B. Jabeera, S.M.A. Shibli and T.S. Anirudhan
Zinc ions, produced by the electrolytic dissolution of zinc metal rods, exhibited excellent inhibition efficiency, especially in combination with the synergistic additions of…
Abstract
Zinc ions, produced by the electrolytic dissolution of zinc metal rods, exhibited excellent inhibition efficiency, especially in combination with the synergistic additions of tungstate and nitrite ions. The optimum ratio of tungstate: nitrite: zinc was found to be 10:10:1 and the combination of tungstate: 100 ppm ‐ nitrite: 100 ppm ‐ zinc: 10 ppm (System A) gave the best results of all the systems studied. This system requires a much smaller concentration of tungstate and nitrite ions, as compared to the concentrations typically used and claimed to offer optimal inhibition efficiency. Long‐term open circuit potential measurements indicated that effective passivation occurred within 3 days of immersion. The passive layer thus formed on the metal surface retained its protective capability for several weeks, even after test coupons were transferred into a depleted inhibitor solution. The possible mechanism of the passivation is discussed.
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R. Saravanane, T. Sundararajan and S. Sivamurthy Reddy
The removal efficiency of lead [Pb(II)], zinc [Zn(II)], nickel [Ni(II)] and chromium [Cr(VI)] from aqueous solutions by adsorption on non‐conventional materials (rice husk and…
Abstract
The removal efficiency of lead [Pb(II)], zinc [Zn(II)], nickel [Ni(II)] and chromium [Cr(VI)] from aqueous solutions by adsorption on non‐conventional materials (rice husk and sawdust) in its natural form and on their chemically modified form is presented. It is found that adsorption potential varies as a function of contact time, concentration, particle size, pH and flow rate. Of all the low cost adsorbents used in this study, sawdust is found to possess greater adsorption efficiency for all metals than rice husk under identical experimental conditions. Chemically activated sawdust could remove 95 percent of Pb(II), 93 percent of Zn(II), 80 percent of Ni(II) and 75 percent of Cr(VI) from the metal bearing industrial effluents.
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The purpose of this study is to prepare a new adsorbent activated carbon immobilized on polystyrene (ACPS) for uranium (VI) and thorium (IV) removal from an aqueous solution…
Abstract
Purpose
The purpose of this study is to prepare a new adsorbent activated carbon immobilized on polystyrene (ACPS) for uranium (VI) and thorium (IV) removal from an aqueous solution. Activated carbon (AC) was derived from biochar material by chemical activation to increase the active sites on its surface and enhance the adsorption capacity. Activated carbon (AC) was immobilized on polystyrene (PS) to improve the physical properties and facilitate separation from the working solution. A feasibility study for the adsorption of uranium (VI) and thorium (IV) on the new adsorbent (ACPS) has been achieved. Adsorption kinetics, isotherms, and thermodynamics models of the adsorption process were used to describe the reaction mechanism.
Design/methodology/approach
Activated carbon was synthesized from biochar charcoal by 2 M H2SO4. Activated carbon was immobilized on the pretreatment polystyrene by hydrothermal process forming new adsorbent (ACPS). Characterization studies were carried out by scanning electron microscope, energy-dispersive X-ray spectrometer, infrared spectroscopy and X-ray diffraction techniques. Different factors affect the adsorption process as pH, contact time, solid/liquid ratio, initial concentration and temperature. The adsorption mechanism was explained according to kinetic, isothermal and thermodynamic studies. Also, the regeneration of spent ACPS was studied.
Findings
The experimental results showed that pH and equilibrium time of the best adsorption were 6.0 and 60 min for U(VI), 4.0 and 90 min for Th(IV), (pHPZC = 3.4). The experimental results fit well with pseudo-second order, Freundlich and Dubinin–Radushkevich models proving the chemisorption and heterogenous adsorption reaction. Adsorption thermodynamics demonstrated that the adsorption process is exothermic and has random nature of the solid/liquid interface. In addition, the regeneration of spent ACPS research showed that the adsorbent has good chemical stability. According to the comparative study, ACPS shows higher adsorption capacities of U(VI) and Th(IV) than other previous bio-adsorbents.
Originality/value
This study was conducted to improve the chemical and physical properties of bio-charcoal purchased from the local market to activated carbon by hydrothermal method. Activated carbon was immobilized on polystyrene forming new adsorbent ACPS for eliminating U(VI) and Th(IV) from aqueous solutions.
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Nirmala Gnanasundaram, Aruna Singh and M Ganesapillai
The purpose of this paper is to harness the potential of microwave pre-treatment to prepare carbon from locally available Sterculia foetida fruit shells for adsorption of heavy…
Abstract
Purpose
The purpose of this paper is to harness the potential of microwave pre-treatment to prepare carbon from locally available Sterculia foetida fruit shells for adsorption of heavy metals, particularly Nickel ions (Ni++), from effluent.
Design/methodology/approach
The pre-treatment methods comprise conventional methods as sun drying and oven drying as well as high intensity microwave drying. Response surface methodology was employed to analyse the optimization of the process. The adsorption behavioural characteristics of the material were established applying adsorption isotherms.
Findings
Adsorption of Ni++ was found to be effective in microwave drying at output power of 300 W. It was observed that the maximum adsorption capacity was attained at pH 6; an adsorbent dosage of 0.25 mgml−1 and initial metal ion concentration of 20 ppm with an interactive effect of initial concentration and dosage.
Originality/value
The research puts emphasise on prospecting of novel biomass for carbonization and application of the same for effective adsorption. Available literature on Sterculia foetida is very limited and this work will serve to create database on the amenability of processing.
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Yijiang Chen, Pei Zhang, Yong Zhou and Fuan Yan
The purpose of this work is to reveal the mechanism of WO42− on surface passivation for Q235 carbon steel in tungstate solution.
Abstract
Purpose
The purpose of this work is to reveal the mechanism of WO42− on surface passivation for Q235 carbon steel in tungstate solution.
Design/methodology/approach
In Na2WO4 solutions with the different concentrations of WO42−, the spontaneous passivation occurred on the surface of Q235 carbon steel when the concentration of WO42− was up to 0.13 mmol/L, which was attributed to the formations of the inner deposition film and the outer adsorption film on the Q235 surface under the action of WO42−.
Findings
The inner deposition film presented a two-layer microstructure: the inside layer was composed of Fe2O3 mainly, and the outside layer comprised Fe(OH)2•nH2O, Fe(OH)3•nH2O, FeWO4 and Fe2(WO4)3.
Originality/value
Both FeWO4 and Fe2(WO4)3 repaired the defects in the outside layer of the inner deposition film; however, the outer adsorption film played a more important role in the surface passivation than the inner deposition film did.
Yan Li, Zhi Xin Ba, Yong Liang Li, Yan Ge and Xi Chang Zhu
This paper aims to investigate the inhibition effect of sodium silicate (SS), sodium alginate (SA) and sodium tungstate (ST) on the corrosion behavior of AZ91D magnesium alloy in…
Abstract
Purpose
This paper aims to investigate the inhibition effect of sodium silicate (SS), sodium alginate (SA) and sodium tungstate (ST) on the corrosion behavior of AZ91D magnesium alloy in 3.5 per cent NaCl solution through polarization curve test at room temperature, electrochemical impedance spectroscopy and weight loss measurement.
Design/methodology/approach
The influence of SA concentration on the inhibition efficiency of the corrosion inhibitor was mainly analyzed. The corrosion morphology and inhibition mechanism of the samples were also analyzed with scanning electron microscopy and energy-dispersive spectroscopy.
Findings
The results show that with the increase of SA concentration, the corrosion inhibition first increases and then decreases. When SA concentration is 0.03 mol/L, the inhibition efficiency is the highest, reaching 98 per cent. The adsorption film formed by SA and other deposition films produce a synergistic effect on the improvement of corrosion resistance of AZ91D magnesium alloy.
Originality/value
The adsorption film formed by SA with other deposition films produces a synergistic effect on the improvement of corrosion resistance of AZ91D magnesium alloy. With the increase of SA concentration, the corrosion inhibition first increases and then decreases. When the concentrations of SA, SS and ST are 0.03 mol/L, 0.015 mol/L and 0.02 mol/L, respectively, the inhibition efficiency of the inhibitor is the highest, reaching 98 per cent.
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Manish Agarwal, Anil Anirudhan and Sanjib Dutta
After completion of the case study, the students will be able to discuss how social entrepreneurs identify problems and convert them into opportunities, analyze the challenges…
Abstract
Learning outcomes
After completion of the case study, the students will be able to discuss how social entrepreneurs identify problems and convert them into opportunities, analyze the challenges faced by social entrepreneurs in setting up and growing a new venture and formulate an expansion strategy for a startup.
Case overview/synopsis
Over 2.6 billion people worldwide needed access to sanitation services, and most of them stayed in rural areas. Lack of access to sanitation had several negative consequences. In the Middle East North Africa (MENA) region, sanitation was one of the major challenges, with 66 million people still lacking basic sanitation facilities. Additionally, a very small proportion of the wastewater was properly treated. This lack of access to sanitation was a major barrier to economic development and poverty reduction. Out of the 17 most water-stressed countries in the world, 11 were in the MENA region. About 15 million people in rural Morocco did not have a proper and sustainable sanitation system. However, there was an enormous opportunity to use wastewater as a resource. The global market for wastewater treatment services was valued at US$53bn in 2021, and it was expected to grow to more than US$71bn by 2026. Two Moroccan scientists – Dr Salma Bougarrani and Dr Lahbib Latrach, who were born and brought up in Morocco and had seen the wastewater problem very closely, decided to help the people at the bottom of pyramid (BoP) after completing their PhD in environment and water treatment technologies and multisoil-layering technology. They founded GREEN WATECH, a social enterprise, in 2018, which provided a low-cost, efficient and practical solution for wastewater management in the rural areas of Morocco. GREEN WATECH won many awards and cash prizes for its product and business plan. The company had already reached five regions of Morocco and positively impacted the lives of thousands of Moroccans. The founders were planning to expand to areas in the rest of Morocco and other African and Middle East countries. GREEN WATECH had the potential to significantly impact the lives of people in rural areas and help improve wastewater management systems in developing countries through its patented technology. However, the founders faced several challenges in making their dream a reality. They needed a bigger team to expand to different locations and countries but were finding it difficult to get the right people. They also needed funds to expand their geographical reach but found it tough to get investors as they were still unable to break even. It remained to be seen how the founders of GREEN WATECH would achieve their expansion goals and help people at the BoP in other developing countries.
Complexity academic level
This case study is suited to the Master of Business Administration/Master of Science and executive program.
Supplementary materials
Teaching notes are available for educators only.
Subject code
CSS 3: Entrepreneurship.
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M.R. Noor El-Din, Marwa R. Mishrif, Satish V. Kailas, Suvin P.S. and Jagadeesh K. Mannekote
This paper aims to formulate a new metal working fluid (MWF) composition including some eco-friendly emulsifiers, corrosion inhibitor, biocide, and non- edible vegetable oil…
Abstract
Purpose
This paper aims to formulate a new metal working fluid (MWF) composition including some eco-friendly emulsifiers, corrosion inhibitor, biocide, and non- edible vegetable oil (castor oil) as the base oil. To achieve this aim, five MWFs with different hydrophilic–lipophilic balance (HLB) value as 10, 9.5, 9, 8.5 and 8 were prepared to identify the optimum HLB value that gives a highly stable oil-in-water emulsion. The performance of castor oil based MWF was evaluated using tool chip tribometer and drill dynamometer. The surface morphology of steel disc and friction pin was performed using scanning electron microscope (SEM) and 3D profilometer. The results revealed that the use of the prepared cutting fluid (E1) caused the cutting force to decrease from 500 N for dry high-speed steel sample to 280N, while the same value for a commercial cutting fluid (COM) was recorded as 340 N at drilling speed and cutting feed force as 1120 rpm and 4 mm/min., respectively.
Design/methodology/approach
A castor oil-based metalworking fluid was prepared using nonionic surfactants. The composition of the metalworking fluid was further optimized by adding performance-enhancing additives. The performance of castor oil based MWF was analyzed using Tool chip tribometer and Drill dynamometer. The surface morphology of steel ball and a disc was done using 3D profilometer and SEM.
Findings
Studies revealed that castor oil-based MWF having Monoethanolamine (MEA) as corrosion inhibitor was found to be highly stable. The drilling dynamometer and tool chip tribometer studies showed that castor oil-based MWF performance was comparable to that of commercial MWF.
Research limitations/implications
This study aims to explore the performance of the castor oil based metalworking fluid (MWF) using tool chip tribometer and drill dynamometer.
Practical implications
The conventional MWFs are petroleum derives and are unsustainable. Use of non-edible plant-based oils for preparing the MWF will not only be conserved environment but also add value addition to agricultural crops.
Social implications
The social Implications is aiming to decrease the environmental impact that results from the using of mineral cutting fluids.
Originality/value
The originality of this work is to replace the mineral oil and synthetic oil based cutting fluids with more eco-friendly alternatives one. In addition, the investigation will focus on developing functional additives required for cutting fluids which are environmentally benign.
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Lamiaa Kamal El-Gabry, Mohamed Fathy Nasr and Amira Adel Abou El-Kheir
This work aims to increase the dyeability of nylon 6 with basic dyeing through the treatment of the fibre with available and cheap nanomaterials, namely; nano bentonite using an…
Abstract
Purpose
This work aims to increase the dyeability of nylon 6 with basic dyeing through the treatment of the fibre with available and cheap nanomaterials, namely; nano bentonite using an economic and simple method.
Design/methodology/approach
Different amounts of nano clay, namely, nano bentonite were dispersed in distilled water using an ultrasonic homogenizer for 1 h. Nylon fabrics were treated with different concentrations of dispersed nano bentonite (1%, 2%, 3%, 4%, 5% wt/v). After half an hour, the samples were padded using SVETEMA laboratory padding system. The padding pressure was adjusted at 3 bar to allow a pickup of 100%. The padded samples were dried at 80°C for 5 min and cured at 160°C for 3 min using ROACHES laboratory thermos-fixation. The cured samples were then washed with running water and left to dry at room temperature.
Findings
The obtained results indicated that the modification of polyamide 6 fibres with nano bentonite had a great impact on their dyeing properties. The obtained shades, absorption behaviour and fastness properties were significantly enhanced. Based on these results, it was concluded that polyamide fabrics could be successfully dyed with basic dyes using economical dyeing conditions.
Originality/value
This paper introduces a new method the loaded the nano-clay on the synthetic fibres, which are nylon 6 to enhance the dyeability with cationic dyes using the physical method without changing the structure of the fibres.