle. The use of a three-salt mixture yielded severe scaling as compared with the application of calcium sulphate dehydrate (CaSO4 × 2H2O), i.e., a result of two different crystallisation mechanisms. We found that the amount of sodium chloride (NaCl), saturation index, cross-flow velocity, and flow regime all play an important role in the scaling of aquaporin FO flat sheet membranes.

A review of cryogels synthesis, characterization and applications on the removal of heavy metals from aqueous solutions.

The physical and chemical attributes of cryogels, such as the macroporosity, elasticity, water permeability and ease of chemical modification have attracted strong research interest in a variety of areas, such as water purification, catalysis, regenerative medicine, biotechnology, bioremediation and biosensors. Cryogels have shown high removal efficiency and selectivity for heavy metals, nutrients, and toxic dyes from aqueous solutions but there are challenges when scaling up from lab to commercial scale applications. This paper represents an overview of the most recent advances in the use of cryogels for the removal of heavy metals from water and attempts to fill the gap in the literature by deepening the understanding on the mechanisms involved, which strongly depend on the initial monomer composition and post-modification agent precursors used in synthesis. The review also describes the advantages of cryogels over other adsorbents and covers synthesis and characterization methods such as SEM/EDS, TEM, FTIR, zeta potential measurements, porosimetry, swelling and mechanical properties.

Degradation and mineralization of 4-tert-butylphenol in water using Fe-doped TiO2 catalysts.

In the present work, the photocatalytic degradation and mineralization of 4-tert-butylphenol in water was studied using Fe-doped TiO2 nanoparticles under UV light irradiation. Fe-doped TiO2 catalysts (0.5, 1, 2 and 4 wt.%) were prepared using wet impregnation and characterized via SEM/EDS, XRD, XRF and TEM, while their photocatalytic activity and stability was attended via total organic carbon, 4-tert-butyl phenol, acetic acid, formic acid and leached iron concentrations measurements. The effect of H2O2 addition was also examined. The 4% Fe/TiO2 demonstrated the highest photocatalytic efficiency in terms of total organic carbon removal (86%). The application of UV/H2O2 resulted in 31% total organic carbon removal and 100% 4-t-butylphenol conversion, however combining Fe/TiO2 catalysts with H2O2 under UV irradiation did not improve the photocatalytic performance. Increasing the content of iron on the catalyst from 0.5 to 4% considerably decreased the intermediates formed and increased the production of carbon dioxide. The photocatalytic degradation of 4-tert-butylphenol followed pseudo-second order kinetics. Leaching of iron was observed mainly in the case of 4% Fe/TiO2, but it was considered negligible taking into account the iron load on catalysts. The electric energy per order was found in the range of 28-147 kWh/m3/order and increased with increasing the iron content of the catalyst.

Seasonal characterisation of municipal solid waste from Astana city, Kazakhstan: Composition and thermal properties of combustible fraction.

This study presents the results of a seasonal municipal solid waste composition campaign, that took place over the period of September 2017 to June 2018 in the capital city of Kazakhstan, Astana. Four sampling campaigns were conducted in order to identify the seasonal variation of municipal solid waste composition, recyclables and energy potential materials, such as combustible fraction, useful for the evaluation of waste-to-energy potential. The combustible fraction was analysed for thermal fuel properties, such as proximate and elemental analyses and gross calorific value. The results over the four different seasons showed that the average recyclable fraction of municipal solid waste on a wet basis of 33.3 wt.% and combustibles fraction was 8.3 wt.%. The largest fraction was the organics (47.2 wt.%), followed by plastic (15.4 wt.%) and paper (12.5 wt.%). Small seasonal variations were observed for organics, paper, plastic and glass fractions. The highest values were found in summer for the organic waste, in spring for paper and plastic and autumn for glass. The recyclables fraction showed an absolute seasonal variation of 5.7% with a peak in the winter season (35.4%) and the combustibles fraction showed a seasonal variation between 8.3 wt.% to 9.4 wt.%. Finally, the average calorific value of the combustible fraction was estimated to be 21.6 MJ kg-1 on a dry basis.

Photocatalytic treatment of organic pollutants in a synthetic wastewater using UV light and combinations of TiO2, H2O2 and Fe(III).

In this study, the photocatalytic treatment of an organic wastewater with/without phenolic compounds by means of ultraviolet irradiation, titanium dioxide and hydrogen peroxide was examined in an annular photoreactor. Specifically, the effect of initial total carbon concentration, catalyst loading and H2O2 amount on the removal of total carbon was first examined in the case of a synthetic organic wastewater. The influence of partial carbon substitution by phenol, 2-chlorophenol, 2,4-discholophenol, trichlorophenol, and 4-nitrophenol on total carbon removal and target compounds' conversion was studied keeping constant the initial organic carbon load. It was shown that the process applied was effective in treating the wastewater for initial total carbon 32 mg L-1, 0.5 g L-1 TiO2, and 66.6 mg L-1 H2O2. Applying UV/TiO2 and UV/H2O2, 58% and 53% total carbon removals were achieved, respectively, but combining TiO2 and H2O2 did not result in a better performance in the case of the synthetic wastewater without any phenolic compounds. In contrast, when a phenolic compound was added, the addition of H2O2 was beneficial, eliminating the differences observed from one phenolic compound to another. The total carbon removals observed were lower than the corresponding final conversions of the target phenolic compounds. Finally, the electric energy per order values were calculated and found to range in 52-248 kWh/m3/order, being dependent from the process applied and the phenolic compound present in the wastewater.

Temperature Profiling of ex-vivo Organs during Ferromagnetic Nanoparticles-Enhanced Radiofrequency Ablation by Fiber Bragg Grating Arrays.

In this paper, we present real-time profiles of temperature during a ferromagnetic nanoparticles (NPs)enhanced radiofrequency ablation (RFA). A minimally invasive RFA setup has been prepared and applied ex vivo on a liver phantom; NPs (with concentration of 5 mg/mL) have been synthetized and injected within the tissue prior to perform the ablation, in order to facilitate the heat distribution to the peripheral sides of the ablated tissue. Temperature detection has been realized in situ with a network of 15 fiber Bragg grating (FBG) sensors in order to highlight the impact of the NPs on the RFA mechanism. Obtained temperature profiles and thermal maps confirm that nanoparticles injection ensures better heat penetration than in case of pristine RFA procedure. The results show that adding NPs solution leads to extending the successfully ablated area achieving a double-sized lesion.

Investigation of rice husk derived activated carbon for removal of nitrate contamination from water.

Development of porous carbons with high specific surface area (>1200mg-1) targeted at nitrate removal from aqueous solutions is investigated by chemical activation of carbonized rice husk. Potassium carbonate is used as activating and desilicating agent. The effect of post-synthetic treatment by gas phase ammoxidation with ozone/ammonia or oxidation with concentrated nitric acid followed by nitrification with urea on main physicochemical properties and on the effectiveness of the activated carbons in nitrate removal is compared with those determined for a pristine activated carbonized rice husk sample. The two-fold enhancement of nitrate removal by the urea-modified activated carbon in comparison with pristine and ammoxidated sample is in direct correlation with the development of surface basic groups.

Comparison between landfill gas and waste incineration for power generation in Astana, Kazakhstan.

The city of Astana, the capital of Kazakhstan, which has a population of 804,474, and has been experiencing rapid growth over the last 15 years, generates approximately 1.39 kg capita(-1) day(-1) of municipal solid waste (MSW). Nearly 700 tonnes of MSW are collected daily, of which 97% is disposed of at landfills. The newest landfill was built using modern technologies, including a landfill gas (LFG) collection system.The rapid growth of Astana demands more energy on its path to development, and the viability analysis of MSW to generate electricity is imperative. This paper presents a technical-economic pre-feasibility study comparing landfill including LFG utilization and waste incineration (WI) to produce electricity. The performance of LFG with a reciprocating engine and WI with steam turbine power technologies were compared through corresponding greenhouse gases (GHG) reduction, cost of energy production (CEP), benefit-cost ratio (BCR), net present value (NPV) and internal rate of return (IRR) from the analyses. Results demonstrate that in the city of Astana, WI has the potential to reduce more than 200,000 tonnes of GHG per year, while LFG could reduce slightly less than 40,000 tonnes. LFG offers a CEP 5.7% larger than WI, while the latter presents a BCR two times higher than LFG. WI technology analysis depicts a NPV exceeding 280% of the equity, while for LFG, the NPV is less than the equity, which indicates an expected remarkable financial return for the WI technology and a marginal and risky scenario for the LFG technology. Only existing landfill facilities with a LFG collection system in place may turn LFG into a viable project.

Household hazardous waste management: a review.

This paper deals with the waste stream of household hazardous waste (HHW) presenting existing management systems, legislation overview and other relevant quantitative and qualitative information. European Union legislation and international management schemes are summarized and presented in a concise manner by the use of diagrams in order to provide crucial information on HHW. Furthermore, sources and types, numerical figures about generation, collection and relevant management costs are within the scope of the present paper. The review shows that the term used to refer to hazardous waste generated in households is not clearly defined in legislation, while there is absence of specific acts regulating the management of HHW. The lack of obligation to segregate HHW from the household waste and the different terminology used makes it difficult to determine the quantities and composition of this waste stream, while its generation amount is relatively small and, therefore, is commonly overlooked in waste statistics. The paper aims to cover the gap in the related literature on a subject that is included within the crucial waste management challenges at world level, considering that HHW can also have impact on other waste streams by altering the redox conditions or causing direct reactions with other non hazardous waste substances.