Arsenic removal by natural and chemically modified water melon rind in aqueous solutions and groundwater

Shakoor, Muhammad Bilal,Niazi, Nabeel Khan,Bibi, Irshad,Shahid, Muhammad,Sharif, Fakhra,Bashir, Safdar,Shaheen, Sabry M.,Wang, Hailong,Tsang, Daniel C.W.,Ok, Yong Sik,Rinklebe, Jö,rg Elsevier 2018 The Science of the total environment Vol.645 No.-

<P><B>Abstract</B></P> <P>Contamination of groundwater with toxic arsenic (As) has become an emerging health and environmental problem around the world, which has seen significant attention amongst the scientists for development of new sorbents to remediate As-contaminated water. Here, we explored the arsenate (As(V)) and arsenite (As(III)) sorption to natural water melon rind (WMR), xanthated WMR and citric acid-modified WMR in aqueous solutions, and determined potential of the most potent sorbent for As removal in groundwater. Xanthated WMR (X-WMR) showed relatively higher As(V) and As(III) removal than the citric acid modified WMR (CA-WMR) and natural WMR. The maximum As(III) (99%) and As(V) (98%) removal was obtained at pH 8.2 and 4.6, respectively, by X-WMR at 4 mg L<SUP>−1</SUP> initial As(V) and As(III) concentrations and sorbent dose of 1 g L<SUP>−1</SUP>. Langmuir isotherm model best fitted (<I>R</I> <SUP> <I>2</I> </SUP> of up to 0.96) the data both for As(III) and As(V) sorption to X-WMR. Sorption kinetics of As(V) and As(III) was well described (<I>R</I> <SUP> <I>2</I> </SUP> of up to 0.99) by the pseudo second-order model on surface of the X-WMR. Thermodynamic investigations revealed that As(V) and As(III) sorption was endothermic and spontaneous. The FTIR spectroscopy depicted the presence of different surface function groups (OH, COOH, S-bearing (C=S, S=O and S–S)) which were involved in As(V) and As(III) sequestration on the sorbents examined here. Significantly, X-WMR showed (up to 49%) greater As(III) and As(V) sorption than that of natural WMR. Our results demonstrated that X-WMR efficiently removed 94%–100% (<I>n</I> = 16) of As from As-contaminated drinking well water which possessed detectable concentrations of some anions (e.g., SO<SUB>4</SUB>, CO<SUB>3</SUB>, HCO<SUB>3</SUB>). This study highlights that the X-WMR has potential to remove As, notably As(III), from solutions and drinking water, and might be utilized as a reactive medium for the treatment of As-contaminated water.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Water melon rind (WMR) was tested for arsenic removal potential from water. </LI> <LI> Xanthated WMR removed up to 99% of As(III)/As(V) in solutions. </LI> <LI> Langmuir and pseudo second-order models provided the best fits for As(III) and As(V). </LI> <LI> FTIR spectra showed arsenic sequestration with surface functional groups of sorbents. </LI> <LI> Xanthated WMR successfully removed 94–100% arsenic from drinking well water. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Human health implications, risk assessment and remediation of As-contaminated water: A critical review

Shakoor, Muhammad Bilal,Nawaz, Rab,Hussain, Fida,Raza, Maimoona,Ali, Shafaqat,Rizwan, Muhammad,Oh, Sang-Eun,Ahmad, Sajjad Elsevier 2017 Science of the Total Environment Vol.601 No.-

<P><B>Abstract</B></P> <P>Arsenic (As) is a naturally occurring metalloid and Class-A human carcinogen. Exposure to As via direct intake of As-contaminated water or ingestion of As-contaminated edible crops is considered a life threatening problem around the globe. Arsenic-laced drinking water has affected the lives of over 200 million people in 105 countries worldwide. Limited data are available on various health risk assessment models/frameworks used to predict carcinogenic and non-carcinogenic health effects caused by As-contaminated water. Therefore, this discussion highlights the need for future research focusing on human health risk assessment of individual As species (both organic and inorganic) present in As-contaminated water. Various conventional and latest technologies for remediation of As-contaminated water are also reviewed along with a discussion of the fate of As-loaded waste and sludge.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Arsenic is recognized as a Class-A human carcinogen. </LI> <LI> Groundwater As contamination has affected over 200 million people worldwide. </LI> <LI> This paper reviews current knowledge regarding As in the environment. </LI> <LI> A critical assessment of remediation of contaminated water is presented. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

THE DRAZIN INVERSES OF THE SUM OF TWO MATRICES AND BLOCK MATRIX

Shakoor, Abdul,Yang, Hu,Ali, Ilyas The Korean Society for Computational and Applied M 2013 Journal of applied mathematics & informatics Vol.31 No.3

In this paper, we give a formula of $(P+Q)^D$ under the conditions $P^2Q+QPQ=0$ and $P^3Q=0$. Then applying it to give some results of block matrix $M=(^A_C^B_D)$ (A and D are square matrices) with generalized Schur complement is zero under some conditions. Finally, numerical examples are given to illustrate our results.

Remediation of arsenic-contaminated water using agricultural wastes as biosorbents

Shakoor, Muhammad Bilal,Niazi, Nabeel Khan,Bibi, Irshad,Murtaza, Ghulam,Kunhikrishnan, Anitha,Seshadri, Balaji,Shahid, Muhammad,Ali, Shafaqat,Bolan, Nanthi S.,Ok, Yong Sik,Abid, Muhammad,Ali, Fawad Informa UK (TaylorFrancis) 2016 Critical reviews in environmental science and tech Vol.46 No.5

<P>Arsenic (As) contamination of groundwater reservoirs is a global environmental and health issue given to its toxic and carcinogenic nature. Over 170 million people have been affected by As due to the ingestion of As-contaminated groundwater. Conventional methods such as reverse osmosis, ion exchange, and electrodialysis are commonly used for the remediation of As-contaminated water; however, the high cost and sludge production put limitations on their application to remove As from water. This review critically addresses the use of various agricultural waste materials (e.g., sugarcane bagasse, peels of various fruits, wheat straw) as biosorbents, thereby offering an eco-friendly and low-cost solution for the removal of As from contaminated water supplies. The effect of solution chemistry such as solution pH, cations, anions, organic ligands, and various other factors (e.g., temperature, contact time, sorbent dose) on As biosorption, and safe disposal methods for As-loaded biosorbents to reduce secondary As contamination are also discussed.</P>

A combined first principles and experimental study on Na₃V₂(PO₄)₂F₃ for rechargeable Na batteries

Shakoor, R. A.,Seo, Dong-Hwa,Kim, Hyungsub,Park, Young-Uk,Kim, Jongsoon,Kim, Sung-Wook,Gwon, Hyeokjo,Lee, Seongsu,Kang, Kisuk The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.38

<P>The electrochemical properties of Na<SUB>3</SUB>V<SUB>2</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>F<SUB>3</SUB> in a Na rechargeable battery were investigated through a combined computational and experimental study. <I>Ex situ</I> XRD results indicate that the reversible sodiation/desodiation occurs <I>via</I> one phase reaction and the structure of Na<SUB>3−<I>x</I></SUB>V<SUB>2</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>F<SUB>3</SUB> remains quite stable upon extraction and insertion of sodium. Notable is that the one phase reaction is accompanied by the negligible variation in lattice parameters (∼1%) and unit cell volume (∼2%) which results in a good cycle performance. It is further noticed that the desodiated phase is thermally stable up to 550 °C implying the excellent safety characteristic of the charged electrode. The first principles calculations elucidate the mechanisms of the structural evolution and the electrochemical behavior of Na<SUB>3−<I>x</I></SUB>V<SUB>2</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>F<SUB>3</SUB> upon battery cycling.</P> <P>Graphic Abstract</P><P>The electrochemical behavior of Na<SUB>3</SUB>V<SUB>2</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>F<SUB>3</SUB> in a sodium-ion cell was investigated through a combined computational and experimental study. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm33862a'> </P>

The Drazin inverses of the sum of two matrices and block matrix

Abdul Shakoor,Hu Yang,Ilyas Ali 한국전산응용수학회 2013 Journal of applied mathematics & informatics Vol.31 No.3

In this paper, we give a formula of (P +Q)D under the conditionsP2Q+QPQ = 0 and P3Q = 0. Then applying it to give some resultsof block matrix M =(A BC D)(A and D are square matrices) with generalizedSchur complement is zero under some conditions. Finally, numericalexamples are given to illustrate our results.

Plant Root Hair in Tap Water: A Potential Cause for Diagnostic Confusion

Sadia Shakoor,Mohammad Wasay,Afia Zafar,Mohammad Asim Beg 대한진단검사의학회 2011 Annals of Laboratory Medicine Vol.31 No.1

Plant root hairs are commonly found artifacts in parasitology specimens and may be confused with helminthes by an untrained eye. We report a case of brain tuberculoma where the tissue sample was contaminated with root hair derived from tap water; the presence of this root hair, which mimicked a larva, led to diagnostic confusion. Therefore, tap water should be considered a source of root hair and vegetable matter.

MORE GENERAL FORMS OF (∈; ∈ ∨Q_k) FUZZY FILTERS OF ORDERED SEMIGROUPS

( Asghar Khan ),( Shakoor Muhammad ),( Mohammed M. Khalaf ) 호남수학회 2017 호남수학학술지 Vol.39 No.2

In the paper [Y. B. Jun, B. Davvaz and A. Khan, Filters of ordered semigroups based on the fuzzy points, JIFS 24 (2013) 619-630]. Jun et al. discussed the notion of (∈; ∈ ∨q_k)-fuzzy left (resp., right) filters as a generalization of the notion of (∈; ∈ ∨q)-fuzzy left (resp., right) filters of ordered semigroups. In this article, we try to obtain a more general form that (∈; ∈ ∨q_k)-fuzzy left (resp., right) filters in ordered semigroups. The notion of (∈; ∈ ∨q^δ_k)-fuzzy left (resp., right) filters is discussed, and several properties are investigated. Characterizations of an (∈; ∈ ∨q^δ_k)- fuzzy left (resp., right) filter are established. A condition for an (∈; ∈ ∨q^δ_k)-fuzzy left (resp., right) filter to be a fuzzy left (resp., right) filter is provided. The important achievement of the study with an (∈; ∈ ∨q^δ_k)-fuzzy left (right) filter is that the notion of an (∈; ∈ ∨q_k)-fuzzy left ( right) filter and hence an (∈; ∈ ∨q)-fuzzy left (resp. right) filter are special cases of an (∈; ∈ ∨q^δ_k)-fuzzy left (resp. right) filter, and thus several results in published papers are becoming corollaries of our results obtained in this paper.

Na₂FeP₂O₇ as a Promising Iron‐Based Pyrophosphate Cathode for Sodium Rechargeable Batteries: A Combined Experimental and Theoretical Study

Kim, Heejin,Shakoor, R. A.,Park, Chansun,Lim, Soo Yeon,Kim, Joo‐,Seong,Jo, Yong Nam,Cho, Woosuk,Miyasaka, Keiichi,Kahraman, Ramazan,Jung, Yousung,Choi, Jang Wook WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.9

<P><B>Abstract</B></P><P>Considering the promising electrochemical performance of the recently reported pyrophosphate family in lithium ion batteries as well as the increasing importance of sodium ion batteries (SIBs) for emerging large‐scale applications, here, the crystal structure, electrochemical properties, and thermal stability of Na<SUB>2</SUB>FeP<SUB>2</SUB>O<SUB>7</SUB>, the first example ever reported in the pyrophosphate family for SIBs, are investigated. Na<SUB>2</SUB>FeP<SUB>2</SUB>O<SUB>7</SUB> maintains well‐defined channel structures (triclinic framework under the <I>P1</I> space group) and exhibits a reversible capacity of ≈90 mAh g<SUP>−1</SUP> with good cycling performance. Both quasi‐equilibrium measurements and first‐principles calculations consistently indicate that Na<SUB>2</SUB>FeP<SUB>2</SUB>O<SUB>7</SUB> undergoes two kinds of reactions over the entire voltage range of 2.0–4.5 V (vs Na/Na<SUP>+</SUP>): a single‐phase reaction around 2.5 V and a series of two‐phase reactions in the voltage range of 3.0–3.25 V. Na<SUB>2</SUB>FeP<SUB>2</SUB>O<SUB>7</SUB> shows excellent thermal stability up to 500 °C, even in the partially desodiated state (NaFeP<SUB>2</SUB>O<SUB>7</SUB>), which suggests its safe character, a property that is very critical for large‐scale battery applications.</P>

Charge/Discharge Mechanism of Multicomponent Olivine Cathode for Lithium Rechargeable Batteries

Park, Young-Uk,Shakoor, R.A.,Park, Kyu-Young,Kang, Ki-Suk The Korean Electrochemical Society 2011 Journal of electrochemical science and technology Vol.2 No.1

Quasi-equilibrium profiles are analyzed through galvanostatic intermittent titration technique (GITT) and potentiostatic intermittent titration technique (PITT) to study the charge/discharge mechanism in multicomponent olivine structure ($LiMn_{1/3}Fe_{1/3}Co_{1/3}PO_4$). From GITT data, the degree of polarization is evaluated for the three regions corresponding to the redox couples of $Mn^{2+}/Mn^{3+}$, $Fe^{2+}/Fe^{3+}$ and $Co^{2+}/Co^{3+}$. From PITT data, the current vs. time responses are examined in each titration step to find out the mode of lithium de-intercalation/intercalation process. Furthermore, lithium diffusivities at specific compositions (x in $Li_xMn_{1/3}Fe_{1/3}Co_{1/3}PO_4$) are also calculated. Finally, total capacity ($Q^{total}$) and diffusional capacity ($Q^{diff}$) are obtained for some selected voltage steps. The entire study consistently confirms that the charge/discharge mechanism of multicomponent olivine cathode is associated with a one-phase reaction rather than a biphasic reaction.