Kisan Koirala, Jose H. Santos, Ai Ling Tan, Mohammad A. Ali and Aminul H. Mirza
This paper aims to develop an inexpensive, portable, sensitive and environmentally friendly electrochemical sensor to quantify trace metals.
Abstract
Purpose
This paper aims to develop an inexpensive, portable, sensitive and environmentally friendly electrochemical sensor to quantify trace metals.
Design/methodology/approach
A sensor was constructed by modifying carbon paste electrode for the determination of lead, cadmium and zinc ions using square wave anodic stripping voltammetry (SWASV). The modified electrode was prepared by inserting homogeneous mixture of 2-hydroxy-acetophenonethiosemicarbazone, graphite powder and mineral oil. Various important parameters controlling the performance of the sensor were investigated and optimized. Electrochemical behavior of modified electrode was characterized by cyclic voltammetry.
Findings
Modified carbon pastes electrodes showed three distinct peaks at −0.50, −0.76 and −1.02 V vs silver/silver chloride corresponding to the oxidation of lead, cadmium and zinc ions at the electrode surface, respectively. The highest peak currents for all the metal ions under study were observed in the phosphate buffer solution at pH 1 with a deposition time of 70 s. The sensor exhibited linear behavior in the range of 0.25-12.5 μg mL-1 for lead and cadmium and 0.25-10.0 μg mL−1 for zinc. The limit of detection was calculated as 78.81, 96.17 and 91.88 ng mL−1 for Pb2+, Cd2+and Zn2+, respectively. The modified electrode exhibited good stability and repeatability.
Originality/value
A chemically modified electrode with Schiff base was applied to determine the content of cadmium, lead and zinc ions in aqueous solutions using SWASV.
Details
Keywords
Ivan Balogh, Mohit Srivastava and Ladislav Tyll
Businesses nowadays face unprecedented pressures from stakeholder groups to become more transparent by issuing comprehensive reports describing their environmental, social and…
Abstract
Purpose
Businesses nowadays face unprecedented pressures from stakeholder groups to become more transparent by issuing comprehensive reports describing their environmental, social and governance (ESG)-related activities, strategies and policies. This paper’s primary motivation is to understand which ESG disclosure factors are relevant for large Czech companies.
Design/methodology/approach
To achieve the above-stated goal, the total ESG disclosure index, consisting of three subindexes (ESG) was constructed and calculated for the 100 largest Czech companies. Furthermore, the relationships between firm-level factors and ESG disclosure indexes were estimated by using censored regression models.
Findings
This study found that revenue, number of employees and profitability positively influenced the total ESG disclosures. On the level of the three ESG components, this study found that revenue positively impacted environmental and governance disclosures while the number of employees positively affected social and governance disclosures. Moreover, profitability affected social and governance disclosures positively for large Czech companies. However, this study did not observe a significant relationship between board attributes and ESG disclosures.
Originality/value
This paper extends academic literature on ESG disclosures by verifying the significance of firm-level factors in the context of Czech business realities before the adoption and transposition of the Corporate Sustainability Reporting Directive. More specifically, this study has investigated the ESG reporting together and separately for ESG factors. This separation is vital as firms vary in reporting processes across these factors.
Details
Keywords
Sandeep Sathe, Shahbaz Dandin, Makrand Wagale and Pankaj R. Mali
This study aims to investigate and compare the influence of various fiber types (polypropylene, steel and glass) on the workability, mechanical properties, ductility, impact…
Abstract
Purpose
This study aims to investigate and compare the influence of various fiber types (polypropylene, steel and glass) on the workability, mechanical properties, ductility, impact resistance, durability and microscopic properties of geopolymer concrete (GPC) with conventional concrete (CC).
Design/methodology/approach
The CC and GPC of M40 grade were incorporated with an optimum 1% of fibers and superplasticizers were added in a ratio of 2% by weight of the geopolymer binder. The slump cone and compaction factor tests were performed to analyze the workability. To evaluate the mechanical performance of GPC, the compressive strength (CS), split tensile strength (STS), flexural strength (FS) and modulus of elasticity (MOE) tests were performed. A falling weight impact test was performed to determine the impact energy (IE) absorbed, the number of blows for initial cracking, the number of blows for complete failure and the ductility aspect.
Findings
Fibers and superplasticizers significantly improve GPC properties. The study found that fibers reduce the brittleness of concrete, improving the impact and mechanical strength compared to similar-grade CC. The steel fibers-reinforced GPC has a 15.42% higher CS than CC after three days, showing a faster CS gain. After 28 days, GPC and CC have MOE in the range of 23.9–25.5 GPa and 28.8–30.9 GPa, respectively. The ultimate IE of the GPC with fibers was found to be 5.43% to 21.17% higher than GPC without fibers.
Originality/value
The findings of the study can be used to explore different combinations of raw materials and mix designs to optimize the performance of GPC.