Removal Of Metformin Research Articles

Natural zeolite as adsorbent for metformin removal from aqueous solutions: Adsorption and regeneration properties

Drugs are being registered in water resources around the world, becoming a palpable environmental problem by altering the natural characteristics of water and, consequently, altering the environment of living organisms. Many techniques can be used to remove drugs present in contaminated waters, among them stands out the adsorption process. In this work, the adsorption of metformin, an antidiabetic drug, using a commercial natural zeolite as an adsorbent was investigated. The material was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray diffractometry (XRD), X-ray Fluorescence (XRF), N2 adsorption/desorption analysis and zeta potential. The efficiency of metformin removal was evaluated under different pH conditions and adsorbent ratios. The most favorable conditions for adsorption were obtained for 1 g/L of zeolite and pH 7.0. The pseudo-second order had a better correlation with the experimental kinetic data, with equilibrium obtained after 6 h, reaching 76 % of removal and adsorption capacity of 6.8 mg/g. The Langmuir isotherm described well the equilibrium and the maximum adsorption capacity was 109 mg/g for 25 °C and 35 °C, and 130 mg/g for 45 °C. The Gibbs free energy for all temperatures studied was less than zero, which indicates a spontaneous process of metformin adsorption on the zeolite surface. NaOH solution showed the highest adsorbent regeneration efficiency, with approximately 36 % desorption in 6 h. It was possible to reuse the adsorbent for three consecutive cycles of adsorption/desorption. Afterward, there was a sudden decrease in the adsorption capacity and a collapsing effect on the material surface.

Highly Adsorptive Organic Xerogels for Efficient Removal of Metformin from Aqueous Solutions: Experimental and Theoretical Approach

Metformin, widely prescribed to treat type 2 diabetes for its effectiveness and low cost, has raised concerns about its presence in aqueous effluents and its potential environmental and public health impacts. To address this issue, xerogels were synthesized from resorcinol and formaldehyde, with molar ratios ranging from 0.05 to 0.40. These xerogels were thoroughly characterized using FT-IR, SEM, TGA, and TEM analyses. Batch adsorption experiments were performed with standard metformin solutions at concentrations of 50 and 500 mg/L, varying pH, and temperature to determine the adsorption isotherms of the synthesized xerogels. The adsorption data revealed a maximum adsorption capacity of 325 mg/g at pH 11 and 25 °C. Quantum chemical calculations revealed that electrostatic interactions govern metformin adsorption onto xerogels. The xerogels’ adsorption capacity was evaluated in competitive systems with CaCl2, NaCl, MgCl2, and synthetic urines. Reuse cycles demonstrated that xerogels could be reused for up to three cycles without any loss in adsorptive efficiency. The adsorption mechanisms of metformin in the adsorption process highlight the strong electrostatic interactions and hydrogen bonds between the adsorbate and the adsorbent material. Xerogels synthesized show promise as efficient adsorbents to remove metformin from aqueous solutions, helping to mitigate its environmental impact.

Development of a sustainable adsorption system based on alginate-encapsulated clay for pharmaceutical pollutant capture in aqueous solution using Box–Behnken methodology

Our study focused on the removal of metformin in aqueous solution. Metformin, an antidiabetic drug, is increasingly detected in wastewater. This study explored the feasibility of using bentonite encapsulated in sodium alginate as a sustainable and efficient sorbent for metformin removal. The adsorbent was characterized by RAMAN, Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), electron-dispersive spectrometer (EDS), and point of zero charge (pHzc). The adsorbent contains various functional groups including hydroxyl (-OH) groups from both bentonite and sodium alginate, carboxyl (-COOH) groups from sodium alginate, and silanol (-Si-OH) groups from bentonite. Batch kinetic studies were carried out as a function of pH, metformin concentration, sorbent amount, and solution temperature. The Freundlich and Langmuir models were used to describe the isotherm data. The maximum monolayer adsorption capacity of the sorbent material was 19,19 mgg−1. The pseudo-second order kinetic model adequately describes the kinetic data. The negative ΔH (−35,253 kJmol−1) confirms an exothermic process, which is further supported by the negative Gibbs energy values (−0,489 to −3,668 kJmol−1), indicating spontaneity and reversibility. Moreover, ΔS° = −0.105 kJ/mol−1.K−1. Response surface methodology was employed to identify the optimal parameters for metformin removal. These parameters were found to be: pH of 6.34, metformin concentration of 5.4 mgL−1, and adsorbent dosage of 3 g L−1 resulted in a remarkable efficiency of 94%. Additionally, bentonite beads (BBs) maintained a significant adsorption capacity for up to three cycles, demonstrating promising reusability. This study highlights that the encapsulation of clay in sodium alginate is a sustainable and effective approach for removing metformin during water treatment.

Photocatalytic degradation of metformin using TiO2-CuO heterojunctions synthesized by green chemistry and immobilized on beach sand granules in fluidized bed annular photoreactor (FBAP)

This research is focused on the degradation of metformin by heterogeneous photocatalysis using TiO2-CuO heterojunctions deposited on beach sand granules in a pilot-scale fluidized bed annular photoreactor (FBAP). The precursor metal oxides were prepared by green chemistry using an aqueous extract of Moringa (Moringa oleifera) and the heterojunctions by ultrasound-assisted wet impregnation for subsequent immobilization through a two-step immersion/calcination methodology. Batch tests showed a synergistic effect of the inorganic substrate due to its inherent adsorption. Besides, TC1 heterojunction (1 wt% of CuO) represents the best option for deposition due to its optical, morphological, and textural properties and favors its photocatalytic activity. Also, an optimal dose of the active phase of 1.0 g/L was identified, guaranteeing this load for the granular catalyst with 4 wt% (g of catalyst/g of beach sand).On the other hand, the values for the pHzpc were 6.45 and 7.26 units, allowing to determine optimal operating pH of 7 and 8 units, respectively, which is attributed to the interaction between the surface loads and the metformin-derived species present in the sample. Optimal values of 18.7 L/min achieved a maximum efficiency of 74.8 % and 3.0 wt% for volumetric flow and the TC1/S mass ratio, respectively; these operation parameters significantly influence the degradation efficiency. Further, the reaction rate was slightly higher for powdered samples against immobilized heterojunctions due to the mass transfer limitations, which generated a difference in performance close to 2.7 %. On the other hand, the reaction byproducts identified were MBG and 4,2,1-AIMT, which are harmless to the biological model C. elegans. Despite this, the segregated nanomaterials and the metal ions leached during the metformin removal generated lethal toxicity. These results reveal the proposed reactor's high potential for treating effluents contaminated metformin and other organic compounds using a granular catalyst with stable performance, including a centrifugation step that removes the segregated nanomaterials.

Metformin-associated lactic acidosis: A mini review of pathophysiology, diagnosis and management in critically ill patients

Metformin is a common diabetes drug that may reduce lactate clearance by inhibiting mitochondrial oxidative phosphorylation, leading to metformin-associated lactic acidosis (MALA). As diabetes mellitus is a common chronic metabolic condition found in critically ill patients, pre-existing metformin use can often be found in critically ill patients admitted to the intensive care unit or the high dependency unit. The aim of this narrative mini review is therefore to update clinicians about MALA, and to provide a practical approach to its diagnosis and treatment. MALA in critically ill patients may be suspected in a patient who has received metformin and who has a high anion gap metabolic acidosis, and confirmed when lactate exceeds 5 mmol/L. Risk factors include those that reduce renal elimination of metformin (renal impairment from any cause, histamine-2 receptor antagonists, ribociclib) and excessive alcohol consumption (as ethanol oxidation consumes nicotinamide adenine dinucleotides that are also required for lactate metabolism). Treatment of MALA involves immediate cessation of metformin, supportive management, treating other concurrent causes of lactic acidosis like sepsis, and treating any coexisting diabetic ketoacidosis. Severe MALA requires extracorporeal removal of metformin with either intermittent hemodialysis or continuous kidney replacement therapy. The optimal time to restart metformin has not been well-studied. It is nonetheless reasonable to first ensure that lactic acidosis has resolved, and then recheck the kidney function post-recovery from critical illness, ensuring that the estimated glomerular filtration rate is 30 mL/min/1.73 m2 or better before restarting metformin.

Synergistic catalysis by Fe-oxide-biochar modified with WS2/PMS system for the removal of metformin

Metformin (MET) is frequently detected in aquatic environments, with its presence posing potential risks to flora and fauna. To enhance the redox cycling efficiency of Fe2+/Fe3+ in the Fenton reaction, a catalyst WSF@BC was synthesized by innovatively loading WS2 and iron oxides onto reed biochar to construct a novel non-homogeneous Fenton-like system for the degradation of MET in wastewater. This study investigated various parameters such as initial pH, peroxymonosulfate dosage, and catalyst dosage to determine their effects on the degradation efficiency. The results indicated that MET was degraded by 85.1 % within 30 min. The synergistic effect of WS2 and FeOx distinctly improved the removal efficiency of MET in this system, whereby SO4− dominated the rapid degradation of MET, as demonstrated by radical quenching experiments, electron paramagnetic resonance spectrometry (EPR) studies, and X-ray photoelectron spectroscopy (XPS) analysis. Frontier orbital theory calculations and intermediate product analyses revealed that the main reaction sites for MET degradation were CN and CN, resulting in reduced toxicity of degradation products. Three potential degradation pathways of MET via denitrification, amino oxidation, and hydroxylation were proposed by theoretical predictions and LC-MS/MS analysis. Additionally, characterization and recycling outcomes demonstrated excellent stability and reusability of the catalyst. This research highlights the significant application value of novel non-homogeneous catalysts for MET degradation in Fenton-like systems and provides theoretical support for achieving complete mineralization of MET.

Insights into the efficient degradation of metformin - An emerging antidiabetic medicine by UV/Sulfite process

The growing utilization of metformin (MET) in diabetes treatment has resulted in its occurrence in wastewater treatment plants, where conventional techniques were proved inadequate in eliminating it. The present study evaluated the potential of UV/sulfite system in degrading MET and analyzed the influence of common factors (i.e UV intensity, dosage of reagent, the pH value of reaction solution) on the target contaminant removal. In comparison with both direct UV photolysis and merely sulfite reduction, the UV/sulfite process had a remarkable enhancement in MET removal, with 96.54% of MET (initial concentration of 15 mg/L) being degraded within 30 minutes. A strong linear relationship (R2 > 0.99) was observed between MET degradation kinetics and UV intensity. The increase of sulfite dosage and solution pH could promote MET degradation to a certain extent in the studied system. Additionally, the hydrated electron (eaq-) was found played the principle role in MET removal through scavenging reactions.

Performance assessment of graphene oxide decorated with silver nanoparticles as adsorbent for removal of metformin from water: Equilibrium modeling, kinetic and thermodynamic studies

In the present study, graphene oxide decorated with silver nanoparticles (GO@AgNPs) was synthesized for the effective removal of metformin from water. The prepared GO@AgNPs was characterized by using Fourier transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric-differential thermal analyses (TGA-DTA), scanning electron microscopy (SEM) coupled with electron dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). Response surface methodology via Box-Behnken design was adopted for optimizing the variables of adsorption of metformin on GO@AgNPs. Under the optimized conditions (contact time = 50 min; pH = 6.5; adsorbent dose = 0.015 g; initial concentration = 50 mg/L) the adsorption capacity and removal efficiency for metformin were 131.7 ±.0.30 mg/g and 99.34% ±.0.33, respectively. The adsorption data obtained at 305, 310, 315 and 320 K were assessed by non-linear adsorption isotherm and kinetic models. Freundlich isotherm model fits best to the measured data. The pseudo second order kinetic equation fits well to the measured kinetic data. The study of impact of temperature on the adsorption demonstrated that the sorption process was endothermic (∆H° = 31.335 kJ/mol; Ea = 32.009 kJ/mol) and spontaneous in nature (∆G° = −11.162, −11.876, −12.537 and −13.268 kJ/mol at 305, 310, 315 and 320 K, respectively). Moreover, the value of sticking probability (S* = 0.00082) illustrated high probability for metformin sticking on the surface of GO@AgNPs. The adsorption/desorption study shows that there was no loss in adsorption capacities upto 6 cycles which demonstrated the effectiveness of GO@AgNPs as a potential adsorbent for remediation of metformin from aqueous system.

Microbially catalyzed anode and cathode microbial electrosynthesis system for efficient metformin removal and volatile fatty acid production

The removal of different pharmaceuticals and personal care products from surface water is crucial. This study focused on the removal and transformation of metformin (MTF), an emerging contaminant in aqueous solutions using a dual biocatalyzed microbial electrosynthesis system (MES). Successful biodegradation of MTF (91 %) was achieved within 120 h with improved bioelectrochemical performance. The current density (−849 mA/m2) with drug loading at 0.5 ppm was 10.3, 7.6, and 2.4 times higher than that of the control, 0.1 ppm, and 0.3, ppm, respectively. Volatile fatty acids (VFAs) production also improved with excellent acetate, propionate, and butyrate production at dual biocatalyzed MES. Liquid chromatography mass spectrometry studies indicated improved mineralization with more MTF bioproducts. MTF regulated the microbial flora through enrichment of the electroactive phyla Proteobacteria and Bacteroidetes. This study provides a new perspective for the use of dual biocatalyzed microbial electrosynthesis systems in bioremediation research.

Calcium-Citrate Anticoagulation during Continuous Renal Replacement Therapy in Patients with Metformin Intoxication: A Case Series, Mathematical Estimation of Citrate Accumulation, and Literature Review

Plain Language SummaryMetformin intoxication is a potentially life-threatening condition characterized by severe metabolic acidosis that could require intensive care unit admission and renal replacement therapy (RRT) for metformin removal. According to current guidelines, a citrate solution is commonly administered to generate regional anticoagulation in RRT due to its effect on chelating ionized calcium, an essential element of the coagulation pathway. Citrate metabolism can be impaired during metformin intoxication, and its administration could lead to accumulation worsening the metabolic acidosis. Citrate is not routinely measured, and its accumulation is clinically diagnosed by the ratio between total and ionized plasma calcium concentration (T/I calcium ratio) >2.5 or estimating the presence of unmeasured anions (UA), calculating the strong ion gap (SIG), i.e., the difference between the strong anions and cation, and the concentration of bicarbonate, dissociated albumin, and phosphates. We compared our results obtained from a case series of three patients with a theoretical model of citrate accumulation. Finally, we reviewed the literature to unveil clinical practice in this scenario. Our results support that diluted citrate can be safely used for RRT in patients with metformin toxicity, and the SIG is a valuable tool to estimate the presence of UA and can be used to detect and monitor citrate accumulation in this context.

Synthesis of a Chemically Modified Biosorbent Based on the Invasive Plant Leucaena leucocephala and Its Application in Metformin Removal

The present study investigated the use of a biosorbent produced from Leucaena leucocephala pods for the removal of metformin from aqueous solutions. The pods were subjected to chemical and thermal treatments and were referred to as L. leucocephala modified, which was characterized using scanning electron microscopy (SEM). The parameters investigated in the sorption process were temperature, contact time, adsorbent dosage, pH, and initial metformin concentration. The experimental data were in accordance with the Langmuir isothermal model. The maximum adsorption capacity reached was 56.18 mg g−1 at 313 K. In the kinetic study, stability was achieved in 300 min, with 53.24% removal, and the pseudo-first-order model agreed well with the experimental data. The thermodynamic parameters indicated a spontaneous, favorable, and exothermic reaction. The presence of NaCl, CaCl2, and MgCl2 negatively affected metformin adsorption. Thus, the importance of the study was that a developed material showed promising results in the removal of metformin, particularly because it is an innovative material, and there are no studies in the literature on drug removal using L. leucocephala.

Effective removal of metformin from water using an iron-biochar composite: Mechanistic studies and performance optimisation

Metformin (MF) is widely used in the prevention and treatment of Type 2 diabetes and gestational diabetes. Following its medical administration, it may pass through the body and be introduced into the wastewater treatment system. However, conventional treatment plants are ineffective in removal of MF from wastewater resulting in its introduction into the aquatic environment. Novel and effective methods of MF removal are therefore required to prevent contamination of natural waters. In this work, a magnetised iron-biochar composite derived from brewery waste (magnetic brewery spent grain; MBSG) was generated and evaluated for its ability to remove MF from aqueous media. Response surface methodology (RSM) was applied to identify optimal adsorption parameters. Extensive instrumental characterisation including XPS, FTIR, EPR, Raman spectroscopy and SQUID were used in conjunction with kinetic, isotherm and thermodynamic studies to determine that H-bonding, electrostatic attraction and so-called π-π (electron donor-acceptor) EDA interactions were the mechanisms involved in the adsorption processes. Modelling showed that the MF adsorption was best described by both the Langmuir and the Freundlich models, with the value of qmax = 15.2 mg/g governed by the pseudo-second order kinetic model; and it was a spontaneous (∆G = −17.7 kJ/mol) and endothermic (∆H =38.5 kJ/mol) process. Desorption studies were conducted to evaluate the potential for regeneration and reuse of the material. These demonstrated citric acid (0.2 M) to have significant potential as a regenerative reagent, but that further optimisation is required. This work revealed that MBSG could be a sustainable and effective adsorbent for the removal of aqueous MF in water treatment.

The acute removal of metformin induces mitochondrial remodeling and increases mitochondrial respiration

Metformin is a candidate to slow biological aging and extend healthspan, as it reduces the risk of morbidity and mortality in people with type 2 diabetes. However, it is not clear how metformin impacts individuals absent of chronic disease. This unknown is important to answer before prescribing metformin to healthy individuals to prolong the healthspan. It has been shown that metformin creates an inefficiency in energy transfer by accumulating within the mitochondria. Therefore, we hypothesized that the effects of metformin on healthspan are context specific; beneficial in the context of low energy demand/mitochondrial capacity but detrimental in the context of high energy demand/mitochondrial capacity. To test this hypothesis, we used 18-month, male rats selectively bred for low and high treadmill running capacity (LCR/HCR) as models of low and high intrinsic mitochondrial function. For both HCR and LCR, we used high-resolution respirometry (Oroboros O2K) on skeletal muscles from controls (CON), 4 weeks of metformin-treatment (MET), 4 weeks of metformin-treatment with a 48-hour metformin washout (MET-WO), and 48-hour washout with metformin added back to the respirometry chamber (MET-WO-SPIKE). A week prior to sacrifice, we labeled the rats with deuterium oxide to assess protein turnover as an indicator of mitochondrial remodeling. In gastrocnemius muscle, the HCR MET-WO had greater Complex I (CI), CI+Complex II (CII), and maximal respiration (MaxR) (115 ± 23, 164 ± 38, 157 ± 35 pmol/(s✕mg), respectively) compared to the CON (70 ± 24, p = 0.02, 114 ± 32, p = 0.01, 115 ± 40 pmol/(s✕mg), p = 0.04, respectively), and MET (63 ± 54, p = 0.007, 90 ± 50, p < 0.001, 91 ± 48 pmol/(s✕mg), p = 0.002, respectively). The HCR MET-SPIKE group had greater CII (83 ± 33 pmol/(s✕mg)) and MaxR (86 ± 35 pmol/(s✕mg)) compared to the MET (p = 0.007 and p = 0.002, respectively). In the soleus, MET-WO (4.15 ± 0.33%/day) had greater mitochondrial fractional synthesis rates (FSRs) compared to MET (3.12 ± 0.62%/day, p = 0.001) in the HCRs. In the LCRs, MET-WO (4.61 ± 0.42%/day) had greater FSRs compared to CON (p < 0.001, 3.07 ± 0.67%/day) and MET (3.12 ± 0.61%/day, p = 0.001). In the tibialis anterior, MET-WO (3.47 ± 0.80%/day) had greater FSRs compared to the MET (2.41 ± 0.47%/day, p = 0.04) within the HCRs with no differences in the LCR. These data show that metformin reduces mitochondrial respiration in HCR rats but not in LCR rats. The presence of metformin produced a greater subsequent response in HCR compared to LCR as shown by its acute removal revealing metformin-induced mitochondrial remodeling. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Adsorption of Metformin on Activated Carbon Produced from the Water Hyacinth Biowaste Using H3PO4 as a Chemical Activator

Water hyacinth biomass was used for the synthesis of activated carbons in the process of chemical activation with H3PO4, followed by controlled carbonization. The study investigates the effect of various impregnation weight ratios of H3PO4 and dry hyacinth (0.5–3.0), as well as different carbonization temperatures (T = 400–800 °C), on the surface characteristics of the produced activated carbons (AC). The activated carbon obtained with an impregnation ratio of 1.5 and a carbonization temperature of 600 °C (1.5 AC/600) showed the highest values of specific surface area of 1421 m2 g−1, representing a selected adsorbent for metformin removal. The chosen sample was characterized by elemental analysis, adsorption–desorption isotherms of nitrogen at −196 °C, via FTIR spectroscopy and the SEM method. The modeling of the experimental adsorption data showed that metformin adsorption: (i) can be best described by the Langmuir isotherm model, with the value of qmax = 122.47 mg g−1; (ii) led the pseudo-second order kinetic model; and (iii) is a spontaneous (ΔG° = −3.44 kJ mol−1) and endothermic (ΔH° = 8.77 kJ mol−1) process. A desorption study has shown that 92% of metformin was successfully desorbed in the presence of a 0.1 MHCl/ethanol mixture (volume ratio 2:1). The recovery of the adsorbent of 84%, after five successive cycles, indicated that the 1.5 AC/600 has potential to be applied in the real systems for water treatment.

Metformin adsorption onto activated carbon prepared by acid activation and carbonization of orange peel

Acid modification of orange peels (OPAC); an agro-waste, using ortho-phosphoric acid was carried out. OPAC was characterized using FTIR and SEM, BET and elemental Analysis techniques respectively. It was then used for the adsorption of metformin (MET) from aqueous solutions. OPAC has different functional groups and prominent pore sizes suitable for the sorption of MET. Experimental parameters such as effects of contact time, MET initial concentrations, solution temperature and solution pH were investigated. Optimum MET adsorption onto OPAC was obtained at a contact time: of 240 minutes, Initial MET concentration: 5 mg/L, Temperature: 323 K, and pH 7. The highest percentage of MET removal using OPAC was 97.23%. Sorption data were fitted into four different isotherm models; Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich. Freundlich isotherm model best explained the sorption data with the high affinity of adsorption (R 2 value) observed at 303 K. Langmuir isotherm gives an optimum monolayer sorption capacity of 50.99 mg/g at 323 K. Kinetic studies of the sorption process were investigated using pseudo-first-order, pseudo-second-order, Elovich, and Intraparticle diffusion kinetic models, and the data fitted best the pseudo-second-order kinetic model. Thermodynamic studies revealed that the sorption process is spontaneous, feasible, and endothermic. The energy of activation, Ea suggests a physisorption mechanism of MET sorption onto OPAC. Conclusively, OPAC was an efficient adsorbent for the sorption of MET from aqueous solutions. NOVELTY STATEMENT Orange peel activated carbon (OPAC) adsorbent gave a higher qo value for metformin removal from aqueous solution than other adsorbents previously reported in the literature. The highest percentage of removal of metformin drug-using OPAC was 97.23%. This is highly commendable.

Biochar from microwave co-pyrolysis of food waste and polyethylene using different microwave susceptors – Production, modification and application for metformin removal

Biochar (BC) production by microwave (MW) co-pyrolysis of food waste (FW) with polyethylene (PE) (mixed in a ratio of 8:1) was performed in the present study using different MW susceptors, i.e. granular activated carbon (G), silica gel (S), cement (C) and flyash (F). BC yield varied from 37 wt% to 45 wt%. The highest yield of 45 wt% was obtained with flyash as MW susceptor. All BC exhibited increased carbon content (57.1–69.0 wt%), fixed carbon (76.0–85.3 wt%), and porous structure with improved thermal stability than the feedstock. The inferential plot exhibited an inverse relationship between yield and carbon of BC with loss tangent (tan δ) and specific surface area (SSA) of the MW susceptor. Alkali (potassium phosphate) modified F-BC (K-F-BC) showed further improvement in porous structures with a good cavity and presence of carbonyl group (CO) and hydroxide group (O–H) on its surface, which showed good adsorptive removal of metformin (MET). Alkali modification of F-BC improved the adsorption capacity by ∼8 times; thus, resulting in ∼62% MET removal within 5 min. Kinetic models suggested the MET adsorption on BC predominantly controlled by intra-particle diffusion (R2 = 0.72–0.98). Adsorption of MET with S-BC and F-BC followed Langmuir isotherm (R2 = 0.99). On the other hand, G-BC, C-BC and K-F-BC followed Freundlich isotherm (R2 = 0.99). Maximum MET adsorption of 0.17 mg/g, 0.23 mg/g, 0.26 mg/g and 0.27 mg/g were observed with F-BC, G-BC, S-BC and C-BC respectively. Alkali modification of F-BC (K-F-BC) improved its adsorption capacity up to 0.34 mg/g. The Surface deposition, pore filling, π-π interaction and chemical bonding of functional groups with K-F-BC were the predominant mechanisms of MET removal by K-F-BC.

Adsorptive removal of metformin on specially designed algae-lignocellulosic biochar mix and techno-economic feasibility assessment

Batch sorption of metformin hydrochloride (MET) onto a specially designed biochar mix consisting of both macro (MAC) and micro (MIC) algae, rice husk and pine sawdust was conducted. Pyrolysis of both MAC and MIC algae mixture was done followed by chemical activation with hydrogen-peroxide. Additionally, sorption of MET under the influence of pH was separately investigated. Batch studies of isotherms were well described by Freundlich model with high non-linearity and Freundlich exponent values ranged anywhere from 0.12 to 1.54. Heterogeneity of MET adsorption to the bonding sites was attributed to the surface functional groups of the modified biochar. Amongst the four biochars, the activated macroalgae biochar (MACAC) and microalgae biochar (MICAC) depicted favourable adsorption of MET with maximum adsorption at pH 7. Up to 76% of MET removal from the environment was obatained using the MACAC biochar. Scanning electron micrographs coupled with energy dispersive X-ray, as well as elemental analyses confirmed formation of oxygen containing surface functional groups due to activation strengthening chemisorption as the main sorption mechanism. Further, Fourier transform infra-red spectroscopy and other surface functional group analyses along with Zeta potential measurements reinforced our proposed sorption mechanism. Lowest zeta potential observed at pH 7 enhanced the electrostatic force of attraction for both the biochars. Negative zeta potential value of the biochars under different pH indicated potential of the biochars to adsorb other positively charged contaminants. From a techno-economic perspective, capital expenditure cost is not readily available, however, it is envisaged that production of pyrolyzed biochar from algal biomass could make the process economically attractive especially when the biochar could be utilised for high-end applications.

Remediation of Metformin Hydrochloride in Aqueous Solution Using Locally Sourced Seaweed (Fucus spiralis) Through HPLC

Metformin hydrochloride is an anti-hyperglycaemic drug that is widely prescribed in the management of noninsulin diabetes mellitus (NIDDM). However, metformin does not undergo complete metabolism in the body thereby excreting significant amount through urine and eventual discharged into the water bodies. Therefore, this work investigates the possibility bio-sorption of metformin by Fucus spiralis seaweed. High performance liquid chromatography (HPLC) and FITR was used for quantifying metformin biosorption. The result shows that Fucus spiralis is a potential biosbent for metformin removal in aqueous solution. The highest removal was up to 74% at 50 µg/mL. It can be mentioned here that this study is the first of it kind in testing seaweed for metformin biosorption.
 In conclusion, biomass (Fucus spiralis) was tested for its efficiency in metformin removal in aqueous solution. Adsorption studies revealed that F. spiralis can be used as potential adsorbent for metformin uptake. Very limited literature investigates the application of seaweeds species for pharmaceutical remediation. Remediation of waste and surface water using readily available adsorbent such as seaweed will be useful as it relates to human health and environmental contamination. HPLC was used in this study but other spectroscopic technique such as UV/vis could be explored to ascertain the optimized method. Further studies would be needed to test other algal species for metformin bio sorption.

Effect of concentration and hydraulic reaction time on the removal of pharmaceutical compounds in a membrane bioreactor inoculated with activated sludge.

SummaryPharmaceuticals are often not fully removed in wastewater treatment plants (WWTPs) and are thus being detected at trace levels in water bodies all over the world posing a risk to numerous organisms. These organic micropollutants (OMPs) reach WWTPs at concentrations sometimes too low to serve as growth substrate for microorganisms; thus, co‐metabolism is thought to be the main conversion mechanism. In this study, the microbial removal of six pharmaceuticals was investigated in a membrane bioreactor at increasing concentrations (4–800 nM) of the compounds and using three different hydraulic retention times (HRT; 1, 3.5 and 5 days). The bioreactor was inoculated with activated sludge from a municipal WWTP and fed with ammonium, acetate and methanol as main growth substrates to mimic co‐metabolism. Each pharmaceutical had a different average removal efficiency: acetaminophen (100%) > fluoxetine (50%) > metoprolol (25%) > diclofenac (20%) > metformin (15%) > carbamazepine (10%). Higher pharmaceutical influent concentrations proportionally increased the removal rate of each compound, but surprisingly not the removal percentage. Furthermore, only metformin removal improved to 80–100% when HRT or biomass concentration was increased. Microbial community changes were followed with 16S rRNA gene amplicon sequencing in response to the increment of pharmaceutical concentration: Nitrospirae and Planctomycetes 16S rRNA relative gene abundance decreased, whereas Acidobacteria and Bacteroidetes increased. Remarkably, the Dokdonella genus, previously implicated in acetaminophen metabolism, showed a 30‐fold increase in abundance at the highest concentration of pharmaceuticals applied. Taken together, these results suggest that the incomplete removal of most pharmaceutical compounds in WWTPs is dependent on neither concentration nor reaction time. Accordingly, we propose a chemical equilibrium or a growth substrate limitation as the responsible mechanisms of the incomplete removal. Finally, Dokdonella could be the main acetaminophen degrader under activated sludge conditions, and non‐antibiotic pharmaceuticals might still be toxic to relevant WWTP bacteria.

An ‘omics approach to investigate the growth effects of environmentally relevant concentrations of guanylurea exposure on Japanese medaka (Oryzias latipes)

Metformin is a widely prescribed pharmaceutical used in the treatment of numerous human health disorders, including Type 2 Diabetes, and as a results of its widespread use, metformin is thought to be the most prevalent pharmaceutical in the aquatic environment by weight. The removal of metformin during the water treatment process is directly related to the formation of its primary degradation product, guanylurea, generally present at higher concentrations in surface waters relative to metformin. Growth effects observed in 28-day early life stage (ELS) Japanese medaka exposed to guanylurea were found to be similar to growth effects in 28-day ELS medaka exposed to metformin; however, effect concentrations were orders of magnitude below those of metformin. The present study uses a multi-omics approach to investigate potential mechanisms by which low-level, 1 ng · L−1 nominal, guanylurea exposure may lead to altered growth in 28-day post hatch medaka via shotgun metabolomics and proteomics and qPCR. Specifically, analyses show 6 altered metabolites, 66 altered proteins and 2 altered genes. Collectively, metabolomics, proteomics, and gene expression data (using qPCR) indicate that developmental exposure to guanylurea exposure alters a number of important pathways related to the overall health of ELS fish, including biomolecule metabolism, cellular energetics, nervous system function/development, cellular communication and structure, and detoxification of reactive oxygen species, among others. To our knowledge, this is the first study to both report the molecular level effects of guanylurea on non-target aquatic organisms, and to relate molecular-level changes to whole organism effects.