The terms 'antioxidant', 'oxidative stress' and 'oxidative damage' are widely used but rarely defined. This brief review attempts to define them and to examine the ways in which oxidative stress and oxidative damage can affect cell behaviour both in vivo and in cell culture, using cancer as an example.

Biochemistry of oxidative stress

Rapid industrialization, with economic prosperity set as the prime goal, has always created some secondary intolerable problems such as heavy metal contamination, wastewater that need remediation. Industrial wastewater is the major contributors to contamination of aquatic and terrestrial ecosystems with toxic heavy metals like arsenic, copper, chromium, cadmium, nickel, zinc, lead, and mercury whose hazardous bio-accumulative nature in biotic systems is attributed to their high solubility in the aquatic environments. There has, therefore, always been a need for the removal and/or recovery of these toxic, non-biodegradable, and persistent heavy metals from the industrial wastewater. For several decades, extensive investigations have been performed for easy, efficient, and economic removal of heavy metals with a varying degree of success. Chemical precipitation, adsorption, ion floatation, ion-exchange, coagulation/flocculation and electrochemical methods have been the most readily available conventional methods for the removal of these heavy metals. These methods however have posed some serious shortcomings such as high sludge production needing further treatment, low removal efficiency and high energy requirements. In the present years, newer more efficient, more economic and innovative technologies are being investigated. Recently photocatalysis, electrodialysis, hydrogels, membrane separation technique and introducing newer adsorbents have been developed for better adsorption. Hence in this paper, we have reviewed efforts and technological advances achieved so far in the pursuit of more efficient removal and recovery of heavy metals from industrial wastewaters and have evaluated their efficiency dependence on various parameters such as pH, temperature & initial dosing.

Technological trends in heavy metals removal from industrial wastewater: A review

Increasing amount of dyes in an ecosystem has propelled the search of various methods for dye removal. Amongst all the methods, adsorption occupies a prominent place in dye removal. Keeping this in mind, many adsorbents used for the removal of hazardous anionic azo dye Congo red (CR) from aqueous medium were reviewed by the authors. The main objectives behind this review article are to assemble the information on scattered adsorbents and enlighten the wide range of potentially effective adsorbents for CR removal. Thus, CR sorption by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites are surveyed and critically reviewed as well as their sorption capacities are also compared. This review also explores the grey areas of the adsorption performance of various adsorbents with reference to the effects of pH, contact time, initial dye concentration and adsorbent dosage. The equilibrium adsorption isotherm, kinetic and thermodynamic data of different adsorbents used for CR removal were also analysed. It is evident from a literature survey of more than 290 published papers that nanoparticle and nanocomposite adsorbents have demonstrated outstanding adsorption capabilities for CR. Graphical abstract ᅟ.

Adsorptive amputation of hazardous azo dye Congo red from wastewater: a critical review.

A comparative study about adsorption of natural palygorskite for methylene blue

Facile fabrication of hydroxyapatite-magnetite-bentonite composite for efficient adsorption of Pb(II), Cd(II), and crystal violet from aqueous solution

In the present work, the natural bentonite (NB) coated with synthesized Fe3O4 magnetite nanoparticles (CB) was firstly used as an adsorbent to sequester Cu(II) ions from the polluted solutions. The characterization study demonstrated a substantial improvement in several adsorptive parameters of NB after coating, like surface area, surface morphology and topography. From the analysis of the pore diameters, it was observed that the CB lies in the mesoporous materials category with diameters in the range of 2–50 nm. The removal efficiency was optimized as a function of the parameters: pH (3–6), CB dose (0.2–1 g/100 mL solution), and initial Cu(II) concentration (up to 200 mg/L). The results of the isotherm study revealed that the experimental data were fitted well onto the Langmuir model with the maximum amount of Cu(II) (46.948 mg/g) being adsorbed at pH 6, when the CB dose was 0.5 g and it shaking was done at 200 rpm speed, in a reaction time of 120 min. The kinetics of Cu(II) adsorption was chemosorption in nature as confirmed by the fitting with pseudo-second-order model. In addition, the results showed that the intraparticle diffusion was not the dominating mechanism. Comparison of the results of this study and those obtained from literature, it suggests that the CB exhibits an excellent sorption capacity for the Cu(II) removal and, therefore, can be used as a potential material in the adsorption systems for Cu(II) removal from rich wastewater.

Bentonite coated with magnetite Fe3O4 nanoparticles as a novel adsorbent for copper (II) ions removal from water/wastewater

Palygorskite clay has been investigated as low cost and ecofriendly adsorbent for the removal Basic Red 2(BR-2) from aqueous solution. Batch adsorption studies are carried out by observing effect of amount of adsorbent dose, contact time, pH, initial concentration of ( BR-2) and particle size of adsorbent on the adsorption capacity of the adsorbent were studied. Adsorption data fits the Langmuir and Freundlich adsorption isotherms. The calculated value of the Langmuir parameter for adsorption capacity of the dye over the adsorbent is 200mg/g adsorbent. This study shows that natural clay is successfully used to remove the Safranin-O dye from aqueous solutions as alternative to activated carbon.

https://archive.aessweb.com/index.php/5003/article/download/3546/5621

Adsorptive removal of dye from industrial effluents using natural Iraqi palygorskite clay as low-cost adsorbent.

In this study, natural Iraqi low- cost locally available clay (palygorskite) was studied for its potential use as an adsorbent for removal Congo red from aqueous solutions. Batch type experiments were conducted to study the effect of contact time, initial pH of the dye solution, initial dye concentration, adsorbent dosage, and particle size of adsorbent on adsorption capacity of Congo red. The adsorption occurred very fast initially and attains equilibrium within 60 min. When the effect of pH of solution dye on the yield adsorption has been carried in a range of 2-10, the adsorption obtained was nearly the same with very slightly effect of pH and it was reported that above 49.07 mg/g of Cong red by palygorskite clay occurred in the pH range 2 to 10. It was observed that the removal of Congo red increase with increasing initial dye concentration and adsorbent dose, but, adsorption capacity decrease with increasing adsorbent dose. The adsorption capacity increase with decreasing particle size of adsorbent. The equilibrium adsorption data were interpreted using Langmuir and Freundlich isotherm models. The obtained results revealed that the equilibrium data closely followed both models, but the Langmuir isotherm fitted the data better. The maximum adsorption capacity was found to be 99 mg/g at ambient temperature. Results indicate that Iraqi palygorskite clay could be employed as a low cost alternative to commercial activated carbon in wastewater treatment for the removal of colour and dyes.

/pdf/natural-iraqi-palygorskite-clay-as-low-cost-adsorbent-for-1m4u5h5lu3.pdf

Natural Iraqi palygorskite clay as low cost adsorbent for the treatment of dye containing industrial wastewater

An experimental investigation on the removal of direct red 28 dye from wastewater by using rice-husk carbon as low cost adsorbent was carried out in a laboratory. Batch type experiments were conducted to study the influence of different parameters such as adsorbent dose, contact time, pH, initial concentration of dye and particle size of adsorbent. The removal data have been analyzed using Langmuir and Freundlich isotherm models. The adsorption process was in conformity demonstrated use of rice husk to obtain low cost adsorbent for dye removal from aqueous solution . Keywords: adsorption,  low cost adsorbent, isotherm, dye .

/pdf/adsorption-studies-of-direct-red-28-dye-onto-activated-1agngms89x.pdf

Adsorption Studies of Direct Red 28 Dye onto Activated Carbon Prepared from Low Cost Material

The use of natural Iraqi porcellanite as a cheap, abundantly and ecofriendly adsorbent has been studied as an alternative substitution of activated carbon for the removal of dye from industrial wastewater. This material was successfully used to remove the basic red 2 dye from aqueous solution in a batch equilibrium adsorption technique. Various factors such as adsorbent dose, contact time, pH, initial dye concentration and particle size of adsorbent were taken into account at room temperature, and promising results were obtained. The well known Langmuir and Freundlich isotherm models were applied for the equilibrium adsorption data and the various isotherm parameters were evaluated. The monolayer saturation capacity for adsorption basic red 2 was found to be 66.22 mg/g adsorbent. Keywords: adsorption,  dye, natural material, isotherm

/pdf/removal-of-basic-red-2-from-industrial-effluents-using-5n621orhdc.pdf

Isra'a Sadi Samaka

Papers

Bentonite coated with magnetite Fe3O4 nanoparticles as a novel adsorbent for copper (II) ions removal from water/wastewater

Adsorptive removal of dye from industrial effluents using natural Iraqi palygorskite clay as low-cost adsorbent.

Natural Iraqi palygorskite clay as low cost adsorbent for the treatment of dye containing industrial wastewater

Adsorption Studies of Direct Red 28 Dye onto Activated Carbon Prepared from Low Cost Material

Removal of Basic Red 2 from Industrial Effluents Using Natural Iraqi Material