Removal of Cr(VI) from Wastewater Using Acrylonitrile Grafted Cellulose Extracted from Sugarcane Bagasse.

A highly efficient low-cost adsorbent was prepared using raw and chemically modified cellulose isolated from sugarcane bagasse for decontamination of Cr(VI) from wastewater. First, cellulose pulp was isolated from sugarcane bagasse by subjecting it to acid hydrolysis, alkaline hydrolysis and bleaching with sodium chlorate (NaClO3). Then, the bleached cellulose pulp was chemically modified with acrylonitrile monomer in the presence Fenton's reagent (Fe+2/H2O2) to carry out grafting of acrylonitrile onto cellulose by atom transfer radical polymerization. The developed adsorbent (acrylonitrile grafted cellulose) was analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Both raw cellulose and acrylonitrile grafted cellulose were used for chromium removal from wastewater. The effects of metal ion concentration, pH, adsorbent dose and time were studied, and their values were optimized. The optimum conditions for the adsorption of Cr(VI) onto raw and chemically modified cellulose were: metal ion concentration: 50 ppm, adsorbent dose: 1 g, pH: 6, and time: 60 min. The maximum efficiencies of 73% and 94% and adsorption capacities of 125.95 mg/g and 267.93 mg/g were achieved for raw and acrylonitrile grafted cellulose, respectively. High removal efficiency was achieved, owing to high surface area of 79.92 m2/g and functional active binding cites on grafted cellulose. Isotherm and kinetics studies show that the experimental data were fully fitted by the Freundlich isotherm model and pseudo first-order model. The adsorbent (acrylonitrile grafted cellulose) was regenerated using three different types of regenerating reagents and reused thirty times, and there was negligible decrease (19%) in removal efficiency after using it for 30 times. Hence, it is anticipated that acrylonitrile could be utilized as potential candidate material for commercial scale Cr(VI) removal from wastewater.

An integrated approach towards marble waste management: GIS, SFA, and recycling options.

Marble units generate an enormous amount of non-biodegradable waste during the processing operations and are considered one of the environmentally unfriendly industrial sectors. This sector has become a global nuisance due to its multi-dimensional damaging nature. Therefore, a multidimensional approach is needed to geographically describe the pollution sources, their waste load, collection mechanism, and their proper disposal or reuse. This article highlights an integrated approach to sorting out the multidimensional issues associated with the marble sector. More than 150 marble processing units (MPUs) are scattered in the study area pouring waste into the environment in the form of slurry. The produced waste roots environmental issues both for fauna and flora of the terrestrial and aquatic segments of the environment. A geospatial-based attempt has been made through geographic information system (GIS) for the identification and description of the pollution sources, MPUs, in the study area. The quantitative assessment has been made through substance flow analysis (SFA) by taking raw marble as the input source and marble product as output. Furthermore, material characterization has been carried out to confirm the chemical composition of the slurry waste for its potential use. Results confirmed that a major part (> 90%) of marble powder is calcium carbonate (CaCO3) which has so many potential uses as raw material. The integrated approach of GIS, SFA, and chemical characterization set forth a model that satisfies multi-dimensional queries regarding pollution sources, pollution load, and sustainable solutions to the problem. The output integrated model provides a digital environmental baseline for the monitoring of MPUs, the amount of waste generated by these MPUs, and its potential reuse options. The proposed model can be utilized worldwide as a decision support tool due to its optimum results.

Marble waste site suitability assessment using the GIS-based AHP model.

Site suitability with regards to environmental protection, public concerns, and the legitimate prerequisite is a basic issue that has been tended to in this study. By and large, marble waste is being unloaded on accessible open spaces or released in water to the close by waterways in the territory, Mohmand marble zone (Shabqadar), Khyber Pakhtunkhwa, Pakistan. Suitability assessment for marble waste collection and disposal was carried out through the integrated approach of analytical hierarchy process (AHP) and geographic information system (GIS) to limit the ecological dangers, public, and government concerns related to marble waste. The available land use was ordered into three main land use classes followed by six sub-classes including water bodies and agriculture (environmental), settlement and social site (social), and marble units and roads (economic). These sub-classes in the investigation region were organized through pairwise correlation and weighted sum analysis, AHP procedure. The AHP results were interpreted through GIS tools of digitization, buffering, and overlay in ArcMap, ArcGIS. The integrated AHP and GIS outcomes were consolidated to get the optimum results of the study, marble waste collection, and disposal options. It was concluded that priority should be given to water bodies followed by agricultural land while protecting the available land use classes from marble waste hazards. The percent priority values calculated are 32.33%, 30.50%, 12.16%, 10.66%, 8.50%, and 6% for water bodies, agricultural land, settlements, marble processing units, roads, and cultural sites respectively. The sequence of priority of the land use values are waterbodies > agriculture > settlement > marble industries > road > cultural site. The proposed integrated model is helpful in site suitability for waste management by the authorities and decision-makers associated with waste management.