Über die Adsorption in Lösungen

Bioremediation of heavy metals using microalgae: Recent advances and mechanisms.

The concentration of chromium (VI) in the soil is an important environmental concern due to its mobility and acute toxicity. Due to its toxicity, removal of this species is very important. The mobility of Cr(VI) is highly governed by its adsorption onto the mineral surfaces. Manganese oxides are naturally-occurring scavengers and have a significant influence on the distribution, and transport of chromate species. Thus, to understand the fate of chromate species and its removal process, it is important to study chromium (VI) adsorption. In this study, birnessite (δ-MnO2), pyrolusite (β-MnO2), hausmannite (Mn3O4), manganite (γ-MnOOH), boehmite (γ-AlOOH), and Mn-Al binary oxide was used as adsorbents to adsorb Cr(VI) over a range of solution pH and initial Cr(VI) concentrations. A combined approach using the Langmuir and Freundlich models, proton stoichiometry and surface complexation model (SCM) have been used to describe the probable Cr(VI) adsorption process. Birnessite was the most potent adsorbent at low pH. The Langmuir model could describe the equilibrium isotherm data well, suggesting a uniform surface nature. Proton stoichiometry indicated that Cr(VI) adsorption involved more than one type of reaction. The findings confirm that Cr(VI) species bind to functional groups by the inner- and outer-sphere chromate complexes, with the extent of binding dependent on solution pH. The study presented herein can be applied to soils with a variety of surface properties, pH, and Cr (VI) concentrations. The study further advances our understanding of the interaction between Cr(VI) and minerals at the solid-water interface.

A mechanistic approach of chromium (VI) adsorption onto manganese oxides and boehmite

Effect of hexavalent chromium on the environment and removal techniques: A review

The dyeing wastewaters are composed of complex chemical compositions, which are toxic and cause biotic risks. For eco-friendly remediation of such toxicants, agro-based materials are used as biosorbent/adsorbent and co-substrate in both physiochemical and biological treatment processes. The present study comprehensively reviews the efficacy of agro-biomass/byproducts (belonging to plants, microbes and animals) either as biosorbents (raw biomass) or adsorbents (modified biomass) for direct removal of dyes and their role as co-substrate to stimulate the biodegradation/decolourization of dyes by bacteria and fungi. In physiochemical process, agro-based biosorbents/adsorbents with porous structures and cellulosic content (≥ 40%) could exhibit excellent potential for removal of both ionic and non-ionic dyes from aqueous medium. Advancement of chemically modified agro-wastes in the form of bio-composites, or doped with nano-materials are used to enhance the sorption of dyes from wastewater in column-flow mode. In biological processes, co-substrate such as jack-fruit-seed-powder, sago-waste, and molasses can act as ē-donor, nutritional supplement, and solid-phase substratum for bacteria in dye decolourization medium, which reduces the color and organic loading in bio-treated water. Such low-cost agro-based co-substrates could be used in bioreactors for biodegradation of dyes and coupled bio-energy production at industrial scale. However, it is required to investigate the potential of biosorbent for real-dyeing-wastewater treatment, comprehensive economic analysis of the agro-based bio-treatment process, a suitable solid-phase co-substrate for immobilization of microorganism to reduce sludge, and reusability of agro-wastes for effective treatment of wastewater.

The utilization of agro-biomass/byproducts for effective bio-removal of dyes from dyeing wastewater: A comprehensive review

Eco-friendly complementary biosorption process of methylene blue using micro-sized dried biosorbents of two macro-algal species (Ulva fasciata and Sargassum dentifolium): Full factorial design, equilibrium, and kinetic studies.

Hexavalent chromium [Cr (VI)] is known as the most toxic form of chromium compounds. It had many hazardous effects on the human health and the environment. Therefore, the objective of this study aimed to remove toxic Cr (VI) from an aqueous solution using pre-treated biomass of marine brown algae Sargassum dentifolium (grinded to micro-size scale). Optimization for Cr (VI) removal efficiency (CRE) was performed through One Factor at A time experiments (OFAT) to determine the low and the high level of each factor. Afterwards, a full factorial experimental design (Many interacted factors at a time) was applied in order to determine the optimum conditions that maximize the CRE. The results of the response optimizer model suggested that the highest removal efficiency of 99.68% can be achieved by applying 1.5 g/ 100 /ml of 0.3868 μm dried algae biomass to 100 ppm Cr-contaminated wastewater with a novel model [contact time flocculation state (CFTs)] for 1 h shaking continued to12 h static, at pH 7.0, and 50 °C. Linear Langmuir and Freundlich isotherm were displayed, and results stated that Langmuir isotherm more applicable to this process which suggested a monolayer adsorption nature of the biosorbent surface.

Adsorption studies of hexavalent chromium [Cr (VI)] on micro-scale biomass of Sargassum dentifolium, Seaweed

\n Hexavalent chromium Cr (VI) is a toxic heavy metal that discharged by many industries into the water streams. It is the most toxic form of chromium compound, which causes significant damage to receiving ecosystems. A microalgal species, Chlorella sp., was used as a biosorbent material to remove Cr (VI) from Cr-contaminated effluents. Furthermore, different variables: pH, temperature, contact time, Cr (VI) concentration and algal dose, were optimized in order to determine the optimum conditions that achieve the highest removal efficiency. The optimization process was achieved through two steps: one factor at a time (OFAT) experiments followed by 25 general full factorial. Moreover, molecular identification was performed using 18S rRNA in order to demonstrate the species of Chlorella, and it was identified as Chlorella sorokiniana. The highest chromium removal efficiency of 99.6793% was achieved at 100 ppm Cr (VI) after three days' contact time. Chlorophyll ‘a’ estimation as a growth indicator stated that Chlorella sorokiniana can tolerate 100 ppm Cr (VI) for three days' exposure. The results suggested that Chlorella sorokiniana is a good biosorbent material and it distinguished by its high ability to uptake Cr (VI) from solutions.

Absorption of hexavalent chromium by green micro algae Chlorella sorokiniana: live planktonic cells

Water contamination with colours and heavy metals from textile effluents has harmed the ecology and food chain, with mutagenic and carcinogenic effects on human health. As a result, removing these harmful chemicals is critical for the environment and human health. Various standard physicochemical and biological treatment technologies are used; however, there are still some difficulties. Adsorption is described as a highly successful technology for removing contaminants from textile-effluents wastewater compared to other methods. Several adsorbent materials, including nanomaterials, natural materials, and biological biomasses, are identified as effective adsorbents for textile effluents. Activated carbon preparation from these different adsorbents is an excellent pre-treatment to remove the adsorption capacity. Therefore, through this study various adsorbent types, especially activated carbon adsorbents will be discussed in addition to the factors affecting adsorption and models applied for optimising the adsorption process. 

Sh. Husien

Papers

Eco-friendly complementary biosorption process of methylene blue using micro-sized dried biosorbents of two macro-algal species (Ulva fasciata and Sargassum dentifolium): Full factorial design, equilibrium, and kinetic studies.

Adsorption studies of hexavalent chromium [Cr (VI)] on micro-scale biomass of Sargassum dentifolium, Seaweed

Absorption of hexavalent chromium by green micro algae Chlorella sorokiniana: live planktonic cells

Review of activated carbon adsorbent material for textile dyes removal: Preparation, and modelling

Potentials of algae-based activated carbon for the treatment of M.orange in wastewater