Chemical structures of extra- and intra-cellular algogenic organic matters as precursors to the formation of carbonaceous disinfection byproducts

Algogenic organic matter (AOM), including extracellular organic matters (EOM) and intracellular organic matters (IOM) can interfere with drinking water treatment processes and cause water quality problems, among which the formation of disinfection byproducts (DBPs), microcystins and odor and taste compounds are of particular concern. In this study, the formations of THMs, Microcystins-LR and 2-MIB during four growth phase (lag phase, exponential phase, stationary phase and death phase) were investigated. The THMs formation potential of EOM and IOM were compared. Higher CHCl3 concentration was found in IOM than that in EOM. In the presence of bromide, more brominated-THMs generated, and the TTHMs increased more rapidly in EOM than IOM. The 2-MIB was found a similar trend with the MC-LR in the four growth phase. The total 2-MIB was gradually increased as a function of the time. The formation of MC-LR and 2-MIB depended on algae density.

Download Full-text

Chemical structure of diamond-like carbon thin films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010017668x ◽

1990 ◽

Vol 48 (4) ◽

pp. 710-711

Author(s):

N.-H. Cho ◽

K.M. Krishnan ◽

D.B. Bogy

Keyword(s):

Electrical Resistivity ◽

Chemical Structure ◽

Diamond Like Carbon ◽

Chemical Structures ◽

Sputtering Power ◽

Data Aquisition ◽

Equilibrium Phases ◽

Electron Energy Loss ◽

Power Densities ◽

Preparation Techniques

Diamond-like carbon (DLC) films have attracted much attention due to their useful properties and applications. These properties are quite variable depending on film preparation techniques and conditions, DLC is a metastable state formed from highly non-equilibrium phases during the condensation of ionized particles. The nature of the films is therefore strongly dependent on their particular chemical structures. In this study, electron energy loss spectroscopy (EELS) was used to investigate how the chemical bonding configurations of DLC films vary as a function of sputtering power densities. The electrical resistivity of the films was determined, and related to their chemical structure.DLC films with a thickness of about 300Å were prepared at 0.1, 1.1, 2.1, and 10.0 watts/cm2, respectively, on NaCl substrates by d.c. magnetron sputtering. EEL spectra were obtained from diamond, graphite, and the films using a JEOL 200 CX electron microscope operating at 200 kV. A Gatan parallel EEL spectrometer and a Kevex data aquisition system were used to analyze the energy distribution of transmitted electrons. The electrical resistivity of the films was measured by the four point probe method.

Download Full-text

Chemical Structures and their Properties of Wood Components

JAPAN TAPPI JOURNAL ◽

10.2524/jtappij.67.1131 ◽

2013 ◽

Vol 67 (10) ◽

pp. 1131-1136

Author(s):

Toshiyuki Takano

Keyword(s):

Chemical Structures

Download Full-text

Unzipping Natural Products: Improved Natural Product Structure Predictions by Ensemble Modeling and Fingerprint Matching

10.26434/chemrxiv.6863864.v1 ◽

2018 ◽

Author(s):

William A. Shirley ◽

Brian P. Kelley ◽

Yohann Potier ◽

John H. Koschwanez ◽

Robert Bruccoleri ◽

...

Keyword(s):

Natural Products ◽

Open Source ◽

Natural Product ◽

Gene Cluster ◽

Public Domain ◽

Product Structure ◽

Fingerprint Matching ◽

Ensemble Modeling ◽

Chemical Structures ◽

Source Gene

This pre-print explores ensemble modeling of natural product targets to match chemical structures to precursors found in large open-source gene cluster repository antiSMASH. Commentary on method, effectiveness, and limitations are enclosed. All structures are public domain molecules and have been reviewed for release.

Download Full-text

Resorcinarene Cavitand Polymers for the Remediation of Halomethanes and 1,4-Dioxane

10.26434/chemrxiv.8847839 ◽

2019 ◽

Author(s):

Luke Skala ◽

Anna Yang ◽

Max Justin Klemes ◽

Leilei Xiao ◽

William Dichtel

Keyword(s):

Drinking Water ◽

Activated Carbon ◽

High Capacity ◽

The United States ◽

Water Sources ◽

Disinfection Byproducts ◽

Porous Polymer ◽

Organic Micropollutants ◽

Executive Summary ◽

Regulatory Limits

Executive summary: Porous resorcinarene-containing polymers are used to remove halomethane disinfection byproducts and 1,4-dioxane from water. Disinfection byproducts such as trihalomethanes are some of the most common micropollutants found in drinking water. Trihalomethanes are formed upon chlorination of natural organic matter (NOM) found in many drinking water sources. Municipalities that produce drinking water from surface water sources struggle to remain below regulatory limits for CHCl3 and other trihalomethanes (80 mg L–1 in the United States). Inspired by molecular CHCl3⊂cavitand host-guest complexes, we designed a porous polymer comprised of resorcinarene receptors. These materials show higher affinity for halomethanes than a specialty activated carbon used for trihalomethane removal. The cavitand polymers show similar removal kinetics as activated carbon and have high capacity (49 mg g–1 of CHCl3). Furthermore, these materials maintain their performance in real drinking water and can be thermally regenerated under mild conditions. Cavitand polymers also outperform activated carbon in their adsorption of 1,4-dioxane, which is difficult to remove and contaminates many public water sources. These materials show promise for removing toxic organic micropollutants and further demonstrate the value of using supramolecular chemistry to design novel absorbents for water purification.

Download Full-text

DISINFEKSI UNTUK PROSES PENGOLAHAN AIR MINUM

Jurnal Air Indonesia ◽

10.29122/jai.v3i1.2314 ◽

2018 ◽

Vol 3 (1) ◽

Author(s):

Nusa Idaman Said

Keyword(s):

Drinking Water ◽

Water Purification ◽

Distribution System ◽

Residual Effect ◽

Drinking Water Treatment ◽

Disinfection Byproducts ◽

Water Disinfection ◽

Pathogenic Microorganisms ◽

Microbiological Contamination ◽

Disinfection Process

Water disinfection means the removal, deactivation or killing of pathogenic microorganisms. Microorganisms are destroyed or deactivated, resulting in termination of growth and reproduction. When microorganisms are not removed from drinking water, drinking water usage will cause people to fall ill. Chemical inactivation of microbiological contamination in natural or untreated water is usually one of the final steps to reduce pathogenic microorganisms in drinking water. Combinations of water purification steps (oxidation, coagulation, settling, disinfection, and filtration) cause (drinking) water to be safe after production. As an extra measure many countries apply a second disinfection step at the end of the water purification process, in order to protect the water from microbiological contamination in the water distribution system. Usually one uses a different kind of disinfectant from the one earlier in the process, during this disinfection process. The secondary disinfection makes sure that bacteria will not multiply in the water during distribution. This paper describes several technique of disinfection process for drinking water treatment. Disinfection can be attained by means of physical or chemical disinfectants. The agents also remove organic contaminants from water, which serve as nutrients or shelters for microorganisms. Disinfectants should not only kill microorganisms. Disinfectants must also have a residual effect, which means that they remain active in the water after disinfection. For chemical disinfection of water the following disinfectants can be used such as Chlorine (Cl2), Hypo chlorite (OCl-), Chloramines, Chlorine dioxide (ClO2), Ozone (O3), Hydrogen peroxide etch. For physical disinfection of water the following disinfectants can be used is Ultraviolet light (UV). Every technique has its specific advantages and and disadvantages its own application area sucs as environmentally friendly, disinfection byproducts, effectivity, investment, operational costs etc. Kata Kunci : Disinfeksi, bakteria, virus, air minum, khlor, hip khlorit, khloramine, khlor dioksida, ozon, UV.

Download Full-text