Functional metal-organic framework as high-performance adsorbent for selective enrichment of pharmaceutical contaminants in aqueous samples

Facile and sensitive analysis methods for pharmaceutical contaminants in aqueous environment are of vital importance for water safety, especially when large amounts of anti-viral drugs are being used, discharged and accumulated. In this work, we used functional metal-organic framework (MOF) as high-performance adsorbent for selective enrichment of such pharmaceutical contaminants in aqueous samples. The MOF was synthesized via a new synthesis method previously developed by our group and immobilized on paper membrane to be used in solid-phase extraction (SPE) device. Different metal ions were anchored by MOF to screen out the adsorbent with the best affinity. The targets were a potential anti-COVID-19 drug favipiravir, and its structural and functional analogues (ingredients or intermediates, other anti-viral drugs). To deeply understand the adsorption mechanisms, quantum calculation and computational fluid dynamics (CFD) simulation were both applied. The experimental and in-silico results together demonstrated that the as-prepared MOF adsorbent possessed high affinity and fast dynamics. The established SPE-based liquid chromatography (LC) method worked well in the range of 10-1000 ng/mL, with only 3 mg of adsorbent per device and 5 mL sample needed, and no mass spectrometer (MS) included, which was very efficient compared to commercial adsorbents. The results met the current detection needs in the application scenario, and inspirable for later design of well-behaved adsorbents.

Removal of ivermectin from aqueous media using commercial, bentonite-based organophilic clay as an adsorbent

The worldwide use of pharmaceuticals is of concern to those researchers who develop new techniques for the removal of these compounds from the aquatic medium. The objective of the present work was to characterize and evaluate the performance of a commercial, bentonite-based organophilic clay in removing ivermectin from aqueous solution. The adsorbent was characterized by nitrogen physisorption, thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Batch-scale adsorption experiments were performed to evaluate the kinetics, isotherms, thermodynamics and effect of pH on removal of this drug and reuse of the clay. The bentonite has a small specific surface area with an irregular surface. The Elovich kinetic model fits the experimental data better than other models, indicating that chemisorption contributes to drug removal in this case. The Langmuir and Sips isothermal models best fit the experimental equilibrium data. The process was shown to be favorable (ΔG°ads<0), endothermic (ΔH°ads>0), with an increase in the degrees of freedom at the solid–liquid interface (ΔS°ads>0), and with characteristics of a physical-chemical adsorption process (Ea = 11.065 kJ mol–1) under the study conditions. Adsorption was favored at the natural pH of the solution and the organophilic clay could be regenerated with water and reused in consecutive adsorption cycles. The amount of ivermectin adsorbed on the organophilic clay ranged from 1.78 to 3.88 mg g–1. The organophilic clay was shown to be a cost-effective potential adsorbent for ivermectin-contaminated water-treatment applications.

A Systematic Review of Amino Acid-Based Adsorbents for CO2 Capture

The rise of carbon dioxide (CO2) levels in the atmosphere emphasises the need for improving the current carbon capture and storage (CCS) technology. A conventional absorption method that utilises amine-based solvent is known to cause corrosion to process equipment. The solvent is easily degraded and has high energy requirement for regeneration. Amino acids are suitable candidates to replace traditional alkanolamines attributed to their identical amino functional group. In addition, amino acid salt is a green material due to its extremely low toxicity, low volatility, less corrosive, and high efficiency to capture CO2. Previous studies have shown promising results in CO2 capture using amino acids salts solutions and amino acid ionic liquids. Currently, amino acid solvents are also utilised to enhance the adsorption capacity of solid sorbents. This systematic review is the first to summarise the currently available amino acid-based adsorbents for CO2 capture using PRISMA method. Physical and chemical properties of the adsorbents that contribute to effective CO2 capture are thoroughly discussed. A total of four categories of amino acid-based adsorbents are evaluated for their CO2 adsorption capacities. The regeneration studies are briefly discussed and several limitations associated with amino acid-based adsorbents for CO2 capture are presented before the conclusion.

The Diffusion Behavior of CO2 Adsorption from a CO2/N2 Gas Mixture on Zeolite 5A in a Fixed-Bed Column

The objective of this research was to investigate the behavior and conditions for CO2 adsorption using a mixture of CO2/N2 over a fixed-bed column of zeolite 5A. The study was performed with a variation in gas composition of CO2/N2 as a 20/80, 50/50, and 80/20 volume %, the adsorption temperatures as 298, 333, and 373 K and the total feed flow rates as 1, 2, and 4 L/h under 100 kPa pressure. The Bohart–Adams, Yoon–Nelson, and Thomas models were used to predict the breakthrough behavior of CO2 adsorption in a fixed column. Furthermore, the adsorption mechanism has been investigated using the kinetics adsorption of pseudo-first-order, pseudo-second-order, Boyd model, and intraparticle model. Increasing the CO2 composition of a gas mixture resulted in a high CO2 adsorption capacity because of the high partial pressure of CO2. The capacity of CO2 adsorption was decreased with increasing temperature because of physical adsorption with an exothermic reaction. The CO2 adsorption capacity was also decreased with increasing feed flow rates with inadequate time for CO2 adsorbates diffusion into the pores of the adsorbent before exiting the packed bed. The CO2 adsorption by zeolite 5A confirmed that the physical adsorption with intraparticle diffusion was the rate-controlling step of the whole process.

Novel adsorbents in remediation of hazardous environmental pollutants: Progress, selectivity, and sustainability prospects

Recent decades witness an enormous increase in concentrations of environmental contaminants of human health concern. The research efforts attempt to develop synthetic (chemicals) and natural (biological) adsorbents for remediation of hazardous heavy metals, pesticides, mycotoxins, antibiotics, and other emerging pollutants. However, application of potential adsorbents in remediation lack selectivity and sustainability prospects. Present review aims to provide a critical discussion on adsorption potential of synthetic and natural adsorbents in sustainability framework. The synthetic adsorbents are discussed in terms of recipes and underlying sorption mechanisms. Herein, pragmatic analysis on novel synthetic adsorbents like ferrate, following green chemistry principles and engineered nanoparticles (NPs) is elucidated. In natural biosorbents (both live and dead biomass), the phyto-technologies, biosorption, natural/engineered biochar, clay, and chitosan are comprehensively reviewed. This panoramic review revealed that phytoremediation and biosorption can be preferred as ‘sustainable bioresource eco-technologies’ for remediation of chemical pollution. The interrelationship between adsorbents and United Nations- Sustainable Development Goals (UN-SDGs) is established. Eco-friendly and cost-effective biosorbents tend to follow the sustainability paradigm unlike traditional chemical adsorbents. In conclusion, the ‘biorefinery’, ‘Water-Energy-Food Nexus’ and ‘biocircular economy’ co-benefits of biosorbents can augment the sustainability indicators to help achieve salient SDGs.

Transforming Plastic Waste into Porous Carbon for Capturing Carbon Dioxide: A Review

Plastic waste generation has increased dramatically every day. Indiscriminate disposal of plastic wastes can lead to several negative impacts on the environment, such as a significant increase in greenhouse gas emissions and water pollution. Therefore, it is wise to think of other alternatives to reduce plastic wastes without affecting the environment, including converting them into valuable products using effective methods such as pyrolysis. Products from the pyrolysis process encompassing of liquid, gas, and solid residues (char) can be turned into beneficial products, as the liquid product can be used as a commercial fuel and char can function as an excellent adsorbent. The char produced from plastic wastes could be modified to enhance carbon dioxide (CO2) adsorption performance. Therefore, this review attempts to compile relevant knowledge on the potential of adsorbents derived from waste plastic to capture CO2. This review was performed in accordance with PRISMA guidelines. The plastic-waste-derived activated carbon, as an adsorbent, could provide a promising method to solve the two environmental issues (CO2 emission and solid management) simultaneously. In addition, the future perspective on char derived from waste plastics is highlighted.

Studies on the CO2 Capture by Coal Fly Ash Zeolites: Process Design and Simulation

At present, mitigating carbon emissions from energy production and industrial processes is more relevant than ever to limit climate change. The widespread implementation of carbon capture technologies requires the development of cost-effective and selective adsorbents with high CO2 capture capacity and low thermal recovery. Coal fly ash has been extensively studied as a raw material for the synthesis of low-cost zeolite-like adsorbents for CO2 capture. Laboratory tests for CO2 adsorption onto coal fly ash zeolites (CFAZ) reveal promising results, but detailed computational studies are required to clarify the applicability of these materials as CO2 adsorbents on a pilot and industrial scale. The present study provides results for the validation of a simulation model for the design of adsorption columns for CO2 capture on CFAZ based on the experimental equilibrium and dynamic adsorption on a laboratory scale. The simulations were performed using ProSim DAC dynamic adsorption software to study mass transfer and energy balance in the thermal swing adsorption mode and in the most widely operated adsorption unit configuration.

Successful use of CytoSorb in a Covid-19 patient with secondary septic shock due to a sacral decubitus infection.

Septic shock is a clinical condition with high mortality (40%-70%) and morbidity. During septic shock, there is a significant release of cytokines and other inflammatory mediators that can cause damage to different organs, known as a "cytokine storm." The cytokine storm can cause hypotension, tissue damage, metabolic acidosis, and renal failure. This clinical picture also seems to be confirmed in the context of Covid-19 patients. Hemoadsorption with CytoSorb represents an adjunctive therapy to attenuate the systemic inflammatory process and helps restore a balanced immune response. We present the clinical case of a 75-year-old man, admitted to our hospital with respiratory failure due to Sars-CoV-2 infection and secondary septic shock due to a sacral decubitus. On admission the patient presented with a clinical picture of mixed acidosis with high levels of lactate and inflammatory indexes. Simultaneously along with antibiotic therapy, we started hemoadsorption treatment with CytoSorb in combination with continuous venous-venous hemodiafiltration. At the end of the treatment the patient had recovered his vital functions and the infection was successfully treated. Use of the CytoSorb device in a Covid-19 positive patient was safe and well-tolerated. Early treatment with CytoSorb decreased interleukin 6 plasma levels and inflammatory indexes, resulting in earlier stabilization of homeostasis. This case report suggests that the use of CytoSorb could be a possible adjuvant therapy in patients with septic shock even when affected by Covid-19.

SARS-CoV-2: Disinfection Strategies to Prevent Transmission of Neuropathogens via Air Conditioning Systems.

Several lines of evidence suggest the role of air-conditioning systems in the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Furthermore, the likelihood of novel coronavirus to take refuge inside a microbial Trojan horse, that is, Acanthamoeba, can further enhance possibility of SARS-CoV-2 transmission in the environment. Here we propose the use of various disinfection strategies that can be employed using filters with antimicrobial fabricated surfaces or using UV irradiation to achieve germicidal properties for removal of pathogenic microbes such as SARS-CoV-2 and amoebae in the ventilation systems.

Neuropathogens and Nasal Cleansing: Use of Clay Montmorillonite Coupled with Activated Carbon for Effective Eradication of Pathogenic Microbes from Water Supplies.

Herein, we propose the use of novel adsorbents, namely micelle clay complexes comprising the clay montmorillonite, coupled with activated carbon for effective eradication of neuropathogenic microbes such as SARS-CoV-2 and Naegleria fowleri from water supplies for ablution/nasal irrigation. These can be incorporated easily to water collection devices, i.e., taps and water bottles, in the domestic setting. These filters are low cost, easy to install, and ideal disinfection systems. Such strategies are particularly useful for communities who have lack of access to safe water supplies, rely heavily on water storage tanks, or lack adequate water sanitation facilities, especially in developing countries.