Chitosan -A Natural Adsorbent for Copper Ions

Abstract -As a result of industrial activities and technological changes, a high and continuously increasing amount of heavy metals and heavy metal containing effluents are released into the environment by different industrial nations. These metals cannot be degraded. Furthermore, because of their toxicity, they are highly detrimental to the environment and human health. Heavy metals accumulate in the food chain and become permanent pollutants in the environment. In the human body they accumulate in different organs causing serious damage. To overcome this problem, the adsorption behaviour of heavy metal ions, in particular copper ions was investigated by apply chitosan flakes, powder, and beads as a natural adsorbent. Metal removal was studied using adsorbance measurements, SEM-EDX, and size measurements. The adsorption capacity of chitosan was determined at different concentration and times. The received adsorption capacities for copper ions were very promising, with a maximum value of 150 mg/g on chitosan powder

Solubility and selectivity effects of the anion on the adsorption of different heavy metal ions onto chitosan

The biopolymer chitosan is a very efficient adsorber material for the removal of heavy metal ions from aqueous solutions. Due to the solubility properties of chitosan it can be used as both a liquid adsorber and a solid flocculant for water treatment reaching outstanding adsorption capacities for a number of heavy metal ions. However, the type of anion corresponding to the investigated heavy metal ions has a strong influence on the adsorption capacity and sorption mechanism on chitosan. In this work, the adsorption capacity of the heavy metal ions manganese, iron, cobalt, nickel, copper, and zinc were investigated in dependence on their corresponding anions sulfate, chloride, and nitrate by batch experiments. The selectivity of the different heavy metal ions was analyzed by column experiments. © 2020 by the authors

A Complementary and Revised View on the N-Acylation of Chitosan with Hexanoyl Chloride

The modification of the biobased polymer chitosan is a broad and widely studied field. Herein, an insight into the hydrophobization of low-molecular-weight chitosan by substitution of amino functionalities with hexanoyl chloride is reported. Thereby, the influence of the pH of the reaction media was investigated. Further, methods for the determination of the degree of substitution based on 1H-NMR, FTIR, and potentiometric titration were compared and discussed regarding their accuracy and precision. 1H-NMR was the most accurate method, while FTIR and the potentiometric titration, though precise and reproducible, underlie the influence of complete protonation and solubility issues. Additionally, the impact of the pH variation during the synthesis on the properties of the samples was investigated by Cd2+ sorption experiments. The adjusted pH values during the synthesis and, therefore, the obtained degrees of substitution possessed a strong impact on the adsorption properties of the final material

Waterborne phenolic, triazine-based porous polymer particles for the removal of toxic metal ions

Highly functional and also highly porous materials are presenting great advantages for applications in energy storage, catalysis and separation processes, which is why a continuous development of new materials can be seen. To create a material combining the promising potential interactions of triazine groups with the electrostatic or hydrogen bonding interactions of phenolic groups, a completely new polymeric resin was synthesized. From an eco-friendly dispersion polymerization in water, a copolymer network was obtained, which includes nine hydroxyl groups and one s-triazine ring per repetition unit. The polymer forms highly porous particles with specific surface areas up to 531 ​m2/g and a negative streaming potential over a great pH range. The adsorption isotherms of Ni2+, Cd2+, and Pb2+ were studied in more detail achieving very good adsorption capacities (16 mg Ni2+/g, 24 mg Cd2+/g, and 90 mg Pb2+/g). Demonstrating excellent properties for adsorption applications. The adsorbent exhibited selectivity for the adsorption of Pb2+ over more commonly occurring but non-toxic metal ions such as Fe2+, Ca2+, Mg2+, and K+. Furthermore, reusability of the material was demonstrated by facile, quantitative desorption of adsorbed Pb2+ with a small amount of diluted HCl, circumventing organic chelators. Subsequently, adsorption was carried out without decrease in adsorption performance

Effects of (complementary) polyelectrolytes characteristics on composite calcium carbonate microparticles properties

This study follows the possibility to tune the thermal stability of some CaCO3/polymer composites by crystal growth from supersaturated solutions controlled by polymer structure or by using nonstoichiometric polyelectrolyte complexes (NPECs). As the ratio between the organic and inorganic parts in the composites controls the Ca2+/polymer network crosslinking density, the CaCO3/polymer weight ratio was kept constant at 50/1, varying the initial concentration of the polyanions solutions (0.05 or 0.06 wt.%), the NPECs molar ratio , n+/n- (0.2 or 0.4), or the inorganic precursors concentration (0.25 or 0.3 M). Poly(2-acrylamido-2-methylpropanesulfonic acid-co-acrylic acid) (PSA) and chondroitin-4-sulfate (CSA) were used as polyanions. Some NPEC dispersions, prepared with the same polyanions and poly(allylamine hydrochloride) (PAH), were also used for calcium carbonate crystallization. The characteristics of the prepared composites were investigated by scanning electron microscopy (SEM), flow particle image analysis (FPIA), particles charge density (CD), zeta-potential (ZP). The thermal stability of the composite particles was investigated as compared to bare CaCO3 microparticles prepared at the same initial inorganic concentrations

Model-based clustering via linear cluster-weighted models

A novel family of twelve mixture models with random covariates, nested in the linear $t$ cluster-weighted model (CWM), is introduced for model-based clustering. The linear $t$ CWM was recently presented as a robust alternative to the better known linear Gaussian CWM. The proposed family of models provides a unified framework that also includes the linear Gaussian CWM as a special case. Maximum likelihood parameter estimation is carried out within the EM framework, and both the BIC and the ICL are used for model selection. A simple and effective hierarchical random initialization is also proposed for the EM algorithm. The novel model-based clustering technique is illustrated in some applications to real data. Finally, a simulation study for evaluating the performance of the BIC and the ICL is presented

Peripheral blood biomarkers in multiple sclerosis.

Multiple sclerosis is the most common autoimmune disorder affecting the central nervous system. The heteroge-neity of pathophysiological processes in MS contributes to the highly variable course of the disease and unpre-dictable response to therapies. The major focus of the research on MS is the identification of biomarkers inbiologicalfluids, such as cerebrospinalfluid or blood, to guide patient management reliably. Because of the diffi-culties in obtaining spinalfluid samples and the necessity for lumbar puncture to make a diagnosis has reduced,the research of blood-based biomarkers may provide increasingly important tools for clinical practice. However,currently there are no clearly established MS blood-based biomarkers. The availability of reliable biomarkerscould radically alter the management of MS at critical phases of the disease spectrum, allowing for interventionstrategies that may prevent evolution to long-term neurological disability. This article provides an overview ofthis researchfield and focuses on recent advances in blood-based biomarker researc

Cardiovascular disease, chronic kidney disease, and diabetes mortality burden of cardiometabolic risk factors from 1980 to 2010: A comparative risk assessment

Background: High blood pressure, blood glucose, serum cholesterol, and BMI are risk factors for cardiovascular diseases and some of these factors also increase the risk of chronic kidney disease and diabetes. We estimated mortality from cardiovascular diseases, chronic kidney disease, and diabetes that was attributable to these four cardiometabolic risk factors for all countries and regions from 1980 to 2010. Methods: We used data for exposure to risk factors by country, age group, and sex from pooled analyses of population-based health surveys. We obtained relative risks for the effects of risk factors on cause-specific mortality from meta-analyses of large prospective studies. We calculated the population attributable fractions for each risk factor alone, and for the combination of all risk factors, accounting for multicausality and for mediation of the effects of BMI by the other three risks. We calculated attributable deaths by multiplying the cause-specific population attributable fractions by the number of disease-specific deaths. We obtained cause-specific mortality from the Global Burden of Diseases, Injuries, and Risk Factors 2010 Study. We propagated the uncertainties of all the inputs to the final estimates. Findings: In 2010, high blood pressure was the leading risk factor for deaths due to cardiovascular diseases, chronic kidney disease, and diabetes in every region, causing more than 40% of worldwide deaths from these diseases; high BMI and glucose were each responsible for about 15% of deaths, and high cholesterol for more than 10%. After accounting for multicausality, 63% (10·8 million deaths, 95% CI 10·1-11·5) of deaths from these diseases in 2010 were attributable to the combined effect of these four metabolic risk factors, compared with 67% (7·1 million deaths, 6·6-7·6) in 1980. The mortality burden of high BMI and glucose nearly doubled from 1980 to 2010. At the country level, age-standardised death rates from these diseases attributable to the combined effects of these four risk factors surpassed 925 deaths per 100 000 for men in Belarus, Kazakhstan, and Mongolia, but were less than 130 deaths per 100 000 for women and less than 200 for men in some high-income countries including Australia, Canada, France, Japan, the Netherlands, Singapore, South Korea, and Spain. Interpretation: The salient features of the cardiometabolic disease and risk factor epidemic at the beginning of the 21st century are high blood pressure and an increasing effect of obesity and diabetes. The mortality burden of cardiometabolic risk factors has shifted from high-income to low-income and middle-income countries. Lowering cardiometabolic risks through dietary, behavioural, and pharmacological interventions should be a part of the global response to non-communicable diseases. Funding: UK Medical Research Council, US National Institutes of Health. © 2014 Elsevier Ltd

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms