Search

With the utilization of used newspaper into the paper making industry, bleaching has been an area of concern to obtain a balance between desired brightness and the amount of treatment it requires. Motivation of this study was to optimize bleaching of recycled newsprint fibers in terms of five variables namely hydrogen peroxide charge, amount of sodium hydroxide employed, pulp consistency, bleaching temperature, and bleaching time. Experimental work was conducted in the laboratory to simulate bleaching plant and it was found that higher peroxide charge is better for improvement in brightness, but it is uneconomical to increase peroxide charge indefinitely. The amount of hydrogen peroxide is added so that the residual peroxide at the end of the reaction is not less than 10% of the initially added peroxide. Sodium hydroxide provides alkalinity which is very important for making the fibers flexible and softening of ink particles but it also contributes to pulp yellowing if residual hydrogen peroxide contents are lesser than the minimum required value. So, for 16 kg t−1 of hydrogen peroxide, 6 kg t−1 of sodium hydroxide prevented the brightness reversion in this study. Higher pulp consistency is better but unavailability of very high consistency pulp mixer in the industry is a limiting factor for higher than 30% pulp consistency. Temperature and time are quite interrelated and, with the given bleaching conditions, a temperature of 95 °C with 10 min residence time was found to be optimum for this study. It was also observed that multiple pre-washings increase brightness and save bleaching chemicals.

A novel solid state reaction method has been followed to prepare LiCoO2 (LCO) using micro porous filter paper as scaffolds. FT-IR spectroscopy confirms the vibration spectrum for the identification of CoO6 as well as LCO. XRD diffraction analyses confirmed the formation rhombohedral crystal system of the prepared LCO materials with R-3m space group. The sharp XRD diffractogram of filter paper scaffold LCO demonstrate its crystallinity and purity. The presence of high intensity (003) plane, formation of Co–O–Co linkage with (104) plane and splitting of (006)/(012); (108)/(110) planes confirm layered structure of the prepared LCO. FESEM demonstrate that the presence of micropores in the cellulose backbone of filter played significant role for the solid state reaction and can be used as a scaffold to change the morphology of LCO in the microstructural aspect. UV-visible spectroscopy study reveals that the band gap energy of filter papers assisted LCO are less than the LCO prepared directly from raw materials.

Using conductive interlayers to act as the "upper current collector" is a common strategy to suppress the shuttle effect in lithium-sulfur batteries. However, the current widely used interlayers generally have the disadvantages of poor conductivity and complicated fabrication. Herein, we report a novel carbon paper prepared by simple wet laid method. The as-prepared carbon paper exhibits excellent conductivity of 11.9 S/cm and 3D conductive structure. Finally, the carbon paper as an interlayer for lithium-sulfur batteries displays an initial capacity of 1091 mAh g-1 at C/5 rate, and remains 631 mAh g-1 after 200 cycles with a decay rate of 0.21% per cycle.

The authors of the title paper (Mater. Res. Express 6 (2019) 116213) claim to have grown a nickel boro phthalate (NBP) crystal by the slow evaporation method. A critical analysis of the paper reveals that the so-called NBP is an improperly characterized material. A reinvestigation of the crystal growth reaction has been performed to unambiguously characterize the product. In this letter to the Editor, it is proved that nickel boro phthalate neither contains nickel nor phthalate but is, in fact, boric acid.

Low concentration of biomarkers (proteins, nucleic acids, metabolites) is a major concern in early disease diagnosis due to the very low concentration of these biomarkers at the early stage of any disease. This challenge can be addressed by preconcentrating the biomarkers to improve the sensitivity of the diagnostic device. This paper describes a novel method to preconcentrate the charged molecules on paper using greenly synthesized iron nanoparticles. The iron nanoparticles were synthesized by utilizing plant extract as stabilizing agent, which both minimizes the cost and protects the environment. Three different samples of the nanoparticles were prepared by changing the charge or attaching a functional group (amine) to the surface. The iron nanoparticles act as a charged nanoporous membrane when deposited on the paper pads inducing electrostatic forces around the membrane leading to the concentration of the charged analytes near the boundary of the membrane. Crystal violet was used as a surrogate for the charged biomolecule. We report ∼24-fold increase in the concentration of crystal violet dye within 120 seconds using the positively charged membrane and the 0.2 mM dye solution. The developed experimental set-up eliminates the need for external pumping device and complex fabrication processes making the proposed method cost-effective, environment-friendly, and simple to use.

In this paper, a simple method for preparing high stability superhydrophobic paper with pH-induced wettability transition was proposed. Firstly, the pH-responsive monomer 2- (dimethylamino) ethyl methacrylate (DMAEMA), the silicon-containing crosslinking monomer 3-trimethoxysilyl propyl methacrylate (TSPM) and the fluorine-containing monomer hexafluorobutyl methacrylate (HFMA) were polymerized to prepare the pH-responsive polymer PHFMA-PTSPM-PDMAEMA. Afterwards, the amino-modified SiO2 was grafted onto the polymer to provide roughness and then coated on the paper to prepare the superhydrophobic paper with pH-responsive properties. Further research found that the modified paper prepared by this method not only has strong stability and transparency, but also can realize the reversible regulation of superhydrophobic & lipophilic and super-oleophobic & hydrophilic properties under different pH-induction, and it has important application value in the field of oil-water separation in industrial applications.

Sodium hyaluronate (HA) stabilized curcumin-Ag (Cur-Ag) hybrid nanoparticles were prepared in the water–ethanol mixture under constant mechanical stirring condition. The obtained HA stabilized Cur-Ag hybrid nanoparticles were characterized by fourier transform infrared spectroscopy, UV–visible spectroscopy, and x-ray diffraction to confirm the formation and structural interactions. The obtained Cur-Ag hybrid nanoparticles showed spherical shape with their size range 5–12 nm that was increased with the increasing a amount of silver ions as confirmed by transmission electron microscopic analysis. Further, a fibrous cellulose filter paper was impregnated with these hybrid nanoparticles and chitosan (CS) as biopolymer via polyelectrolyte complexation. The morphological analysis confirmed the uniform distribution of hybrid nanoparticle system onto the cellulose fibers of the fibrous filter paper. As per disc diffusion method, the Cur-Ag hybrid nanoparticles impregnated CS-coated filter paper exhibited excellent antibacterial properties against gram-negative Escherichia coli (E.coli) bacteria compared to HA stabilized Cur only. Moreover, as prepared hybrid nanoparticles impregnated biocomposite system is eco-friendly with efficient antibacterial property and have good potential to be used in medical applications.

Paper is a fascinating material for electronic platform devices due to being an inexpensive and environment friendly material. Terahertz wave is able to penetrate paper, thus paper-based terahertz metamaterial will be great terahertz devices. Creating multiple symmetrical Split Ring Resonator (SRR) on upper side paper and depositing metallic plane on back side paper yield terahertz metamaterial absorber. The maximum of absorbance peak for numerical and analytical results are 98% at 0.92 THz and 99% at 0.92 THz, respectively. The superposition of multiple reflections of terahertz wave generated on paper and yielding destructive interference phenomenon. Numerical and analytical works have been carried out in this works and showed good agreement.

Present work reports the green synthesis of highly stable, non-toxic, environmental friendly, fluorescent carbon quantum dots (CQD) via simple synthetic route using the waste carbon paper as their precursor. The as-synthesized CQD were post-synthetically modified with (3-Aminopropyl)triethoxysilane (APTES) as a nitrogen source for amine functionalized CQD (NCQD) formation. When excited at wavelength λex = 350 nm, the maximum emission intensity of NCQD was observed at wavelength λem = 450 nm. The QDs show blue colored luminescence with significant photoluminescence quantum yield (~5.1%). Transmission electron microscopy and Energy-dispersive x-ray spectroscopy data show their size about 4.8 nm and the presence of nitrogen in elemental composition respectively. XRD and selected area electron diffraction patterns reveal their amorphous nature. This NCQD based sensing probe selectivity displays the high sensitivity for trinitrotoluene (TNT) in 4.4 nM to the 26.4 μM range. The probe delivers a 7.4ppb detection limit at 1.3% relative standard deviation.

This paper presents a novel boron diffusion process using boron paper as the boron source to form a p+ layer. It was found that sheet resistance was invariable with changing the distance between boron paper and Si wafers, and diffusion uniformity was the best at a distance of 0.3 cm. Sheet resistance (Rs) decreased with increasing diffusion temperature, showing a value of 6.9 ?/ at 1050 ?C with a high diffusion uniformity of 99.173%. The junction depth increased from 195 nm to 517 nm with diffusion temperature raised from 900 ?C to 1050 ?C. The influence of diffusion time on the performance of B diffusion from boron paper was similar with that of temperature.

Porous conducting carbon fiber paper (PCCFP) is one of the vital component of the gas diffusion layer (GDL) in a fuel cell. This PCCFP serves as the most suitable substrate for the GDL due to its electrical conductivity, mechanical properties, and porosity. In this approach, carbon fiber composite papers were developed by incorporating different fractions of natural graphite (NG) in the matrix phase, i.e. Phenolic resin, and using the combined process of paper making and carbon–carbon composite formation technique. These prepared samples were then heat treated at 1800 °C in an inert atmosphere. The effect of natural graphite incorporation was ascertained by characterizing porous carbon paper by various techniques i.e. X-ray diffraction, Raman spectroscopy, Scanning electron microscopy, electrical and mechanical properties, and I–V performance in a unit fuel cell assembly. The inclusion of NG certainly enhance the properties of the carbon matrix as well as improving the conductive path of carbon fibers. In this study addition of 1 wt.% of natural graphite demonstrated a significant improvement in the electrical conductivity and performance of PCCFP and resulted in the improvement of power density from 361–563 mW cm−2. This paper reports that the uniform dispersion of NG was able to generate a maximum number of macrosize pores in the carbon paper that strengthened the flexural modulus from 4 to 12 GPa without compromising the porosity required for the GDL.

Recycled cellulosic paperboards may include mineral oils after the recycle process, which together with their poor water resistance limit their use as food packaging materials. In this work, we demonstrate that a proper functionalization of the recycled paper with two successive polymer treatments, imposes a mineral oil migration barrier and simultaneously renders it waterproof and grease resistant, making it an ideal material for food contact. The first poly (methyl methacrylate) treatment penetrates the paper network and creates a protective layer around every fiber, permitting thus the transformation of the paperboard to a hydrophobic material throughout its thickness, reducing at the same time the mineral oil migration. Subsequently, the second layer with a cyclic olefin copolymer fills the open pores of the surface, and reduces the mineral oil hydrocarbons migration at levels below those proposed by the BMEL. Online liquid chromatography-gas chromatography coupled with flame ionization detection quantitatively demonstrate that this dual functional treatment prevents the migration of both saturated (mineral oil saturated hydrocarbons) and aromatic hydrocarbon (mineral oil aromatic hydrocarbons) mineral oils from the recycled paperboard to a dry food simulant.

In the present work, a free-standing paper-like sample made of a three-dimensional web of multiwall carbon nanotubes that exhibit cross-linking and wall sharing is characterized with respect to its electrical, electrochemical, surface and wetting properties. All these parameters are studied simultaneously to assess the potential of the sample for demanding applications with multiple material requirements. It is observed that many characteristics of the one-dimensional counterpart are retained by the three-dimensional web. In addition, the properties of this nanostructured material are compared against zero-, one- two- and three-dimensional carbon-based materials, while potential applications that require high electrical conductivity and energy storage capabilities and related properties, are discussed.

Generally olive oil generated two forms of waste by-products: solid olive residue (SOR) and olive wastewater (OWW). In the present study a promising solution is given to treat both SOR and OWW waste by-products. The first process consists of converting the solid olive residue to activated carbon using pyrolysis process at 600 °C, followed by steam activation procedure at three different temperatures. The attained activated carbon was examined by different experimental techniques such as FTIR, SEM, BET and iodine number. The surface area was increased by increasing stream activation temperature (reach 1020 m2 g−1 BET). However, the steam activation at 700 °C was found to be ideal for environmental and economic performance. On the other hand, the activated carbon at 700 °C displayed high removal capacity of both polyphenolic compounds and COD from olive wastewater. In fact, after 2 h of treatment, 95.5% of COD and 84.2% of polyphenolic compounds were completely removed.

Lignocellulosic fibers have been widely used to reinforce polymer composites. Chemical modification of the fibers can improve the fiber properties and fiber-polymer interfacial compatibility. This study considered an eco-friendly process that can reduce environmental pollution by modifying lignocellulosic fibers using seawater rather than chemical reagents. The effects of seawater modification on the physical, chemical, and thermal properties of lignocellulosic fibers obtained from wheat straw were investigated. After seawater modification, the modified fibers had a lower number of hydrogen bonds, hemicellulose, lignin, and silicon content, and higher water absorption, crystallinity, surface roughness, and thermal stability. Considering the essential components of seawater, the contribution of NaCl during the modification process was the most significant, followed by that of the bivalent salts (MgCl2 + CaCl2 + SrCl2), Na2SO4, and trace-component (KCl + NaHCO3 + KBr + H3BO3 + NaF).

Scientific investigations on the non-chemical modification of lignocellulosic fibers are important for engineers when they design green wood-plastic composites. Two types of lignocellulosic fibers, namely rice husk and rice straw fibers, were studied. The physicochemical and thermal properties of the fibers with and without seawater modification were compared. The results suggested that seawater modification improved the physicochemical and thermal properties of the fibers, and that it specifically increased the surface roughness, crystallinity, and pyrolysis temperature at 5% weight loss, and decreased the silicon, hemicellulose, and lignin content of the fibers. Compared with rice husk fibers, rice straw fibers exhibited a high growth ratio of crystallinity and pyrolysis temperature at 5% weight loss, and a high loss ratio of silicon. Seawater modification of rice husk and rice straw fibers could improve fiber–polymer compatibility.

In order to reduce the hydrogen cyanide (HCN) release in cigarette mainstream smoke, a new type of porous corncob (PCC) material which was different from traditional corncob-based activated carbon was prepared by a two-step chemical reaction of carboxymethylation and cupric ion complexation. Fourier Transformation Infrared Spectroscopy (FTIR) showed that the carboxymethyl group had been introduced onto the corncob, the carboxymethyl content and the cupric ion loading amount were measured. The x-ray photoelectron spectrometer (XPS) results showed that the Cu content on the surface of PCC was much higher than that of the whole material. The scanning electron microscope (SEM) and nitrogen adsorption-desorption results suggested that PCC had a porous structure. With the increase of the amounts of chloroacetic acid and sodium hydroxide in carboxymethylation reaction and the concentration of cupric ion aqueous solution in complexing reaction, the BET surface areas and pore volumes increased, while the most probable pore sizes of PCCs were close to each other. Compared with the control cigarette, the addition of PCC could effectively remove the HCN release in cigarette mainstream smoke, and the highest reduction rates of HCN per total particulate matter (TPM) was 72.4 %.

Accidental marine oil discharge causes severe environmental pollution and thus remediation is essential. However, the removal and recycling of the spilled oil using economical and highly efficient methods are still major challenges. In this work, an oil absorbent of corn straw fibers (CSF) were prepared via a one-step direct modification with hydrophobic octyltrimethoxylsilane (OTS). With the surface modification, the CSF exhibited both superhydrophobicity and superoleophilicity, and the contact angles of water and oil on the as-prepared samples were 156 ± 1° and 0°, respectively. Owing to the oleophilicity and hydrophobicity features of the CSF, it could be used to selectively absorb oil in water. The adsorption capacity of the as-prepared absorbents for diesel oil, the recyclability, and the reaction mechanism between OTS and the CSF were investigated in detail. The oil absorbent could still remain superhydrophobic even after eleven successive cycles of oil-water separation. With the characteristics of easy biodegradability, durability, and recyclability, as well as the facile procedures involved, oil absorbent of CSF prepared by direct OTS-modification is expected to be used for oil spill cleanup and recovery.

Carbon fabric reinforced Epoxy (C-E) composites filled with different weight percentage of silane treated flyash cenosphere (CSP) particles were synthesized using hand layup process followed by compression moulding method. The fabricated samples were subjected to mechanical tests and two body multipass abrasive wear test (2BMAW) in accordance with American society for testing and materials (ASTM). Mechanical results showed addition of CSP particles in C-E composites tends to improve property such as density, hardness, flexural and impact strength. Meanwhile Taguchi method with Grey relational analysis (GRA) was implemented for 2BMAW test to optimize the wear process parameters with multi-response characteristics. Filler wt% (Filler content), Grit size of abrasive (emery paper), sliding distance (m) and Load (N) were selected as wear process parameters for which responses were coefficient of friction (COF), specific wear rate (SWR) and hardness (BH) of the composites. Analysis of variance (ANOVA) result based on grey relational grade (GRG) revealed that filler wt% (filler content) and sliding distance were found as most significant process parameter influencing the wear performance of the composites by 55% and 19% respectively followed by Grit size of emery paper and applied load. Finally microstructure analysis of the fractured and worn sample has been studied using scanning electron microscope to understand the mode of failure mechanism.

The main objective of this study is to evaluate the effect of rice starch and polyvinyl acetate (PVAc) as binding agents on mechanical, thermal and water absorption properties of molded rice bran/rice straw (RB/RS). Rice bran (RB) and rice straw (RS) were molded in form of paper sheet using compression-molding technique. Tearing resistance of RB/RS was enhanced by 135%–140% after the addition of PVA and rice starch binders. Thermal stability of RB/RS was affected positively by PVAc and negatively by rice starch binders. Fractured surface analysis of inverted optical microscope indicated that RB/RS samples have clear visible phase separation without binding agent compared to RB/RS with binders of PVAc and rice starch.

In this study, the investigation of mechanical properties of epoxy based composites was conducted experimentally. The matrix material used in the research work was epoxy resin and jute and basalt fibre were used as the reinforcement material for the preparation of the hybrid composite. Each hybrid composite consists of eight stack of layers of fibres oriented accordingly to achieve high strength. Tensile test, compressive test and wear test were performed to investigate the mechanical properties and machinability of the composite material. Tests were carried out according to the ASTM standards. Tensile test and compressive test were performed in universal testing machine and wear test was performed on pin-on-disc wear testing machine. Each hybrid composite consists of eight stacks of layers of fibres oriented accordingly to achieve high strength. It was observed that the tensile modulus of the epoxy based hybrid composite increases with increase of layers of basalt fibre. It was observed that the compressive modulus and compressive strength also increase rapidly. Silicon carbide emery paper was used for the testing of abrasive wear rate of the specimen. Taguchi technique was used to optimize the parameters and the input parameters used in the wear analysis includes; the type of the specimen, load and density. Specific wear rate for each specimen was calculated and the main effects plots for signal-to-noise ratio were drawn and analyzed in this research work.

Rice husk is considered as a waste in the rice industry but is proficient in manufacturing different materials, such as zeolites, which is produced in large quantities all over the world, for example in Brazil. Zeolite is an adsorbent support material, which can be synthesized from rice husk ash (RHA) with external sources of aluminium (ESA). The scientific community has been conducting several measures to minimize the environmental impacts caused by greenhouse gases. Several mitigation processes are presently investigated, which includes carbon dioxide injections into adsorbent materials (e.g. zeolites). The efficiency of this technology involves a zeolitic material with high crystallinity and high concentrations of SiO2 and Al2O3 (aluminosilicates). In the present work, zeolites have been synthesized from rice husk ash (SiO2 source) and external aluminium sources (Al2O3 - alumina, gibbsite and metakaolin) to fulfill that purpose. With the aid of XRF, XRD, SEM/EDS and FTIR techniques, the zeolitic material was characterized in two distinct crystalline phases: Mordenite and ZSM-5. The synthesis was carried out by the ideal addition of ESA (2.5 g) to RHA. According to the literature, the zeolitic materials formed by the mixture of Mordenite and ZSM-5 can be availed for gas separation and greenhouse gas storage.

Biomass is a renewable resource that is becoming more import due to environmental concerns and possible oil crisis. Thus, optimizing its use is a current challenge for many researchers. Lignin, which is a macromolecule with complex chemical structure, valuable physicochemical properties, and varied chemical composition, is available in large quantities in pulp and paper companies. The objective of this work is the physicochemical characterization of two Kraft lignin samples with different purities, and the study of its thermal conversion into charcoal. The lignin characterization was based on chemical, TGA, DSC, FT-IR, particle sizes, and FEG-SEM analyses. These analyses show that the lignins are mainly composed of guaiacyl and syringyl units, with residues of 30–36 wt.%, in inert atmosphere, depending on the lignin purity. From these results, the more purified lignin with higher carbon yield (%C) was selected for charcoal production. The heat treatment (HT) for carbonization of lignin, at different times (90, 180, and 420 min), resulted in different %C (41–44 wt.%). Longer HT resulted in higher %C and in charcoals with smaller pore sizes. Nanopores (~50 nm) are observed for the charcoal obtained with the longest HT.

In this paper, a facile and a fast synthesis process of reduced graphene oxide (rGO) is introduced by using a modified Marcano method. A modification of the chemical synthesis method was developed, which uses a small amount of strong acids, a low oxidation temperature and a short stirring process. X-ray diffraction (XRD) pattern and Fourier transform infrared spectrometry (FTIR) spectra confirmed that rGO was successfully synthesized. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed rGO in sheet form. Based on energy dispersive x-ray spectrometry (EDX), the surface of the prepared rGO sample was dominated by ~90% of C atoms. Four-point probe measurements showed the electrical conductivity of the prepared rGO sample at 1180 S m−1. Based on the electrochemical impedance spectrometry (EIS) results gives 2.1 Ω charge transfer resistance between the electrode and the electrolyte to the prepared rGO sample. This study provides a new perspective on rGO synthesis using a wet chemical process.

The current study presents the synthesis of polyaniline-Scenedesmus biocomposite and its use as an efficient adsorbent for removal of contaminants from aqueous solutions. Initially, the Scenedesmus strain was cultivated in municipal wastewater. The Physico-chemical analysis of municipal wastewater after microalgae growth depicted 85.5% reduction in total nitrogen, 83.2% reduction in phosphorus and 89.3% reduction in chemical oxygen demand which clearly reveals that this strain can be efficiently used to avoid eutrophication caused by municipal wastewaters. The biomass of Scenedesmus strain obtained was harvested and de-oiled. The de-oiled biomass was further used for the adsorptive removal of Reactive red 120 (RR 120) from aqueous solutions. The biomass was treated with H2SO4 and was used in three different forms; free, immobilized and polyaniline composite and all these three different forms of biomass showed adsorption potential of 713.02, 682.52 and 752.68 (mg g−1) respectively. Characterization of biomass was carried out by SEM, FT-IR and pHpzc determination. Kinetic study showed best fitness of pseudo second order kinetic model and experimental data was best fitted with Freundlich adsorption isotherm model. The study results indicated that this strain has good potential for adsorptive removal of contaminants from wastewaters.

Kenaf is a plant which grows fast and has good environment adaptability. It is one of the most traditional natural cellulosic fiber plants in the word. However, the high lignin content and small fiber size block its application on textile fiber production and bioenergy refinery. Nanocellulose turns out a promising way to take advantage of the kenaf resource. Herein, combined microwave and chemical treatment was employed to extract nanocellulose from kenaf bast directly. The fiber size and chemical components during the extraction processes were analyzed. Then the kenaf nanocellulose is characterized by transmission electron microscopy, x-ray diffraction and thermogravimetric analysis. The results suggest that: most of the non-cellulosic materials such as lignin and hemicellulose was removed from kenaf bast after microwave and bleaching progress, producing micron size fibers; the kenaf nanocellulose extracted by the combined microwave and chemical treatment showed an acicular morphology with nano-size fiber; it has a higher cristallinity but a bit lower thermal stability compared with raw kenaf bast. In a word, this combined treatment is significantly effectual for preparing kenaf nanocellulose. It is expected that the results can serve theoretical basis for subsequent utilization of kenaf nanocellulose.

Recently, the preparation of flexible graphene-based micro-supercapacitors has attracted considerable attention. In this paper, a flexible and all-solid-state micro-supercapacitor was fabricated by LightScribe technology. Additionally, the influences of the drop-cast amount of graphene oxide (GO) and the numbers of LightScribe times on the performance of the supercapacitor were systematically investigated by means of cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge. It was determined that the electrochemical performance of the micro-supercapacitor was optimal when the drop-cast amount was 0.38 mg cm−2. Moreover, a positive correlation was found between the capacitance and the number of LightScribe times. The maximum capacitance was 2.9 mF cm−2, which was reached with 20 rounds of LightScribe.

All water treatment plants produce waste/residue amid the treatment of raw water. This study selectively investigates the clariflocculator sludge for its physicochemical characteristics and potential reuse options. Sieve analysis, XRF, SEM, XRD, FTIR, and TG-DTA instrumental techniques have been used to characterize the sludge sample. Results show that clariflocculator sludge contains about 78% fine sand having grain size range 150–75 μm. SiO2, Al2O3, Fe2O3 and CaO constitute the maximum percentage of chemical compounds present in the sludge and quartz is the main crystalline phase of the sludge. Recycling and reuse of this sludge, especially, as fine sand in preparing mortar, concrete mix and other civil engineering products would pave the way for constructive utilization with safe and sustainable sludge management strategies.

This work aims to determine the effect of graphene oxide (GO) and reduced graphene oxide (rGO) incorporation as filler on the corrosion protection ability of epoxy coatings in saline media. GO was derived from graphite powder following modified Hummers' method, whereas rGO was obtained after reduction of GO with hydrazine solution. About 1 wt.% of GO or rGO were incorporated in epoxy resin by solution mixing process followed by ball milling. GO and rGO-based epoxy composite coatings were coated on mild steel substrates using film coater. The coated samples were characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests after 1 and 24 h immersion in 3.5% NaCl. The results suggested that GO-based epoxy composite coatings showed high impedance and low corrosion rate.