Search results

The purpose of this paper is to focus on the removal of hexavalent chromium [Cr(VI)] from wastewater by using activated carbon-supported Fe catalysts derived from walnut shell prepared using a wetness impregnation process. The different conditions of preparation such as impregnation rate and calcination conditions (temperature and time) were optimized to determine their effects on the catalyst’s characteristics.

The catalyst samples were characterized using thermogravimetric analysis, scanning electron microscopy and Fourier transform infrared spectroscopy. The adsorption of Cr(VI) by using using activated carbon supported Fe catalysts derived from walnut shell as an adsorbent and catalyst was investigated under different adsorption conditions. The parameters studied were contact time, adsorbent dose, solution pH and initial concentrations.

Results showed that higher adsorption capacity and rapid kinetics were obtained when the activated walnut shell was impregnated with Fe at 5 per cent and calcined under N₂ flow at 400°C for 2 h. The adsorption isotherms data were analyzed with Langmuir and Freundlich models. The better fit is obtained with the Langmuir model with a maximum adsorption capacity of 29.67 mg/g for Cr(VI) on Fe5-AWS at pH 2.0.

A comparison of two kinetic models shows that the adsorption isotherms system is better described by the pseudo-first-order kinetic model.

This paper aims to investigation of processes for Pb²⁺ elimination from water/wastewater as a significant public health issue in many parts of world. The removal of Pb²⁺ ions by various nanocomposites has been explained from water/wastewaters. ZnO-based nanocomposites, as eco-friendly nanoparticles with unique physicochemical properties, have received increased attention to remove Pb²⁺ ions from water/wastewaters.

In this review, different ZnO-based nanocomposites were reviewed for their application in the removal of Pb²⁺ ions from the aqueous solution, typically for wastewater treatment using methodology, such as adsorption. This review focused on the ZnO-based nanocomposites for removing Pb²⁺ ions from water and wastewaters systems.

The ZnO-based nanocomposite was prepared by different methods, such as electrospinning, hydrothermal/alkali hydrothermal, direct precipitation and polymerization. Depending on the preparation method, various types of ZnO-based nanocomposites like ZnO-metal (Cu/ZnO, ZnO/ZnS, ZnO/Fe), ZnO-nonmetal (PVA/ZnO, Talc/ZnO) and ZnO-metal/nonmetal (ZnO/Na-Y zeolite) were obtained with different morphologies. The effects of operational parameters and adsorption mechanisms were discussed in the review.

The findings may be greatly useful in the application of the ZnO-based nanocomposite in the fields of organic and inorganic pollutants adsorption.

The present study is novel, because it investigated the morphological and structural properties of the synthesized ZnO-based nanocomposite using different methods and studied the capability of green-synthesized ZnO-based nanocomposite to remove Pb²⁺ ions as water contaminants.

The current review can be used for the development of environmental pollution control measures.

This paper reviews the rapidly developing field of nanocomposite technology.

The critical dimension and the one that can unify knowledge through systemic interrelationships, is unification of the purely a priori with the purely a posteriori parts of total reality into a congruous whole. This is a circular cause and effect interrelationship between premises. The emerging kind of world view may also be substantively called the epistemic‐ontic circular causation and continuity model of unified reality. The essence of this order is to ground philosophy of science in both the natural and social sciences, in a perpetually interactive and integrative mould of deriving, evolving and enhancing or revising change. Knowledge is then defined as the output of every such interaction. Interaction arises first from purely epistemological roots to form ontological reality. This is the passage from the a priori to the a posteriori realms in the traditions of Kant and Heidegger. Conversely, the passage from the a posteriori to a priori reality is the approach to knowledge in the natural sciences proferred by Cartesian meditations, David Hume, A.N. Whitehead and Bertrand Russell, as examples. Yet the continuity and renewal of knowledge by interaction and integration of these two premises are not rooted in the philosophy of western science. Husserl tried for it through his critique of western civilization and philosophical methods in the Crisis of Western Civilization. The unified field theory of Relativity‐Quantum physics is being tried for. A theory of everything has been imagined. Yet after all is done, scientific research program remains in a limbo. Unification of knowledge appears to be methodologically impossible in occidental philosophy of science.