2015) Removal and recovery of Ni(II) ions from synthetic wastewater using surface modified Strychnos potatorum seeds: experimental optimization and mechanism, Desalination and Water Treatment, 53:1, 171-182, A B S T R A C TStrychnos potatorum seeds have been utilized for the preparation of adsorbent, surface modified S. potatorum seeds (SMSP), by sulfuric acid treatment with 1:2 ratios of precursor to sulfuric acid. The adsorption process depends on the solution pH, adsorbent dose, contact time, initial Ni(II) ions concentration, and temperature. The adsorption kinetics of Ni(II) ions removal by the SMSP was relatively fast and it reaches the equilibrium at 30 min. The maximum removal of Ni(II) ions was observed at an optimum conditions: pH of 5.0, adsorbent dose of 5 g/L, contact time of 30 min, and at temperature of 30˚C for an initial Ni(II) ions concentration of 100 mg/L. In order to investigate the adsorption kinetics for the removal of Ni(II) ions by SMSP, pseudo-first-order and pseudo-secondorder kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits the experimental data better than the pseudo-first-order kinetic model with good coefficient of determination values. Adsorption mechanism was discussed with different models such as intraparticle diffusion, Boyd kinetic, and shrinking core models. It was observed that the adsorption process was controlled by both film and particle diffusion. The effective diffusivity and diffusivity values were estimated from the Boyd kinetic and shrinking core models, respectively. Adsorption isotherm data were tested with the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. It was observed that the Freundlich model fits the isotherm data better than other isotherm models with good coefficient of determination values. The Freundlich constant "n" was found to be of 3.888 g/L which indicates that the adsorption of Ni(II) ions onto the SMSP followed the physical process. The thermodynamic parameters such as change in free energy, enthalpy, and entropy were also calculated. It was found that the adsorption process was spontaneous and exothermic in nature.

Freshwater ecosystems are being contaminated by heavy metals pollution. The primary source of contamination is wastewater discharged from urban, industrial, and agricultural facilities. The contaminated water contains hazardous amounts of heavy metals mixed in the freshwater ecosystem, causing deleterious impacts on marine life and humans. This review paper highlights the contamination of the freshwater ecosystem of Pakistan with heavy metals. Heavy metals concentration in sediments, water, and fish were assessed in the food chain, and their relationship with sites and sources was explored. It was observed that heavy metals present in freshwater and sediments bio-accumulate into fish organs. It was also found that some parts of freshwaters like River Ravi, Chenab, Kabul, and Indus were highly contaminated, and they posed negative impacts on fish and human health. River Ravi, receiving a huge amount of industrial and sewage wastewater from urban centers and industries of Central Punjab, was highly contaminated compared to other Rivers of Pakistan. The ecosystem health of River Indus was the best among all the rivers of Pakistan due to the enormous volume of water flow and less number of industrial units along with it. Freshwater fish of River Indus, Chenab, and Jhelum are consumable for humans. The presence of heavy metals also causes social, environmental, and economic problems. Therefore, the wastewater should be treated before discharge into freshwater streams and rivers to lessen the harmful impacts of heavy metals on marine life and human beings.

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PurposeThis study aims to identify the barriers to building supply chain resilience and assess the contextual relationship between them in the Indian micro, small and medium enterprise (MSME) sector for the post COVID-19 era.Design/methodology/approachBarriers to supply chain resilience were extracted from the extant literature and were evaluated using the grey sets and Decision-Making Trial and Evaluation Laboratory (DEMATEL) approach from strategic, tactical and operational business perspectives. The responses from experts on the identified barriers were collected through a structured questionnaire. The prominence-net effect results obtained after the DEMATEL application helped identify the most prominent barriers, their net cause and effect, and their correlation with each other.FindingsA total of 16 barriers to resilience, identified from the literature, were considered for analysis. The findings of the study revealed that the lack of flexibility is the most critical causal barrier to building a resilient supply chain. Lack of planned resource management was also found to be an influential barrier. The study also identified the supply chain design, need for collaboration and technological capability as important factors for the MSME sector to focus on.Research limitations/implicationsThe study is limited to assessing barriers to the supply chain resilience of MSMEs in India. More extensive research may be needed to reveal the global trend.Practical implicationsThe study is significantly important for the MSMEs looking to establish resilient supply chains. Managers can use the findings to identify the weak links in the supply chain for strategic and tactical planning and can take corrective actions.Originality/valueThe study pinpoints the key linkages between barriers that impede MSMEs to make their supply chains resilient and robust to mitigate the impact of future disruptions and adversities. The work may be used by practitioners to further their attention on the significant challenges.