Biosorption of nickel from aqueous solution by Tithonia diversifolia

AbstractThis study investigated the feasibility of Mexican sunflower (Tithonia diversifolia), a common plant that inhabits the highway of the south western Nigeria, as a novel biosorbent for nickel from solutions. pH profile, time dependency and cation interference studies were conducted using stem biomass of this plant. Nickel uptake exhibited substantial enhancement both in terms of the kinetics of uptake as well as the loading capacity. Results of the investigation showed that the unmodified biomass was able to remove over 70% of the nickel content of a solution, whereas NaOH modification improved the adsorption efficiency to over 77% in the same contact time of 60 min. The optimum pH of adsorption was recorded as 5 for the metal using both types of biomass. However,modification improved the adsorption efficiency to a pH lower than 4. The kinetic study conducted showed that the adsorption process follows Lagergren’s pseudo-second order reaction with R2 values equal to 0.9988 and 0.9989 for both types of biomass. The presence of cations such as calcium and magnesium also interfered negatively with the adsorption process. Between 20–35% reductions in the metal adsorbed were recorded in the presence of a 1 M concentration of Mg, Ca or mixed Mg and Ca ions. Langmuir model of adsorption isotherm gave the best fit for this sorption process with R2 values of 0.994, 0.995 and 0.997 for Mg, Ca and mixed Mg and Ca studies, respectively

Assessment of anti-corrosion potentials of extract of Ficus asperifolia -Miq (Moraceae) on mild steel in acidic medium

FullThe inhibitory potentials of ethanolic extracts and four fractions of the stem bark of Ficus asperifolia Miq. for the corrosion of mild steel were assessed using weight loss method, Fourier atomi absorption spectroscopy,scanning electron microscopy (SEM). The effects of varying immersion period,concentration of the inhibitors and temperatures for mild steel corrosion in 5 M HCl acid solution were carried out. A detailed kinetic reaction, thermodynamic (Ea, ∆H, ∆S) and adsorption isotherm studies were obtained. The crude extract of F. asperifolia (EFA) has the highest inhibition efficiency of 55%. The inhibitory efficiency of the four fractions of F. asperifolia (EFA) compared with the crude extract was in the order ethyl acetate > n-hexane > butanol > EFA > Aqueous. The inhibition efficiency was found to increase with increase in the extracts concentration but decreased with temperature. Corrosion rate increases with time but decreases with extracts concentration. The kinetic studies of the data followed a first order reaction. Thermodynamic studies revealed that corrosion inhibition may be due to spontaneous mixed adsorption of the plant constituents on the metal surface. Experimental data were fitted to Langmuir, Freundlich and Temkin adsorption isotherms. The plant investigated showed a good potential for green corrosion inhibitors. Investigation of phytochemical constituents showed that the extracts contain alkaloids, flavonoids, saponins, tannins anthraquinones and reducing sugars

Reaction Kinetics for Nitrosation of DAF-2 in Air Saturated Nitric Oxide Solution

Staff PublicationUnderstanding the reaction rate constant of a probe compound with its target molecule is essential for its selection and use in biological and non-biological systems. Over the past decade, the probe, 4, 5-diaminofluorescein (DAF-2) has been widely employed for the detection and imaging of nitric oxide (NO•) in various media. However, the rate constant for the nitrosation of DAF-2 in air-saturated nitric oxide solution is far from being understood. For the first time, we have determined the second order rate constant for the reaction of DAF-2 with NO• (k2) in airsaturated solution using competition kinetics method. An alternative competition kinetics method which involves a reciprocal plot of the reactant (DAF-2) and triazolofluorescein (DAF-2T), the product formed from the reaction of DAF-2 with NO• was developed and compared to the standard competition kinetics method. Our particular approach in this system is based on the use of oxy-hemoglobin (HbO2), a potent scavenger of NO• against the DAF-2 which serves as the detector molecule. The product, DAF-2T, is separated from the reaction mixture by reversed-phase high performance liquid chromatography and its fluorescence intensity signals were measured at excitation and emission of 495 and 515 nm respectively. The results showed that the second order reaction rate constant of DAF-2 with NO• in air-saturated aqueous solution are comparable, with the average value of (6.28 ± 0.45) × 10 6 M-1s -1 . Also, DAF-2 can react with NO• directly thereby by-passing the N2O3-mediated formation of DAF-2T at low NO• formation rate

Biosorption of Cadmium (II) and Chromium (VI) from Aqueous Solution by Chemically Modified Tithonia Diversyfolia Biomass

Staff PublicationThe search for alternative and innovative treatment technologies for the effective removal of heavy metals from aqueous wastes has been a research of concerted effort due to the inherent limitations exhibited by the conventional methods such as less efficiency, sensitive operating conditions, energy requirements and generation of toxic sludge or other waste products. Biosorption, the passive uptake of heavy metals by biomaterials has been studied recently because of its high efficiency and cost effectiveness. Therefore, the biosorption capacity of Tithonia diversyfolia biomass chemically modified with sodium hydroxide for the removal of cadmium and chromium ions from aqueous solution was investigated. The effects of temperature, contact time, initial concentration of metal ions, adsorbent dosage and pH on the biosorption of Cd2+ and Cr6+ ions were assessed. Thermodynamic parameters such as free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) during the biosorption were evaluated. The results showed that the biosorption process of Cd2+ and Cr6+ by chemically modified Tithonia diversyfolia (CMTD) biomass was feasible and exothermic under the studied conditions. The equilibrium process was well described by the Langmuir isotherm model, with a maximum biosorption capacity of 46.75mg/g and 48.00mg/g for Cadmium and Chromium ions, respectively. Kinetic studies indicated that the biosorption of metal ions followed a pseudo-second order equation

Extraction of Cu, Zn, and Ni from waste silica-rich integrated circuits by sulfation roasting and water leaching

Staff PublicationHigh-tech electrical and electronic equipment contain large numbers of silica-rich integrated circuits (SRICs) which after its end of life generate huge amount of waste; however, its valuable metal contents can be properly recycled. Extraction of Cu, Ni, and Zn from pulverized SRIC obtained from discarded waste electrical and electronic equipments (WEEE) by sulfation roasting followed by water leaching was studied. Co-extraction of other metals such as Fe, Al, and Pb present in the sample was also explored. Effects of H2SO4/SRIC ratio, roasting temperature, time, and varying water leaching conditions on the extraction efficiencies were evaluated. The optimum conditions for Cu, Zn, and Ni extractions were determined as H2SO4/SRIC ratio 0.5, roasting temperature 300 °C, roasting time 60 min, leaching temperature 50 °C, leaching time 60 min, and liquid–solid ratio = 10:1 (i.e., 100 mL/10 g) with extraction efficiencies of 61.9, 84.9, and 93.6% for Cu, Ni, Zn, and co-extractions of Fe and Al were 71.1 and 55.6, respectively. Under the optimum conditions, approximate 20% Fe3+ was naturally precipitated which is advantageous for the subsequent step. Comparatively, higher extraction efficiencies of Cu, Zn, and Ni were observed in water leaching of H2SO4-roasted sample than direct H2SO4 leaching of raw sample keeping other leaching conditions constant. Lead retained in the roasted–leached residue was extracted with dilute HCl leaving silica and Al in the final leached residue. Process flow sheet for the extraction of Cu, Ni, Zn, and Pb and reuse of silicon from waste SRICs was proposed

Plant genomics in Africa: present and prospects

Plants are the world’s most consumed goods. They are of high economic value and bring many health benefits. In most countries in Africa, the supply and quality of food will rise to meet the growing population’s increasing demand. Genomics and other biotechnology tools offer the opportunity to improve subsistence crops and medicinal herbs in the continent. Significant advances have been made in plant genomics, which have enhanced our knowledge of the molecular processes underlying both plant quality and yield. The sequencing of complex genomes of African plant species, facilitated by the continuously evolving nextgeneration sequencing technologies and advanced bioinformatics approaches, has provided new opportunities for crop improvement. This review summarizes the achievements of genome sequencing projects of endemic African plants in the last two decades. We also present perspectives and challenges for future plant genomic studies that will accelerate important plant breeding programs for African communities. These challenges include a lack of basic facilities, a lack of sequencing and bioinformatics facilities, and a lack of skills to design genomics studies. However, it is imperative to state that African countries have become key players in the plant genome revolution and genome derived-biotechnology. Therefore, African governments should invest in public plant genomics research and applications, establish bioinformatics platforms and training programs, and stimulate university and industry partnerships to fully deploy plant genomics, particularly in the fields of agriculture and medicine

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic