A critical review on textile wastewater treatments: Possible approaches.

Dyes are an important class of organic pollutants and are well known for their hazardous effects on aquatic life in general and human beings in particular. In order to reduce the negative effects of dye contaminated wastewater on humans and the environment, the wastewater must be treated carefully before discharge into main streams. Advances in science and technology have led to the evolution of several techniques for the removal of dyes from industrial and domestic effluents. In this review, the more recent methods for the removal of dyes from water and wastewater have been discussed. Wastewater treatment techniques such as adsorption, oxidation, flocculation–coagulation, membrane filtration and biological treatment have been highlighted. In addition, efforts were made to review all the available techniques and recently published studies from 2010–2014. Furthermore, the performance and special features of these technologies have been summarised. Advantages and limitations of each technique are also presented. A thorough literature survey revealed that chemical oxidation, adsorption, and biological treatments have been the most frequently investigated techniques for dye removal over the past few years.

https://pubs.rsc.org/en/content/articlepdf/2015/ra/c4ra16959j

Recent advances in new generation dye removal technologies: novel search for approaches to reprocess wastewater

The biosorption process has been established as characteristics of dead biomasses of both cellulosic and microbial origin to bind metal ion pollutants from aqueous suspension. The high effectiveness of this process even at low metal concentration, similarity to ion exchange treatment process, but cheaper and greener alternative to conventional techniques have resulted in a mature biosorption technology. Yet its adoption to large scale industrial wastewaters treatment has still been a distant reality. The purpose of this review is to make in-depth analyses of the various aspects of the biosorption technology, staring from the various biosorbents used till date and the various factors affecting the process. The design of better biosorbents for improving their physico-chemical features as well as enhancing their biosorption characteristics has been discussed. Better economic value of the biosorption technology is related to the repeated reuse of the biosorbent with minimum loss of efficiency. In this context desorption of the metal pollutants as well as regeneration of the biosorbent has been discussed in detail. Various inhibitions including the multi mechanistic role of the biosorption technology has been identified which have played a contributory role to its non-commercialization.

/pdf/bioadsorbents-for-remediation-of-heavy-metals-current-status-281t0rob6y.pdf

Bioadsorbents for remediation of heavy metals: Current status and their future prospects

https://cyberleninka.org/article/n/13265.pdf

Kinetics and equilibrium study for the adsorption of textile dyes on coconut shell activated carbon

Sorption is an effective, reliable, and environmentally friendly treatment process for the removal of phosphorus from wastewater sources which otherwise can cause eutrophication of receiving waters. Phosphorus in wastewater, if economically recovered, can partly overcome the future scarcity of phosphorus resulting from exhaustion of natural phosphate rock reserves. The authors present a comprehensive and critical review of the literature on the effectiveness of a number of sorbents, especially some novel ones that have recently emerged, in removing and recovering phosphate. Mechanisms and thermodynamics of sorption, as well as regeneration of sorbents for reuse using acids, bases, and salts, are critically examined.

/pdf/removal-and-recovery-of-phosphate-from-water-using-sorption-2b6ruloeuo.pdf

Removal and Recovery of Phosphate From Water Using Sorption

Adsorption of hexavalent chromium from aqueous solution by modified corn stalk: A fixed-bed column study

Emerging single atom catalysts (SACs), especially carbon-based SACs are appealing materials in environmental catalysis because of their ultrahigh performances, environmental friendliness, structural/chemical robustness, and the maximum utilization of active metal sites. The metal centres, carbon matrixes, and coordination characteristics collectively determine the electronic features of carbon-based SACs, and their behaviours in catalysing peroxide activation and efficiencies in advanced oxidation processes (AOPs). However, there is lack of a comprehensive and critical review reporting the successful marriage of carbon-based SACs in AOP-based remediation technologies. It is particularly necessary to systematically compare and reveal the catalytic sites and the associated mechanisms of carbon-based SACs in diverse AOP systems. In this review, we highlight the synthetic strategies, characterisation, and computation of carbon-based SACs, and for the first time, showcase their innovative applications in AOP technologies. We unveil the origins of versatile catalytic oxidation pathways in different AOP systems and the mechanisms of micropollutant degradation over carbon-based SACs, distinguished from the upsized counterparts (metals/oxides and carbon substrates). We also provide directions to the rational design of on-demand SACs for green chemistry and environmental sustainability. Also, we suggest a designated and integrated experimental/theoretical protocol for revealing the structure-catalysis relations of SACs in AOP applications, and propose the prospects for future opportunities and challenges.

Single-atom catalysis in advanced oxidation processes for environmental remediation.

An environmentally friendly, facile, and economical Fe/N co-doped carbonaceous material (Fe-N@C) was prepared by the in-situ pyrolysis of Fe/N rich Enteromorpha biomass for peroxymonosulfate activation and organic contaminants degradation. Results indicated that Enteromorpha-based catalysts prepared at high pyrolysis temperature displayed some highly graphitic nanosheets with rich nitrogen doped. The graphitic N derived from the intrinsic N in Enteromorpha showed the high correlation with the paracetamol (PCM) removal rate; this was confirmed by the Density Functional Theory (DFT) calculation, showing the high adsorption energy (ΔEads, −2.62 eV) of PMS molecular adsorbed onto the graphitic N area. A weak correlation between the PCM removal rate and adsorption capacity was also observed, revealing that the PCM catalytic reaction could be greatly accelerated after the pre-adsorption. It was interesting that the intrinsic Fe in Enteromorpha did not affect the PCM degradation, but PCM removal rate of acid treated Fe-N/C was improved as more active sites were formed after the Fe extraction by acid treatment. Both the radical pathways of O2 − and non-radical 1O2 generated in the Fe-N@C/PMS system were the primary mechanisms for the PCM degradation, which was consistent with the Fukui function values of f° and f- based on the DFT calculation. In addition, high stability of the carbon-based catalysts was observed after three runs and calcinating regeneration, which showed the promising applications for environmental remediation.

In-situ pyrolysis of Enteromorpha as carbocatalyst for catalytic removal of organic contaminants: Considering the intrinsic N/Fe in Enteromorpha and non-radical reaction

Using sulfate saturated bio-sorbent and cobalt(II) acetate as precursors, the homogeneous assembly of S-Co3O4 in nitrogen doped carbon martix (Co-S@NC) was obtained for the first time in an one-step pyrolysis. The reactions between peroxymonosulfate (PMS) and Co-S@NC for dinotefuran (DIN) decomposition were investigated. Co3O4 in Co@NC were primarily coordinated with the pyridinic N as catalytic sites. The adsorbed sulfate as S dopant was incorporated into the Co3O4 in carbon matrix due to the role of N as anchors, and the DIN decomposition of S-doped samples increased by 1.71 times as compared to the S-free sample (Co@NC). S incorporation can promote the formation of non-radical 1O2 and various radicals. In addition, DFT calculations indicated the enhanced electronic conductivity after S incorporation, which would facilitate the DIN decomposition in Co-S@NC/PMS system. This work enables the first insight into the role of adsorbed sulfate as effective S dopant for PMS activation.

Sulfate saturated biosorbent-derived Co-S@NC nanoarchitecture as an efficient catalyst for peroxymonosulfate activation

In this work, Co3O4 embedded nitrogen and sulfur co-doped porous char (Co3O4@NSC) was prepared after one-pot pyrolysis of N, S in-rich rubber powder (RP) to determine the binding relationship between Co nanoparticles and multiple doped heteroatoms. Results indicated pyridinic N was more easily to coordinate with Co3O4 nanoparticles, forming the pyridinic N-Co binding in Co3O4@NSC, which was the dominant catalytic sites for peroxymonosulfate (PMS) activation. Paracetamol (PCM) degradation was greatly facilitated with Cl- surrounding in Co3O4@NSC/PMS system due to the formation of large amounts of HOCl generated from the direct reaction of Cl- with PMS. The Cl↓ serving as a precursor of HOCl by reacting with PMS can be further strengthened by pyridinic N-Co bindings in Co3O4@NSC than the NSC. As a result, the pyridinic Co-N sites not only acted as the essential catalytic sites for PMS activation, but also accelerated the formation of HOCl at high level of Cl-.

Co3O4 anchored in N, S heteroatom co-doped porous carbons for degradation of organic contaminant: role of pyridinic N-Co binding and high tolerance of chloride

Xing Xu

Papers

Adsorption of hexavalent chromium from aqueous solution by modified corn stalk: A fixed-bed column study

Single-atom catalysis in advanced oxidation processes for environmental remediation.

In-situ pyrolysis of Enteromorpha as carbocatalyst for catalytic removal of organic contaminants: Considering the intrinsic N/Fe in Enteromorpha and non-radical reaction

Sulfate saturated biosorbent-derived Co-S@NC nanoarchitecture as an efficient catalyst for peroxymonosulfate activation

Co3O4 anchored in N, S heteroatom co-doped porous carbons for degradation of organic contaminant: role of pyridinic N-Co binding and high tolerance of chloride