Hybrid Sorbents for Removal of Arsenic

The paper analyzes data on the removal of arsenic by sorption methods using materials that have prospects for large-scale application in water treatment. These materials include transition metal oxides in the micro- and nano-dimensional form, including those in the composition of composite materials with inorganic matrices, or hybrid sorbents in the composition with polymer resins or natural biopolymers. Examples of the use of composite (hybrid) sorbents for the removal of arsenic from solutions with low concentrations (at the level of MPC) are given. The objective of this article was to sum the up-to-date information about the most important features of chitosan-containing and chitosan-carbon materials we developed in view their use in arsenic removal processes at low concentrations to concentrations that meet WHO requirements. The paper presents data on the sorption properties of Mo-containing activated carbon fibers and chitosan-carbon composite materials towards arsenic (V) when it is extracted from bidistilled and tap water under static and dynamic conditions. The factors of the different behavior of the sorbents depending on the form of a biopolymer deposited on the fiber and the stability of the sorbents during the sorption of arsenic are discussed.

Alkaline refining of crude lead: a method of arsenic removal and the behavior of arsenic in the process

In this work, the alkaline refining of arsenic in crude lead was studied with a mixture of sodium hydroxide and sodium carbonate as alkaline refining agents. Taking the arsenic removal rate as the research object, the effects of reaction temperature, holding time, Na2CO3:NaOH, the dosage of refining agent were investigated. The arsenic removal rate is 79.09% under the optimum experimental conditions as follows: reaction temperature 823 K, holding time 60 min, Na2CO3:NaOH 1:4, refining agent dosage 10%. The oxidation purification mechanism of arsenic was studied by XPS, SEM-EDS, XRD and FT-IR. The results show that arsenic in the crude lead is gradually oxidized by oxygen and lead oxide during arsenic removal process, and the arsenic trioxide is eventually converted into sodium arsenate (Na3AsO4) and lead arsenate (Pb2As2O7) in the slag.

Adsorptive Removal of Arsenic by Synthetic Iron-loaded Goethite: Isotherms, Kinetics, and Mechanism

Arsenic contamination in the groundwater is a worldwide concern. Therefore, this study was designed to use synthetic iron-loaded goethite to remove arsenic. Adsorption was significantly pH-dependent; hence, pH values between 5.0 and 7.0 resulted in the highest removal of arsenate and arsenite. Langmuir and Freundlich isotherms were almost perfectly matched in terms of strong positive coefficient of determination “R2” arsenate – 0.941 and 0.992 and arsenite – 0.945 and 0.993. The adsorption intensity “n” resulted as arsenate – 2.542 and arsenite – 2.707; besides separation factor “RL” found as arsenate – 0.1 and arsenite – 0.5, respectively. However, both “n” and “RL” leads to a favourable adsorption process. Temkin isotherm yielded in equal binding energies “bt” showing as 0.004 (J/μg) for both arsenate and arsenite. Jovanovic monolayers isotherm was dominated by the Langmuir isotherm. This resulting in maximum adsorption capacity “Qmax” of arsenate – 1369.877 and arsenite – 1276.742 (μg/g), which approaches to the saturated binding sites. Kinetic data revealed that adsorption equilibrium was achieved in 240 – arsenate and 360 – arsenite (minutes), respectively. Chemisorption was found effective with high “R2” values 0.981 ­– arsenate and 0.994 – arsenite, respectively, with the best fitting of pseudo-second order. Moreover, Brunauer Emmett Teller (BET), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) were used to determine the morphological content, surface area, crystalline structure, and chemical characteristics of the adsorbent. It is anticipated that optimal arsenic removal was achieved by the porosity, chemical bindings, and surface binding sites of the adsorbent.

Search for a molecular mechanism of action of the potentized homeopathic drugs in living organisms

The mechanism of action of the potentized homeopathic drugs, particularly those diluted beyond Avogadro’s limit, is still a debatable issue and various hypotheses in this regard have been advocated by many. In our studies since 1980, we found that certain ultra-highly diluted homeopathic remedies could produce ameliorative effects in various model test organisms like bacteria, fungus, mice and human beings, while the succussed alcohol (placebo) could not. These drugs could antagonize/ameliorate several types of experimentally induced tumors/cancers in mice as evident from electron microscopic studies and certain specific cancer biomarkers. They also demonstrated significant effect on cell viability and apoptotic effect (mostly mitochondria mediated) on cancer cells in culture (also in experimental mice), as revealed from various assays like AnnexinV-FITC, TUNEL, DNA fragmentation, DAPI, COMET, HOECHST 33258, Rhodamine 123 etc while the succussed alcohol (“vehicle”) failed to show such effect. Expression of some key signal proteins and mRNA expressions like Bcl2 family proteins, Cytochrome c, Apaf 1, PARP, Caspase family, p53 and p38 etc in experimental mice model could be modulated by potentized homeopathic drugs. Under arsenic stress, the bacterium Escherichia coli, and the fungus Saccharomyces cerevisiae, and macrophage cells in culture responded favorably to the treatment of potentized homeopathic drug, Arsenicum Album 30C and homeopathically prepared Glucose 30C, as evident from modulation of several parameters like ROS accumulation, SOD activity, lipid peroxidation and expression level of certain relevant genes (Ars B, pts-G genes using real-time PCR) denoting detoxification, mainly via arsenic removal mechanism and suitable enzymatic modulation. Ultra-highly diluted potentized drugs (at potency 30C or above) could demonstrate protective changes simultaneously in multiple parameters (most of them under genetic control) of study, and their action continued for sometime even after the drugs were withdrawn; this indicates the ability of the drugs to trigger “gene action” involving up-regulation or down-regulation of a cascade of downstream genes, getting the recovery process into motion. The convincing evidences that support a “gene regulatory hypothesis” to explain the molecular mechanisms of action of the potentized drugs will be discussed in the light of some of our recent experimental findings on fungus, bacteria and bacteriophages.

Role of Public Awareness Ensuring the Sustainability of Arsenic Mitigation

Arsenic poisoning is the largest mass poisoning in history. It causes numerous toxic effects to human health which ultimately leads to cancer or Alzheimer’s disease. Nearly 300 million people over 180 countries worldwide are suffering from the arsenic contaminated groundwater more than WHO directed limit. Despite of its potential fatal toxicities, there is no effective treatment for arsenicosis. Cost-effective arsenic removal technology is also a matter of considerable research. This study aimed to summarize the individual and social issues related to arsenic problem and the remedies suggested by different authors to cope with the adverse effects of arsenic. Reported studies emphasized that only mass awareness and mass education can stop the spreading of this disaster. This study will be helpful for future research on the awareness on arsenic contamination and studies on assessing behavior in different context. Policymakers may find it as helpful resource since it describes the problem from grass-roots level. Researchers’ of pharmaceuticals and medicines may be inspired to perform their research in this field.

Neural Network and Random Forest-Based Analyses of the Performance of Community Drinking Water Arsenic Treatment Plants

A plethora of technologies has been developed over decades of extensive research on arsenic remediation, although the technical and financial perspective of arsenic removal plants in the field requires critical evaluation. In the present study, focusing on some of the pronounced arsenic-affected areas in West Bengal, India, we assessed the implementation and operation of different arsenic removal technologies using a dataset of 4000 spatio-temporal data collected from an in-depth field survey of 136 arsenic removal plants engaged in the public water supply. Our statistical analysis of this dataset indicates a 120% rise in the average cumulative capacity of the plants during 2014–2021. The majorities of the plants are based on the activated alumina with FeCl3 technology and serve about 49% of the population in the study area. The average cost of water production for the activated alumina with FeCl3 technology was found to be ₹7.56/m3 (USD $1 ≈ INR ₹70), while the lowest was ₹0.39/m3 for granular ferric hydroxide technology. A machine learning-based framework was employed to analyze the impact of water quality and treatment plant parameters on the removal efficiency, capital, and operational cost of the plants. The artificial neural network model exhibited adequate statistical significance, with a high F-value and R2 of 5830.94 and 0.72 for the capital cost model, 136,954, and 0.98 for the operational cost model, respectively. The relative importance of the process variables was identified through random forest models. The models indicated that flow rate, media, and chemicals are the predominant costs, while contaminant loading in influent water and a coagulating agent was important for removal efficiency. The established framework may be instrumental as a decision-making tool for water providers to assess the expected performance and financial involvement for proposed or ongoing arsenic removal plants concerning various design and quality parameters.