Comparison of non-catalytic and catalytic ozonation processes of three different aqueous single dye solutions with respect to powder copper sulfide catalyst

Treatment of textile wastewaters containing dyes has not been very successful by conventional methods such as biological treatment. In order to overcome this problem, ozonation based on the oxidation of organic pollutants has been studied by researchers. Catalytic ozonation and advanced oxidation processes (ACPs) are used in order to increase the efficiency of sole ozonation further. In this work, catalytic ozonation in the presence of copper sulfide (CuS) powder as a catalyst was investigated in the treatment of aqueous single dye solutions, namely solutions of Acid Red-151 (AR-151), Remazol Brilliant Blue-R (RBBR) and Reactive Black-5 (RB-5). In the catalytic ozonation experiments, the effects of important ozonation parameters such as solution pH, ozone and catalyst dosages and the initial concentration of each dye on reaction kinetics and mechanism were studied

Crosslinked polyDADMAC gels as highly selective and reusable arsenate binding materials

High porosity cationic hydrogels synthesized via crosslinking co-polymerization of diallyldimethylammonium chloride (DADMAC) with N,N'-tetraallylpiperaziniumdichloride (TAP) showed high affinity towards arsenate anions over a wide pH range within notably short periods. Batch tests indicated that poly(DADMAC) hydrogels removed 99% of the arsenate anions from aqueous solutions at pH 6-10 and exhibited a maximum arsenic removal capacity of 0.12 g arsenic per gram of hydrogel. DADMAC hydrogels performed well at various pH levels after a short contact time (i.e., 10 min). Evidence of the ion exchange mechanism was based on experiments with solutions containing competing chloride and sulfate ions. An "intra-particle diffusion model" was proposed for the kinetics of arsenic removal. This gel was determined to be a good candidate for use in practice due to its easy regeneration either by treating with a 8.24 g/L of NaCl solution or by reducing the pH of the medium to below 1.0