The development of magnetic biochar from biomass and the prospect of developing magnetic nanomaterials have attracted many researchers worldwide. The conversion of this biomass into something more prospective has reduced the waste management issue without any hassle. Magnetic biochar which is derived from various types of biomass exhibits a good magnetic property with high surface area and significant morphology through various production methods. These magnetic biochar showed a remarkable application as an adsorbent for various wastewater treatments and were cooperated in certain selected polymer composites for application in supercapacitor. This study provides an extensive summary of various production methods of magnetic biochar along with its application in wastewater treatment and selected polymer cooperation.

Synthesis of magnetic biochar from agricultural waste biomass to enhancing route for waste water and polymer application: a review.

The pseudo-second-order (PSO) kinetic model has become among the most popular ways to fit rate data for adsorption of metal ions, dyes, and other compounds from aqueous solution onto cellulose-based materials. This review first considers published evidence regarding the validity of the mechanistic assumptions underlying application of the PSO model to adsorption kinetics. A literal interpretation of the model requires an assumption that different adsorption sites on a solid substrate randomly collide with each other during a rate-limiting mechanistic step. Because of problems revealed by the literature regarding the usual assumptions associated with the PSO model, this review also considers how else to account for good fits of adsorption data to the PSO model. Studies have shown that adsorption behavior that fits the PSO model well often can be explained by diffusion-based mechanisms. Hypothetical data generated using the assumption of pseudo-first-order rate behavior has been shown to fit the PSO model very well. In light of published evidence, adsorption kinetics of cellulosic materials is expected to mainly depend on diffusion-limited processes, as affected by heterogeneous distributions of pore sizes and continual partitioning of solute species between a dissolved state and a fixed state of adsorption.

/pdf/implications-of-apparent-pseudo-second-order-adsorption-2uofk89b31.pdf

Implications of Apparent Pseudo-Second-Order Adsorption Kinetics onto Cellulosic Materials: A Review

Layered titanates (Na2Ti3O7·nH2O) with exchangeable sodium cations located in the interlayer have been synthesized by simple hydrothermal treatment of Ti precursor in concentrated NaOH solutions. By proper control of the synthesis conditions, different morphologies of nanofibers and nanosheets are obtained. The metastable layered structure of the titanates collapses during the ion exchange, resulting in irreversible ion exchange. Target cations (eg., Ag + , Cu 2+ , Pb 2+ and Eu 3+ ) are completely concentrated from water and then tightly immobilized in the interlayer which is of great significance for the removal and subsequent safe disposal of hazardous metal cations. The ion exchange of the nanosheets is much more efficient than that of the nanofibers and other inorganic ion exchangers due to the larger surface area, less stable layered structure and larger amount of interlayer water of the nanosheets. The ion exchange of the titanates is also very selective. Valence, hardness, and radius of cations are main factors affecting the selectivity. Cations trapped in the interlayer are released by an acid-induced phase transformation of the titanate nanosheets to rutile. Then the rutile can be used as a new Ti precursor to synthesize the titanate nanostructures, resulting in a full cycle of material use. The nanosheets may find applications in the decon tamination and safe disposal of radioactive and heavy metal cations and also in the collection of valuable cations from water.

Highly Efficient, Irreversible and Selective Ion Exchange Property of Layered Titanate Nanostructures

Removal of natural organic matter (NOM) from water by ion exchange - A review.

Brine is a saline wastewater generated from several industries (e.g., desalination, energy and oil production) and its disposal can have adverse environmental impacts. To address this issue, brine treatment seems to be a promising option to eliminate the wastewater discharge, while also recovering extra freshwater and valuable materials such as salts. This can be achieved through minimal liquid discharge (MLD) and zero liquid discharge (ZLD) strategies. In this work, MLD and ZLD frameworks are analyzed and evaluated under 9 criteria (framework stages, technologies, freshwater recovery target, feed brine salinity, energy consumption of each technology, GHGs emissions, cost impact, resource recovery and social impact). Moreover, a case-study is presented under two different scenarios, Scenario 1 (MLD system) and Scenario 2 (ZLD system). Results showed that the energy consumption of the ZLD system is 10.43 kW h/m3 which is 1.93 times higher than the energy consumption of the MLD system (5.4 kW h/m3). The total freshwater recovery of the MLD system is 84.6 %, whereas the total freshwater recovery of the ZLD system is 98.15 %. Overall, the results suggest that the MLD and ZLD strategies can be valuable strategies for wastewater utilization, reuse, and resource recovery.

Minimal Liquid Discharge (MLD) and Zero Liquid Discharge (ZLD) strategies for wastewater management and resource recovery – Analysis, challenges and prospects

Heavy Metals contained in industrial waste streams are removed therefrom by flocculation using a source of ferric ions and an alkaline material at a basic pH. Both the flocculated heavy metals and the coagulant chemicals are recovered by acidifying the floc to a pH of between 3.2 and 3.7. This liberates the heavy metals back into solution but does not destroy the floc particles. After separation and removal of the concentrated heavy metal solution, the floc is further acidified to completely dissolve it. This dissolved ferric ion containing solution may then be reused to treat succeeding portions of heavy metal containing waste streams. The concentrated heavy metals solution may also be recycled or the metals contained therein recovered for reuse or disposed of in an acceptable manner.

Method of removing heavy metals from industrial waste streams

Introduction and Historical Perspective Chapter 1. Basic Concepts from General Chemistry and Fundamental Hydraulics Basic Chemistry Review Terminology Nomenclature Grades of Chemicals Dilutions Lab Analysis pH Acidity Alkalinity Basic Hydraulics Review Terminology Turbine Equations References Suggested Reading Chapter 2. Cold Process Lime-Soda Softening Hardness Softening Basic Principles Bar Charts Example Problem and Solution Process Equations Example Problem and Solution References Chapter 3. Fundamental Principles and Concepts of Ion Exchange Introduction Basics Batch/Columnar Operation Basic Columnar Operation Natural Ion Exchangers Synthetic Ion Exchangers Synthetic Cation Exchangers Synthetic Anion Exchangers Selectivity Order of Selectivity Selectivity Determination Resin Structure Capacity Particle Size Process Description Backwash Regeneration Rinse Service Example Problems and Solutions References Chapter 4. Laboratory-Scale Testing of Ion Exchange Introduction Columns Reservoirs Column Operations Flow Rates Resin Conditioning Cautions Charging Backwashing Regeneration References Chapter 5. Ion Exchange Applications and Design The Basic Flow Sheets Demineralization Flow Scheme Configurations Silica Removal Degasification Heavy Raw Water Composition Plant Size Cost of Regenerants Effluent Water Composition Flow Schemes Alkalinity Reduction Flow Schemes Design Example Problem and Solution Industrial Flow Schemes Nickel Removal Chromium Removal Ion Exchange as a Chemical Feeder References Appendix: Tables and Conversion Factors Index

Environmental Ion Exchange: Principles and Design

A method and apparatus for water softening using less than approximately 20 micron diameter fine mesh magnetized ion exchange particles in columnar operation. The particles are formed by encapsulating a core of magnetic material in ion exchange resin. The particles are magnetized and disposed in a column where they attach to magnetic mesh retention means such as stainless steel wool. The design of the column permits use of the fine mesh ion exchange particles and their properties of rapid exchange rates and efficient utilization of resin capacity while avoiding prior art problems of plugging, fouling, and excessive pressure drop.

Columnar fine mesh magnetized ion exchange resin system

An exfoliated vermiculite cation-exchange column is used to remove multivalent heavy metals (copper, zinc, nickel, chromium, etc.) from metal plating wastes. The exfoliated vermiculite may be either chemically or relatively low-temperature thermally expanded vermiculite ore. It preferably has a cation exchange capacity of over 80 meq/100g. Exfoliated vermiculite particle sizes of less than approximately 10 mesh are preferred as the column packing. The ion-depleted vermiculite from the exchange column after use can be further expanded thermally and used as a lightweight filling material.

Method for removing of multivalent heavy metals from metal plating waste effluents

A disinfectant composition for use in water conditioning systems in produced by dry mixing sodium chloride and a chlorinated cyanurate and pelletizing the mixture. The composition releases free chlorine to disinfect brine solutions used in regenerating domestic water conditioning ion exchange columns and prevents bacterial contamination of such columns.

James E. Etzel

Papers

Method of removing heavy metals from industrial waste streams

Environmental Ion Exchange: Principles and Design

Columnar fine mesh magnetized ion exchange resin system

Method for removing of multivalent heavy metals from metal plating waste effluents

Disinfectant chlorinated cyanurate containing compositions and method of use